Prevalence of Malassezia spp. in the ears of asymptomatic cattle and cattle with otitis in Brazil.

Yeasts of the genus Malassezia are lipophilic microorganisms that are saprophytes that can act as opportunistic pathogens in animals. Malassezia pachydermatis is commonly isolated from the ear canal and skin of healthy dogs, or in association with seborrheic dermatitis and otitis externa conditions. The objective of the present study was to determine the occurrence of Malassezia spp. in the ears of healthy bovines and bovines with otitis. Specimens (secretion or cerumen) were collected with sterile swabs, inoculated onto Mycosel medium, supplemented with olive oil, and incubated at 35 degrees C for 1 week. Yeasts were identified according to morphological characteristics, growth in Dixon medium at 32 degrees C and Sabouraud glucose medium modified by the addition of Tween 20, 40 or 80. The results showed that 54.7% of the cultures were positive in bovines with otitis (75) and 34.6% were positive in healthy bovines (378). Analysis of the positive cultures (41) from animals with otitis allowed presumptive identification of 24 strains corresponding to M. globosa (12), M. slooffiae (5), M. furfur (5) and M. sympodialis (2). Further studies on a larger number of animals may confirm the trend verified thus far, i.e. a higher frequency of isolation of Malassezia spp. from animals with otitis than from healthy animals (P<0.01) and a predominance of the species M. globosa.