A 5-year-old boy recently adopted from Haiti is seen by a primary care physician. The boy appears to have an infection of the hair and scalp. The physician suspects a dermatophyte and removes infected hairs by plucking them with forceps. The sterile container with the specimen is sent to the laboratory for culture.

QUESTIONS

1. What agar and incubation temperature might the laboratorian choose for primary culture?

2. The laboratorian notices that the fungus is a slow grower, taking 12 days to grow. What other details should be noted?

3. The colony appears downy, flat, and spreading. It has a light tan front and red-brown reverse. What is the next step for identifying this fungus?

4. Rare club-shaped microconidia and sterile hyphae are noted with terminal chlamydospores. The laboratorian decides the dermatophyte is a Microsporum species. How might M. canis be differentiated from M. audouinii?