Dados do Trabalho

Título

ANIMAL MODEL OF CUTANEOUS DERMATOPHYTOSIS ORIGINATED BY TRICHOPHYTON MENTAGROPHYTES

Fundamentação/Introdução

Dermatomycoses are responsible for affecting 20-25% of the world's population. These pathogens use keratin as a source of nutrition, thus allowing the colonization and infection of structures such as skin, hair and nails. Few researches has been performed for the understanding of these infections. Thus, the development of animal models is required to evaluate new treatments, to knowledge about pathogenicity factors or host immune response mechanisms.

Objetivos

To develop an experimental model of cutaneous dermatophytosis originated by Trichophyton mentagrophytes in mice.

Delineamento e Métodos

The in vivo experimental protocol was approved by the Ethics Commission on Animal nº 5708300418. Male Swiss mice (n=10) were used and for infection a strain of T. mentagrophytes, stored in Medical Mycology-UEM. Briefly, the animals were anesthetized and an area of 2.5x2.5 cm of the back was delimited, being performed in this region the epilation of the hairs and excoriation of the skin. A suspension of 1x10⁶ microconidia ml-¹ was applied to the marked area. The application of the inoculum was carried out three consecutive days. For the evaluation of dermatophytic infection, the direct mycological examination (DME) of the resulting lesions was performed using the following score: (+) visualization in 1 microscopic field; (++) in 2 fields and (+++) in 3 fields or high fungal load in the last three microscopic fields. The hair root invasion (HRI) test, was used to evaluate the ability of the infection to progression to the hairs. Thus, the infected area was divided into four quadrants, the same proportion of hairs were uprooted per quadrant, planted on the surface on potato-dextrose agar and evaluated qualitatively by the presence or absence of fungal growth.

Resultados

The DME showed onset of fungal infection on the 4th day after infection, presenting a score of (+++). The peak of the infection was in the 6th day, the mycological decrease started the 10th day presenting the visualization of (++), remaining this until the 15th day. The HRI assay confirmed the ability of this fungi to originate a secondary infection in the root of the hair, from the primary cutaneous infection.

Conclusões/Considerações Finais

Our study evidenced that this animal model is satisfactory, showing evident permanence of fungus until the 15th day of infection. This is a relevant model for the study of the pathogenesis and treatment of dermatophytosis caused by T. mentagrophytes.

Palavras-chave

Animal model; skin dermatophytosis; Trichophyton mentagrophytes