openstax microbiology test bank Related

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A sample stained using Romanovsky-Giemsa method revealed crescent-shaped protozoa with pointed ends and blue cytoplasm. What is the causative agent?

  • A. Toxoplasma
  • B. Plasmodium
  • C. Leishmania
  • D. Trypanosoma
Correct Answer: A

Rationale: The correct answer is A: Toxoplasma. The crescent-shaped protozoa with pointed ends and blue cytoplasm described in the question are characteristic of Toxoplasma gondii, the causative agent of toxoplasmosis. Toxoplasma staining with Romanovsky-Giemsa method typically shows these specific morphological features. Plasmodium causes malaria and does not exhibit the described morphology. Leishmania and Trypanosoma are both kinetoplastid parasites, but they do not typically present as crescent-shaped protozoa with blue cytoplasm. Therefore, based on the specific characteristics described in the question, the correct answer is Toxoplasma.