• Because most watery diarrhea is self-limiting, testing is usually not indicated in general.
• A stool culture is indicated if the patient has grossly bloody stool, severe dehydration, signs of inflammatory disease, symptoms lasting more than three to seven days, or is immunuosuppressed [6].
• Routine microscopy of fresh stool is inexpensive and can identify the presence of numerous fecal leukocytes, suggesting an invasive bacterial infection.

Microscopic evidence of Entamoeba trophozoites containing red blood cells provides sufficient basis for treating for amoebic dysentery instead of shigellosis. Notably, finding cysts or trophozoites without red blood cells in a bloody stool does not indicate that Entamoeba is the cause of illness, since asymptomatic infection is frequent among healthy persons.