Proteus food poisoning

作者：admin  点击次数：15  发布时间：2025-04-27

Proteus mainly includes P. ulgaris, P. mirabilis, P. morganii, P. ulgaris and P. mirabilis. The first three can cause food poisoning, P. morganii can cause summer diarrhea in infants, and P. morganii is related to histamine poisoning.
1. Pathogens and their biological characteristics
Proteus is a Gram-negative bacillus without spores and membranes. It is widely distributed in soil, sewage and garbage in nature. It is often carried in the intestines of humans and animals. The normal human carrier rate is 1%~10%, and the carrier rate of people with a history of diarrhea can be as high as 50%. The main Proteus that cause food poisoning are P. ulgaris
and P. mirabilis. Proteus is aerobic or facultatively anaerobic, and can reproduce at 4~7℃. It is a low-temperature bacterium, so it can reproduce in food stored at low temperatures. The rate of this bacterium in food is related to the freshness, transportation and storage of the food. The rate of bacteria in humans, animals, and food may vary depending on the season. It is generally higher in summer and autumn, and lower in winter. Therefore, Proteus food poisoning often occurs in summer and autumn, and is more common in July to September. Proteus has weak resistance to heat and can be killed by heating at 55°C for 1 hour or boiling for several minutes.
2. Foods that cause poisoning and sources of pollution
Mainly animal foods, especially cooked meat and cooked products of animal offal, as well as meat of dead livestock. In addition, there are reports of Proteus food poisoning caused by soy products, leftovers, aquatic products, etc. Proteus in food mainly comes from external pollution: ① human carriers contaminate cooked products; ② tools, containers and packaging materials contaminated by Proteus contaminate cooked foods; ③ cross-contamination between raw and cooked foods, mainly due to the fact that the tools and containers for handling raw and cooked foods are not strictly separated during food cooking and processing, and raw and cooked foods are mixed. If contaminated food is stored at higher temperatures in summer and autumn, Proteus will grow and multiply in large quantities in the food. If it is not reheated or heated incompletely before consumption, it will cause poisoning after consumption. It is worth noting that after cooked products are contaminated by Proteus, there is often no change in sensory properties, which can easily be ignored and lead to food poisoning. 3. Clinical manifestations of poisoning
Proteus food poisoning is mainly infectious. The incubation period of this food poisoning is generally 5~8h, 1~3h as short as 60h. The main manifestations are abdominal cramping and acute diarrhea, some accompanied by nausea, vomiting, headache, fever, and body temperature is generally between 38~39℃. The course of the disease is short, and it can generally recover in 1~3d, and death is rare. The prognosis is good. The incidence of Proteus food poisoning is generally 50%~80%, and its level varies with the degree of food contamination and the health status of the eater.
4. Prevention of Proteus food poisoning In addition to preventing pollution, controlling reproduction and thoroughly heating and killing pathogens before eating, the prevention of food poisoning caused by human carriers and cross-contamination of raw and cooked foods should also be controlled. To this end, food companies and catering companies should establish strict hygiene management systems, improve food hygiene, employees should undergo regular physical examinations, and carriers should not engage in related work.
(III) Staphylococcus food poisoning
Staphylococci are widely present in the air, soil, water, feces, sewage and food, mainly from the nasal cavity, throat, skin, hair and purulent lesions of animals and humans.
1. Pathogens and their biological characteristics
Staphylococci are Gram-positive facultative anaerobic bacteria without spores. There are 19 species in this genus, and 12 species have been detected from the human body, such as Staphylococcus aureus (S.aureus), Staphylococcus epidermidis (S.epidenmidis) and saprophytic Staphylococcus saprophyticus (S.saprophyticus). Staphylococcus aureus is highly resistant and can survive for several months under dry conditions. It is more resistant to heat than general non-spore bacteria. It is killed by heating to 80℃ for 30 minutes. The optimal growth temperature is 30~37℃. It can grow between pH 4.5~9.8, and the optimal pH is 7.4. Because it can tolerate low water activity (0.86), it can reproduce in foods with high salt (10%~15%) or high sugar concentration. Staphylococcus aureus is the most common staphylococcus that causes food poisoning. It is estimated that more than 1 million cases of food poisoning in the United States are caused by this bacterium each year. Recent research reports have shown that more than 50% of Staphylococcus aureus strains can produce enterotoxin under laboratory conditions. This enterotoxin is a simple protein, but it is not affected by trypsin and has strong heat resistance. It does not lose its activity when heated at 100℃ for 1.5 hours. Therefore, it cannot be destroyed by general cooking temperatures. It can only be destroyed by 30 minutes in 218~248℃ oil. Staphylococcus food poisoning often occurs in summer and autumn, but can also occur in other seasons.
2. Foods that cause poisoning and sources of contamination
The most common poisoning foods in China are milk and dairy products, eggs and egg products, and various cooked meat products, followed by frozen foods containing dairy products, and some foods containing starch. The main sources of food contamination are people and animals that carry bacteria. ① Patients with purulent skin diseases, acute upper respiratory tract inflammation, and oral diseases, or healthy people's throats, nasal cavities, skin, and hair often carry enterotoxin-producing strains, and contaminate food through hands, droplets, or air (the nasal and pharyngeal carrier rate of healthy people is generally 20%~30%). ② When dairy animals suffer from mastitis, 60% of the pathogens are caused by staphylococci. Therefore, the milk of dairy animals suffering from mastitis often contains enterotoxin-producing staphylococci. ③ When livestock and poultry meat suffer from local suppurative infections, the staphylococci in the infected area contaminate the meat or other foods.
After food is contaminated by staphylococci, if it is stored at a temperature of about 37°C with poor ventilation and reduced oxygen partial pressure, enterotoxins are easy to form. In addition, the more serious the degree of food contamination, the faster the staphylococci reproduce and the easier it is to form toxins.
3. Clinical manifestations of poisoning
Staphylococcal food poisoning is mainly caused by enterotoxins, which act on the abdominal viscera and stimulate the vomiting center of the medulla oblongata through nerve conduction, resulting in food poisoning with vomiting as the main symptom. It is characterized by an acute onset and a short incubation period, generally 2 to 3 hours, and often within 4 hours. The main symptoms are nausea, severe and repeated vomiting, abdominal pain and other gastrointestinal symptoms.