Azole resistance using agar screening in environmental isolates of Aspergillus species from Pakistan

Background: Azole resistance in clinical and environmental Aspergillus isolates has been reported globally. The environmental route of resistance follows the use of fungicides in agricultural practices and is known to be more common than the clinical route of resistance. We aimed to screen for azole resistance in Aspergillus species from environmental sources in Pakistan. Material and Methods: This was a cross-sectional, observational study conducted from November 2021 to June 2023 at Aga Khan Aga Khan University Hospital, Karachi. Environmental Aspergillus isolates from across Pakistan were screened for azole resistance using previously described methods. Soil samples were collected from different towns and cities of Pakistan using convenience sampling. A suspension of soil in normal saline was cultured on SDA to yield fungal colonies, and onto media containing posaconazole, voriconazole and itraconazole in defined concentrations to screen for resistance. Growth on antifungal containing media was considered to be resistant. Results: Soil was collected from 171 different sites across Pakistan. A total of 249 Aspergillus isolates were recovered from these soil samples. These included 99 (39.7%) A. niger, 84 (33.7%) A. flavus, 31 (12.4%) A. fumigatus, and other species. None of the isolates grew on any of the antifungal containing media, indicating no resistance. Conclusion: Our study finds no indication of azole resistance in environmental isolates from Pakistan. However, methodologies such as MIC determination and genotypic sequencing are needed for a more robust analysis. Keywords: Aspergillus species, Agar screening, Azole resistance, Environmental, Pakistan