Arthroconidia as vectors of dermatophytosis.

The characteristic macro- and microconidia produced by dermatophytes in cultures and those living as saprobes are not produced in any dermatophyte lesions observed to date. However, arthroconidia, defined as a genetically programmed disarticulation of septate hyphae to produce a chain of conidia, are produced by dermatophytes, both in culture and in lesions, under certain predisposing conditions. Arthroconidia are seen, for example, within nail-bed infections caused by Trichophyton rubrum; within nail-plate infections caused by Trichophyton mentagrophytes interdigitale; and in the infections of scalp hair by soil or geophilic dermatophytes, where chains of arthroconidia form near or on the surface of the infected hairs. Dr. Rashid discusses his electron microscope studies of the adherence and germination of arthroconidia and the penetration of the germ tubes and initial hyphae into the stratum corneum.