Master the board step 3

Infectious Diseases
KOH Prep
Basic Science Correlate
Fungi have chitin in their outer wall. Chitin is a polymer that will not break
down with KOH. Chitin is what makes up crab and lobster shells. Epithelial
cells melt and fungi remain behind in a KOH prep because the chitin in the
fungus is tougher than epithelial cells.
Treatment
··
Topical antifungal medication (if no hair or nail involvement): Clotrimazole,
miconazole, ketoconazole, econazole, terconazole, nystatin, or ciclopirox
··
Oral antifungal medication for scalp (tinea capitis) or nail (onychomycosis)
--
Terbinafine: Causes increased liver function tests
--
Itraconazole
--
Griseofulvin (for tinea capitis): Has less efficacy than either terbinafine
or itraconazole
17