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Nutritional Bacterial Toxicosis
Bacterial toxicosis includes staphylococcal toxicosis and botulism.
Staphylococcal toxicosis (staphylococcal intoxication, staphylococcal food poisoning). It makes up more than 30% of all bacterial food poisoning.
Among the vast group of staphylococci, pathogenic and non-pathogenic species are distinguished. Pathogenic staphylococci cause inflammatory diseases of the skin, nasopharynx, etc., as well as food poisoning.
Staphylococcus aureus (Staphylococcus aureus) is g + cocci, facultative anaerobes, optimal development temperature of 37 ° C, grow well on substrates rich in carbohydrates and proteins. Most of these bacteria form a golden pigment. Some types of Staphylococcus aureus produce enterotoxin, while others do not. Food poisoning is caused only by S. aureus, capable of producing enterotoxin (enterotoxigenic strains), which is the direct cause of intoxication. Currently, six serological types of staphylococcal enterotoxins have been identified: A, B, C, D, E, F.
The temperature limits of the reproduction of Staphylococcus aureus are from 7 ° C to 50 ° C. Toxin formation is observed in the temperature range of 19-39 ° C, but optimal toxin formation is observed at 28-37 ° C.
At a temperature of 7-19 ° C and 39-50 ° C, staphylococcus can develop, but there is no toxin formation. At a refrigerator temperature of +4 - +6 ° C, staphylococcus does not grow and, therefore, does not form a toxin.
Staphylococcus aureus tolerates heating at a temperature of 80 ° C for 10 minutes. High concentrations of sodium chloride (more than 12%) and sugar (more than 60%) inhibit the development and propagation of staphylococcus. The acid reaction of the medium is unfavorable for staphylococcus - at pH 4.5 and below, its growth stops. In frozen foods, it is viable for several months, at a normal storage temperature of more than 4 months.
Staphylococcus enterotoxin is resistant to high and low temperatures, chlorine, does not inactivate when heated to 100 ° C for 30 minutes. It finally breaks down when boiling only after 2.5-3 hours, and at a temperature of 120 ° C - after 20 minutes. Enterotoxin is sensitive to an acidic environment - at a pH below 3.0 it is completely destroyed.
The source of food contamination with pathogenic staphylococci is a person. The most common way of food contamination is by airborne droplets, since patients with staphylococcal diseases of the upper respiratory tract (tonsillitis, rhinitis, pharyngitis, etc.) actively release them into the environment when breathing, coughing, sneezing. A dangerous source of contamination of products is workers with staphylococcal skin lesions (festering cuts, burns, abrasions, abscesses) who contaminate staphylococci with equipment, tools, utensils, etc.
Of great epidemiological importance in the spread of staphylococcal foodborne diseases are bacterial carriers. Pathogenic staphylococcus is found in the nasopharynx of almost every second person.
Staphylococcal infections are also caused by animals with mastitis and other inflammatory diseases. Products of animal origin can become infected with staphylococci during the life of animals (milk with mastitis) or when cutting carcasses.
Under favorable conditions, intensive development of staphylococci and toxin formation in a wide variety of products (dairy, meat, fish, vegetables) is possible. As a rule, foods seeded with Staphylococcus aureus do not have external signs of spoilage.
A favorable environment for the development of staphylococci is milk. This is confirmed by the frequency of intoxication caused by milk and its processed products. At a temperature of 35-37 ° C, enterotoxin is formed in milk after 5-8 hours, and at room temperature (18-20 ° C) - after 8-18 hours. The cause of intoxication may be cottage cheese and curd products made from unpasteurized milk, rennet cheese, sour cream, feta cheese. The formation of enterotoxin is also possible in boiled and pasteurized milk, in the curd mass during the infection of these products after heat treatment. Cases of poisoning by ice cream made from milk containing enterotoxin are known.
A particularly favorable environment for the propagation of staphylococci and the formation of enterotoxin is confectionery with custard, which contain a lot of moisture, starch and a relatively high concentration of sugar. Enterotoxin is formed in custard at a temperature of 30 ° C after 12 hours, and at 37 ° C - after 4 hours. At a temperature of +4 ° C, the toxin does not accumulate.
Meat and meat products are a good environment for the development of staphylococci. Enterotoxin in minced meat and portioned meat (raw and cooked) accumulates at a temperature of 35-37 ° C after 14-16 hours, in a paste - after 10-12 hours, in finished cutlets at room temperature - after 3 hours.
Staphylococcal food poisoning can occur with the use of canned fish, the taste and smell of which does not change, bombing is not observed.
Perhaps the intensive production of enterotoxin in plant products. So, in mashed potato enterotoxin at room temperature storage accumulates after 5-8 hours. Food toxicosis is known when consuming okroshka, semolina and wheat porridge and other dishes. It should be noted that food products that have undergone heat treatment and are freed from antagonist microbes are more often the cause of staphylococcal intoxication than raw unprocessed foods.
The incubation period for staphylococcal toxicosis is from 30 minutes to 3 hours. Nausea, repeated vomiting, sharp cramping abdominal pains are observed. The temperature is usually normal, loose stools are not always. Recovery in 1-3 days. Children can have severe forms.
Preventive measures to prevent contamination of pathogenic staphylococci with food products include the timely detection of people with purulent inflammatory processes of the skin, upper respiratory tract (tonsillitis, catarrh, etc.) and their removal from contact with food. A special place belongs to the observance of personal hygiene rules by workers engaged in the manufacture of finished culinary and cream products.
It is extremely important to create conditions that prevent the formation of enterotoxin in foods. For storage, the optimum temperature is 2-4 ° C, at which the multiplication and accumulation of enterotoxin do not occur. Of great importance is also the observance of the established terms for the sale of perishable products.
Equally important in the prevention of staphylococcal toxicosis is ensuring a high sanitary level, improvement and mechanization of production processes, as well as a systematic increase in hygienic knowledge on the prevention of food poisoning.
Botulism is one of the most severe food poisoning. It occurs when eating foods containing toxins of botulinum bacillus.
The name of the disease comes from lat.
botulus, which refers to sausage, since at first this disease was associated with sausage and ham.
The causative agent of botulism is widespread in nature. It lives in the intestines of humans, warm-blooded animals, fish, rodents, birds, is found in soil, silt of water bodies.
Clostridium botulinum - a spore-forming stick in the form of a tennis racket, a strict anaerobic, emits toxin and gas. Seven types of pathogen are known - A, B, C, D, E, F, G, differing in the structure of the toxin. The most toxic is type A. In Russia, mainly types A, B, and E. are found. Toxins of each type are neutralized only by the corresponding antitoxic serum.
Vegetative forms of the pathogen are unstable in the environment - they die at a temperature of 60 ° C.
Spores of botulinum bacillus are extremely resistant. Complete destruction is noted at a temperature of 100 ° C for 5-6 hours, at a temperature of 105 ° C - for 2 hours, at a temperature of 120 ° C, spores die in 10-12 minutes. Spores are resistant to low temperatures and remain viable for over a year in refrigerators at a temperature of -16 ° C. They tolerate drying well, remaining viable for about a year, resistant to various chemical agents.
The causative agent of botulism is sensitive to an acidic environment, its development stops at pH 4.5 and below. This property is widely used in the production of canned food, as as in an acidic environment botulinum does not emit toxin. High concentrations of sodium chloride (8%) and sugar (55%) inhibit spore germination.
Optimum conditions for the development and toxin formation of botulinum bacillus are created at a temperature of 25-30 ° C. At a temperature of 15-20 ° C, microbial reproduction and toxin formation proceed more slowly and completely cease at a temperature of 4 ° C (with the exception of type B).
Botulism toxin (botulinum toxin) is the strongest of all known bacterial toxins. It is a nerve poison. The lethal dose for humans is 5-50 ng / kg body weight. In an acidic environment, the toxin is stable, and in a slightly alkaline (pH 8.0), it loses activity by 90%. It is highly resistant to preservatives - salting, freezing, pickling. Therefore, if the toxin has already accumulated in the food product, then canning does not inactivate it.
The resistance of the toxin to high temperatures is relatively low: when heated to 80 ° C - the toxin is destroyed after 30 minutes, at 100 ° C - within 10 minutes. In this regard, high temperature is one of the most important ways to combat botulism toxin. So, the toxin is inactivated by boiling pieces of meat, fish and other products for 50-60 minutes.
The causative agent of botulism enters food products in different ways: meat can be seeded during slaughter and carcass cutting; seeding of fish can occur through the outer covers when they are damaged during fishing or through the intestines; plant products are seeded by spores across the soil.
The causative agent of botulism is capable, under favorable conditions, of reproduction and toxin formation in many products of animal and plant origin. Botulism occurs mainly when consuming canned foods without prior heat treatment; when using canned foods with low acidity; raw smoked ham; meat and fish slightly salted dried and smoked products.
The most favorable conditions for the development of Clostridium botulinum are the anaerobic conditions of canned foods. In meat, fish and other canned food, the propagation of the pathogen is accompanied by the release of gases that cause persistent microbiological bombardment. At the same time, the organoleptic properties of the product do not noticeably change, sometimes there is only a faint smell of rancid fat.
The vast majority of cases of botulism are associated with the use of home-canned foods: salted and pickled mushrooms in hermetically sealed jars; salted, dried and smoked fish; canned vegetables and fruits and berries; canned meat; sausages; smoked ham and others. The greatest danger is mushrooms and vegetables with low acidity in rolled up jars. The mode of processing canned food at home does not ensure the death of spores of the botulinum bacillus.
In products with a dense consistency, the accumulation of toxin can be observed in separate places as a result of the created anaerobic conditions that contribute to the reproduction of the pathogen. This can explain the cases of poisoning not all people who consumed the same product.
The incubation period is from 2-12 hours to 7 days. The shorter the incubation period, the harder the disease.
The first typical signs of botulism, the toxin of which affects the central nervous system, are dry mouth, blurred vision, double vision, “fog” and “mesh” before the eyes, drooping eyelids. At the same time, speech and swallowing disorders occur due to muscle paralysis - the voice becomes weak, speech is slurred, swallowing and chewing are difficult. Then, respiratory muscle paralysis, respiratory arrest, and death can occur very quickly. The duration of the disease varies, on average, from 4 to 8 days. The prognosis for botulism is always serious. In the absence of adequate therapy, mortality is about 25%.
A highly effective therapeutic agent is the introduction of antitoxic anti-botulinum serum on days 1-3, which prevents death.
Botulism prophylaxis should be aimed at strict observance of sanitary-technical and health-improving measures in all branches of the food industry, prevention of the pathogen entering the raw materials, prevention of spore germination and propagation of vegetative forms, as well as the formation of toxin in the finished canned product (creation of aerobic conditions and acidic environment, proper heat treatment).
An effective measure to prevent the development of the causative agent of botulism in food products includes the rapid processing of raw materials and the timely removal of entrails. So, in deer fish (especially sturgeon), botulinum from the intestine penetrates the muscles relatively quickly and multiplies with the release of toxin. In the manufacture of ham, it is also necessary to exclude contamination of the carcasses with the contents of the intestine, and salted the ham in cold conditions.
It is not recommended that homemade cooking of hermetically sealed canned food from mushrooms, meat, fish. It is unacceptable to preserve poorly washed mushrooms (especially lamellar), stale and spoiled fruits and vegetables. Canned food with a sign of bombing is not allowed for sale.
An important factor in the prevention of botulism is public health education on the rules for the preparation, conservation and storage of food.
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