Microscopy of wet film.
Culture on selective media for Salmonella, Shigella and Campylobacter spp, and (if clinically appropriate) for Aeromonas hydrophila, Yersinia spp, Vibrio parahaemolyticus, Vibrio cholerae and Shiga toxin-producing Escherichia coli.
Molecular genetics using PCR probes may be used to detect Shiga toxin-producing E. coli.
Testing for Clostridium difficile toxin is required in antibiotic-associated diarrhoea; some laboratories also culture for Clostridium difficile.
In children, EIA for detection of rotavirus and adenovirus antigen.
PCR or electron microscopy for norovirus, and the like, in the investigation of diarrhoeal outbreaks.
Viral culture, detection in the investigation of meningitis and encephalitis.