Which infection is diagnosed by a saline wet prep showing motile, flagellated organisms?

Which infection is diagnosed by a saline wet prep showing motile, flagellated organisms?

• A. Bacterial vaginosis
• B. Candidiasis
• C. Trichomoniasis
• D. Gonorrhea

Answer: (C)

Seeing motile, flagellated organisms on a saline wet mount points to Trichomonas vaginalis infection. The protozoan is actively motile and has flagella, which gives this distinctive appearance on a fresh vaginal or urethral/cervical specimen. This contrasts with other common causes of vaginitis: bacterial vaginosis is suggested by clue cells and a positive whiff test rather than motile parasites; candidiasis shows budding yeast and pseudohyphae on microscopy (often seen with KOH prep); and gonorrhea is diagnosed by detecting Neisseria gonorrhoeae (gram-negative diplococci in neutrophils or via NAAT), not by observing motile flagellated organisms on a saline prep.

Seeing motile, flagellated organisms on a saline wet mount points to Trichomonas vaginalis infection. The protozoan is actively motile and has flagella, which gives this distinctive appearance on a fresh vaginal or urethral/cervical specimen. This contrasts with other common causes of vaginitis: bacterial vaginosis is suggested by clue cells and a positive whiff test rather than motile parasites; candidiasis shows budding yeast and pseudohyphae on microscopy (often seen with KOH prep); and gonorrhea is diagnosed by detecting Neisseria gonorrhoeae (gram-negative diplococci in neutrophils or via NAAT), not by observing motile flagellated organisms on a saline prep.