FUNGAL MICROSCOPY AND CULTURE - skin, hair, nails
Skin scrapings, hair (plucked), nail clippings. As much material as feasible should
be provided. The growing edge of the infection is the best area to sample. Skin biopsy:
fresh and formalin fixed.
Method: Microscopy: keratinised tissues are treated with potassium hydroxide
and stained with eg lactophenol blue or fluorescent dyes to detect hyphae of
dermatophytes. Paraffin sections of biopsies are occasionally required. Culture:
many pathogenic fungi will grow slowly on conventional media but may be recovered
more reliably on special fungal media, which require incubation for up to 4 weeks.
Susceptibility tests to antifungal agents are unreliable but can occasionally be
of value to detect resistance.
Application: Investigation of suspected yeast infection, tinea, ringworm (dermatophyte
infection). Suspected deep fungal skin infections (biopsy required) eg sporotrichosis,
mucormycosis, chromomycosis, mycetoma.
Interpretation: Typical microscopic appearance indicates fungal infection but
does not identify the particular fungal species. Culture of yeast or fungus provides
Reference: Merz WD and Roberts GD. In: Murray PR et al eds. Manual of Clinical
Microbiology. 6th ed. ASM Press 1995.