Antifungal activity of monensin on Malassezia in vitro isolated from canines with otitis external

Abstract

Objective. Evaluate the antifungal activity of monensin on Malassezia in Vitro, isolated from canines with external otitis (EO), and delimitate their susceptibility to monensin, wich will be cultured in vitro. Methodology. This research was conducted on 30 canine patients, suffering from clinical external otitis, and treated at ¨Fundación Arca¨ and private veterinary clinics.  These canine patients exhibited clinical signs such as pain, erythema of pinna, pruritus, head shacking and head tilting. Malassezi pachidermatis was identified as the etiological agent through cytology with diff-quick staining, and samples were evaluated under a microscope to confirm the presence of Malassezia for in vitro culturing. The antimicrobial activity of monensin was assessed using four different concentrations: 1%, 5%, 10%, and 20% in petri dishes. Results. The results showed that all 30 canine patients tested positive for Malassezia, but the antimicrobial activity of monensin did not yield any favorable results compared to other commercially used antifungal agents like ketoconazole, fluconazole, and griseofulvin. Ketoconazole exhibited the highest antifungal activity against Malassezia. Conclusion. Malassezia develops a significant role in this disease, and various treatments have been investigated and implemented form this fungus. However, with the evolution of the species, new resistances have emerged, resulting in persistent chronic infections. Monensin does not act against this microorganism at the concentrations used in this study; therefore, new studies are needed to analyze pharmacological components, including various natural oils, with the aim of avoiding toxic and adverse effects for the canines.