Vibrio parahaemolyticus food poisoning

作者：admin  点击次数：15  发布时间：2025-04-28

Vibrio parahaemolyticus is also known as pathogenic halophilic bacteria, also known as enteritis Vibrio. It mainly exists in offshore seawater, bottom sediments and seafood such as fish and shellfish. In 1950, a sardine food poisoning incident occurred in Osaka, Japan, with 120 patients, of whom 20 died. In 1955, the bacteria was also isolated from the feces of patients in Zhangchuan, China. 1. Pathogens and their biological characteristics
Vibrio parahaemolyticus is a halophilic bacterium that often appears in various forms such as arc, rod, and filament. It is a Gram-negative, non-spore-forming facultative anaerobic bacterium.
Vibrio parahaemolyticus is widely distributed in seawater. The growth and reproduction of this bacterium requires a certain amount of salt and cannot grow on a salt-free culture medium. It can grow and reproduce rapidly in an environment with a temperature of 30~37℃ and a salt content of about 3%, and the optimal pH is 7.4~8.2. The resistance of this bacterium is relatively weak. It can be killed by heating at 55℃ for 10 minutes or 90℃ for 1 minute. It has weak resistance to low temperature and can die after 24~48 hours at 0~2℃. It is sensitive to acid and cannot grow when the pH is less than 6. It can be killed by treating it with 1% acetic acid for 1 minute. The survival time of this bacterium in fresh water generally does not exceed 2 days, but it can survive up to 50 days in seawater. Some strains of Vibrio parahaemolyticus can produce heat-resistant hemolytic toxins under certain conditions, which can dissolve human or immune blood cells. This phenomenon is called the "Kanagawa phenomenon". The Kanagawa phenomenon is related to the pathogenicity of Vibrio parahaemolyticus. About 90% of Vibrio parahaemolyticus detected in patients' feces are positive for the Kanagawa phenomenon. Vibrio parahaemolyticus food poisoning has obvious regional and seasonal characteristics. The incidence rate is higher in coastal areas of my country and Japan that like to eat seafood. Summer and autumn, especially June to September, are the peak seasons for Vibrio parahaemolyticus food poisoning. In addition to the temperature and humidity conditions, the most significant feature is that it is related to the listing of seafood. 2. Foods that cause poisoning and pollution sources
Since Vibrio parahaemolyticus is widely distributed in seawater, the infection rate of marine fish, shrimp, shellfish and other seafood is very high, and they are the main foods that cause this type of food poisoning. Sources of Vibrio parahaemolyticus in food:
(1) Contamination of seafood by Vibrio parahaemolyticus in offshore seawater and seabed sediments According to surveys, the infection rate of Vibrio parahaemolyticus in several major seafoods is: 40% to 90% for hairtail, 79.8% for sea crab, 93% for cuttlefish, and 35% for cooked saltwater shrimp. The infection rate of seafood varies in different seasons. The infection rate is lower in winter, or even negative; the infection rate is higher in summer, averaging 94.8%.
(2) Contamination of various foods by carriers in the population. The rate of Vibrio parahaemolyticus carriers in coastal areas of food service workers, healthy people and fishermen is 11.7%, and the rate of carriers in people with a history of intestinal diseases can reach 31.6% to 88.8%. Carriers can contaminate various foods.
(3) Indirect contamination. The rate of Vibrio parahaemolyticus carriers in cooking utensils used in coastal areas is 61.9%. If food containers, cutting boards, kitchen knives and other tools for handling food are not distinguished between raw and cooked, Vibrio parahaemolyticus can contaminate cooked food or cold dishes through these tools.
(4) Flies carry bacteria and contaminate food.
In addition, domestic sewage and feces are also important sources of contamination. If the contaminated food is stored at a high temperature, not heated before eating (raw food) or heated incompletely, and not cooked thoroughly; or the food is re-contaminated after cooking, Vibrio parahaemolyticus can enter the human intestine with the food and cause food poisoning.
3. Clinical manifestations of poisoning The main cause of Vibrio parahaemolyticus food poisoning is the entry of a large number of live bacteria into the intestines, and it can also be caused by the heat-resistant hemolytic toxins it produces. Characteristics of poisoning: acute onset, incubation period is generally 11~18h, the shortest is 4~6h, the longest is 32h, and the condition is more serious with a short incubation period. The main symptoms are abdominal pain, diarrhea (mostly watery stools, and mucus and bloody stools in severe cases), nausea, vomiting, and the body temperature is generally 37~38℃. There are also symptoms such as headache, sweating, and thirst. The prognosis of Vibrio parahaemolyticus food poisoning is generally good. Most patients recover to normal 2~3 days after onset, and a few severe patients die due to shock and coma. The incidence rate is 35%~90%.
4. Prevention
The prevention of Vibrio parahaemolyticus food poisoning is basically the same as that of Salmonella food poisoning. In addition, special attention should be paid to the cooking of aquatic products. They should be cooked thoroughly and never eaten raw. For raw aquatic products (such as seafood), they must be soaked and preserved in 40% salt water (saturated salt water). They should be rinsed repeatedly with clean water or soaked with vinegar before eating.
(V) Food poisoning caused by Bacillus cereus
Bacillus cereus is a bacterium that has been causing an increasing trend of food poisoning in recent years. On December 29, 2005, the Korean government announced that kimchi and other products would be tested for Bacillus cereus, with a standard of 10,000 cfu/g.
1. Pathogens and their biological characteristics Bacillus cereus is a Gram-positive, aerobic bacillus that can grow under anaerobic conditions. Generally, spores are formed after 6 hours of growth. It is a conditional pathogen. The optimal temperature for the growth and reproduction of this bacterium is 28~37℃, and it will not reproduce below 10℃. Its reproductive bodies are relatively heat-resistant and need to be killed by heating at 100℃ for 20 minutes, while the spores can withstand heating at 100℃ for 30 minutes, or dry heat at 120℃ for 60 minutes to be killed. The bacteria can grow in the pH range of 6~11, and its growth and development is significantly inhibited below pH5.
Bacillus cereus is divided into strains that produce and those that do not produce enterotoxins. Among the strains that produce enterotoxins, there are two different types of enterotoxins, one of which causes diarrhea (diarrhea toxin) and the other causes vomiting (vomitotoxin). Diarrhea enterotoxin is not heat-resistant and can be inactivated by heating at 45℃ for 30 minutes or 56℃ for 5 minutes. It is sensitive to protease and trypsin. Almost all enterotoxin-producing Bacillus cereus can produce this enterotoxin in a variety of foods. Vomitoxin is a low-molecular heat-resistant enterotoxin that is not destroyed by heating at 126℃ for 90 minutes. It is not sensitive to acid, alkali, pepsin and trypsin. Vomitoxin is often formed in rice-based foods. Bacillus cereus food poisoning has obvious seasonality, with most cases occurring in summer and autumn, especially from June to October.
2. Food causing poisoning