Human androgenic steroids affect growth of dermatophytes in vitro

Abstract

Hormonal effects on fungal growth are of particular interest to medical mycology. In the skin, androgenic steroids metabolized within pilosebaceous units may have direct effects on dermatophytes that invade hair follicles. In this study, 10(-1) to 10(2) mg 1(-1) testosterone, 5-alpha-dihydrotestosterone, dehydroepiandrosterone, androstenedione and androstanedione were used in agar dilution assays to test their effects on thallus diameters of Trichophyton rubrum, Epidermophyton floccosum, T. tonsurans, T. mentagrophytes and Microsporum canis. All dermatophytes responded in a dose-dependent manner with reduced diameters of thalli. Growth of T. rubrum and E. floccosum was completely or strongly suppressed by 10(2) mg 1(-1) androstenedione and androstanedione. A minor inhibition of all strains was obtained with 10(1) to 10(2) mg 1(-1) testosterone, dehydroepiandrosterone and 5-alpha-dihydrotestosterone, the last being least inhibitory for all species. Trichophyton mentagrophytes and M. canis were least responsive to most hormones. The high susceptibility of T. rubrum and E. floccosum to intrafollicular androstenedione and androstanedione could be one reason why these two species are unable to cause tinea capitis. Receptor-mediated effects and an unspecific interference with fungal sterol metabolism are discussed as mechanisms of fungal inhibition by steroidal hormones.

Dermatophytosis: a 16-year retrospective study in a metropolitan area in southern Brazil

“…In the hair follicles of the scalp and face, an autonomous control over the androgenic steroid hormones metabolism occurs, and this fact could affect colonization with these species [23,24]. This would explain why these fungi do not easily attack the scalp and face, in agreement with our study, which showed a negative association of T. rubrum with these locations and only one case of face infection with E. floccosum.…”

Quantitative analysis of the effects of antimycotic agents on the hyphal growth of Trichophyton rubrum: a preliminary study

“…1 There were significant differences between the TBF and ITCZ groups at 42 and 48 h (P < 0.05). 2 Values were significantly different from that at 0 h in the TBF group (P < 0.05).…”

“…These findings indicate that the ITCZ group did not completely inhibit the growth of TR within 48 h. On the other hand, the TBF group showed a significant decrease in the mean density of cross points compared with the control and ITCZ groups and did not Values were significantly different from that at 0 h in the control (P < 0.05). 2 There was a significant difference between the control and ITCZ groups (P < 0.05). 3 There was a significant difference between the control and TBF groups (P < 0.05).…”

“…Thallus diameter is commonly measured as a quantitative parameter to evaluate hyphal growth. 1,2 However, this measurement may not be the best parameter for evaluating hyphal growth precisely because the thallus does not always grow equally in all directions and may not grow sufficiently to measure its diameter, especially under the influence of antimycotic agents. Therefore, parameters other than thallus diameter are needed for this purpose.…”

Pathogenese der Tinea

“…Solche Mannane und weitere Exoantigene von Trichophyton rubrum können die Phagozytose von Trichophyton-rubrum-Konidien durch Makrophagen reduzieren [23]. [41][42][43][44]. Die Tatsache, dass eine Tinea capitis ganz überwiegend Kinder betrifft und nach der Pubertät selten ist, könnte mit den starken Änderungen der follikulären Hormonkonzentrationen während der Pubertät zusammenhängen.…”