A study on the antifungal susceptibility pattern of Aspergillus species

Increasing trends in invasive fungal infections including aspergillosis are observed worldwide. Varying drug resistance patterns are seen with different Aspergillus species. Selection of appropriate antifungal is pivotal in treatment of chronic and invasive aspergillosis. Hence understanding the local epidemiology and resistance patterns of Aspergillus species is of utmost importance. This study aims to analyse the antifungal susceptibility pattern of clinically relevant Aspergillus species isolates from clinical specimen.

This study was done on the Aspergillus species isolates from various clinical specimens from January 2021 to May 2025. Antifungal susceptibility testing was performed by broth microdilution method after speciation using automated methods. The minimum inhibitory concentration of the isolates for 10 antifungal drugs were determined. Interpretation of results were done by using CLSI M59 document.

Aspergillus fumigatus was the commonest species (52/151 isolates) among all the isolates and among respiratory samples. Aspergillus flavus (51/151) was the overall second commonest species isolated, but commonest from sinonasal samples. The minimum inhibitory concentration for voriconazole was less than or equal to the epidemiological cut off value among 97.55% of the common Aspergillus species. About 97.3% had their minimum inhibitory concentrations for amphotericin B lower than epidemiological cut off value, while excluding inherently resistant species like Aspergillus terreus.

Voriconazole and posaconazole may be considered as empiric therapy for invasive aspergillosis based on our data. Considering the MIC results in our study, we suggest that amphotericin B along with a triazole may be used as salvage therapy for refractory cases of A. flavus infections. Antifungal susceptibility testing is advocated in situations such as difficult to treat infections, relapse and increased morbidity for clinically relevant isolates which supports careful selection of antifungals for treatment.