Concordance between otic cytology and culture in diagnosis of external otitis canine by Malassezia spp

ABSTRACT Objective. To determine the correlation between microbiological culture and otic cytology for diagnoses of external otitis by Malassezia in dogs. Materials and methods. 158 ear swabs of dogs with clinical diagnosis of external otitis were analyzed by cytology, mycological culture and metabolic tests. Results. Were obtained a positive results by cytology of 62% and 75.3% by culture. The 31.1% of isolates were identified as M. pachydermatis, 12.6% as M. furfur and 56.3% were classified as Malassezia spp., because was not possible to define the species. We found a positive concordance between cytology and culture for Malassezia spp., of 0.76 with a kappa index of 0.448 (95% CI 0.30 to 0.60) which represents a moderate strength of concordance between the two techniques, without regard the identified species. Conclusions. The use of a diagnostic test is not enough to establish the participation of Malassezia spp., as a causal disease agent

Phenotypic characterization of canine Malassezia spp., isolates

Objective. To characterize and identify yeasts of the genus Malassezia by phenotypic features. Materials and methods. First, the macroscopic and microscopic morphological characteristics were described. In addition we performed biochemical and physiological assays as Tweens and Cremophor, including more. Results. Our results evidenced of 105 isolates obtained from dogs diagnosed with external otitis, it was possible to identify two distinct species from 46 isolates within the Malassezia genus: 36.19% (n=38) were identified as M. pachydermatis and 7.62% (n=8) as M. furfur. According to phenotypic patterns the remaining 56.19% (n=59) were reported as Malassezia spp., possibly corresponding to M. furfur and/or M. pachydermatis. Conclusions. Results emphasize the necessity to characterize according to species. It is not feasible to define Malassezia by species based on morphological, biochemical, and physiological findings. Therefore, molecular genotyping should be performed to identify markers allowing a more precise isolate identification. This would broaden our epidemiological knowledge regarding different species involved in canine otitis pathologies