SUSCETIBILIDADE IN VITRO DE Malassezia pachydermatis FRENTE A AGENTES ANTIFÚNGICOS E FRAÇÕES DE ÓLEOS ESSENCIAIS

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The yeast Malassezia pachydermatis belongs to the normal microbiota of animals, and is usually implicated as responsible for otitis media and recently by various forms of dermatitis, mainly in dogs. This study aimed to evaluate the in vitro susceptibility of 26 M. pachydermatis isolates against the antifungals fluconazole, itraconazole, ketoconazole, clotrimazole, miconazole, terbinafine and nystatin, and to the combinations of these with thymol, carvacrol and cinnamaldehyde by the checkerboard method, based on document M27-A3. The activity of itraconazol, ketoconazole and clotrimazole against 20 isolates of M. pachydermatis, through simultaneous and sequential exposure of these agents, was also evaluated by the disk-diffusion technique. The minimum inhibitory concentration (MIC) for fluconazole ranged from 1-64 μg/mL, itraconazole 0.01-1 μg/mL, ketoconazole 0.01-0.5 μg/mL, clotrimazole 0.5-32 μg/mL, miconazole 2-32 μg/mL, terbinafine 0.12-32 μg/mL and nystatin 16-64 μg/mL. High rates of synergism were observed in the combinations of nystatin + thymol (88.46%), nystatin + carvacrol (88.46%), nystatin + cinnamaldehyde (73.07%), clotrimazole + thymol (69.23%), clotrimazole + carvacrol (69.23%), miconazole + thymol (65.38%), miconazole + carvacrol (76.92%) and miconazole + cinnamaldehyde (65.38%). However, high rates of indifference were observed in the combinations of fluconazole + thymol (53.84%), carvacrol + fluconazole (46.15%), fluconazole + cinnamaldehyde (65.38%), thymol + itraconazole (61.53%), carvacrol + itraconazole (69.23%), itraconazole + cinnamaldehyde (65.38%), terbinafine + thymol (73.07%), terbinafine + carvacrol (65.38%), terbinafine + cinnamaldehyde (73.07%) and clotrimazole + cinnamaldehyde (61.53%). Ketoconazole combined with thymol, carvacrol and cinnamaldehyde had the highest rates of antagonism (42.3%). The prior exposure of M. pachydermatis to itraconazole resulted in a reduction of the inhibition halo when compared with itraconazole and ketoconazole used simultaneously (p

Malassezia pachydermatis é uma levedura pertencente à microbiota normal de animais e, usualmente, apontada como responsável por otites externas e recentemente por diversas formas de dermatites, principalmente em cães. Este estudo teve como objetivo avaliar a suscetibilidade in vitro de 26 isolados de M. pachydermatis frente aos antifúngicos fluconazol, itraconazol, cetoconazol, clotrimazol, miconazol, terbinafina e nistatina, e combinações desses com timol, carvacrol e cinamaldeído, através do método de checkerboard, baseado no documento M27-A3. Também foram avaliadas a atividade do itraconazol, cetoconazol e clotrimazol, em 20 isolados de M. pachydermatis, através da exposição simultânea e sequencial desses agentes utilizando-se a técnica de disco-difusão. Isoladamente, as concentrações inibitórias mínimas (CIMs) para o fluconazol variaram de 1- 64 μg/mL, para o itraconazol 0,01-1 μg/mL, para o cetoconazol 0,01-0,5 μg/mL, para o clotrimazol 0,5-32 μg/mL, para o miconazol 2-32 μg/mL, para a terbinafina 0,12-32 μg/mL e para a nistatina 16-64 μg/mL. Altas taxas de sinergismo foram observadas nas combinações de nistatina + timol (88,46%), nistatina + carvacrol (88,46%), nistatina + cinamaldeído (73,07%), clotrimazol + timol (69,23%), clotrimazol + carvacrol (69,23%), miconazol + timol (65,38%), miconazol + carvacrol (76,92%) e miconazol + cinamaldeído (65,38%). No entanto, fluconazol + timol (53,84%), fluconazol + carvacrol (46,15%), fluconazol + cinamaldeído (65,38%), itraconazol + timol (61,53%), itraconazol + carvacrol (69,23%), itraconazol + cinamaldeído (65,38%), terbinafina + timol (73,07%), terbinafina + carvacrol (65,38%), terbinafina + cinamaldeído (73,07%) e clotrimazol + cinamaldeído (61,53%) tiveram altas taxas de indiferença. Cetoconazol combinado com timol, carvacrol e cinamaldeído apresentaram as maiores taxas de antagonismo (42,3%). A exposição prévia de M. pachydermatis ao itraconazol resultou em uma diminuição da zona de inibição, quando comparado com o itraconazol e cetoconazol usados simultaneamente (p