Identification of Common Dermatophytes.

Microscopic morphology of the micro and/or macroconidia is the most reliable identification character, but you need a good slide preparation and you may need to stimulate sporulation in some strains. Culture characteristics such as surface texture, topography and pigmentation are variable and are therefore the least reliable criteria for identification. Clinical information such as the site, appearance of the lesion, geographic location, travel history, animal contacts and race is also important, especially in identifying rare non-sporulation species like M. audouini, T. concentricum and T schoenleinii etc. Note: mating experiments are not practical for the clinical mycology laboratory.

Three genera are recognised:

Epidermophyton:
Smooth thin-walled Macroconidia only present, no microconidia, colonies a green-brown to khaki colour.

Microsporum:
Macroconidia with rough walls present, microconidia may also be present.

Trichophyton:
Microconidia present, smooth-walled macroconidia may or may not be present.