Family Nurse Practitioner Exam

A KOH (potassium hydroxide) prep is used to diagnose which condition?

1. Herpes zoster infections

2. Yeast infections

3. Herpes simplex infections

4. Viral infections

The correct answer is: Yeast infections

A KOH (potassium hydroxide) prep is particularly useful in diagnosing yeast infections, primarily because it helps identify fungal elements in specimens, such as skin or vaginal secretions. When KOH is applied to a sample, it breaks down keratin and other organic material, allowing the clinician to visualize fungal hyphae or budding yeasts under a microscope. This makes it an effective diagnostic tool for conditions like candidiasis, commonly known as a yeast infection. In contrast, herpes zoster and herpes simplex infections are caused by viral pathogens, and their diagnosis typically relies on clinical presentation, serological tests, or PCR rather than KOH prep. Viral infections in general cannot be diagnosed through KOH preparation, as this method specifically targets fungi, not viruses. Therefore, the utility of KOH prep in yielding clear visualization of fungal elements in suspected yeast infections solidifies its role in this particular diagnosis.