Caracterización fenotípica de aislamientos de Malassezia spp., de origen canino

Abstract

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. Keywords: Biochemical techniques, external otitis, Malassezia, morphology. (Source: CAB) RESUMENObjetivo. Caracterizar e identificar levaduras del género Malassezia, mediante características fenotípicas. Materiales y métodos. Inicialmente se describieron las características morfológicas macroscópicas y microscópicas, adicionalmente se realizaron pruebas bioquímicas y fisiológicas como Tween y Cremophor, entre otras. Resultados. De 105 aislamientos de caninos diagnosticados previamente con otitis, 46 fueron caracterizados hasta especie, así: El 36.19% (n=38) correspondió a M. pachydermatis, el 7.2% (n=8) a M. furfur; y 56.19% (n=59) restante fueron reportados como Malassezia spp., debido a los patrones fenotípicos atípicos que presentaron, y que podrían corresponder a variantes de M. furfur y/o M. pachydermatis. Conclusión. Estos resultados enfatizan la necesidad de hacer una caracterización a nivel de especie y/o genotipos mediante marcadores moleculares que permitan una identificación más precisa de los aislamientos. Con el presente estudio, se contribuye al conocimiento de las diferentes especies involucradas en patologías óticas en caninos.

Alternative approaches for treating canine otitis externa caused by Malassezia pachydermatis

“…However, accurate diagnosis requires cytological examination (Angus, 2004;Graham-Mize & Rosser Junior, 2004;Kashif et al, 2016). While fungal culture is the gold standard for diagnosis, it is not commonly used in routine clinical practice, unlike antifungal susceptibility testing (Hurtado-Suárez et al, 2016;Puig et al, 2019). The standard treatment protocol for otitis externa in dogs usually involves the topical application of a combination of drugs, such as an antifungal, an antibiotic, and a glucocorticoid, into the external ear canal (Bensignor & Grandemange, 2006;Rosychuk, 1994).…”