What Is Staphylococcal Food Poisoning?

Staphylococcal food poisoning is an acute disease caused by eating food contaminated with Staphylococcus aureus and its enterotoxins. The common foods that cause bacillary food poisoning are starch (such as leftovers, porridge, rice noodles, etc.), milk and dairy products, fish, eggs, etc. When the contaminated food is left at room temperature for 20 to 22 ° C for more than 5 hours The bacteria multiply and produce enterotoxin. This toxin is very heat-resistant. After boiling for 30 minutes, it can still maintain its virulence and cause disease. The disease is mostly in summer and autumn.

Basic Information

English name: staphylococcal food poisoning
Visiting department: Gastroenterology, Emergency Department

Common causes: Eat foods contaminated with staphylococcal enterotoxin
Common symptoms: Sudden onset, nausea, vomiting, middle and upper abdominal cramps and pain, diarrhea

Causes of staphylococcal food poisoning

Staphylococci belong to the family Micrococcus, and are spherical or oval, Gram-positive bacteria. The toxin has eight serotypes namely AB, C1, C2, C3D, E and F. The same strain can produce two or more types of enterotoxin, but often one type of toxin is the main type. Cross-immunity exists between A and E, B and C, respectively. All types of enterotoxin can cause food poisoning, but type A and D enterotoxin cause food poisoning most often, followed by type B and type C. The poisoning dose of enterotoxins to humans is generally considered to be 20 ~ 25g. After Staphylococcus contaminates food, under the condition of insufficient oxygen, the temperature is 20 ~ 30 ° C, and breeding for 4 ~ 5 hours will produce a large amount of enterotoxins. Food poisoning can occur if people eat Staphylococcus contaminated food containing enterotoxin.

Clinical manifestations of staphylococcal food poisoning

The incubation period is 2 to 5 hours, rarely exceeding 6 hours. Sudden onset, nausea, vomiting, cramping pain in the mid-upper abdomen, followed by diarrhea. Vomiting is most prominent, vomiting can carry bile mucus and blood, diarrhea is watery or thin, ranging from several times to dozens of times a day, severe cases can cause dehydration, collapse and muscle cramps due to severe vomiting. Most of the body temperature is normal or slightly high, and most patients recover quickly within a few hours or 1 to 2 hours. May be accompanied by low potassium, low sodium and other symptoms.

Staphylococcal food poisoning test

Direct microscopy

Suspicious food, vomit, and feces are smeared, and Gram staining is used to detect staphylococci under the microscope according to the morphology, arrangement and staining characteristics of bacteria. Generally, it requires 25% more bacteria than other bacteria. Each gram of food contains hundreds of millions of bacteria. Just set up.

2. Bacterial culture

Suspicious food, vomit, or feces are cultured on a high-salt blood agar medium or with lithium chloride egg yolk. If staphylococcus is not detected, the diagnosis is not denied, because the staphylococcus bacteria are killed when the food is heated, but the enterotoxin is resistant to high temperature and cannot be destroyed, and can still cause disease.

3. Serological test for toxin determination

Serology is used to directly detect enterotoxins in food extracts, cultures or filtrates.

4. Other auxiliary inspections

Animal experiments. Suspicious food or vomitus was inoculated into broth culture medium and the filtrate was injected into the cat's abdominal cavity. Food poisoning symptoms occurred within 4 hours, suggesting the possibility of enterotoxin.

Diagnosis of staphylococcal food poisoning

Based on the eating of suspicious food, the same person with a history of disease combined with a short incubation period, short duration of gastrointestinal symptoms, no fever, fast recovery and other characteristics can make a preliminary diagnosis. The diagnosis can be confirmed if a large number of toxic Staphylococci or food specimens are isolated from the patient's vomit or stool.

Differential diagnosis of staphylococcal food poisoning

The disease needs to be distinguished from cholera and paracholera, acute bacterial dysentery, viral gastroenteritis, and non-bacterial food poisoning.

Staphylococcal food poisoning complications

Severe disease can cause dehydration, collapse, and muscle spasms due to severe vomiting.

Treatment of staphylococcal food poisoning

General treatment

Light patients need no special treatment and can heal themselves. In severe cases, a 1: 5000 potassium permanganate solution can be used for gastric lavage, and then 20 ml of castor oil is used to remove diarrhea in order to remove unabsorbed enterotoxin and pathogenic bacteria.

2. Symptomatic and supportive therapies

Severe vomiting and diarrhea can be treated with metoclopramide and intramuscular injection; chlorpromazine or atropine can also be injected intramuscularly. At the same time, supplement water and electrolyte to maintain water, electrolyte and acid and alkali balance.

3. Antimicrobial treatment

Since the disease is mainly caused by enterotoxins, antibacterial drugs are generally not required. For severe infections, those with high fever may choose the following antibiotics: such as oxacillin, cloxacillin, cefalotin, cefazolin and so on. 4 6g / d is divided into two or three times by adding 200ml of saline for intravenous drip, and quinolone can also be used. If conditions permit, effective antibiotics can be selected according to the drug sensitivity test.

Prognosis of staphylococcal food poisoning

Generally, the prognosis is good, and the course of disease is mostly 1 to 3 days. Dehydration, acidosis, and shock can occur in patients with the original chronic underlying disease and severe patients, which is life-threatening.

Prevention of staphylococcal food poisoning

Strengthen diet management, isolate patients suffering from mastitis, cooks with skin abscesses or those engaged in the food industry should temporarily resign from their work.