How to classify food poisoning depending on the onset of symptoms?

Health Care, Medicine 193 Comments

What decide the severity of food poisoning are the symptoms: exposure to a particular type of food as well as the time interval between exposure to the suspect food and the onset of symptoms.

Rapid symptoms within 6-12 hours are due to organisms that make a toxin in the food before the food is consumed. Symptoms are predominantly upper intestinal like vomiting. Examples are Staphylococcus aureus, Bacillus cereus emetic toxin and botulism.

Symptoms after 24 hours are due to pathogens that make toxin once they have been ingested. They mainly cause diarrhea that may be watery (Vibrio cholerae or E. coli) or bloody (Shiga toxin-producing E. coli).

Symptoms after variable time are due to microbes that cause pathology by either damaging the epithelial cell surface or by actually invading across the intestinal epithelial cell barrier. They can produce a wide spectrum of clinical presentations from watery diarrhea (Cryptosporidium parvum, enteric viruses) to inflammatory diarrhea (Salmonella, Campylobacter, Shigella) or systemic disease (L. monocytogenes).

Food poisoning can also be classified depending on the type of symptoms vomiting or diarrhea. A sudden onset of nausea and vomiting is likely due to the ingestion of a preformed toxin, such as S. aureus enterotoxin or B. cereus emetic toxin, or a chemical irritant. There is no risk of person-to-person spread.

When the poisoning presents with diarrhea, the likely organisms are V. cholerae, Clostridium perfringens, enterotoxigenic E. coli (ETEC), B. cereus, rotavirus, astroviruses, enteric adenoviruses, and Noroviruses, and the parasitic organisms, Cryptosporidium parvum and Cyclospora cayetanensis.

There are clinical clues that should raise suspicion that a foodborne microbe is causing inflammatory diarrhea. Such symptoms and signs include: Passage of diarrhea with blood or mucus; presence of severe abdominal pain and occurrence of fever. The most likely pathogens in patients with inflammatory diarrhea are Salmonella or Campylobacter.