In vaginal infections presenting with a fishy odor after KOH, the most likely etiologic organism is which of the following?

In vaginal infections presenting with a fishy odor after KOH, the most likely etiologic organism is which of the following?

• A. Gardnerella vaginalis
• B. Candida albicans
• C. Trichomonas vaginalis
• D. Escherichia coli

Answer: (A)

A fishy odor after adding potassium hydroxide to vaginal discharge points to bacterial vaginosis, which is due to anaerobic bacteria and their volatile amines released in the test. Gardnerella vaginalis is the organism most commonly associated with this presentation, making it the best answer. Candida albicans typically causes itching with a thick, white, curd-like discharge, and the KOH test does not produce a fishy odor. Trichomonas vaginalis presents with a frothy discharge that is often malodorous and may show vaginal mucosal changes, but its hallmark isn’t the fishy odor on a KOH prep. Escherichia coli is not the usual cause of BV and wouldn’t explain the characteristic odor with the KOH test.

A fishy odor after adding potassium hydroxide to vaginal discharge points to bacterial vaginosis, which is due to anaerobic bacteria and their volatile amines released in the test. Gardnerella vaginalis is the organism most commonly associated with this presentation, making it the best answer. Candida albicans typically causes itching with a thick, white, curd-like discharge, and the KOH test does not produce a fishy odor. Trichomonas vaginalis presents with a frothy discharge that is often malodorous and may show vaginal mucosal changes, but its hallmark isn’t the fishy odor on a KOH prep. Escherichia coli is not the usual cause of BV and wouldn’t explain the characteristic odor with the KOH test.