Vibrio parahaemolyticus food poisoning

Introduction to Vibrio parahaemolyticus food poisoning BibrioParahemolyticus food poisoning, also known as halophilic food poisoning, is caused by eating food containing the bacteria, mainly pirated seafood. Clinically, acute onset, abdominal pain, vomiting, diarrhea and watery stools are the main symptoms. Severe cases often have dehydration and shock symptoms. Intestinal tract of a salty sardine food poisoning occurred in Osaka, Japan in October 1950. Vibrio parahaemolyticus was isolated for the first time in excreta and food. basic knowledge The proportion of sickness: 0.003%-0.005% Susceptible people: no special people Mode of infection: non-infectious Complications: disturbance of consciousness dehydration shock

Causes of Vibrio parahaemolyticus food poisoning

(1) Causes of the disease

Vibrio parahaemolyticus Vibrio spp., Gram-negative capsular bacillus, polymorphic cocci and slightly curved Vibrio, varying in size, generally 0.7-1.0 m in length, one end of the cell Single flagella, active and halophilic growth, the most suitable medium is 2% to 4% salt, the most suitable temperature is 37 ° C, pH 7.4 ~ 8.5, 1-3 minutes in vinegar, death, The cells were inactivated by heating at 56 ° C for 5 to 10 minutes, and died in 1% hydrochloric acid for 5 minutes. The colony morphology often differed depending on the culture conditions, and was mostly oval on SS medium or blood agar medium on the salt protein agar. It is a cocci, the causative factor is the heat-resistant hemolysin (TDH) and the heat-labile hemolysin (TRH) produced by the bacterium. The molecular weight of TDH is 42×103, and can not be inactivated at 100 ° C for 10 min, human, monkey, Dogs, rats' red blood cells are sensitive to TDH. Vibrio parahaemolyticus isolated from diarrhea patients has a "Kanagawa phenomenon" positive on Wagatsuma agar, so it is thought that the disease may be related to heat-resistant hemolysin, in addition to experimental mice. The heart is toxic, and intravenous injection of small doses of TDH for a few seconds can kill mice. The molecular weight of TRH is 48×103, which is composed of two subunits with a molecular weight of 24×103. TRH has 68.6% homology with TDH, but TRH is not heat-resistant, and is inactivated at 60 ° C for 10 min. It can cause intestinal mucosal congestion, edema, mild erosion, and can cause secretory intestinal fluid retention and diarrhea through cAMP and cGMP pathways. Vibrio parahaemolyticus is sensitive to acid. When pH is below 6, it can not grow. It dies within 1 to 3 minutes, and rapidly propagates in 3% to 6% sodium chloride solution. It is a cycle every 8 to 9 minutes. The halophilic mechanism of this bacteria is related to the K-H reverse transport system and is resistant to high temperature. Small, 5 to 10 minutes at 65 °C can die; in tap water at room temperature, die within 1 day; river water, pond water, well water no more than 2 days of death; but still survive in seawater after 47 days, in -20 ° C peptone water After 11 weeks, it can still survive. This strain has weak resistance to common disinfectants and can be killed by low concentration of phenol and coal phenol soap solution. Vibrio parahaemolyticus has flagella (H), capsular polysaccharide ( K) and bacterial (O) anti-caries, flagella (H) anti-caries are common to all strains, do not contribute to typing, so O and K anti-caries Based on the serotype classification, there are 12 kinds of O-resistant cockroaches, and at least 59 kinds of K-resistant cockroaches. According to their different bacterial cells and flagellar sputum, they can be divided into 25 serotypes. B, E, H are foods. The main serotype of poisoning, according to phage typing, at least nine types have been obtained in China.

(two) pathogenesis

The pathogenicity of Vibrio parahaemolyticus has been clear to humans, but the pathogenesis of this disease has not yet been fully clarified. It has been shown that the intake of a certain number of live bacteria (105-107) can cause human disease, and bacteria can invade the intestinal mucosa. Epithelial cells, pathological damage found in the intestinal tract, indicating that the direct invasion of bacteria has an important role, it is confirmed that TDH and TRH in addition to hemolytic activity, also contains enterotoxin, can cause intestinal swelling, congestion and Intestinal fluid retention, causing diarrhea, the diarrhea-causing mechanism of Vibrio parahaemolyticus is considered to be closely related to the antibacterial toxin component of Vibrio cholerae. The thermotolerant toxin (CT) similar to Vibrio cholerae can be mediated by cAMP and cGMP. It causes secretory diarrhea. In addition, the heat-resistant hemolysin has a specific cardiotoxic effect, which can cause lesions in rat and guinea pig cardiomyocytes, which can cause atrial fibrillation, premature contraction, pathological changes for acute enteritis, and duodenum. The upper part of the jejunum and ileum is more obvious. It can be seen that the intestinal mucosa is diffusely congested, edema, deep into the muscular layer and serosal layer, mild erosion, but no ulcer, histological neutrophil infiltration Visceral (stomach, liver, spleen, lung) congestion, recently found that urease is related to the disease diarrhea, patients with different physical and immune systems, clinical manifestations vary in severity, polymorphic, mountainous, inland residents go to the coastal areas and infection The disease is more serious and the clinical manifestations are typical; the incidence of the disease in coastal areas is generally mild.

Vibrio parahaemolyticus food poisoning prevention

Preventive measures are similar to those caused by other bacteria. The key is to strengthen health promotion and improve people's health.

1 Strengthen the sanitation treatment of seafood, and clean, salt, refrigerate and transport seafood products in strict accordance with the hygiene regulations.

2 Prevent cross-contamination of raw and cooked foods, do not eat seafood, separate lettuce and cooked vegetables, prevent cross-infection, stir-fry seafood, and store the food before re-cooking. , raw crab, salty grilled shrimp, etc., if eaten raw, must be vinegar for 5min, kill the pathogen.

Vibrio parahaemolyticus food poisoning complications Complications, consciousness, dehydration shock

Can be complicated by toxic shock, severe diarrhea can lead to dehydration, circulatory failure, accompanied by hoarseness and muscle spasm, and even conscious disturbances.

Symptoms of Vibrio parahaemolyticus food poisoning Common symptoms High fever Abdominal discomfort Abdominal pain Diarrhea Mucus nausea pharyngeal respiratory muscles... Toxic performance

The course of the disease varies from 1 to 6 days, and can be self-limited, generally recovering faster.

The incubation period is generally 6 ~ 20h, the shortest 1 ~ 3h, the longest can reach 96h, the onset of rapid, first with chills, fever, general malaise, abdominal discomfort begins, followed by upper abdomen, umbilical hernia, paroxysmal cramps, It is accompanied by nausea, vomiting and diarrhea. The stool varies from several times to more than 20 times a day. The stools are more yellow watery. A few are bloody watery stools. Very few have pus and bloody stools, but few have a sense of urgency and seriousness. Diarrhea can lead to dehydration, circulatory failure, accompanied by hoarseness and muscle spasm, and even conscious disturbances. Children often have high fever, body temperature is 38 ~ 40 ° C, symptoms of poisoning are significant, intestinal symptoms are lighter than adults, the disease The course of disease is 3 to 5 days. Except for some old and weak patients, the general prognosis is good. The clinical manifestations of this disease include the dysentery type, toxic shock type and chronic enteritis type.

Inspection of Vibrio parahaemolyticus food poisoning

1. Blood picture: In the early stage of the disease, the total number of white blood cells increased, mostly in (10 ~ 20) × 109 / L, classified more than 80% of neutrophils.

2. Fecal microscopy: visible white blood cells or pus cells, often accompanied by red blood cells, easy to be misdiagnosed as bacillary dysentery, fecal culture can detect Vibrio parahaemolyticus, the vast majority quickly turned negative, only a few continued positive for 2 to 4 days.

3. Bacterial culture: 1 to 2 days after onset, the positive rate of fecal culture is high, the positive rate is reduced after 2 days, suspicious foods, such as seafood, pickles and other bacterial cultures, sometimes can also isolate bacteria, currently using VITEK-AMS microbes automatically The analysis system is used for the analysis and identification of fecal bacteria in patients with diarrhea, which can be diagnosed accurately and quickly.

4. Polymerase chain reaction: (PCR) technology for detection of Vibrio parahaemolyticus DNA This technique is simple, rapid, specific and sensitive.

5. Serum agglutination test: The serum agglutination titer is higher in the early stage of the disease, and most of the time it turns to negative. If the titer reaches 1:801:160, the disease can be diagnosed. In the recovery period, the heat-resistant hemolysin is detected. For antibodies, the titer is often significantly increased from 1:80 to 1:160.

Diagnosis and identification of Vibrio parahaemolyticus food poisoning

According to the onset season, the history of sea food, collective disease, clinical manifestations of abdominal pain, diarrhea, vomiting, abdominal tenderness, blood pressure drop and water or bloody stool, pus and mucus, etc., can make a preliminary diagnosis, such as from suspicious food The detection of Vibrio parahaemolyticus in the stool can confirm the diagnosis.

Differential diagnosis

1. Acute bacterial dysentery: It is characterized by fever, diarrhea, pus and mucus, and there is urgency and weight. The feces are cultured with Shigella dysenteriae.

2. Cholera: frequent diarrhea, accompanied by vomiting, often showing significant loss of water, and culture of cholera vibrio in feces.

3. Hemorrhagic enteritis: more common in children, not related to eating, for sporadic cases, clinical manifestations of bloody stool, severe abdominal pain and umbilical tenderness, sometimes abdominal tenderness, with muscle tension, severe symptoms of poisoning, longer course Fecal culture without Vibrio parahaemolyticus growth.

4. Allergic purpura: There is abdominal pain, bloody stools, skin purpura, joint pain, etc., stool culture is negative.

5. The disease should also be differentiated from staphylococcal food poisoning, enterotoxin-producing Escherichia coli, and Salmonella food poisoning.

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