Adherence of arthroconidia and germlings of anthropophilic and zoophilic varieties of Trichophyton mentagrophytes to human corneocytes as an early event in the pathogenesis of dermatophytosis

The association (adherence) between human corneocytes and arthroconidia of Trichophyton mentagrophytes strains 12l and 126, and T. interdigitale strain 4 was studied in vitro. Adherence of arthroconidia to corneocytes from either the palm and sole occurred and increased with time up to 6 h, by which time germination of arthroconidia had started. Significant differences were seen between the T. mentagrophytes strains and T. interdigitale in their adherence to corneocytes from the palm. When adherence values for plantar corneocytes were compared, significant differences were found between T. mentagrophytes and T. interdigitale. Not all corneocytes from either site had adherent arthroconidia, although there was a time-dependent increase in the numbers of corneocytes with adherent fungal cells. By scanning and transmission electron microscopy it was seen that there was a loose association between arthroconidia and corneocytes with no apparent damage to the corneocyte membrane. Adherence of germlings of T. interdigitale to corneocytes from the palm appeared to be mediated by germling outer cell wall fibrils. Hyphal branches and secondary germlings were observed to enhance the attachment of the parent hypha to adjacent corneocytes.