Food infections and poisoning. How do food poisoning differ from intestinal infections? Typhoid fever, paratyphoid A and B
CONTAMINATION WITH MICROORGANISMS AND THEIR METABOLITES
Lesson plan:
1. Foodborne infectious diseases.
2. Acute intestinal infections.
3. Zoonoses.
4. Food poisoning.
5. Mycotoxicosis.
6. Food poisoning of non-microbial origin.
7. Helminthic diseases.
An infectious disease is a process that occurs in the human body when pathogenic or pathogenic microorganisms penetrate it. The source of infection can be a sick person or animal, whose secretions (feces, urine, sputum, etc.) contain pathogenic microbes. In addition to the patient, the source of infection may be bacteria carrier, those. a person in whose body the causative agent of the disease resides, but the person himself remains practically healthy.
Pathogenic microorganisms enter the human body through the respiratory organs, mouth, skin and other routes, with soil, air, water, food, etc. From the moment the pathogen enters the human body until the manifestation of the disease, a certain period of time passes, called hidden, or incubation, period. During this period, microorganisms develop with the formation of toxic substances - toxins.
In the fight against pathogenic microbes, a person’s defenses act, which depend on his general state of health, therefore the manifestation and duration of the disease vary.
Sometimes people turn out to be immune to certain infectious diseases. This immunity is called immunity, which can be natural (congenital or acquired after an illness) or artificial (created by vaccinations). Artificial immunity can be active (occurs after the introduction of a vaccine) and passive (occurs after the administration of serums).
Diseases that arise in humans from pathogenic microbes that enter the body with food (or water) are called foodborne infectious diseases. These include acute intestinal infections(typhoid fever, dysentery, cholera, salmonellosis, etc.). Some diseases are transmitted to humans from sick animals (tuberculosis, brucellosis, foot and mouth disease, anthrax, etc.). They are called zoonoses.
Acute intestinal infections- these are the most common diseases, called “dirty hand diseases”, the pathogens of which can enter the human body through the mouth with food prepared in violation of sanitary and hygienic rules.
Pathogens of intestinal infections retain their viability in the external environment for a long time. Thus, the dysentery bacillus does not die on vegetables and fruits within 6...17 days, the typhoid bacillus on bread - within 30 days, and the cholera pathogen in water - up to 2 years.
Dysentery - a disease that occurs when a microbe - dysentery bacillus - enters the human intestines with food. The incubation period of the disease is 2 ... 5 days. Signs of the disease: weakness, fever, pain in the intestines, repeated loose stools, sometimes with blood and mucus. After recovery, a person may remain a carrier of the bacteria.
The causative agents of dysentery are immobile rods, aerobes, and do not form spores. The optimal temperature for their development is 37 °C, they die at a temperature of 60 °C within 10 ... 15 minutes, and tolerate cooling well.
Dysentery is transmitted through vegetables, fruits, water, dairy products consumed raw, and any prepared food contaminated during preparation and storage in unsanitary conditions.
Typhoid fever - a severe infectious disease caused by typhoid fever. The incubation period of the disease is 7 ... 23 days. Signs of the disease: acute intestinal dysfunction, severe weakness, rash, prolonged high fever (up to 40 ° C), delirium, headache, insomnia. After recovery, prolonged carriage of the bacteria is possible.
The causative agents of typhoid fever are motile rods that do not form spores, conditional anaerobes. The optimal temperature for their development is 37 °C. They are resistant to cold and drying, but die at 60°C after 15...20 minutes.
Human infection occurs through water and various food products (milk, dairy products, jellies, jellied dishes, sausages), which are prepared, stored, and transported in violation of sanitary and hygienic rules.
Cholera - a particularly dangerous infection that enters the human body through the mouth. The incubation period of the disease is 2 ... 6 days. Signs of the disease: sudden, uncontrollable diarrhea and vomiting, severely dehydrating the body, weakness, headache, dizziness, temperature 35 "C, convulsions. If emergency measures are not taken, death may occur. After recovery, bacterial carriage is possible.
The causative agent of the disease is Vibrio cholerae. The optimal temperature for its development is 37 "C. It tolerates low temperatures and freezing well, it dies when dried, from exposure to sunlight, when boiled for 1 minute, in an acidic environment - instantly.
The infection is transmitted through water and food prepared and stored in unsanitary conditions.
Epidemic hepatitis(infectious jaundice, Botkin's disease) is an acute infectious disease with predominantly liver damage. The disease is named after S.P. Botkin, who established its infectious nature. The incubation period is from 14 days to 6 months. The disease begins gradually: weakness, loose stools, fever, then
the liver enlarges, dark urine is secreted, and yellowness of the skin and mucous membranes appears. The illness lasts 2...3 weeks, sometimes it lasts up to 2...3 months. More often it ends in recovery, but sometimes complications arise in the form of cholecystitis and cirrhosis of the liver.
The causative agent of the disease is a filterable virus, resistant to drying, freezing, and dies when boiled for 30 ... 40 minutes. The virus only affects humans. The patient has it in the blood and is excreted in urine and feces.
Infection occurs by consuming food and water contaminated with the virus, by violating personal hygiene rules (dirty hands, flies) or through blood.
Hepatitis B is especially dangerous for human health and life, the virus of which enters the body of a healthy person, in addition to the mentioned routes, and through sexual contact through contact with a sick person. Hepatitis B can be complicated by severe liver cirrhosis, which can be fatal.
Salmonellosis- a disease caused by Salmonella microbes occurs 3...5 hours after eating food contaminated with bacteria. In the intestines, Salmonella causes inflammation of the mucous membrane. When bacteria die, a toxin is released, which, together with living microbes, is absorbed into the blood. The patient experiences nausea, vomiting, abdominal pain, diarrhea, headache, dizziness, high temperature (38 ... 39 ° C). The disease lasts 2...7 days. The mortality rate for salmonellosis is 1%. After recovery, cases of bacterial carriage are possible.
Salmonella are short, mobile rods that do not form spores, conditional anaerobes, named after the scientist Salmon, who discovered them. Their development optimum is 37°C, they develop well at room temperature, are stable in the external environment, stop development at 4°C, and die at 70...75°C for 30 minutes.
The source of salmonella spread is animals: large and small cattle, pigs, horses, birds, especially waterfowl, dogs, rodents. With the feces of these animals, salmonella enters the soil and water.
There are various reasons why food products are contaminated with Salmonella. Catering establishments may receive products contaminated with salmonella (primary seeding). Such products include meat, poultry, eggs, milk, fish. The most common cause of salmonellosis is meat and meat products. Contamination of meat can occur during the life of the animal. When such animals are forced to be slaughtered, the meat is always contaminated with salmonella. Contamination of meat is possible both during slaughter and during cutting of carcasses through contamination with intestinal contents.
Birds, especially waterfowl (geese, ducks), become infected in the same way as livestock. Poultry eggs, especially goose and duck eggs, become infected during formation and laying, milk - during milking and processing. Fish become infected through bodies of water; Salmonella penetrates its muscle tissue from the intestines.
Salmonellosis can occur from secondary seeding food with salmonella in case of violation of sanitary rules for its preparation and storage. Secondary contamination of dishes prepared after heat treatment is most possible: jelly, jellied meat, minced meat for pancakes and pies, pates, salads, vinaigrettes. Violation of personal hygiene rules, flies, dirty tableware and kitchen utensils, especially cutting boards, also contribute to the occurrence of salmonellosis.
Measures to prevent acute intestinal infections in public catering establishments are as follows:
1. examination of cooks, confectioners and other catering workers for bacterial carriage at least once a year;
2. observance of personal hygiene rules by cooks, confectioners and other food service workers;
3. careful care of kitchen and tableware, equipment, compliance with the markings of cutting boards;
4. strict adherence to cleanliness in the workplace and workshop;
5. extermination of flies, cockroaches and rodents;
6. boiling water from open reservoirs when used; it for food and drink;
7. Thorough washing of vegetables, fruits, berries, especially those eaten raw;
8. use of meat with a mark indicating that it has passed veterinary and sanitary control;
9. quick preparation of chopped semi-finished products, including cutlet mass, thereby preventing the proliferation of salmonella;
10. strict adherence to the technology of processing and preparation of meat, fish, dairy dishes and egg dishes;
11. mandatory secondary heat treatment of perishable meat dishes (jelly, jellied meat, minced meat for pancakes, pates, boiled meat and poultry after cutting) during the cooking process;
12. protecting salads, vinaigrettes and other cold dishes from contamination by hands during preparation;
13. storage of prepared food for no more than the established period at a temperature of 2 - 6 °C or hot not lower than 65 °C; repeated heat treatment of long-stored food.
Zoonoses- infectious diseases characteristic of animals.
Brucellosis- a severe infectious disease accompanied by attacks of fever, swelling and pain in the joints and muscles. The incubation period is 4 ... 20 days. The duration of the disease is from several weeks to several months. The causative agent is Brucella - a small rod-shaped bacterium with an optimal development temperature of 37 ° C, which dies during heat treatment. Human infection occurs through
milk, dairy products (cheese, feta cheese, butter) and meat, in which Brucella survives from 8 to 60 days.
Tuberculosis- an infectious disease that most often affects the lungs and lymph nodes. Humans become infected from sick animals, birds and people. The causative agent of the disease is the tuberculosis bacillus, which is resistant to drying and freezing and persists on food products for up to 2 months. It dies when boiled for 10 minutes.
The tuberculosis bacillus enters the body of a healthy person with raw milk and dairy products, as well as with poorly cooked or fried meat obtained from animals with tuberculosis. Infection is transmitted from a sick person through airborne droplets or contact.
anthrax- a particularly dangerous acute infectious disease of animals and humans that affects the skin, lungs or intestines. With this disease, all functions of the body are disrupted, the temperature rises to 40 ° C, weakness of cardiac activity occurs, and in the intestinal form, vomiting and diarrhea appear. Fatalities are common.
The causative agent of anthrax is a bacillus whose spores are very resistant to environmental influences and chemicals. The infection is transmitted through the meat and milk of sick animals; in direct contact with them and animal products (wool, leather, etc.).
The main role in the prevention of this terrible disease belongs to strict veterinary control of animals. Meat from sick animals cannot be processed; sick animals are destroyed.
foot and mouth disease- a contagious disease of viral origin, transmitted to humans from sick animals through meat and milk. This disease manifests itself in the form of inflammation and ulceration of the oral mucosa.
The foot-and-mouth disease virus is not resistant to heat treatment and weak organic acids; it dies when meat is cooked.
Measures to prevent zoonotic diseases in public catering establishments are as follows:
1. Checking the presence of a mark on meat carcasses, indicating a veterinary and sanitary inspection of raw materials.
2. Thoroughly boiling and frying meat dishes.
3. Boiling milk, using curdled milk. Samokvass is used only for preparing dough, and unpasteurized cottage cheese is used for preparing dishes that are subject to heat treatment.
Food poisoning- acute diseases that arise from eating food containing substances of microbial and non-microbial nature that are toxic to the body. Unlike intestinal infections, food poisoning occurs quickly in people and lasts several days, but in some cases it becomes very severe and can be fatal. Children, elderly people and people suffering from gastrointestinal diseases are especially sensitive to food poisoning.
Most poisonings have similar symptoms of the disease: abdominal pain, nausea, vomiting, fever, diarrhea, dizziness. Such patients urgently need to call a doctor and provide first aid: rinse the stomach with 3 ... 5 glasses of clean water or a weak solution of potassium permanganate, or a solution of soda and induce artificial vomiting.
Food poisoning, depending on the cause of the disease, can be of microbial (bacterial and mycotoxicosis) and non-microbial origin (Fig. 3.1).
Food poisoning of bacterial origin arise from eating food containing live pathogenic microbes or their poisons. Bacterial poisoning accounts for up to 90% of all food poisoning cases. They mainly occur in the summer, since the warm season promotes the proliferation of microbes in food.
Poisoning caused by living bacteria that enter the body with food is called food poisoning. toxic infections. This group of poisonings includes poisoning by opportunistic microbes. The peculiarity of these diseases is that the formation of poison (toxin) occurs in the human body, where microbes enter along with food.
Poisoning caused by poisons accumulated in food during the life of bacteria is called bacterial toxicoses. These include botulism and staphylococcal poisoning.
Poisoning by opportunistic microbes arise from the entry into the human body of a large number of E. coli or microbes - Proteus. Poisoning occurs like salmonella infections, but is less severe. Escherichia coli and Proteus live in the gastrointestinal tract of humans and animals and are widespread in nature. Food poisoning occurs only when food is heavily contaminated with these microbes. When food is slightly contaminated, poisoning does not occur, which is why these microbes are called opportunistic (opportunistic).
E. coli gets into food products when personal hygiene rules are violated, especially from the cook’s dirty hands, when he violates sanitary rules for preparing and storing food, or when workplaces, workshops, and kitchen equipment are kept unsanitary.
The number of E. coli found during a sanitary examination of equipment, utensils, utensils, cooks’, confectioners’ hands and food serves as an indicator of the sanitary condition of a catering establishment.
To assess the sanitary condition of food products and water in them, the coli-titer is determined, i.e. the smallest amount of test material containing 1 E. coli. The lower the titer, the higher the contamination of the product with E. coli, the worse the sanitary condition of the product, the more reason to fear that it may contain pathogenic microbes. For drinking water, milk and some meat products, coli titer limits are specified in the standards.
Measures to prevent toxic infections caused by E. coli and Proteus boil down to the following:
1. eliminating the causes of food contamination by microbes;
2. preventing the proliferation of microbes;
3. thorough heat treatment of food products;
4. proper food storage.
Botulism- food poisoning containing a potent poison (toxin) of the botulinus microbe. Poisoning occurs within 24 hours after ingesting contaminated food.
The main signs of the disease are: double vision, decreased clarity of vision (feeling of fog, grids before the eyes), headache, unsteady gait. Then loss of voice, paralysis of the eyelids, involuntary movement of the eyeballs, tension of the masticatory muscles, paralysis of the soft palate, and difficulty swallowing may occur. All these signs are the result of brain poisoning. Without timely treatment, death from respiratory distress may occur. In the absence of treatment with a special serum, the fatal outcome of the disease reaches 70%.
Botulinus is a spore-bearing long rod (bacillus), mobile, anaerobic, unstable to heat, dies at 80 ° C for 15 minutes. Under unfavorable conditions, botulinus forms very persistent spores that can withstand heating up to 100°C for 5 hours, delay their development in an acidic environment, and die at 120°C for 20 minutes (sterilization). When spores get into food products under favorable conditions grow into a vegetative cell (botulinus bacillus), which during the day at a temperature of 15 to 37 ° C and the absence of air releases a toxin - a strong poison.
for humans it is considered 0.035 mg. The development of botulinus is accompanied by the formation of carbon dioxide and hydrogen, as evidenced by swollen lids of cans (bombing). The toxin is formed in the deep layers of the product, basically without changing its quality; only a slight smell of rancid oil is noted. The toxin is destroyed throughout the entire depth of the product when it is heated to 100 °C for 1 hour. Botulinus is found in nature in soil, sea silt, water, and is found in the intestines of fish and animals.
If sanitary rules for preparation and storage are violated, food may become contaminated with botulinus. Basically, botulism is caused by various canned foods, especially homemade ones, due to their insufficient sterilization; ham, ham, sausages due to improper storage; fish, especially sturgeon, as a result of violations of the rules of fishing, cutting and storing it.
To prevent botulism in public catering establishments it is necessary:
1. check all canned food for bombing and store them in a refrigerator;
2. accept fresh sturgeon fish for production only in frozen form; speed up the processing process;
3. store ham, hams, sausages at a temperature of 2-6 "C, strictly adhere to the deadlines for sale;
4. observe the rules of sanitary conditions and thorough heat treatment during the cooking process;
5. comply with the conditions, terms of storage and sale of prepared food.
Staphylococcal poisoning is an acute disease resulting from eating food containing staphylococcal toxin. The disease occurs 2 ... 4 hours after eating food contaminated with poison, accompanied by cutting pain in the abdomen, repeated profuse vomiting, general weakness, headache, dizziness at normal body temperature. Poisoning lasts 1...3 days. There are no deaths.
The causative agent of the disease is Staphylococcus aureus, which forms colonies in the form of clusters of golden grapes, is immobile, and dies at a temperature of 70 ° C for 30 minutes. When exposed to various food products, especially those with high humidity and containing starch and sugar, staphylococcus multiplies and secretes poison at temperatures from 15 to 37 ° C, both in the presence of air and without it. At the same time, the quality of the product does not change. The poison (enterotoxin) is neutralized by boiling at 100 °C for 1.5 ... 2 hours. Staphylococcus aureus is widespread in nature (found on festering wounds of humans and animals).
The main products and causes of this poisoning are the following: milk and dairy products (cottage cheese, yogurt, kefir, cheese curds, etc.), infected with microbes through abscesses on the udders of cows or the hands of milkmaids; cream confectionery products and any prepared food contaminated with staphylococcus sick (pustular skin diseases or sore throat)
pastry chefs or cooks; canned fish in oil contaminated with microbes during the cooking process.
To prevent staphylococcal poisoning it is necessary:
1. daily check cooks and confectioners for the presence of pustular skin diseases, sore throat and inflammation of the upper respiratory tract;
2. strictly observe the temperature regime for heat treatment of all dishes and products;
3. store prepared food for no more than the established period at a temperature of 2 ... 6 ° C or hot at least 65 ° C;
4. be sure to boil milk, use unpasteurized cottage cheese for dishes subject to heat treatment, and yogurt - only for dough; fermented milk products (kefir, fermented baked milk, yogurt, acidophilus) are poured into glasses from bottles, without pouring into cauldrons;
5. store confectionery products with cream at a temperature of 2 ... 6 ° C, observe the deadlines for their sale. In the summer, custard, butter, and curd creams should be made only with the permission of local centers of the State Sanitary and Epidemiological Supervision;
6. store canned fish in oil at a temperature not exceeding 4 °C.
Mycotoxicoses- poisoning resulting from the ingestion of food contaminated by the poisons of microscopic fungi into the human body. Mycotoxicosis occurs mainly from the consumption of contaminated grain and leguminous products. Poisonings in this group include ergotism, fusariotoxicosis, and aflotoxicosis.
Fusariotoxicoses arise as a result of consumption of grain products that have overwintered in the field or have become moist and moldy. Such grain is affected by microscopic fungi that release toxic substances. Poisoning with the poisons of this mushroom manifests itself in the form of a sore throat or in the form of a mental disorder - poisoning with “drunken bread”. A measure to prevent poisoning is strict adherence to grain storage rules.
Aflotoxicosis - poisoning caused by the poisons of microscopic fungi when consuming peanuts and products made from wheat, rye, barley, rice that have become moist and moldy during storage. To prevent poisoning, it is necessary to comply with the storage conditions for flour, cereals, and peanuts.
Food poisoning of non-microbial origin. Poisonings in this group make up about 10% of the total number of poisonings.
According to the classification, poisoning of non-microbial origin is divided into:
1. poisoning with foods that are poisonous by nature - mushrooms, stone fruit kernels, raw beans, some types of fish;
2. poisoning with temporarily poisonous products - potatoes, fish during the spawning period;
3. poisoning with toxic impurities - zinc, lead, copper, arsenic.
Mushroom poisoning is mainly seasonal in nature, because it is more often observed in spring and late summer when they are collected and consumed in large quantities. Strings, toadstool, fly agarics, false honey mushrooms and a number of other mushrooms are poisonous. Mushroom poisoning is very dangerous. Thus, consumption of toadstool causes death in 90% of cases.
Measures to prevent these poisonings: dried, salted and pickled forest mushrooms should be supplied to catering establishments sorted by type. Only champignons grown in greenhouses can be used fresh.
Poisoning with stone fruit kernels arise due to the presence in them of the glycoside amygdalin, which, when hydrolyzed in the human body, forms hydrocyanic acid. At public catering establishments it is prohibited to use the kernels of plums, peaches, apricots, cherries and bitter almonds in the production of confectionery products.
Raw bean poisoning due to the presence of phasin poison in it, which is destroyed during heat treatment. Poisoning often occurs from the consumption of bean flour and concentrates, the production of which is currently prohibited. When preparing food from beans, special attention should be paid to the heat treatment mode.
Poisoning with certain types of fish(marinka, barbel, pufferfish) occurs due to the fact that their eggs and milt are poisonous. These types of fish must be supplied to catering establishments gutted.
Sprouted potato poisoning caused by the presence of solanine glycoside, contained in the eyes and skin of tubers. There is especially a lot of solanine in unripe, sprouted and green potatoes. In order to prevent this poisoning, it is necessary to thoroughly peel and clean the eyes of the potatoes. In spring, heavily sprouted tubers should be boiled only peeled; their decoctions cannot be used.
Zinc poisoning occurs when using galvanized utensils for cooking and storing food. According to sanitary rules, in catering establishments this utensil is used only for storing bulk products and water.
Lead poisoning possible when using tinned and glazed ceramic dishes for cooking. According to sanitary standards, the lead content should not exceed 1% in the glaze of pottery, and 12% in the glaze of pottery.
Copper poisoning occurs when using copper utensils, which are prohibited in public catering establishments.
Arsenic poisoning observed when it gets into food products due to careless storage of arsenic preparations or when consuming vegetables and fruits treated with pesticides containing arsenic. Measures to prevent this poisoning include thorough washing of vegetables and fruits and monitoring the storage and use of pesticides.
Helminthic diseases(helminthiases) occur in humans as a result of damage to the body by worms (helminths), the eggs or larvae of which came from food prepared in violation of sanitary rules.
Worms go through three stages in their development - eggs, larvae and adult helminths. In most cases, the adult stage of development of worms occurs in the human body (primary host), and the larval stage in the body of animals or fish (intermediate host).
Helminthic diseases manifest themselves in humans as anemia, retarded growth and mental development in children, etc.
A healthy person becomes infected from a patient who releases worm eggs into the external environment with feces. Worm eggs, entering the body of animals or fish with food, turn into larvae that infect various organs and muscles. In the human body, the larvae turn into adult worms. Most often, a person is affected by the following worms: roundworms, tapeworms, trichinella, tapeworm, opisthorchiasis, echinococcus.
Echinococcus- tapeworm 1 cm long; Its main hosts are dogs, wolves, and foxes, in which the helminth parasitizes in the intestines. An intermediate host is a person in whose body the larva of echinococcus infects the brain, lungs, and liver. Human infection occurs through poorly processed vegetables, fruits, water from open reservoirs and through dirty hands after contact with sick animals.
To prevent helminthic diseases in public catering establishments it is necessary:
1. check cooks, confectioners and other workers for helminthic infections at least once a year;
2. thoroughly wash vegetables, fruits, berries, especially those eaten raw;
3. boil water from open reservoirs when using it for food;
4. check the presence of brands on meat carcasses;
5. thoroughly boil and fry meat and fish;
6. observe the rules of personal hygiene, cleanliness in the workplace, in the workshop, and destroy flies.
Diseases arising from the consumption of food products infected with toxigenic microorganisms are called foodborne diseases. Contamination of food products with these microbes can occur through the hands of personnel in food production, trade and catering establishments, as well as through bacilli, bacteria and virus carriers working in these areas; through the air of production premises, through water that does not meet sanitary requirements, and ice obtained from it, which comes into contact with products during storage; through dirty containers. Fruits, vegetables and berries become contaminated when grown in soil fertilized with feces. Meat and milk can be contaminated with toxinogenic microflora if they are obtained from sick animals.
Based on the origin and symptoms of the disease, foodborne diseases are usually divided into several groups:
Foodborne infections- these include infectious diseases in which food products are only transmitters of toxigenic microbes; they do not multiply in them, but can remain viable and virulent for a long time.
For a disease to occur, it is enough to contain a small number of pathogen cells in the product, which, once in macroorganisms, actively multiply and cause a certain disease. The source of food contamination by foodborne pathogens are people and animals (patients and carriers of infections).
Food poisoning(intoxication) - pathogens, unlike pathogens of food infections, are able to live and actively reproduce on food. At the same time, food products, without noticeably changing their organoleptic properties, become toxic as a result of the accumulation of toxins in them.
Foodborne illnesses is a group of diseases that occupy an intermediate position between typical infections and food poisoning. They occur like intoxications, like acute gastrointestinal diseases, and at the same time they are contagious.
Diarrhea“travelers” - the occurrence of frequent loose stools due to a change in place of residence. People who travel to other countries and continents may experience diarrhea as a result of consuming local food and water containing different microflora.
Foodborne infections
Typhoid fever- severe infectious disease. The incubation period is 7-23 days. Pathogens are pathogenic only for humans. These are small, mobile, non-spore-forming rods that are facultative anaerobes. The optimal temperature for their development is about 37°C. They are sensitive to heat and die in a few seconds when boiled. These bacteria easily tolerate drying and low temperatures. The causative agents of the disease enter the body through the mouth, esophagus, are localized in the small intestine, and then enter the intestinal lymph nodes and other organs. When pathogen cells are destroyed, a potent toxin is released in the body. The disease is manifested by inflammation and ulceration of the small intestines, accompanied by acute diarrhea, feverish rise in temperature and general weakness.
Bacterial dysentery- the disease is caused by a number of biologically close bacteria, united in the genus Shigella. Dysentery bacteria are facultative anaerobes, the optimal growth temperature is 37°C, they are quite stable in the external environment: they survive on soil for several months, tolerating low temperatures well; They are stored for a long time in milk, cottage cheese, on unwashed vegetables and fruits, as well as in raw water. The source of dysentery is a sick person who excretes dysentery bacilli in their feces.
Dysentery begins acutely with a rise in temperature to 38-39°C; the patient is bothered by chills, headache, body aches, cutting pains in the lower abdomen occur, stool becomes rapid, liquid, with mucus, sometimes with blood. The act of defecation is accompanied by nagging pain (tenesmus).
The disease will spread through dirty hands, from where pathogens get on food products, through vegetables, fruits, water, raw dairy products and any prepared food through contamination during preparation or storage in unsanitary conditions.
Cholera- severe infectious disease. The causative agent is Vibrio - a mobile, non-spore-forming, gram-negative, comma-shaped rod. Vibrio cholerae is a facultative anaerobe; the optimal temperature for its growth is 25-37°C. At a temperature of 55°C it dies after 25-30 minutes, at a temperature of 80°C - after 5 minutes. Vibrio is resistant to low temperatures, but sensitive to the acidity of the environment. The incubation period ranges from several hours to several days.
Signs: sudden uncontrollable diarrhea and vomiting, severe dehydration, headache, weakness, dizziness, temperature drops to 35°C, convulsions, possible death.
Brucellosis- a disease that affects not only humans, but almost all animals and birds. Brucella are strict anaerobes, the optimal growth temperature is 37°C. Brucella of small and large livestock have the form of cocci and coccobacteria, while brucella of pigs have the form of rods. They are gram-negative, immobile, and do not form spores. They can be preserved in food products for a long time, but quickly die under the influence of high temperatures.
The most dangerous pathogen for humans is brucellosis in sheep and goats. The disease is associated with the consumption of milk and dairy products. The incubation period is 4-20 days. The disease occurs when pathogens enter the mucous membranes of the mouth, eyes, and even through intact skin. Then they enter the lymph nodes, enter the blood and spread throughout the body, penetrating the liver, kidneys, spleen, bone marrow, and lungs. Usual symptoms: general weakness, chills, swelling and pain in joints and muscles, severe headache, insomnia, irritability, various skin rashes. Preventive measures include boiling milk before consumption and boiling meat until the temperature inside the pieces reaches at least 80°C.
Tuberculosis- infectious, chronic disease. Tuberculosis bacteria are thin, straight or slightly curved rods, sometimes have small swellings at the ends, are immobile, and do not form spores or capsules. They are typical aerobes, the optimal growth temperature is 37°C. Resistant to various environmental factors, including acids. When boiled, they die within 5-10 seconds.
The source of infection is sick people, less often animals. The disease spreads through the air by droplets or contact. Infection usually occurs through the respiratory tract, but sometimes through the intestines through consumption of contaminated food.
Hepatitis A- a contagious form of jaundice. The hepatitis A virus is found in the feces, plasma, bile and stomach contents of sick people at the end of the incubation period and in the acute stage of the disease. The virus has a spherical shape. The virus is very persistent - without water and at the North Pole it survives for several months and even years, and is not afraid of exposure to chemicals - acids, ether, alcohol. But it dies when boiled in just 5 minutes. The source of the virus is sick people and virus carriers. The pathogen is transmitted from patients to healthy people through infected feces and water, food, and also through flies. The incubation period is 3-6 weeks. The disease is characterized by jaundice, liver pain, low-grade fever; total duration - 1.5-2 months.
anthrax- an acute and very dangerous infectious disease of animals and humans. Anthrax bacilli are large in size; are located in pairs or short chains in the body and in long chains in nutrient media. The bacilli are immobile; in the body of animals and humans they form capsules surrounding both individual individuals and chains. The causative agent of anthrax is an aerobe and a facultative anaerobe, the optimal growth temperature is 37-38ºC. The spores are highly resistant; they can withstand boiling for a long time and even autoclaving at a temperature of 130°C for 5-10 minutes; remain for years in the soil, on skins, hair, etc.
Human infection can occur as a result of direct contact with sick animals, by eating meat or milk of sick animals, through infected raw materials and products made from them.
Signs: headaches, dizziness, nausea, vomiting, diarrhea, and death often occurs after 5-8 days.
foot and mouth disease- foodborne infectious disease of a viral nature. It is a contagious disease of cattle, blue and sheep that can be transmitted to humans. The foot and mouth disease virus is one of the smallest in size. It is not resistant to heat, alkalis, and antiseptic substances. In the external environment at a temperature of 37°C it remains viable for several days; in animal secretions it remains viable for up to 2 months. A person becomes infected from sick animals through direct contact. The incubation period is about a week. General weakness appears, and blisters appear on the inflamed mucous membrane of the mouth, which turn into painful ulcers. The disease is usually mild, but sometimes ends in death.
Foodborne infections are contagious diseases in which food products are only transmitters of toxigenic microbes; they do not multiply in them, but can remain viable and virulent for a long time.
Intestinal infections - cholera, typhoid fever, paratyphoid fever, salmonellosis, dysentery;
Viral infections - hepatitis A, rotavirus infection;
Zoonotic infections - anthrax, brucellosis, zoonotic tuberculosis, foot and mouth disease;
Helminthic infestations - taeniasis, trichinosis, opisthorchiasis, geohelminthiasis.
Acute intestinal infections are characterized by intestinal lesions and a fecal-oral mechanism of infection transmission. These include typhoid fever, dysentery, cholera, infectious hepatitis, rotavirus infection, etc. The spread of infection is dominated by food and water transmission factors.
The sources of acute intestinal infections are mainly sick people (or animals), as well as bacteria carriers. Chronic carriage involves the release of the pathogen into the environment for several months, years, or even life. Infection can occur through contact with a sick person or a bacteria carrier, or through consumption of contaminated water or contaminated food products. Flies, cockroaches and rodents may be involved in the transmission of pathogens. Intestinal infections have long been called diseases of “dirty hands,” since the unwashed hands of a patient or a bacteria carrier can transfer pathogens to food, dishes, and various objects, which leads to the spread of infection.
The causative agents of intestinal infections are resistant to external influences and remain viable for a long time outside the human body: in tap water for up to 3 months, in river water for up to 30 days. In silt - several months, on vegetables and fruits from 5 to 14 days. The most favorable environment for the activity of pathogens of intestinal diseases is food products, especially milk, minced meat products, jelly, vegetable salads and culinary products. In them, microorganisms and, above all, the dysentery bacillus, can multiply in a wide range of temperatures (from 20 to 40 ° C) and pH values.
At the same time, it should be noted that the causative agents of dysentery, as well as vibrios cholera, have low heat resistance and die when heated to 70°C for 30 minutes. General principles for the prevention of intestinal infections include:
High level of improvement of food enterprises;
Compliance with hygienic requirements in the production and sale of food and food products;
Timely identification of patients, as well as carriers, and their timely isolation;
Strict adherence to the sanitary regime and personal hygiene rules;
timely implementation of preventive vaccinations.
Typhoid fever is a serious infectious disease. Pathogens are pathogenic only for humans.
The optimal temperature for their development is about 37°C. They are sensitive to heat and die in a few seconds when boiled. The action of disinfectant solutions of phenol, bleach, and chloramine kills them within a few minutes. These bacteria easily tolerate drying and low temperatures. The causative agents of the disease enter the body through the mouth, esophagus, are localized in the small intestine, and then enter the intestinal lymph nodes and other organs. When pathogen cells are destroyed, a potent toxin is released in the body. The incubation period is about two weeks. The disease is manifested by inflammation and ulceration of the small intestines, accompanied by acute diarrhea, feverish rise in temperature and general weakness. Many people who have suffered these diseases, after recovery, excrete bacteria for a long time in their feces and thus serve as spreaders of the disease.
Bacterial dysentery. This disease is caused by a number of biologically related bacteria. The optimal growth temperature is 37°C. These bacteria are quite stable in the external environment: they survive on the soil for several months, tolerating low temperatures well; They are stored for a long time in milk, cottage cheese, on unwashed vegetables and fruits, as well as in raw water. The source of dysentery is a sick person who excretes dysentery bacilli in their feces.
In typical cases, dysentery begins acutely, with a rise in temperature to 38°-39°C; the patient is bothered by chills, headache, body aches. Symptoms of damage to the intestinal tract sometimes appear a little later - cutting pain occurs in the lower abdomen, often in the left half, stool becomes rapid, liquid, with mucus, sometimes mixed with blood.
Dysentery is a disease that is usually widespread. The source of infection is people suffering from acute or chronic dysentery. The disease spreads in most cases through dirty hands, from where pathogens land on food products, vegetables, fruits, banknotes, and in river and sea water and remain viable for several weeks.
Cholera is a serious infectious disease characteristic only of humans. The causative agent is Vibrio.
Under the influence of living conditions, the shape of a cell can change significantly. Vibrio cholerae is a facultative anaerobe; the optimal temperature for its growth is 25°-37°C, the extreme limits of growth are 14-42°C. At 55°C it dies after 25-30 minutes, at 80°C - after 5 minutes. On food products it lasts up to 10-15 days, in soil - 2 months, in water - several days. Vibrio is resistant to low temperatures, but sensitive to the acidity of the environment. Vibrio cholerae produces a potent endotoxin and exotoxin-enterotoxin (strong poison). The incubation period lasts from several hours to several days. The severity of the disease varies; There are severe transient forms that end in death.
Preventive measures are the same, but special attention must be paid to maintaining the rules of sanitation and personal hygiene, and controlling flies.
Hepatitis A - infectious hepatitis has been known for a very long time. The virus is very persistent - without water and at the North Pole it survives for several months and even years, and is not afraid of exposure to chemicals - acids, ether, alcohol. But it dies when boiled in just 5 minutes. The source of the hepatitis A virus is sick people and virus carriers. The mechanism of infection with hepatitis A is the same as for intestinal infections. The pathogen is transmitted from patients to healthy people through infected feces and water, food, and also through flies. With hepatitis A, the incubation period lasts 3-6 weeks. The disease is characterized by jaundice, liver pain, low-grade fever; total duration -1.5-2 months.
There are erased forms of the disease and healthy carriage of the pathogen. The main way to resist hepatitis A is strict adherence to personal hygiene rules and timely vaccination.
Zoonotic infections. Zoonotic infections are infectious diseases common to humans and animals. These include anthrax, brucellosis, foot and mouth disease, tuberculosis, tularemia, leptospirosis, etc.
The source of human infection is, as a rule, meat and milk of infected animals. For the prevention of zoonotic infections, veterinary examinations of dairy cows and animals before slaughter, as well as veterinary and sanitary examination of meat and milk, and compliance with sanitary and hygienic requirements when using conditionally acceptable products are extremely important.
After examination, a purple mark is applied to the meat of healthy animals. Catering establishments are required to accept only meat from healthy animals and meat that has already been rendered harmless.
Sick, overworked, weakened or emaciated animals can produce infected meat or milk. Conditional meat is always marked with a red mark, and next to it is a stamp indicating the method of its neutralization. The neutralization of meat by cooking is carried out in separate pieces up to 2 kg and up to 8 cm thick in open cauldrons for 3 hours, and closed ones for 2.5 hours.
Anthrax is an acute and very dangerous infectious disease of animals and humans. In Russia, this disease was called anthrax in connection with a large epidemic described in the Urals in 1786-1788. S. S. Andreevsky. The causative agent of anthrax: the optimal growth temperature is 37-38°C, develops well on ordinary media. The spores are highly resistant; they can withstand boiling for a long time and even autoclaving at 130°C for 5-10 minutes; remain for years in the soil, on skins, hair, etc. Vegetative cells die at 75°C in 2-3 minutes.
Human infection can occur as a result of direct contact with sick animals or through infected raw materials and products made from them (fur collars, hats, mittens, etc.).
Anthrax in humans can manifest itself in three forms: cutaneous, pulmonary, and intestinal. The cutaneous form occurs through direct contact with animals and animal products. The pulmonary form appears as a result of anthrax spores entering the respiratory tract. The intestinal form occurs when eating meat or milk from sick animals; When infected, headaches, dizziness, nausea, vomiting, diarrhea appear, and after 5-8 days death often occurs.
Anti-anthrax serums are used for treatment. In disease prevention, the main role belongs to strict veterinary control over slaughter animals and sanitary supervision of the hygienic condition of slaughterhouses. Sick animals cannot be processed; their corpses
must be burned.
Tuberculosis is an infectious, chronic disease. Bacteria are resistant to various environmental factors, including acids. They can persist in dried sputum for up to several weeks, on clothes and underwear for up to 2 months; when boiled they die within 5-10 s, in milk heated to 65-70°C - after 30 s.
Many animals suffer from tuberculosis. Tuberculosis in humans is caused by two types of mycobacteria: human (infection most often through the respiratory tract) and bovine (infection through milk and dairy products). Humans can also become infected with the avian species of Mycobacterium tuberculosis by eating insufficiently cooked meat from sick chickens or chicken eggs. The source of infection is sick people, less often animals. The disease spreads through the air by droplets or contact; cases of dust infection are known. Infection usually occurs through the respiratory tract, but sometimes through the intestines through consumption of contaminated food.
The main importance in the fight against tuberculosis is the general improvement of working and living conditions.
Foot and mouth disease is a foodborne infectious disease of a viral nature. It is a contagious disease of cattle, pigs and sheep that can be transmitted to humans. The foot and mouth disease virus is not resistant to heat, alkalis, or antiseptic substances. In the external environment at a temperature of -37°C it remains viable for several days; persists in animal secretions for up to 2 months. A person becomes infected from sick animals through direct contact: when caring for them, during primary processing of carcasses, or when consuming contaminated raw milk. The incubation period lasts about a week. General weakness appears, and blisters appear on the inflamed mucous membrane of the mouth, which turn into painful ulcers. The disease is usually mild, but can sometimes result in death. The fight against foot and mouth disease is carried out by preventing the disease among animals.
Brucellosis is a disease that affects not only humans, but almost all animals and even birds. Brucellosis bacteria can survive in food products for a long time. They die quickly when exposed to high temperatures. The most dangerous pathogen for humans is brucellosis in sheep and goats. The disease is in most cases associated with the consumption of milk and dairy products. The incubation period is from 4 to 20 days. Infection occurs when pathogens enter the mucous membranes of the mouth, eyes, and even through intact skin. Subsequently, brucellae enter the lymph nodes, and then enter the blood and spread throughout the body. Common signs are general weakness, chills, swelling and pain in joints and muscles, severe headache, insomnia, irritability, and various skin rashes. Preventive measures include mandatory boiling of milk before consumption and boiling of meat until the temperature inside the pieces reaches at least 80°C.
Prevention of geohelminthiases consists of strict adherence to the sanitary regime in public catering establishments, rules of personal hygiene and hygienic requirements for the processing and storage of vegetables, herbs, berries, etc. At home, special attention should be paid to washing and cleaning soil from vegetables, berries and herbs with vegetable gardens, the soil of which is fertilized with non-neutralized feces.
Biohelminths are caused by helminths, the biological development cycle of which requires an intermediate host.
Teniosis (taeniarinhoz, taeniasis) occurs in humans when consuming meat from cattle and pigs infected with the larvae of the unarmed tapeworm). This meat is called Finnish. A person usually becomes infected by tasting raw meat, or by eating sliced meat, insufficiently heat-treated beef or pork. Tenidosis causes malignant anemia and disruption of the synthesis of vitamin B12 in the human body.
Trichinosis is caused by a small worm just a few millimeters in size. Trichinosis occurs not only in humans, but also in animals that eat meat and eat carrion. Among domestic animals, it mainly affects pigs, cats, and dogs. Trichinosis is a serious disease. If treatment is not started during treatment, complications such as myocarditis, pneumonia, etc. may develop. Meat that has not undergone trichinosis can only be boiled
As preventive measures, the fight against echinococcosis among animals, especially dogs, is carried out (catching stray animals, examination, deworming of infected guard and domestic dogs). It is necessary for a person to observe the rules of personal hygiene (thorough washing of hands before eating, as well as washing vegetables, fruits, berries, melons, etc.)
The cause of some helminthiases can be the consumption of fish and other aquatic organisms (crabs, shrimp, shellfish, etc.). The greatest epidemiological danger to humans is posed by fish infected with tapeworm and cat fluke.
Diphyllobothriasis is characterized by a long course, severe intoxication and anemia (anemia).
Consumption of contaminated fish and fish products in raw (stroganina) or insufficiently heat-treated form leads to a serious illness in people, as a rule, it is severe, with severe anemia. Neutralization of fish infected with larvae occurs by frying small fish, portioned pieces of flattened fish or cutlets for 15 minutes, when boiling - instantly, when salting - after 1 - 2 weeks, when freezing at a temperature of -12 oC or -27 oC - for 3 days or 9 hours, respectively, at -4 ° C - after 9-10 days.
For the prevention of the disease, the protection of water bodies from fecal pollution in areas where diphyllobothriasis is endemic is of primary importance. It is also necessary to conduct periodic mass helminthological surveys of the population of these areas in order to identify and sanitize infested people. Personal prevention should consist of strict adherence to the rules for preparing fish dishes.
Human infection occurs with diphyllobothriasis. Helminths parasitize the human body for up to 10 years and cause severe disorders of the gastrointestinal tract, liver, pancreas and anemia.
Fluke larvae die at a higher temperature than plerocercoids. The fish should be fried in a flattened form (skin side down) for 20 - 25 minutes until the temperature inside the piece reaches 75 - 80 ° C, fish cutlets are fried for 20 minutes, the fish is boiled in pieces for at least 20 minutes from the moment the water boils, meatballs for 10 minutes . Neutralizing fish by cold is ineffective, since the larvae are protected by a capsule and are resistant to low temperatures; they also do not die during cold smoking.
Foodborne infections. Their characteristics and symptoms
TO food infections include infectious diseases that arise from eating foods contaminated with microbes of various infectious diseases.
Food products can become contaminated with pathogenic microbes due to untidy hands, poor washing after visiting the restroom, etc. Pathogenic microbes are transferred to food products by insects (flies, cockroaches) and rodents (rats, mice). In addition, pathogenic microbes can enter a food product from a sick animal (for example, milk from tuberculosis or brucellosis cows).
Tuberculosis
Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis and characterized by the formation of specific granulomas in various organs and tissues (usually in the lungs) and a polymorphic clinical picture. The causative agent of the disease is mycobacterium tuberculosis, or Koch's wand. In the active form of tuberculosis, Koch's bacillus quickly multiplies in the patient's lungs and destroys the lungs, poisoning the human body with its waste products, releasing toxins into it. Process in progress tuberculosis intoxication, otherwise poisoning of the human body. Mycobacteria tuberculosis have significant resistance to various physical and chemical agents, cold, heat, moisture and light. Under natural conditions, in the absence of sunlight, they can remain viable for several months. Mycobacteria persist in street dust for 10 days. On the pages of books they can remain alive for three months. Mycobacteria persist in water for a very long time (150 days). Mycobacteria tuberculosis They withstand the processes of decay and can survive for several months in buried corpses. Mycobacterium tuberculosis transmitted mainly by airborne droplets, entering the respiratory system from a sick person to a healthy person, causing tuberculosis lungs. In addition to the lungs, tuberculosis can affect various human organs and tissues: eyes, bones, skin, genitourinary system, intestines, etc. If untreated, mortality from active tuberculosis reaches 50% within one to two years. In the remaining 50% of cases, untreated tuberculosis becomes chronic. A chronic patient can live for some time, continuing to secrete mycobacteria tuberculosis and infect others. Pathogens tuberculosis They are very variable and quickly become resistant to drugs; they are difficult not only to destroy with drugs, but also to detect. Tuberculosis Not only people get sick, but also animals, which can be a source of infection. tuberculosis bacillus most often transmitted by airborne droplets. Not only cough and sputum are dangerous, but also dust. In humid places without access to the sun, the pathogen tuberculosis lives for months. Rarely tuberculosis received from food (milk or meat), water (if water bodies are contaminated with wastewater from tuberculosis hospitals or farms with sick livestock) or in utero. Sometimes tuberculosis people who dissect corpses or cut up meat carcasses become infected through wounds on the skin. Infection tuberculosis very often observed in childhood and adolescence. Not everyone is infected tuberculosis will get sick. Emergence tuberculosis depends on the weakening of the body, living conditions, nutrition, smoking, alcoholism and other harmful factors. If a person is healthy, lives in a normal home, eats well, his immune system copes with tuberculosis bacilli. If Koch's bacillus gets into the lungs (or other organ that first enters tuberculosis bacillus) a primary focus of inflammation develops, which is expressed in the appearance of symptoms of normal inflammation. But unlike a banal infection, the inflammatory process during tuberculosis develops very slowly (this is a chronic infection that lasts for years) and is prone to necrosis of the primary focus of inflammation. The complaints of patients are very diverse. Conventionally, they can be divided into nonspecific: malaise, weakness, low-grade fever, poor appetite, weight loss, pale skin, etc. and specific (typically characteristic of tuberculosis): sweating at night and in the morning (as a manifestation of intoxication, debilitating the patient), temperature ranges between morning and evening are no more than 0.5 degrees, obsessive prolonged cough, etc.
Intestinal diseases are most often transmitted through contaminated food products: dysentery (microbes that cause dysentery, dysentery bacilli), typhoid fever and paratyphoid fever. The spread of infections can be facilitated by milk, which is a good breeding ground for pathogenic microbes.
Dysentery
Amoebic dysentery. The causative agents of amoebic dysentery (amoebiasis) are pathogenic variants, or invasive strains, of amoebas Entamoeba histolytica. This species is widespread, but more than 90% of infected people are asymptomatic carriers. Long-term observations show that only some invasive strains E.histolytica pathogenic for humans; infection with non-invasive variants does not cause disease. Invasive strains have the ability to effectively overcome natural defense mechanisms.
The main reservoir of the causative agent of amoebic dysentery in nature is the human population. Transmission occurs through excrement-contaminated hands, water, or fruits and vegetables grown using human feces as fertilizer. Trophozoites of invasive strains Entamoeba histolytica penetrate the wall of the large intestine and cause inflammation (colitis) with the formation of necrotic ulcers. The disease can be mild or severe and is accompanied by abdominal pain and frequent loose stools mixed with blood. In severe cases, perforation of the intestinal wall is possible; if the vascular wall is damaged, the pathogen can spread through the bloodstream to the liver, lungs, and brain, which leads to the development of abscesses. Typically, amoebic dysentery has a chronic course of a “smoldering” nature, with an imperceptible onset and periods of exacerbations and remissions. Diagnosis can be difficult. Isolation of vegetative forms is of decisive importance in recognizing amebic ulcerative colitis E. histolytica in fecal samples, in clots of mucus from the colon, or in biopsy material. The symptoms of chronic amoebiasis often do not differ from the clinical manifestations of chronic ulcerative colitis, a disease whose cause remains unknown. A good therapeutic effect is achieved by using a combination of two drugs: metronidazole, which kills trophozoites, and diiodohydrosiquinol, directed against cysts.
Bacterial dysentery. The causative agents of bacterial dysentery are bacteria of the genus Shigella, although sometimes Salmonella, Campylobacter and other related bacteria can cause clinically similar diseases. At home, bacterial dysentery is most often transmitted through the fecal-oral route, for example, while caring for a patient, through various household items contaminated with the patient’s secretions. Among homosexual men, infection can occur through sexual contact. In countries with tropical climates, flies play an important role, transferring bacteria to food. Infected milk and dairy products can be a source of nosocomial outbreaks.
All representatives of the genus Shigella produce a toxin, under the influence of which the intestinal epithelial cells begin to secrete fluid - diarrhea develops; loose stools containing mucus, pus and often blood, similar to cholera discharge. Later, the cells damaged by the toxin die; their death is accompanied by inflammation, ulceration of the intestinal wall and other symptoms of dysentery. In children, general intoxication may be accompanied by neurological symptoms (vomiting, convulsions). Unlike amoebic dysentery, bacterial dysentery is characterized by a rapid increase in symptoms, fever and dehydration; the disease is usually shorter lasting and does not become chronic.
A mandatory component of treatment for bacterial dysentery is drinking plenty of fluids containing mineral salts and sugar. The use of antibiotics speeds up recovery, but the development of antibiotic-resistant forms is possible.
If the preparation technology is incorrect and sanitary and hygienic requirements are not observed when storing jellies, vinaigrettes, and salads, the latter can be a source of the spread of intestinal infections. To prevent human infection with typhoid fever, dysentery, infantile paralysis, paratyphoid fever, tuberculosis, brucellosis and foot-and-mouth disease through milk, you should only consume boiled or pasteurized milk.
Typhoid fever
Typhoid fever (typhoid fever - English, Abdominaltyphus - German, abdominale fievre - French) is an acute infectious disease caused by Salmonella typhi, characterized by fever, symptoms of general intoxication, bacteremia, enlarged liver and spleen, enteritis and peculiar morphological changes in the intestinal lymphatic system. The causative agent of typhoid fever (S. typhi) belongs to the family Enterobacteriaceae, genus Salmonella, species Salmonella enterica, subspecies enterica, serovar typhi and is morphologically no different from other salmonella. This is a gram-negative, motile rod with peritrichous flagella, does not form spores or capsules, and grows well on ordinary nutrient media. Biochemically it differs from other salmonella in the fermentation of glucose without gas formation and the delayed release of hydrogen sulfide. The antigenic structure of S. typhi is characterized by the presence of somatic O (9, 12, Vi) - complex and flagellar antigen H (d). Depending on the amount and location of the Vi-antigen, 3 variants of cultures are distinguished.
FOOD INFECTIONS AND THEIR PREVENTION
GENERAL CONCEPTS ABOUT INFECTIOUS DISEASES AND PATTERNS OF THEIR SPREAD
Infectious, or contagious, are diseases that are caused by pathogens. Their main difference from other diseases is that they can be transmitted from a sick person to a healthy person and, under certain conditions, affect large groups of people.
In the process of evolution, certain relationships have developed between microbes and humans. Many microbes that live in the human body constitute its normal microflora. Some of them create an unfavorable environment for the development of pathogenic microbes, while others promote digestion processes. However, some of these microbes under certain conditions (for example, a decrease in the body's resistance) can acquire pathogenic properties. Such microorganisms are usually classified as opportunistic.
Pathogens include microorganisms that cause infectious diseases. Pathogenic microorganisms are characterized by strict specificity, i.e., each pathogen can cause a specific disease, for example, typhoid bacillus - typhoid fever, dysentery - dysentery.
A characteristic biological feature of pathogenic microbes is their ability to produce toxins and other harmful substances that have a pathogenic effect on the body. Pathogenic microbes produce two types of toxins: exotoxins And endotoxins . Exotoxins are released into the environment during the life of microorganisms, and endotoxins are released only after their death and destruction.
The process of interaction between a pathogenic microorganism and a macroorganism (human body) is usually called an infection. Forms of infection can manifest themselves in different ways and depend on the type, degree of virulence and quantity of microbes introduced into the body, and on the state of reactivity of the body at a given stage.
In one case, a form of interaction is established between a person and the pathogen that has entered him, in which the body is removed from a state of equilibrium with the environment, as a result of which its physiological functions are disrupted and an infectious disease develops.
In another case, the process of interaction between a person and a microorganism proceeds more favorably, and the signs of the disease do not appear sharply. Often a person suffers such diseases “on his feet”. Such forms of infections are called atypical, or erased.
The third form of interaction is an asymptomatic “latent” infection, or so-called carriage. In this case, there are no external signs of the disease.
With a high immunobiological reactivity of the body, the microbes that enter it do not find favorable conditions for development and die.
The emergence and spread of any infectious disease is possible only when the pathogen finds favorable conditions in the body for its existence and development. Once in the external environment, the pathogen retains vital activity, the ability to penetrate the body of a healthy person and cause disease.
Many contagious diseases only affect people; such infections are called anthroponoses (from the Greek “anthropos” - person and “nosos” - disease). These include, for example, dysentery, typhoid fever, cholera, measles, diphtheria, etc. The main source of infection in this case is a sick person.
Infectious diseases that affect only animals are usually called zoonoses (from the Greek “zoon” - animal, “nosos” - disease). Diseases that affect humans and animals are referred to as “zooanthroponoses” (tuberculosis, brucellosis, anthrax, foot-and-mouth disease, tularemia, etc.). The main source of these infections is a sick animal.
The process of spreading infection (epidemic process) is a continuous chain of successively developing, interconnected cases of infection that arise in a group of people under certain natural and especially social conditions.
The occurrence of diseases in a community is determined by three mandatory links: the presence of a source of infection, ways of its spread and the susceptibility of the population.
The condition for the occurrence of a single case of an infectious disease or epidemic is the presence of a source of infection.
A sick person is one of the most dangerous sources of infection, since he releases large quantities of bacteria, moreover, in the most virulent state, which increases the risk of infection of others and the environment.
Patients with atypical, erased forms of the disease pose a particular danger, since these persons can be in contact with others for a long time, infecting them and environmental objects, including food products (if they work in food factories).
In addition to sick people and animals, bacteria carriers can serve as sources of infection. Bacterial carriage often occurs after contracting infectious diseases, when both humans and animals release microorganisms into the environment for some time. These are the so-called carriers - convalescents (who have recovered from illness).
Bacteria carriage can also occur as a result of infection of healthy people by sick or convalescent people. Such carriers are considered healthy.
The epidemiological significance of bacterial carriers as sources of infection is extremely high, since they are not detected in a timely manner due to the absence of visible signs of the disease; Bacteria carriers working in the production and sale of food products are of particular importance.
Therefore, the presence of a source of infection is a prerequisite for the occurrence of infectious diseases.
However, the presence of a source of infection does not mean that an infection necessarily arises and spreads among people in its area of influence. The second necessary condition for the emergence and spread of infectious diseases is the presence in the environment of certain factors through which transmission of infection occurs.
Elements of the external environment through which microorganisms are transmitted from an infected organism to a healthy one are called infection transmission factors. These include water, soil, air, food products, household items, apparatus, equipment, utensils, as well as rodents, insects, etc. Depending on the factors, there are water, food, airborne, soil, contact, and transmissible routes of transmission of infectious diseases. diseases.
The most common route of transmission of infection, found in almost all infectious diseases, is contact, i.e. transmission through contact. A distinction is made between direct contact - transmission of infection through direct contact of the skin and mucous membranes with the source of infection and indirect contact - through household and industrial items.
When an infection is transmitted through the air, the pathogen is carried with droplets of mucus released from the respiratory tract of the patient or the bacteria carrier (measles, whooping cough, influenza, diphtheria, tuberculosis, etc.). A number of infections (cholera, typhoid, dysentery, etc.) can be transmitted by water when drinking contaminated water, when swimming in it, when using it for household needs, when washing vegetables, dishes, equipment, etc.
The food route of spread of infections differs from those listed above in that food products can not only transmit infection, but also serve as a favorable breeding ground for the proliferation and accumulation of microbes.
Contamination of food products occurs in various ways: directly from a sick animal from which this product was obtained (milk, meat, eggs), from a sick person or a bacteria carrier during the preparation or processing of products, through equipment, utensils, water, air, etc.
Transmissible is the route of transmission through insect transmitters (mosquito - for malaria, louse - for typhus, etc.).
Soil may be a factor in the transmission of infection. For some infections, the soil is only a place of more or less short-term residence of the pathogen (intestinal infections), from where it can then penetrate water supplies, food products; for other infections, the soil is a place of long-term residence of the pathogen (spore-bearing microbes - anthrax, botulism, wound infections and etc.).
However, for the spread of infectious diseases, the presence of a source of infection (patient or bacteria carrier) and transmission factors (water, food, environmental objects, etc.) is not enough, since immune persons in contact with infected environmental objects, or food, water, or directly with patients or carriers may not get sick. A diagram of the mechanism of transmission of intestinal infections is shown in Fig. 1.
Rice. 1 Scheme of the mechanism of transmission of intestinal infections
1 - infected organism; 11 - healthy body; 1 - excretion of the pathogen; 2 - presence of the pathogen in the external environment; 3 - introduction of the pathogen into the body
The third obligatory condition influencing the occurrence and spread of infectious diseases is the presence of persons susceptible to the disease. Susceptibility is the ability of the human body to become ill when encountering a pathogen.
The intensity and nature of the epidemic depend on the degree of susceptibility of the population to infection.
The immunity of the body as a whole is determined by nonspecific resistance (general protective factors) and specific immunity. Resistance is understood as the body’s nonspecific resistance to the action of various factors.
Nonspecific resistance includes, for example, the ability of the skin and mucous membranes, in the presence of bactericidal substances (lysozyme, interferon, antibodies), to resist the penetration of pathogens of many diseases into the body, regardless of the characteristics of each of them. In other words, nonspecific factors do not have a pronounced selective effect on the pathogen. Nonspecific factors also include phagocytosis, which was discovered by the Russian scientist I. I. Mechnikov. The essence of this phenomenon is associated with the ability of white blood cells (leukocytes) and cells of some body tissues to capture and digest microbes that enter the body. Such cells were called phagocytes (eater cells) by I.I. Mechnikov.
Specific immunity provides protection against only one infection and does not affect the degree of susceptibility to other infections. For example, immunity developed to the causative agent of typhoid fever does not protect against dysentery. Specific immunity can be innate and acquired. In turn, innate immunity is distinguished between species and hereditary (individual). Species immunity is based on the complete immunity of human or animal tissues and organs to certain pathogens. For example, humans are immune to canine distemper and swine fever, animals are immune to cholera, dysentery, typhoid fever, etc. Acquired immunity is formed throughout life - after suffering infectious diseases or as a result of artificial immunization, i.e. vaccinations. Active immunity occurs when vaccines (live weakened or killed bacteria or neutralized products of their vital activity) are introduced into the body; Passive immunity is caused by the introduction of ready-made immune sera (antibodies) into the body.
Consequently, if at least one of the three links is excluded from the epidemic chain - the source of infection, the route of transmission, the susceptible community - the circulation of the pathogen stops, and the disease does not spread further.
However, the body’s susceptibility to infectious diseases and the forms of its manifestation largely depend on social factors - working conditions, living conditions, nutrition, climatic conditions, etc. Social conditions significantly influence the prevalence and activity of sources of infection (patients and carriers), the possibility of transmission and spread infections through various environmental objects and the degree of susceptibility of the population to infection.
Consequently, the principle of the unity of the body and the external environment is reflected in epidemiology and helps to reveal and understand the patterns that underlie the infectious process occurring in an individual and in a team, which is important for the development of scientifically based measures for the control and prevention of infectious diseases.
GENERAL PRINCIPLES FOR PREVENTION OF INFECTIOUS DISEASES
As already indicated, an important role in the epidemic process of the emergence and spread of infectious diseases belongs to social factors.
In our country, much attention is paid to measures aimed at preventing infectious diseases.
Prevention of infectious diseases is a complex of various measures, among which the most important are:
· increasing the level of sanitary culture of the population;
· carrying out government measures aimed at eliminating the causes contributing to the emergence and spread of infectious diseases;
· Carrying out medical activities.
Increasing the level of sanitary culture of the population. The degree of sanitary culture of the population significantly affects the level of all infectious diseases, especially the spread of intestinal infections. A significant reduction in these infections is facilitated by the population mastering hygienic skills. For example, sanitary propaganda in the field of food hygiene, both among the general public and among workers in food enterprises, helps prevent foodborne illnesses, that is, diseases that can be transmitted through food.
Government measures include the constant improvement of working and living conditions of the population, raising their material well-being and cultural level. Reducing the incidence of many infectious diseases depends on housing and housing and communal services construction, construction of water supply and sewerage, proper and timely removal of sewage and waste, etc. Housing conditions can influence not only the spread of sources of infection and the possibility of intensive transmission, but also the state of the general and specific resistance of the population to infection. Thus, the spread of intestinal infections largely depends on the presence of sewerage and water pipes.
Measures to combat infectious diseases are divided into preventive, or precautionary, and anti-epidemic, carried out regarding already existing diseases.
Preventive and anti-epidemic medical measures are aimed at neutralizing the source of infection, breaking the routes of transmission of infection and increasing the level of immunity of the population to this infection.
Dietary conditions and food quality are also of great importance in the spread of infection: eating contaminated foods can lead to the spread of a particular infection; Insufficiency and malnutrition (in particular, lack of vitamins and proteins) can contribute to the spread of infectious diseases by reducing the resistance to it of poorly nourished people.
Neutralization of the source of infection (patient or bacteria carrier) is an important preventative measure for many diseases. The forms of source neutralization are different. Thus, an infected person, as a source of infection, is isolated at home or hospitalized. For the purpose of prevention, for example, intestinal infections and other diseases (tuberculosis, skin diseases, sexually transmitted diseases, etc.), food enterprises, including public catering, provide for mandatory bacteriological and medical examination of persons and employees entering work for timely identification, isolation and treatment of patients and bacteria carriers.
The fight against the spread of infection involves improving the health of the external environment, the objects of which can serve as factors for the transmission of infection. To improve the health of the external environment, general sanitary and disinfection measures are used aimed at preventing the possibility of transmitting infections through contact and household contact through water, soil, food and other environmental objects, as well as improving the entire range of living conditions to increase the overall resistance of the body (collective).
Among the measures aimed at breaking the transmission routes of infection, sanitary control of timely and rational cleaning of populated areas, water supply and sewerage, sanitary regime in public catering establishments, child care institutions, industrial enterprises, etc. plays an important role. This group of measures includes disinfection work in foci of infection and at various facilities.
Disinfection measures are aimed directly at the destruction of infectious agents (causative agents of infectious diseases) and, according to the object of influence, are divided into:
· disinfection - destruction of the infectious principle;
· pest control – destruction of insects that transmit infection;
· deratization - destruction of harmful rodents that are carriers of infection.
All disinfection measures, according to the time of implementation, are divided into current disinfection, which is carried out in the environment of the patient or bacteria carrier in order to neutralize secretions, and preventive (preventive), which is carried out as planned, regardless of the presence of diseases; The object of this disinfection is mainly public places (food factories, transport, train stations).
The population's immunity to infections is increased through specific prevention and chemotherapy.
With active immunization, immunity to this infectious disease is formed. Carrying out chemoprophylaxis of people helps to create a certain concentration of an antibacterial drug in their body, ensuring the death of the pathogen.
An important role in creating the immunity of the population is played by increasing nonspecific resistance, improving nutrition, fortifying food, hardening the body, etc. All measures aimed at eliminating and preventing infectious diseases are carried out simultaneously in all three of the above areas - isolation of the source of infection; disruption of the transmission route; creating population immunity.
INTESTINAL INFECTIONS AND THEIR PREVENTION
Acute intestinal infections include typhoid fever, paratyphoid fevers A and B, dysentery, cholera, infectious hepatitis, etc.
This group of diseases is characterized by the same type of localization of the pathogen (intestines), the same mechanisms and routes of infection (fecal-oral, contact-household), similar intestinal manifestations of the disease (disorder of the intestinal tract), as well as general principles of control and prevention. The only sources of infection are the sick person and the bacteria carrier; with the exception of paratyphoid B, the source of which, besides humans, can be some animals (cattle, pigs, birds).
A special role in the spread of intestinal infections belongs to the food and waterways, which is associated with the long survival of pathogens in water and food. The survival times of pathogens of intestinal infections in food products are shown in Table. 1. As a rule, food products become infected with pathogens of intestinal infections through the dirty hands of carriers or patients with erased forms of the disease; the greatest danger is posed by persons working at food enterprises. Food can become contaminated through contaminated water used to wash food, tableware and kitchen utensils
Contamination of food products is also possible through the transfer of pathogens of intestinal infections by flies and rodents. A great danger in the transmission of infection is posed by infected food products that are not heat-treated before consumption (vinaigrettes, vegetables, fruits, berries, etc.) or become infected after heat treatment (milk, dairy products, cottage cheese, sour cream, various culinary products).
Based on the general patterns of the spread of infectious diseases, the modern system of combating intestinal infections includes measures aimed at neutralizing the source of infection, breaking the paths of its spread and increasing the immunity of the population. In the prevention of these infections, the most important measures are:
1. sanitary improvement of homes, enterprises, streamlining of water supply, removal and neutralization of sewage and waste;
2. timely detection and isolation of bacteria carriers at food enterprises;
3. strict observance of personal hygiene rules by employees of these enterprises, improving their sanitary culture and literacy;
4. compliance with sanitary and hygienic requirements for the maintenance of premises, equipment, inventory, utensils, containers, systematic monitoring of the effectiveness of their sanitization;
5. compliance with established hygienic requirements at all stages of processing, storage, and sale of food products;
6. systematic control of rodents and flies;
7. carrying out preventive vaccinations against intestinal infections according to epidemic indicators.
Table 1
| Product Name | Microbes | Survival time (days) |
| Vegetables and fruits | Typhoid fever stick Paratyphoid microbes Vibrio cholerae |
14 weeks or more |
Butter |
Paratyphoid microbes |
|
Meat, hot smoked fish Raw meat and fish |
Typhoid fever stick Vibrio cholerae Vibrio cholerae |
|
| Yogurt, kefir, yogurt | Paratyphoid microbes | 4 – 8 |
|
sausages |
Paratyphoid microbes Dysentery bacillus Sonne |
|
Rye bread Rye bread crust |
Paratyphoid microbes Dysentery bacillus Sonne |
|
| Wheat bread and buns | Paratyphoid microbes | 15 – 60 |
| Meat cutlets | Dysentery bacillus Sonne | 5 – 8 |
| Jelly | Dysentery bacillus Sonne | 1 – 1,5 – 2 |
| Pate | Dysentery bacillus Sonne | 4 – 7 – 8 |
| Sour cream | Dysentery bacillus Sonne | 11 – 86 |
| Salad | Dysentery bacillus Sonne | 6 |
| Cherries, apples, strawberries | Dysentery bacillus Sonne | 3 – 4 |
| Milk | Dysentery bacillus Sonne | 17 |
| Tomatoes | Dysentery bacillus Sonne | |
| Bread crumb | Dysentery bacillus Sonne | |
| Cottage cheese made from pasteurized milk | Dysentery bacillus Sonne | 4 – 8 |
| Grape | Dysentery bacillus Sonne | |
| Cheese | Vibrio cholerae | A few days |
Typhoid fever, paratyphoid A and B
Typhoid fever and paratyphoid fevers A and B are acute infectious diseases of a bacterial nature. The causative agents of typhoid fever and paratyphoid fevers A and B belong to the family of intestinal bacteria of the Salmonella genus. In terms of morphology, they differ slightly from each other, do not form spores or capsules, and are motile. Based on the type of respiration, they are classified as facultative anaerobes.
The optimal temperature for the development of typhoparatyphoid bacteria is 37 ° C, but they can grow at 25-40 ° C. They can withstand heating up to 50 ° C for 60 minutes, up to 58-60 ° C for 30 minutes, and die instantly at 100 ° C. Solutions of 5% phenol and 3% chloramine kill these pathogens within 2-3 minutes.
From the body of a sick person, the causative agents of these infections are released into the external environment along with feces, urine and saliva. The greatest danger in the dispersion of bacteria is urine, in which the number of bacteria can reach up to 180 million microbial bodies in 1 ml.
These infections are characterized by contact, household, water and food routes of infection.
In the external environment, typhoid paratyphoid bacteria can persist for a long time. They easily tolerate drying and low temperatures; preserved in ice for several months. In running water, typhoid and paratyphoid bacteria survive for 5-10 days, in stagnant water for about a month, in the silt of a reservoir for several months.
The causative agents of typhoid fever and paratyphoid fever remain viable in food products for a relatively long time (see table). These bacteria, depending on the type of food and certain conditions, can remain viable in food products for several days, months and even years (ice cream). Infection with typhoid and paratyphoid pathogens is extremely dangerous, since in certain products these pathogens can not only persist for a long time, but also multiply. Typhoid paratyphoid diseases are characterized by seasonality: the largest number of cases are registered in the summer-autumn period. This is explained by the fact that during this period the conditions for the survival and reproduction of bacteria in the external environment, including in food products, are most favorable.
The incubation period for typhoid fever can last from 7 to 28 days, and for paratyphoid fever - from 2 days to 2 weeks. Isolation of the pathogen from the patient’s body begins at the end of the incubation period V the height of the disease. The disease begins gradually: fatigue, malaise, and headache appear. The temperature also increases gradually and by the end of the first week of illness reaches 39-40 ° C. Starting from the fourth week, the temperature gradually drops and the patient begins to recover. Sometimes the disease occurs in a milder form (usually with paratyphoid fever or sometimes in persons immunized against typhoid fever). Most of those who have recovered from the disease are freed from pathogens, but 3-5% remain carriers for a long time, and some remain carriers for life (chronic carriers).
Chronic bacteria carriers are the main sources of infection.
Dysentery
Dysentery is an infectious disease of a bacterial nature.
Currently, many independent types of dysentery bacilli are known, among which the most common pathogens are Grigoriev-Shiga, Flexner and Sonne.
The prevalence of these pathogens in our country at different periods of time was uneven. So, at the beginning of the 20th century. Grigoriev-Shiga dysentery predominated. In the 30-40s, the proportion of the Flexner pathogen increased everywhere. From the 50s to the present day, the circulation of Sonne sticks has prevailed.
The causative agents of dysentery belong to the genus Shigella . All types of dysentery bacteria are different in their biochemical activity, which, along with other characteristics (toxin formation, antigenic structure), forms the basis for their differentiation. Grigoriev-Shiga bacteria produce exotoxin, other species contain endotoxin. Dysentery bacilli are immobile, do not form spores or capsules, and are facultative anaerobes. The optimal temperature for their development is 37° C. However, Sonne bacilli can develop at a temperature of 40-45° C.
It should be noted that the stability of different types of dysentery bacilli in the external environment is not the same. The more resistant one is the Sonne dysentery bacillus. Thus, it remains viable in river water for 6-35 days, in well water for up to 26 days, and in tap water for up to 92 days. On the surface of the fly's body and in its intestine, the rod is viable for 2 - 5 days.
Unlike other types of dysentery pathogens, the Sonne bacillus can not only survive for a long time, but also reproduce in food products (see Table 1). In addition, the causative agent of dysentery is not less pathogenic than other species, and therefore primarily causes mild and atypical forms of the disease, which often remain unclear and pose a danger to others. Such patients or bacteria carriers working in food factories are especially dangerous.
The incubation period for dysentery is from 7 to 48 hours. The disease caused by the Sonne dysentery bacillus is relatively mild. Typically the temperature rises little or not at all. When the disease occurs, abdominal pain and loose stools appear (the frequency of stools does not exceed 2-5 times), sometimes with an admixture of mucus and blood. In mild forms, the disease lasts from 3 to 8 days, in severe forms it lasts up to several weeks.
Foodborne illnesses
Unlike pathogens of intestinal infections, pathogens of toxic infections are characterized by moderate pathogenicity for humans. Therefore, a prerequisite for their occurrence is the consumption of food and food products richly contaminated with these microorganisms. In other words, toxic infections occur only in cases where favorable conditions are created for the reproduction and abundant accumulation of these microorganisms in a food product and entering the human body with food.
Food toxic infections include salmonellosis (according to the classification of K. S. Petrovsky) and poisoning caused by opportunistic pathogens.
Salmonellosis.
The causative agents of salmonellosis belong to the family of intestinal bacteria of the genus Salmonella. To date, the Salmonella genus includes over 2000 types of Salmonella, of which about 100 types are pathogenic for humans.
The leading role in the occurrence of diseases belongs to S . thyphi murium , Senteriditis , S . cholerae . The most common causative agent of toxic infections is S . thyphi murium(about 65-75% of cases of food poisoning are of salmonella origin). Salmonella are short, non-spore-bearing rods; according to their method of respiration, they are facultative anaerobes. They reproduce well at room temperature, but most intensively at 37°C. Some species do not die when frozen to -48...-82°C and tolerate drying well. Salmonella are resistant to the effects of table salt and remain viable in meat brine (29% salt) for 4-8 months. at a temperature of 6-12°C. They survive in water and on various objects at room temperature for up to 45-90 days.
When heated to 60°C, Salmonella survive for an hour, at 75°C for 5 minutes, and at 80°C they die instantly. Salmonella survive in food products for a relatively long time, and they not only remain viable, but also multiply without causing changes in the organoleptic properties of the products.
Salmonella is widespread in nature. The main reservoir of these pathogens are animals (cattle, pigs, sheep, horses), birds, especially waterfowl (geese, ducks) and pigeons, as well as cats, dogs, rats, mice. The source of salmonella can be sick people or bacteria carriers who have had this infection. Carriage in survivors can last from several days to several years.
The causative agents of salmonellosis are released into the external environment in feces, urine, milk, and saliva.
The most common cause of the disease is meat infected during the life of an animal (endogenously) - a patient or a bacteria carrier. Before slaughter, as a result of weakening of the immune-biological state of the body, organs and tissues are contaminated with Salmonella. If sanitary and hygienic rules are violated, meat can become infected during slaughter, cutting of carcasses, transportation, storage and cooking.
It has been established that in 75-80% of cases the cause of salmonellosis is the consumption of various meat dishes, prepared mainly from cattle meat, less often from pork and poultry meat. Often the cause of salmonellosis is the meat of forcedly slaughtered animals, especially meat that has not been subjected to proper sanitary and veterinary control.
Products made from minced meat (minced meat) pose a great danger, since during the grinding process, salmonella located in the lymph nodes spread throughout the entire mass of minced meat, and if stored incorrectly, they multiply intensively.
Salmonella infections may occur when consuming jelly. Contamination of jelly with salmonella usually occurs when the technology for its production is violated: cooked and crushed substrates are not boiled again; cooked meat is ground on equipment used for raw meat; the jelly cools slowly in a warm room; The jelly storage temperature is not low enough.
The cause of foodborne salmonellosis can be the consumption of liver, blood and other boiled sausages, pasta with minced meat, cooked “navy style”, etc.
Salmonella toxic infections can also occur when consuming eggs and poultry meat, especially waterfowl. The infestation of waterfowl eggs is sometimes 30-40% (V.A. Kilesso). Salmonella infection can be caused by egg powder and melange, the production of which was not carried out in a sanitary manner.
Milk and dairy products are of great importance as a factor in the transmission of salmonellosis. Salmonella can get into milk when the cow's udder is contaminated with intestinal microbes. Diseases that arise from consuming culinary products such as salads, vinaigrettes, etc. are also described.
The incubation period for salmonellosis lasts from 10 to 48 hours. The disease begins acutely: the temperature rises to 38-40 ° C, headache, weakness, loss of appetite, joint pain, sometimes chills, abdominal pain, nausea, vomiting, chair. The illness lasts from 3 to 7 days.
Food intoxication caused by opportunistic pathogens.
Microorganisms that can cause toxic infections, in addition to salmonella, include intestinal And protea sticks , streptococci , perfringens sticks, cereus , pathogenic halophiles and other little-studied bacteria.
According to the literature, about 10% of the total number of toxic infections are caused by opportunistic pathogens. These toxic infections occur when there is a significant accumulation of pathogens in food due to violation of sanitary rules for processing, storage and timing of sales of food products.
E. coli . The group of E. coli is widespread in nature. They live in the intestines of humans, birds, and other warm-blooded animals, with whose excrement they enter the external environment. Escherichia coli are nonspore-free facultative anaerobes, are highly resistant and can persist for a long time in water, soil and other environmental objects. At a temperature of 55 ° C they die only after an hour, at a temperature of 60 0 C - after 15 minutes. When cooking semi-finished products (temperature 65-70°C), they die within 10 minutes. E. coli develop most intensively at a temperature of 37°C. However, they can reproduce at room temperature.
The main source of toxic infections caused by Escherichia coli bacteria is humans.
Most often, diseases occur when consuming ready-made culinary products contaminated with these microbes: meat, fish and especially minced meat. Salads, vinaigrettes, mashed potatoes, milk and dairy products can also cause the disease.
Toxic infections caused by bacteria of the intestinal group are characterized by a short incubation period (4 hours), a rapid course and rapid manifestation of gastrointestinal disorders. Recovery occurs on the 2-3rd day.
Bacteria genus Proteus widespread in nature and known as putrefactive bacteria. Proteus bacteria are motile, sporeless, facultative anaerobes. Their optimal development temperature is from 20 to 37 0 C, however, reproduction can occur at temperatures from 6 to 43 ° C. These microorganisms can multiply at pH 3.5-12; withstand heating to 65° C for 30 minutes; resistant to drying out and high concentrations of table salt. Organoleptic properties of the product with massive contamination with bacteria of the genus Proteus do not change. Among the many representatives of the Protea group, only certain species are capable of causing foodborne illnesses. The most common cause of food poisoning is Proteus mirabitis . Proteus vulgaris found mainly in rotting substrates.
Proteus bacillus remains viable for a long time in the external environment, including in food products.
Human and animal feces can serve as a source of food contamination. The presence of protea in food indicates a violation of the sanitary regime and its shelf life. Raw foods, processed foods and finished products can also be contaminated. According to G.P. Smorodov (1974), based on a survey of 499 patients with Proteus infection, a connection was established between diseases and the consumption of meat and meat products in 33.4% of patients, fruits and vegetables in 18, fish and fish products in 15 .4, dairy products - 7.6%, salads - 3.2%, other products (mushrooms, cakes, etc.) - 18.6% of cases.
In the occurrence of toxic infections of Proteus etiology, contamination of ready-made dishes that have already undergone heat treatment, or cold snacks eaten without additional heat treatment is of great importance. Contamination can occur when cutting boiled or fried meat, vegetables and other prepared foods on the same tables and boards, using the same knives and meat grinders that were used to cut raw foods, especially if kitchen utensils and equipment are kept in an unsanitary condition.
The disease occurs as a type of poisoning caused by E. coli.
Streptococci . They are widespread in nature. Streptococci are found on the skin, mucous membranes and intestines of healthy people, as well as in the external environment - air, water, soil. Streptococci are facultative anaerobes and are gram-positive. Food poisoning is known to be caused by hemolytic, viridans and non-hemolytic strains of streptococci.
The source of contamination of foodstuffs and food with streptococci are sick people and carriers of streptococci, especially among personnel of food enterprises. Therefore, the main thing in the prevention of these poisonings is to improve the sanitary regime of enterprises, as well as the prevention of upper respiratory tract diseases and compliance with personal hygiene rules by food enterprise workers.
Enterococci . This group includes many variants of bacteria that have proteolytic properties and, when highly concentrated in food products, can cause food poisoning.
Enterococci are widespread in nature and are permanent inhabitants of the intestines of humans and warm-blooded animals. They are highly stable in the external environment and can be preserved in food products for a long time. For example, after pasteurization of milk, enterococci remain viable (up to 80% of all residual microflora).
Research (A.P. Kuprina, 1967) has established that enterococci can accumulate massively in a wide variety of food products at room temperature and reach a maximum concentration within 24 hours. The author found enterococci in sausages, ready-made dishes and semi-finished products in 31% of cases in titers 10 -1 - 10 -3.
The basic preventive measures are the same as for poisoning caused by streptococci.
Perfringens stick - it is one of the most common microorganisms in nature. Found in soil, water, food and feed products, human and animal excrement. The perfringens bacillus is spore-bearing and belongs to obligate anaerobes. Currently, six pathogenic types of perfringens are known: A, B, C, D, E and F. Foodborne toxic infections are caused by heat-resistant strains of type A and F, the spores of which can withstand boiling for 1 to 6 hours. The spores of these pathogens persist on pieces of meat (in 20-25% saline solution) for 1.5 months. The perfringens bacillus reproduces most actively at a temperature of 45-46°C. It multiplies in food products at temperatures not lower than 15-20°C. It does not develop in an acidic environment (pH below 4); the toxin forms at pH 5.5 and above. Under favorable conditions, this pathogen can multiply quickly, reaching hundreds of millions per 1 g of product.
Most often, toxic infections are associated with eating meat and meat products (fried, boiled meat, canned meat) that have been stored at room temperature for a long time. In a study of various products from retail chains and catering establishments, Cl.perfringens was found in 33% of raw meat samples, 48% of semi-finished meat products, 100% of minced cutlets and 19% of raw milk samples (Yu. I. Pivovarov).
When microorganisms multiply in food, the appearance of the food and the organoleptic properties of the food change imperceptibly. The exceptions are milk, which coagulates under the influence of the perfringens bacillus, and meat broth, lemon juice, and juices, which become cloudy due to the multiplication of microbes. Great care should be taken when handling canned meat and smoked products prepared at home, since a significant percentage of foodborne toxic infections caused by the perfringens bacillus occur in this category of products.
Due to the fact that the pathogen belongs to spore forms, is resistant to thermal influences, reproduces intensively at relatively high temperatures (45-46°C), the main preventive measures are strict adherence to the regime of technological processing processes, temperature storage conditions (not lower than 60°C) C) ready-made dishes and their timely sale (no later than 3 hours).
Toxic infections caused by perfringens bacillus type A are usually mild; the incubation period lasts 6-12 hours; the disease is accompanied by disorders of the gastrointestinal tract and ends within one day. Poisonings caused by other types of toxin are fatal in 30-40% of cases.
Cereus bacteria are gram-positive rods, spore-bearing, aerobes. Their optimal breeding temperature is 30°C. Spore forms of Cereus can withstand heating up to 105-125°C for 10-13 minutes. Spores germinate already at 3-5°C. These bacteria are a permanent inhabitant of the soil, therefore they are widespread in environmental objects. Cereus bacillus is found in tap water in 43% of cases.
Spore forms You. cereus withstand heating to 70-80°C for 30 minutes and boiling at 100°C for 10 minutes.
The cereus wand is resistant to low temperatures, its spores can withstand deep freezing. It is also resistant to high concentrations of table salt (10-15%) and sugar (30-60%). The cereus bacillus, multiplying in food products of animal and plant origin, does not cause changes in their organoleptic properties.
Poisoning due to consumption of meat, fish, vegetable and confectionery products has been described.
The incubation period for toxic infection caused by the Cereus bacillus is 4-16 hours. The disease is accompanied by abdominal pain, nausea, vomiting, and loose stools. The duration of the disease is 1-2 days.
Pathogenic halophiles . The causative agent of food poisoning is Vibrio, a gram-negative, facultative anaerobe that infects marine fish and crustaceans. The optimal growth temperature is 30-37°C, pH 7.5-8.8.
Diseases caused by this microorganism are most often associated with eating raw seafood or undercooked seafood. The pathogenic halophilic vibrio was first discovered in 1953 in Japan; Currently, this microorganism has been isolated from samples of marine fish from all continents. Microbes multiply mainly in dead fish and, under favorable conditions, quickly accumulate in it.
The disease occurs only when food is heavily contaminated with vibrios (more than 10 6 in 1 g). With the disease, gastrointestinal tract disorder is observed. Recovery occurs in 1-2 days.
Prevention of foodborne diseases.
Measures to prevent microbial contamination of food products of animal origin are aimed at eliminating intravital and post-mortem infection of meat and milk, as well as ensuring the necessary sanitary regime during their receipt and processing. For this purpose, meat processing enterprises carry out constant veterinary and sanitary supervision over slaughter animals, the conditions of slaughter, primary processing and cutting of carcasses. A thorough veterinary and sanitary examination of the meat is carried out.
At food industry, catering and trade enterprises, hygienic requirements for the maintenance of premises, equipment, utensils, utensils and containers must be strictly observed. Particular attention is paid to the placement of cutting lines; Counter flows of raw materials, semi-finished products, finished products, and food waste must be excluded. It is important to provide independent lines for processing poultry meat, especially waterfowl, as well as compliance with sanitary requirements for the maintenance of equipment and tables of these lines.
To protect finished products from bacterial contamination, it is necessary to allocate special personnel, inventory and equipment. Equally important for protecting products from infection is strict adherence by staff to the rules of personal hygiene, increasing their general sanitary literacy and culture.
Mechanization and automation of production processes are of great importance, which makes it easier to work, improve the quality of products and improve the sanitary condition of the enterprise.
With the widespread use of cold and heat in the process of processing and storing food and products, conditions are created that limit the vital activity of pathogens of toxic infections or cause their death.
It is known that even with well-organized veterinary and sanitary control, the possibility of the release of intravitally infected carcasses or their contamination during processing and transportation cannot be ruled out. Therefore, the use of cold when storing food, as well as compliance with the heat treatment regime, are the most effective measures to prevent toxic infection. The same measures include compliance with deadlines for the sale of food products, in particular the rapid sale of finished products. Particular attention should be paid to minced meat products, in which, if the technological processing regime and sales deadlines are violated, abundant development of microflora is possible.
Waterfowl eggs, due to possible contamination with salmonella, are supplied to catering establishments only hard-boiled; intended for the preparation of okroshka, salads and for sale in buffets. They are cooked at special cooking stations: duck eggs - for 13 minutes, goose eggs - 14 minutes from the moment the water boils. The shelf life of boiled eggs: in the presence of cold - up to 5 days, and in the absence of it - 3 days.
Cholera
Cholera is an acute infectious disease. Cholera is considered a particularly dangerous infection, as it is capable of infecting large populations in a short time.
The causative agents of cholera are two types of microorganisms - Vibrio cholerae Koch (classical) and Vibrio El Tor. In terms of their basic morphobiochemical properties, these vibrios differ little from each other. However, cholera caused by the El Tor pathogen has a number of epidemiological features associated with lower pathogenicity. With cholera caused by Vibrio El Tor, there is a significant number of erased atypical forms and the formation of a longer carriage after the disease, as well as healthy carriage. In addition, El Tor vibrio is more resistant to environmental factors. All this can affect the timely identification and isolation of patients.
Vibrios have the appearance of slightly curved rods; they do not form spores or capsules. By type of respiration - obligate aerobes. Vibrio cholerae are able to reproduce at temperatures of 16-40° C. The optimal development temperature is 25-38° C. They are unstable to high temperatures and disinfectants. In a humid environment at a temperature of 80°C they die after 5 minutes, when heated to 60°C they die after 30 minutes, and when boiled, after a minute. They die quickly at a concentration of active chlorine of 0.3 mg per 2 liters of water. Vibrio cholerae is very sensitive to the action of acids, which is taken into account when disinfecting objects in outbreaks and neutralizing the environment. However, cholera pathogens are able to survive for a long time in the external environment. In feces they remain viable for over 3 days, in soil - from 8 to 91, in running water - 3-5, in reservoirs or wells 7-13, in sea water - from 10 to 60 days. Vibrios cholerae survive well in food products. Depending on the type of product and storage conditions, Vibrio cholerae can remain viable for up to a month (see Table 1).
The incubation period lasts from several hours to 5 days. The disease usually begins suddenly. Vomiting and frequent loose stools appear. Fluid loss on the first day can reach 10-15 liters or more. Sometimes there are so-called fulminant forms, which occur without diarrhea and vomiting, but with a rapid onset of death. Mild forms of cholera are often encountered, which are characterized only by intestinal upset, and the patient recovers quickly. These forms of cholera are most often caused by Vibrio El Tor. The period of excretion of cholera vibrios in convalescents and vibrio carriers rarely exceeds 3 weeks and only in exceptional cases does the excretion continue up to 48-56 days. However, there are cases where people who have had the disease periodically excrete Vibrio cholerae for 1-3 years.
CONCLUSION
Having analyzed the above, it is impossible not to dwell on the principles and methods of preventing foodborne infections. Which consist in timely detection of pathogens, prevention of their occurrence, microbiological and sanitary control in the food industry.
GENERAL PRINCIPLES OF MICROBIOLOGICAL AND SANITARY CONTROL IN THE FOOD INDUSTRY
The task of microbiological control is to quickly detect and identify ways of penetration of pest microorganisms into production, foci and the degree of their reproduction at individual stages of the technological process; preventing the development of foreign microflora through the use of various preventive measures; its active destruction through disinfection in order to obtain high-quality finished products. Microbiological control should be carried out systematically by factory laboratories. It is carried out at all stages of the technological process, from raw materials to the finished product, on the basis of state standards (GOST), technical specifications (TU), instructions, rules, guidelines and other regulatory documentation developed for each branch of the food industry. Individual food production facilities have their own microbiological control schemes, which define the objects of control, sampling points, frequency of control, indicate which microbiological indicator needs to be determined, and provide standards for permissible total bacterial contamination.
Microbiological control will be effective and will contribute to significant improvements in the operation of the enterprise. only if it is combined with sanitary and hygienic control, the purpose of which is the detection of pathogenic microorganisms. They are detected by the content of E. coli. Sanitary and hygienic control includes checking the purity of water, air in industrial premises, food products, the sanitary condition of technological equipment, inventory, containers, and the hygienic condition of service personnel (cleanliness of hands, clothes, etc.). It is carried out both by the microbiological laboratory of the enterprise and by sanitary and epidemiological stations according to methods approved by the USSR Ministry of Health.
In food production based on the vital activity of microorganisms, systematic microbiological control is required over the purity of the production culture, the conditions of its storage, dilution, etc. Foreign microorganisms in the production culture are identified by microscopy and inoculation on various nutrient media. Microbiological control of a production crop, in addition to checking its biological purity, also includes determining its physiological state, biochemical activity, the presence of production-valuable properties, reproduction rate, etc. In those food industries where enzyme preparations are used, microbiological control of their activity and biological purity is also required .
Food control.
To assess the quality of raw materials, semi-finished products, auxiliary materials, and finished products in our country, two indicators are mainly used - total bacterial contamination (TBC) and the number of coliform bacteria (mainly E. coli).
General bacterial contamination. It is determined mainly by the cup method. The analysis includes four stages: preparing a series of dilutions from selected samples (when examining the surface of a product or equipment, a sample is taken by washing or scraping from a certain area); inoculation on a standard solid nutrient medium (to identify bacteria - on meat-extract agar in Petri dishes); growing crops within 24 - 28 hours in a thermostat at 30 °C; counting of grown colonies. The number of colonies grown on each plate is recalculated per 1 g or 1 ml of product, taking into account dilution. The final result will be the arithmetic average of the results of counting colonies in 2-3 cups.
The results obtained will be less than the true contamination of the product, since the plate method takes into account only saprophytic mesophilic bacteria (aerobes and facultative anaerobes). Thermophilic and psychrophilic bacteria do not grow due to the discrepancy between the optimal temperature; anaerobes do not grow because cultivation is carried out under aerobic conditions; other bacteria (in particular, pathogenic ones) do not grow due to inconsistency of the nutrient medium and cultivation conditions. Dead cells do not form colonies. However, these microorganisms can be ignored and the analysis error can be neglected, since saprophytes are the main causative agents of food spoilage.
In some industries (canning, sugar, baking, etc.) additional microbiological indicators are used, for example, the number of anaerobic, thermophilic, spore-forming and other microorganisms characteristic of each type of object under study. To take them into account, there are special methodological techniques described in the relevant regulatory documentation. For example, to determine the percentage of spore-forming bacteria, inoculation is carried out from test tubes with sample dilutions, preheated for several minutes in a boiling water bath. During inoculation, only spore-bearing bacteria grow from heated samples, and all the rest from unheated samples. Then the percentage of spore-forming forms of microorganisms is calculated.
The higher the rate of total bacterial contamination, the greater the likelihood that pathogenic microorganisms that cause infectious diseases and food poisoning will enter the object under study. Typically, 1 g (or 1 ml) of a product that has not undergone heat treatment contains no more than 100 thousand saprophytic mesophilic bacteria. If their number exceeds 1 million cells, then the stability of the finished product during storage is reduced and its use can be harmful to human health.
The definition of coliform bacteria is based on the ability of E. coli to ferment lactose into acid and gas. During sanitary and hygienic control of raw materials, semi-finished products, and finished products, testing for the presence of coliform bacteria is limited to the so-called first fermentation test.
Fermentation sample carried out by inoculating test tubes with a special differential diagnostic medium for Escherichia coli (Kessler's medium with lactose) of various volumes (or portions) of the test object - 1.0; 0.1; 0.01; 0.001 ml (or g). Test tubes with inoculations are placed in a thermostat at 37 °C for 24 hours, then they are examined and the fermentation titer is determined, i.e. those test tubes in which growth (turbidity of the medium) and gas formation as a result of fermentation are observed. In the absence of gas formation, the control object is considered not contaminated with E. coli. In the presence of gas formation, the coli titer is calculated for various control objects using special tables. There are standards for permissible total bacterial contamination and E. coli content in control objects.
Water control.
For sanitary and hygienic assessment of water, two microbiological indicators are used: the total number of bacteria in water and the coli index, which are determined in accordance with GOST 18963-73 “Drinking water. Methods of sanitary and bacteriological analysis".
Total bacteria count - this is the number of colonies of aerobic and facultative anaerobic mesophilic saprophytic bacteria that grow when 1 ml of undiluted water is inoculated on meat peptone agar (MPA) for 24 hours at 37 °C.
To assess water quality, the most important thing is not the total number of bacteria, but the presence of pathogenic microorganisms in it. A microbiological indicator of water contamination by pathogenic bacteria of the intestinal group is coli-index . In accordance with GOST 2874-82 “Drinking water, hygienic requirements and quality control,” the total number of bacterial cells in 1 ml of water should be no more than 100, and the coli index should be no more than 3 in 1 liter.
Water analysis is carried out when using the city water supply once a quarter, and if you have your own water supply - once a month.
Identification of pathogenic microorganisms in water (causative agents of typhoid fever, cholera and dysentery) is carried out by local sanitary and epidemiological stations only according to epidemiological indicators.
Air control of industrial premises.
For sanitary and hygienic assessment of indoor air, two indicators are determined.
The first is the total number of saprophytic microorganisms in 1 m 3 of air. The air of food production workshops is considered clean if it contains no more than 500 saprophytic microorganisms per 1 m3. The second indicator is the amount of sanitary indicative microorganisms in the same volume of air - hemolytic streptococci and staphylococci. There are currently no standards for this indicator. Their detection in the air of industrial premises indicates a sanitary problem of this facility and the possibility of infectious diseases among personnel caused by microflora of the respiratory tract, which is transmitted through the air (sore throat, influenza, whooping cough, diphtheria, tuberculosis, etc.). Such air can become a source of contamination of food products, and therefore pose a potential danger to human health. Determination of sanitary-indicative microorganisms in the air is carried out only according to epidemiological indications by sanitary-epidemiological stations.
For sanitary and hygienic air control, sedimentation and aspiration analysis methods are used, the description of which is available in the regulatory documentation.
Control of equipment, inventory, containers.
To prevent contamination of raw materials and semi-finished products by foreign microorganisms during their processing and finished products during storage, a necessary condition is to maintain cleanliness in the workplace, in production premises, sanitary processing of equipment, inventory, and containers.
Under sanitary treatment This means mechanical cleaning of working surfaces from food residues, thorough rinsing with hot water and detergents; disinfection and a final thorough rinse with hot water until the disinfectant (disinfectant) is completely removed. Disinfection aims to destroy the remaining microflora. Equipment can be disinfected by steaming it with saturated steam, which kills both vegetative cells and microbial spores. Disinfection can also be carried out with chemical disinfectants. Final treatment with hot water plays a dual role: on the one hand, disinfectant residues are removed, on the other hand, surfaces are heated, which contributes to their rapid drying.
After sanitary treatment, sanitary and hygienic quality control of washing and disinfection of equipment, inventory, and containers is carried out, which includes determining the total bacterial contamination of washouts from technological equipment; The swabs are taken using sterile stainless metal stencils with the middle cut out (cut area 10, 25 or 100 cm2). This area is wiped with a sterile cotton swab soaked in sterile water in a 10 ml tube. after which the swab is immersed in this test tube, the contents are thoroughly mixed and 1 ml of the swab is inoculated onto meat-extract agar. After thermostatting the crops at 30 °C for 24-28 hours, the total bacterial contamination is determined in terms of 1 cm 2 of the surface under study.
In washouts from well-washed equipment, the total number of microorganisms and coli index should not exceed their content in clean water entering the wash.
It is impossible to control the quality of washing and disinfection of pipelines, sleeves, hoses in this way, since it is difficult to wash off their inner surface using a stencil. In this case, the total number of microorganisms and the coli index are determined in the last wash water by microscopy and culture. The total bacterial contamination and coli index of the wash water should not differ from the indicators of the water used in production. To control the quality of equipment washing and disinfection, samples are taken at the moment when the equipment is prepared for use. Swabs are taken from small equipment (stirrers, probes, thermometers, knives, syringes, etc.) with a sterile swab with the entire surface of the object and examine for the total number of microorganisms and the presence of E. coli. From tables, racks, trays, buckets, shovels, etc., swabs are taken with a sterile swab using a baked stencil and similar analyzes are performed.
To control the quality of washing and disinfection of containers (barrels, cans, tanks), samples of the last wash water are microscopically examined or plated on solid nutrient media. The total number of microorganisms in 1 ml and the coli index should not differ significantly from the contamination of water used in production.
Monitoring the cleanliness of personnel's hands and clothing.
If personal hygiene is not observed (clean hands, clean clothes), especially during manual operations, microorganisms, including pathogenic ones, can come into contact with food products.
Bacterial contamination of hands and clothing is determined by examining the microflora of washings. In swabs taken before starting work, the total bacterial contamination and the presence of E. coli are usually determined. Hand cleanliness is assessed by the number of microorganisms in 1 ml of wash:
The presence of coliform bacteria in washes from hands and clothing is not allowed. Monitoring compliance with the rules of personal and industrial hygiene is carried out by sanitary inspection workers and sanitary posts.
DISINFECTION IN THE FOOD INDUSTRY
To maintain proper sanitary and hygienic conditions at food industry enterprises, an effective way to destroy and suppress the development of foreign microorganisms is disinfection.
Disinfection (disinfection) is the destruction in environmental objects of saprophytic microorganisms - pests of a given production, which cause damage to raw materials, semi-finished products and finished products, as well as pathogenic microorganisms that cause food infections and food poisoning. Disinfection of equipment, inventory, containers, production and service premises of food enterprises is a preventive measure to prevent contamination of products by microorganisms. It is carried out systematically in accordance with established sanitary requirements for each industry. This is the so-called current , or preventive, disinfection.
In addition, at food enterprises it is possible to carry out emergency disinfection according to epidemiological indications:
in case of suspected food poisoning, in case of infectious diseases among personnel, upon receipt of infected raw materials, semi-finished products, containers, etc.
Depending on the type of active agent, disinfection methods can be physical or chemical. Physical means of disinfection include: quartz and ultraviolet irradiation, ultrasound, high temperatures (burning, calcination, boiling, scalding of dishes, containers and equipment, treatment with live steam).
Chemical disinfectants include a large number of chemicals that have an antimicrobial effect.
Effect of antimicrobial chemicals on microorganisms.
In addition to nutritional chemicals that have a positive effect on microorganisms, there are a number of chemicals that inhibit or completely stop their growth. Chemicals cause either microbicidal (death of microorganisms), or microbostatic effect (their growth is suspended, but after the removal of this substance, growth resumes again). The nature of the action (microbicidal or microbostatic) depends on the dose of the substance, the time of its exposure, as well as temperature and pH. Small doses of antimicrobial substances often stimulate the development of microorganisms. As temperature increases, the toxicity of many antimicrobial substances generally increases. Temperature affects not only the activity of the chemical itself, but also microorganisms. At temperatures exceeding the maximum for a given microorganism, even small doses of such substances cause their death. The pH of the environment has a similar effect.
The same microorganism exhibits different degrees of resistance to different antimicrobial substances. The same substance can have different effects on different types of microorganisms - some cause rapid death, others stop their development, and others may have no effect at all. This depends on the presence of spores and capsules that are resistant to chemicals. Antimicrobial substances have a much stronger effect on vegetative cells than on spores.
Of the inorganic substances, salts of heavy metals (mercury, copper, silver), oxidizing agents - chlorine, ozone, iodine, hydrogen peroxide, bleach, potassium permanganate), alkalis and acids (caustic soda, sulfur, hydrogen fluoride, boric) have a strong antimicrobial effect. acids), some gases (hydrogen sulfide, carbon monoxide, sulfur dioxide, carbon dioxide). Organic substances (alcohols, phenols, aldehydes, especially formaldehyde) also have a detrimental effect on microorganisms. The mechanism of the destructive action of antimicrobial substances is different and depends on their chemical nature. For example, alcohols and ethers dissolve CPM lipids, as a result of which they easily penetrate the cell and interact with its various components, which disrupts the normal functioning of the cell. Salts of heavy metals, formalin cause rapid coagulation of cytoplasmic proteins, phenols - inactivation of respiratory enzymes, acids and alkalis - hydrolysis of proteins. Chlorine and ozone, which have a strong oxidizing effect, also inactivate enzymes. Antimicrobial chemicals are used as disinfectants and antiseptics.
Disinfectants substances cause rapid (within a few minutes) death of bacteria; they are more active in environments poor in organic matter, destroying not only vegetative cells, but also spores. They do not cause the emergence of resistant forms of microorganisms. Microbicidal action antiseptics , unlike disinfectants, it appears after 3 hours or more. The greatest activity occurs in environments containing organic substances. Antiseptics destroy only vegetative cells and cause the formation of resistant forms of microorganisms.
Antimicrobial substances such as phenols, chloramine, formalin, in high concentrations (2-5%) are disinfectants, but their solutions, diluted 100-1000 times, can be used as antiseptics. Many antiseptics are used as food preservatives (sulphurous, benzoic, sorbic acids, juglone, plumbagin, etc.).
Disinfectants in the food industry are used, as a rule, to treat the working surfaces of machines and other technological equipment, equipment, containers, utensils and premises. In the food industry, only drugs that do not have a toxic effect on the human body and are odorless and tasteless can be used. In addition, they must have an antimicrobial effect at a minimum concentration, dissolve in water and be effective over a short period of action. Their stability during storage is also of great importance. The preparations should not have a destructive effect on the material of the equipment, they should be cheap and easy to transport.
To treat equipment at food industry enterprises, chlorine-containing substances are mainly used, the disinfecting effect of which is due to the release of active chlorine. Typically, solutions containing 150-200 mg of active chlorine per liter are used for disinfection. The most vulnerable areas in terms of bacterial contamination are treated with solutions containing 400 mg of active chlorine per liter. The duration of equipment processing must be at least 15 minutes. Inorganic chlorine-containing disinfectants include: bleach, antiformin (a mixture of bleach, soda ash and caustic soda), sodium hypochlorite; to organic - chloramine B, new synthetic drugs (dichlorodimethylhydantoin) and complex combinations of new chloroactive compounds with surfactants (for example, sulfochloranthine, which has both a wetting, washing and high antimicrobial effect). Formaldehyde (an aqueous solution of formaldehyde), milk of lime, soda ash and caustic soda are also used as disinfectants.
Organic synthetic disinfectants, the so-called quaternary ammonium compounds, have high antimicrobial activity in small doses. Their advantage over existing antimicrobial agents is that they are highly soluble in water, odorless, tasteless, low toxic to the human body, do not cause corrosion of metals, and do not irritate the skin of personnel’s hands. Among the domestic drugs in this group are cetozol and catamine-AB. The mechanism of action of this class of compounds on microorganisms is not yet entirely clear. It is believed that they damage the cell wall of bacteria, resulting in a sharp increase in cell permeability, denaturation of proteins, inactivation of enzyme systems and lysis (dissolution) of microorganisms.
Many gaseous substances (formaldehyde, sulfur dioxide, ethylene oxide and β-propiolactone) have a strong bactericidal effect.
When using disinfectants to treat equipment, the following general rules must be observed: use them only after thorough mechanical cleaning of the equipment; disinfectant solutions must be freshly prepared; After disinfection, all treated equipment and communications are thoroughly washed until the disinfectant is completely removed.
Drinking water, as well as industrial water, is usually disinfected in a variety of ways - with the help of strong oxidizing agents (large amounts of water - chlorine, small amounts of chlorine compounds, iodine, heavy metal ions), by ozonation, irradiation with ultraviolet rays with a wavelength of 200-295 nm, treatment with gamma radiation, ultrasound.
For air disinfection, chlorine-containing preparations and triethylene glycol in the form of their vapors or aerosols are most often used. These disinfectants reduce the total number of microorganisms in the air by more than 90%. Ozonation and ultraviolet irradiation give good results for disinfecting the air of production workshops and refrigeration chambers. Periodic use of physical (ventilation, filtration) and chemical methods of disinfection, purification and disinfection of air and their combination with wet cleaning of premises can significantly reduce bacterial contamination of the air in industrial and domestic premises.
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