Influence of temperature on dermatophytes

Effect of Household Laundering, Heat Drying, and Freezing on the Survival of Dermatophyte Conidia

Dermatomycoses are one of the most common dermatological infectious diseases. Dermatophytoses, such as tinea pedis (athlete’s foot) in adults and tinea capitis in children, are the most prevalent fungal diseases caused by dermatophytes. The transmission of anthropophilic dermatophytoses occurs almost exclusively through indirect contact with patient-contaminated belongings or environments and, subsequently, facilitates the spread of the infection to others. Hygienic measures were demonstrated to have an important role in removing or reducing the fungal burden. Herein, we evaluated the effectiveness of physical-based methods of laundering, heat drying, and freezing in the elimination of Trichophyton tonsurans, T. rubrum, and T. interdigitale conidia in diverse temperatures and time spectra. Based on our findings, laundering at 60 °C was effective for removing the dermatophyte conidia from contaminated linens. On the contrary, heat drying using domestic or laundromat machines; freezing at −20 °C for 24 h, 48 h, or one week; and direct heat exposure at 60 °C for 10, 30, or 90 min were unable to kill the dermatophytes. These results can be helpful for clinicians, staff of children’s communities, and hygiene practitioners for implementing control management strategies against dermatophytoses caused by mentioned dermatophyte species.

Submicroscopic morphology of Trichophyton mentagrophytes grown at different temperatures

Several modifications were observed in Trichophyton mentagrophytes cultivated at 19 degrees and 37 degrees C, i.e. nine degrees below and above the optimum of 28 degrees C. The phenomena included inhibition of the growth rate, changes in the gross aspects of the cultures as well as of the microscopic and submicroscopic morphology of the hyphal cells. At the ultrastructural level, in particular, it was shown that, at the suboptimal temperature, although the organelle structure in both young and aged hyphal cells remained nearly unchanged, unusual bodies of probable storage significance and plasmalemmasomes were formed. At the supraoptimal temperature, the youngest cells showed a normal organization but were richer in glycogen clusters and enveloped by a cell wall thicker than the ones at the optimal condition. In the cells far from the apex, the endomembrane integrity was lost and consequently an autolytic activity occurred. Degradation phenomena were detectable also at cell wall level. The cytological changes observed were tentatively correlated with a possible different sensitivity of the membrane system at the experimented temperature conditions.