Diarrhoea (Acute) - Quick Reference

This is a Quick Reference article, and it refers to adult patients. See also the main article Diarrhoeal diseases caused by microbes Diarrhoeal Diseases Caused by Microbes.

Essentials

Most commonly viral (rotavirus, norovirus)
Severe clinical picture is suggestive of a bacterial cause.
Protozoa (giardia, amoeba)
The aetiology of acute diarrhoea may also be other than intestinal infection (abdominal condition requiring surgical intervention, severe systemic infection).

Routine stool culture (salmonella, shigella, campylobacter and yersinia)
In suspected clostridium infection stool culture or toxin
If an epidemic is suspected, a stool sample for viral pathogens, including norovirus.
Protozoa: parasites, worm ova (eggs)

Pathogen	Clues
Rotavirus, norovirus	Epidemics in schools, day care centres, other institutions
Adenovirus	Small children, immunosuppressed patients
Hepatitis A virus	Travel in endemic regions, inadequate hygiene, intravenous drug users
Salmonella, S. aureus, E. coli, campylobacter, yersinia	Food history (meat, eggs, milk, unwashed vegetables)
Listeria	Food (vacuum packed fish products), pregnancy
Clostridium difficile	History of recent antibiotic use, immunosuppression
Protozoa	Travel (giardia), contaminated water, vegetables

Main symptom	Incubation period	Most likely cause	Possible food source
Vomiting	1-6 hrs	S. aureus toxin	Eggs, salads, meat, milk products
	24-48 hrs	Viruses (Norwalk)	Seafood, salads, fruit
	8-16 hrs	Clostridium perfringens	Meat, poultry
Vesiripuli	1-3 days	Enterotoxic E. coli	Contaminated water or food
Vesiripuli	10-72 hrs	Enteroviruses	Contaminated water or food
Inflammatorinen ripuli	1-3 days	Salmonella	Eggs, poultry, meat, unpasteurised milk products
	2-5 days	Campylobacter	Poultry, water, unpasteurised milk products
	1-3 days	Shigella	Contaminated water or food

Fluids by mouth and other symptomatic treatment is usually all that is needed.
Loperamide can be used as symptomatic medication (contraindicated in acute bacterial infection).
Probiotics can be tried.
Empirical antibiotic treatment (e.g. ciprofloxacin 500 mg twice daily, norfloxacin 400 mg twice daily, treatment period 3-5 days) can be justified in the following cases:
- traveller's diarrhoea with fever, mucous stools ≥ 4 times/24 hours
- prolonged duration (> 5 days), diarrhoea ≥ 8 times/24 hours, signs of dehydration or immunosuppression.
Antimicrobial medication according to aetiology:
- salmonella, shigella, E. coli: a fluoroquinolone (ciprofloxacin, levofloxacin) p.o. 5-7 days
- Clostridium difficile: metronidazole 400 mg three times daily, p.o. in mild cases, vancomycin i.v. in severe cases
- campylobacter: a macrolide for 3-5 days.