Escherichia coli food poisoning

作者：admin  点击次数：15  发布时间：2025-04-29

Escherichia is commonly known as Escherichia coli. Escherichia coli is often isolated from Escherichia. In 1885, Buchner first described Escherichia coli. In 1886, Esch-erich found similar bacteria in feces and called it Escherichia coli. In 1945, British Bray found that the diarrhea-type mass poisoning of young children was caused by Escherichia coli, so the bacteria is also called pathogenic Escherichia coli. In 1996, 6259 elementary school students in 62 elementary schools in Sakai City, Osaka, Japan were infected with enterohemorrhagic Escherichia coli 0157:H7, of which 92 cases were complicated with hemorrhagic colitis and hemorrhagic uremia, and several students died. Subsequently, it spread to 36 prefectures in Japan, with 9451 patients and 12 deaths, shocking the world. In 2001, the enterohemorrhagic Escherichia coli 0157:H7 food poisoning that broke out in Jiangsu, Anhui and other places in China caused 177 deaths and more than 20,000 poisonings.
1. Pathogens and their biological characteristics
Escherichia is a group of Gram-negative rods. Escherichia coli mainly exists in the intestines of humans and animals and is excreted in nature with feces. This genus is a normal intestinal flora, usually non-pathogenic, and sometimes can synthesize a considerable amount of vitamins and inhibit the reproduction of a type of bacteria that decomposes protein. This bacterium has strong survival in nature and can survive in soil and water for several months. The minimum water activity for its reproduction is 0.96~0.935. There are also pathogenic Escherichia coli. When the human body's resistance is weakened or people eat food contaminated by a large number of live pathogenic Escherichia coli, food poisoning often occurs. Currently known pathogenic Escherichia coli include the following four types:
(1) Enterotoxigenic Escherichia coli (ETEC) is similar to Vibrio cholerae and can produce enterotoxins that cause severe diarrhea and cholera-like acute gastroenteritis symptoms (rice-like stools), but does not invade intestinal epithelial cells. It is the main pathogen of diarrhea in infants and young children and travelers. (2) Enteroinvasive Escherichia coli (EIEC) This bacterium has the ability to invade intestinal epithelial cells and multiply inside the cells, causing local inflammation and ulcer formation, resulting in bacillary dysentery-like symptoms. However, this bacterium does not have the ability to produce enterotoxins and mainly invades older children and adults.
(3) Enteropathogenic Escherichia coli (EPEC) does not produce enterotoxins. The invasion points are the duodenum, jejunum and upper ileum. It is the main pathogen of diarrhea in infants and young children.
(4) Enterohemorrhagic Escherichia coli (EHEC) The main serotype reported recently is Escherichia coli 0157:H7, which can produce a certain cytotoxin (Vem toxin) and has a strong pathogenicity. It mainly infects children under 5 years old, and the clinical feature is hemorrhagic colitis.
Pathogenic Escherichia coli has weak resistance to heat and can be killed at 60℃ for 15~20min.
2. Foods causing poisoning and contamination routes
The season of occurrence and food causing poisoning of Escherichia coli food poisoning are similar to those of Salmonella food poisoning. The main reason for food contamination: Pathogenic Escherichia coli exists in the intestines of humans and animals. The rate of pathogenic Escherichia coli in the intestines of healthy people is 2%~8%; the rate of pathogenic Escherichia coli in patients with adult enteritis and infant diarrhea is higher than that of healthy people, reaching 29%~52%. Pathogenic Escherichia coli is excreted with feces and contaminates water sources and soil. Contaminated soil, water and the hands of carriers can contaminate food, or contaminate food through contaminated utensils.
3. Clinical manifestations of poisoning Different pathogenic Escherichia coli have different pathogenic mechanisms, resulting in different clinical manifestations: (1) Acute gastroenteritis type The incubation period is generally 10-15h, the shortest is 6h, and the longest is 72h. It is mainly caused by ETEC and EPEC. It is a typical symptom of pathogenic Escherichia coli food poisoning and is relatively common. Patients may have symptoms such as fever (38~40℃) and headache. Typical manifestations are diarrhea, upper abdominal pain and vomiting. The stool is watery or rice soup-like, 4 or 5 times a day. Severe vomiting and diarrhea may lead to dehydration, and the course of the disease is 3~5d.
(2) Acute bacillary dysentery type The incubation period is generally 48~72h. It is mainly caused by EIEC. The main manifestations are bloody stools, pus, mucus, bloody stools, tenesmus, abdominal pain, and some patients have vomiting. Fever 38~40℃, which can last for 3~4 days, and the course of disease is 1~2 weeks.
(3) Hemorrhagic colitis type has been proven to be caused by EHEC, and its causative bacteria are mainly Escherichia coli 0157H7. The prodromal symptoms of poisoning are abdominal cramps and short-term self-limiting fever and vomiting. Non-bloody diarrhea occurs within 1~2 days, and then leads to hemorrhagic colitis with severe abdominal pain and bloody stools.
4. Prevention
(1) Same as Salmonella food poisoning.
(2) Pay special attention to personal hygiene and develop hygienic habits.
(3) Pay attention to environmental hygiene, especially strengthen the sanitation control of human and animal feces, sewage treatment and sewers to avoid food contamination.
(VII) Clostridium botulinum food poisoning
Clostridium botulinum food poisoning, also known as botulism, is a type of food poisoning caused by the ingestion of Clostridium botulinum toxin. Although the incidence of bacterial toxin-type food poisoning is not high, it is one of the food poisonings with the highest mortality rate, which can be as high as more than 50%, so botulism is a serious food poisoning. 1. Pathogens and their biological characteristics Clostridium botulinum (Clostridium botulinum), also known as Clostridium botulinum (botulinum), is a Gram-positive anaerobic bacterium that can produce exotoxins, namely botulinum toxin. At a temperature of 20~25℃, it forms oval spores that are thicker than the bacterial body. When the pH is lower than 4.5 or greater than 9.0, or when the ambient temperature is lower than 15℃ or higher than 55℃, Clostridium botulinum cannot reproduce and does not produce toxins. This bacterium is not resistant to heat and can die after heating at 80℃ for 10~15min, but it has strong resistance after forming spores. It needs to be treated with high-pressure steam at 121℃ for 30min, dry heat at 180℃ for 5~15min, or wet heat at 100℃ for 5h to kill it. Clostridium botulinum is widely distributed in nature, especially in soil, where it is detected at a high rate.
Clostridium botulinum food poisoning is caused by botulinum toxin. Botulinum toxin is a strong neurotoxin that inhibits the release of acetylcholine, a neurotransmitter, leading to muscle paralysis. In severe cases, it can cause cranial nerve paralysis. Clostridium botulinum food poisoning is not only caused by eating food contaminated with botulinum toxin, but also by the germination and reproduction of spores (or propagules) ingested with food in the intestines to produce toxins, which can also cause poisoning.
Botulinum toxin is the most toxic chemical poison and biological toxin known to date, with an absolute lethal dose of about 0.148 for humans. Botulinum toxin is very stable to digestive enzymes (pepsin, trypsin), acid and low temperature. The toxin cannot be destroyed in normal gastric juice for 24 hours, but alkali and heat can easily destroy it and make it lose its activity. For example, it can be completely destroyed by heating to 100℃ for 10~20min or 80℃ for 30min. It is also easily destroyed in a solution with pH>9. 2. Foods that cause poisoning and sources of contamination
Botulinum food poisoning can occur all year round, but most cases occur from March to May, and also from January to February. The types of food that cause poisoning are often related to eating habits. In Xinjiang, my country, poisoning is mostly caused by home-made fermented bean and grain products, such as stinky tofu, bean paste, fermented black beans and noodle sauce; in Qinghai, it is mainly caused by meat products that are sealed and stored over the winter; in the UK, it is mainly poultry meat; in other European countries (Germany, the Netherlands, Belgium, etc.), the main foods that cause poisoning are mostly ham, sausage and other meat products; in the United States, it is mainly caused by home-made canned fruits and vegetables, aquatic products, meat and dairy products; in Japan, the most poisoning cases are caused by home-made fish and fish roe products. Sources of Clostridium botulinum in food: Clostridium botulinum is widely present in soil, plant kingdom, animal feces, seabed, lake water and river water. The main source of food contamination by Clostridium botulinum is soil. Grains, vegetables, fruits, meat, fish, etc. contaminated by soil may carry Clostridium botulinum or its spores. After food is contaminated by Clostridium botulinum or spores, Clostridium botulinum multiplies and produces toxins under suitable temperature and humidity, low osmotic pressure and acidity, and anaerobic conditions. If it is not thoroughly heated before consumption, it will cause food poisoning.
3. Clinical manifestations of poisoning Clostridium botulinum food poisoning is a neurological food poisoning, and its symptoms are mainly neurological symptoms, and gastrointestinal symptoms are rare. The main symptoms are: dizziness and weakness at first, followed by symptoms of ophthalmoplegia such as blurred vision, ptosis, diplopia, poor eye movement, etc. (ophthalmoplegia symptoms are specific symptoms of this poisoning, and almost all patients are no exception): chewing weakness, difficulty opening the mouth, difficulty swallowing, neck muscle weakness, head drooping, etc., and finally respiratory muscle paralysis occurs, causing difficulty in breathing and death. Most patients are conscious and do not have a fever.
The incubation period of Clostridium botulinum food poisoning is longer than that of other bacterial food poisoning, generally 1~7 days or longer. The mortality rate of food poisoning caused by Clostridium botulinum is high. If antitoxin treatment is not available, the mortality rate is 30% to 70%. The shorter the incubation period, the higher the mortality rate. In recent years, polyvalent anti-botulinum toxin serum has been widely used in China to treat this disease, and the mortality rate has dropped to below 10%. After treatment, patients recover after 4 to 10 days and generally have no sequelae.
4. Prevention
(1) Thoroughly clean food ingredients. Fresh ingredients should be used during food processing to avoid soil contamination. Before processing, the attached mud and sand should be thoroughly washed off.
(2) Thoroughly sterilize canned food. When producing canned food, strictly follow the operating procedures. If fat tints appear during storage, they should be inspected. If they cannot be inspected, they should be discarded.
(3) Prevent the production of toxins. Processed food should avoid re-contamination and storage at high temperatures or under hypoxic conditions to prevent the production of botulinum toxin.
(4) Thoroughly heat food before consumption. Generally, the temperature is 100℃ for 10 to 20 minutes to destroy various types of toxins.