In vitro effects of omeprazole in combination with antifungal compounds againstMalassezia pachydermatis

Abstract

AbstractBackgroundFungal and yeast infections, including those caused byMalasseziaspp., are becoming increasingly difficult to treat, likely due to the occurrence of drug resistance.ObjectivesThis study aimed to evaluate the antifungal effects of omeprazole (OME), a proton pump inhibitor, against antifungal‐resistantMalassezia pachydermatisand to investigate the potential synergistic effects between OME and other antifungal compounds.MethodsIn total, 15 samples ofM. pachydermatisisolated from the skin of dogs were tested. The susceptibility ofM. pachydermatisto itraconazole, ketoconazole, miconazole, terbinafine and OME was assessed using a modified broth microdilution (BM) method. The in vitro efficacy of OME alone and in combination with other antifungal compounds was evaluated for all isolates using the BM chequerboard method. The data obtained were analysed using the fractional inhibitory concentration index (FICI).ResultsThe minimum inhibitory concentration (MIC) values of antifungal compounds and OME against quality control strain (M. pachydermatisCBS1879) were lower than the MIC90values of same drugs against clinically collected strains. There was no significant difference in MIC values between drugs alone and combination. According to the analysis by the FICI method, no interaction was observed with OME and antifungal compounds.ConclusionsMostM. pachydermatisstrains were resistant to azole antifungal compounds. OME exerted antifungal effects againstMalasseziaspp. and even showed good effects on antifungal‐resistant strains. No synergistic effects were observed between the antifungal compounds and OME.