Table 3.

Specific Historical Clues to the Etiologic Diagnosis of Acute Diarrhea^legend

History	Possible Enteric Pathogens	Additional Tests
Bloody stools	Salmonella, Shigella, Campylobacter, enterohemorrhagic Escherichia coli, Clostridium difficile, E. histolytica	Stool specimen for culture, ova and parasites, and C. difficile toxin
Recent antibiotic therapy, chemotherapy	C. difficile, Salmonella	Stool specimen for C. difficile toxin
Travel (Mexico, Africa, Middle or Far East)	Enterotoxigenic E. coli, and other bacterial pathogens and parasites	Stool for ova and parasites
Several family or friends similarly affected	Various food poisoning syndromes:	None usually required
	Staphylococcus, Clostridium, Bacillus cereus, Salmonella
Homosexual males	Herpes, Chlamydia, syphilis, E. histolytica, Shigella, Giardia, gonococcus, Cryptosporidium	Sigmoidoscopy; rectal biopsy; stool specimen for ova and parasites; culture for gonococcus, herpes, and chlamydia; serologic test for syphilis
Rectal pain, severe tenesmus	Campylobacter, Salmonella, Shigella,	As above for homosexual males
	Gonococcus, Herpes, Chlamydia, E. histolytica
Severe or persistent abdominal pain	Campylobacter, Yersinia, Clostridium	Notify laboratory for special culture
	perfringens, Aeromonas
Hospital-acquired	C. difficile, elixirs, drugs	Stool specimen for C. difficile toxin
Day-care centers, mental institutions	Giardia, C. difficile, Salmonella, Shigella, rotavirus	Stool for ova and parasites, culture, C. difficile toxin

^legendModified from (7).