Infectious Agents and Microbiology Practice Test 2025 - Free Microbiology Practice Questions and Study Guide

Amebic dysentery, also known as amoebic colitis, is primarily caused by the protozoan Entamoeba histolytica. This organism invades the intestinal wall, leading to inflammation and ulceration, which presents with symptoms such as diarrhea, bloody stool, abdominal pain, and cramping.

Entamoeba histolytica is ingested through fecal-contaminated food or water, and it can exist in both a cyst form, which is highly resistant to environmental conditions, and a trophozoite form, which is the active, motile form that causes disease. The ability of this protozoan to cause significant tissue damage and its pathological effects are key features that define amebic dysentery.

The other microorganisms mentioned do not cause amebic dysentery. For example, Balantidium coli is associated with balantidiasis, Plasmodium falciparum is responsible for malaria, and Mycobacterium leprae is the causative agent of leprosy. Each of these organisms has distinct modes of transmission and disease manifestations, which clearly delineate their pathologies from that of Entamoeba histolytica.