microbiology an introduction 12th edition test bank Related

Review microbiology an introduction 12th edition test bank related questions and content

A stool sample from a patient with chronic diarrhea revealed cysts with four nuclei. What is the most likely causative agent?

  • A. Entamoeba histolytica
  • B. Giardia lamblia
  • C. Balantidium coli
  • D. Trichomonas hominis
Correct Answer: A

Rationale: The correct answer is A: Entamoeba histolytica. This is because it is a protozoan parasite known to cause amoebic dysentery, presenting with chronic diarrhea and cysts with four nuclei in the stool sample. Giardia lamblia (B) causes giardiasis with trophozoites and cysts with two nuclei. Balantidium coli (C) is a ciliated parasite causing dysentery with large trophozoites. Trichomonas hominis (D) is a non-pathogenic flagellate often found in the human intestine. Thus, based on the specific characteristics of the cysts and clinical presentation, Entamoeba histolytica is the most likely causative agent.