Isolation of dermatophytes and saprotrophic fungi from the hair coat of cats without skin disorders in the metropolitan area of Porto Alegre-RS, Brazil.

Background: Dermatophytoses are one of the most frequent skin diseases of pets and livestock in the world. Contagion among animal communities, diffi culty in implementing control measures, and the eventual transmission of ringworm to people explain its great importance. Microsporum canis causes a zoonosis that has increased in several countries, outnumbering classical anthropophilic dermatophytes. The objective of this study was to isolate dermatophytes from the hair coat of cats without skin disorders in the metropolitan area of Porto Alegre, south of Brazil, as well as evaluate the infl uence of age, sex, hair length, habitat and access or not to the street as potential risk factors. Materials, Methods & Results: Samples were obtained from 191 cats with no skin disorders by rubbing sterilized carpet squares on the cats’ skin (head, neck, dorsum, limbs and tail) and cultured for dermatophytes on Sabouraud dextrose agar with chloramphenicol and cyclohexamide and incubated at 27°C for up to 21 days. Only the genus Microsporum (8,4%) was isolated from positive specimens: M. canis (5,8%) and M. gypseum (2,6%). On 15 samples (7,8%) there was no fungal growth. From the remaining 160 samples (83,8%), several saprotrophic fungi were isolated: hyaline fi lamentous fungi [Penicillium sp. (27), Aspergillus sp. (23), Scopulariopsis sp. (22), Acremonium sp. (10), Chrysosporium sp. (7), Paecilomyces sp. (7), Fusarium sp. (2) and unidentifi ed hyalohyphomycetes (13)]; dematiaceous fi lamentous fungi [Cladosporium sp. (39), Alternaria sp. (10), Curvularia sp. (10) and unidentifi ed phaeohyphomycetes (14)]; Zygomycetes [Rhizopus sp. (2) and Mucor sp. (1)] and yeasts [Malassezia sp. (2) and Candida sp. (4)]. Inittialy, the possibility of association between predictors variables and a variable answer was evaluated by an univariate logistic regression model. Variables with large amounts of missing data (>10%) and limited variability (<20%) were not included in the multivariable model. The remaining variables were submitted to a multivariate logistic regression by backwards selection at level of P < 0.05. The discriminatory power of the model was measured under the area below the ROC curve. Discussion: The most common etiological agent of ringworm in pets is Microporum canis, dermatophyte frequently isolated from the hair coat of cats without skin disorders. This species represents a major risk of contagion for human beings, as well as for other animals. Due to the lack of clinical signs, there are no prevention measures that could be implemented in order to reduce the risk of microepidemic outbreaks in human family members, mainly children. There are meager informations about the complex mechanisms of infection and factors infl uencing susceptibility of the animals, but fungal isolation from healthy cats associated with epidemiological features are important tools in the diagnosis and management of the problem. The data from this study indicate a higher relative risk for the isolation of dermatophyte when the cat was male and was allowed to walk outdoors, in the magnitude of 3.43 and 3.52, respectively. The multivariate analysis did not identify any protective factor against dermatophytosis. The fi nal model had a discriminatory power of 72%. Some results of this research are quite similar to others conducted around urban areas of different countries across the world. It is emphasized that human beings can be contaminated from apparently healthy cats and the necessity of prophylactic measures in order to reduce the spread of dermatophytosis.