Diagnosis
Nausea/vomiting with or without diarrhea, with or without cramps. Symptoms are often organism-specific.
While pricey, there is a PCR panel that can get all the usual suspects in less than a day. That way you can spend money without bothering to take a good exposure history.
Epidemiologic Risks
Often you are what you eat or drink. You can eat a bug or a preformed toxin, then it makes you vomit like Vesuvius or crap like, well, is there a volcano that starts with c? I like alliteration. Mount Cleveland?
Everything you eat is covered with a thin layer of shit, sometimes containing pathogens. So deep fry your food.
And the (MMWR) is a nice way to keep up on whatever new way to spread infection rears its ugly head. Our centralized/industrialized food chain makes it easy for contamination and subsequent spread of infections in almost any food.
Microbiology
Viral causes: CMV, Norovirus causes 13% of all gastroenteritis-associated ambulatory visits, with ∼50% of such visits occurring during November–February (PubMed), sapovirus.
Bacillary causes: Aeromonas, Bacillus, E. coli, Campylobacter, Klebsiella oxytoca, Listeria monocytogenes (your lab will not be looking for it), Plesiomonas, Salmonella, S. aureus (it may well cause disease, especially MRSA), Shigella, Vibrio, Yersinia.
Toxin mediated: B. cereus (long incubation), B. cereus (short incubation), Clostridium botulinum, Clostridia difficile, Clostridium perfringens, S. aureus.
Parasites: Cyclosporidia, Cryptosporidia, Entamoeba histolytica, Giardia, Isospora.
Eosinophilic: Ancylostoma caninum, A. costaricensis, Anisakis.
Empiric Therapy
Mostly supportive. It depends on which of the above organisms you are concerned about. Most will get better on their own and do not need treatment. For bacillary diarrhea, usually a quinolone OR rifaximin except for Campylobacter jejuni.
Treatment of Escherichia coli may make HUS more likely BUT treatment of E. coli associated travelers diarrhea may lead to less irritable bowel syndrome.
Pearls
People blame the most recent meal, but with the exception of staphylococcal and bacillus toxins, to get nausea and vomiting takes more than 6 hours to a couple of days.
C. perfringens is the cause of 10% of outbreaks and is mistaken for norovirus (PubMed).
Rants
Stomach flu. No such thing. The flu is a coughing illness. How are you going to cough out your butt? It is a stupid and confusing term.
Last Update: 07/26/18.