In vitro inhibitory activity of spice-derived essential oils for multi-drug resistant Aspergillus fumigatus recovered from poultry feed

ABSTRACT Aspergillus fumigatus is a respiratory pathogen, which has the potential to cause brooder pneumonia in poultry chicks and aspergillosis in birds and farmers. Frequent and irrational use of antifungals has led to the development of resistance in the fungal species. The present study aimed to evaluate the antifungal activity of essential oils (EOs) from four different spices against multi-drug resistant (MDR) A. fumigatus isolated from 40 poultry feed samples. Twenty fungal isolates were identified to be A. fumigatus based on the macroscopic and microscopic characteristics, which were confirmed by targeting and amplifying the species-specific rodA gene (313 bp). Five (5/20) isolates were found to be MDR by the disk diffusion method. EOs were tested as an alternative strategy for 5 MDR isolates of A. fumigatus. Clove EO provided better activity by 6 log10 reduction for 30-90 min exposure as compared to other EOs, therefore, shortlisted for well-diffusion and minimum inhibitory concentration (MIC) method. Clove EO provided promising results as compared to fluconazole, amphotericin B, ketoconazole, nystatin and voriconazole as its mean ZOI (39.6 ± 6.34) were better than all other commercial antifungals (p< 0.001). Mean MIC was reported to be 0.195 ± 0.11 µl/ml. Safety testing of the EO produced 74-82% cell viability for the range of 0.390 - 0.097 µl/ml as compared to DMSO. Findings of the present study highlight that clove EO can be source of a good therapeutic agent for infections of MDR isolates of A. fumigatus.