Avaliação da virulência in vitro de isolados clínicos e ambientais de fungos dermatófitos.

Abstract

Dermatophytes are a fungi group that require keratin for growth, colonizing the skin and appendages of animals and people. Although not obligatory pathogens, Microsporum gypseum, M. canis, and Trichophyton spp. are related to infections in animals, usually associated with circular lesions on the skin. Dermatophytosis by geophilic dermatophytes occurs to a lesser extent, having M. gypseum as the main etiologic agent involved. Among the factors linked to the ability of dermatophytes to infect animals, we highlight enzymes such as DNase, gelatinase, lipase, keratinase, elastase, and collagenase, which were evaluated in the present study. The behavior of domestic animals to be in close contact with the ground, in backyards, public roads, and parks justify the study of geophilic dermatophytes virulence factors and the changes on the enzymatic production between clinical and environmental isolates, which may contribute to control strategies and prevention of dermatophytosis. The main goal of this study was to evaluate the production capacity of enzymes related to the pathogenicity of dermatophytes (DNase, lipase, gelatinase, keratinase, elastase, and collagenase), among environmental and clinical isolates. The environmental strains were obtained by the technique described by Vanbreuseghem (1952), which uses pre-sterilized equines hair mixed with the moist soil, using soil samples from different Brazilian locations. The clinical specimens were obtained from animal hairs and crusts sent to the Veterinary Microbiological Diagnostic Service / UFRRJ and isolated in Mycosel® medium. The enzymatic evaluation of the dermatophytes was performed by spectrophotometry absorbance (collagenase, elastase, and keratinase), enzymatic degradation in Petri dishes (DNase and lipase) and liquefaction in tubes (gelatinase). In a total of 30 clinical isolates, M. canis (11), M. gypseum (7), M. nanum (2), T. mentagrophytes (4) and Trichophyton sp. (6), were identified. Among the 30 environmental isolates are M. gypseum (25), M. nanum (1) and Trichophyton sp. (4). There was no statistically significant difference in the production of keratinase, elastase, lipase, and gelatinase between the clinical and environmental groups, with the synthesis of all the enzymes for most evaluated isolates. There was a statistically significant difference between the groups in the production of collagenase and DNase, with emphasis on the absence of DNase production by most of the environmental isolates. Thus, dermatophytes from clinical and soil samples are able to produce keratinase, elastase, collagenase, DNase, lipase and gelatinase, enzymes related to different stages of the dermatophytic infection in animals and humans.