Antifungal Resistance Analysis of Environmental Isolates of Aspergillus in North India

Abstract

Triazoles are the major group of antifungals for treating Aspergillus infections. The morbidity and mortality associated with these infections is high and rate of treatment failure is more in patients infected with azole resistant Aspergillus. The azole resistant Aspergillus isolates have been recovered from both azole treated and azole naive patients. Thus, there may be an environmental route of exposure to azole resistant Aspergillus. The present study was envisaged for the isolation and enumeration of environmental isolates of Aspergillus resistant to medically available antifungal azole drugs in North Indian environment. A total of 25 soil samples were collected from North Indian agricultural farms where azole pesticides were being used. The soil samples were screened for Aspergillus isolates by serial dilution pour plate method. Further, their drug susceptibility testing was performed using disc diffusion, E- strip and micro-broth dilution method against medically available triazoles: itraconazole, ketoconazole, fluconazole and voriconazole. A total of 41 Aspergillus species were isolated from the soil samples. Based on conventional microscopic assay, 13 of them were identified as Aspergillus fumigatus, 9 as Aspergillus niger, 5 as Aspergillus terreus, 3 as Aspergillus nidulans, 1 as Aspergillus flavus and 9 as other Aspergillus species. Resistance for all tested antifungal drugs was detected in 7.3% Aspergillus isolates and 43.7% isolates were resistant to any of the tested azole drugs. The results demonstrated that Aspergillus isolates resistant to medical triazoles are present in the agricultural farms.

Keywords

• aspergillus
• antifungals
• azole resistance
• antifungal susceptibility test.