Screening for Azole Resistance among Aspergillus spp isolated from Soil of Hospitals and a University Campus in Gorgan, Iran

Aspergillosis is a widely distributed infectious disease, which is difficult to manage. According to recent studies, the prevalence of resistant Aspergillus fumigatus has increased from 3.3% to 6.6%. Acquired triazole resistance in Aspergillus species is an evolving global health challenge, which has made the control of diseases caused by Aspergillus a concern. This study was performed to investigate prevalence of azole resistance in Aspergillus isolates from environmental samples.

In this study, 316 soil samples were collected from three hospitals and a university campus in Gorgan (Iran) from July to September 2017. Two grams of each sample were suspended in 5 ml of 0.2M NaCl with 1% Tween 20. Then, 100 µl of the suspension was plated on sabouraud dextrose agar (SDA) supplemented with chloramphenicol, SDA supplemented with chloramphenicol and voriconazole (VOR, 1 mg/L) and SDA supplemented with chloramphenicol and itraconazole (ITC, 4 mg/L). The plates were incubated at 37 °C and examined for growth after 24, 48 and 72 hours.

We detected Aspergillus fumigatus, Aspergillus flavus, Aspergillus niger and Aspergillus nidulans isolates in 187(59.2%), 84(26.6%), 147(46.5%) and 65(20.6%) samples, respectively. We found no VOR resistant isolate. However, 21 (25%) A. flavus and 16 (8.6%) A. fumigatus isolates were intermediate for VOR. In addition, seven (8.3%) A. flavus, 68 (36.4%) A. fumigatus, 41 (27.9%) A. niger and three (4.5%) A. nidulans isolates were resistant to ITC.

We were able to detect A.fumigatus, A. flavus, A. niger from all four sampling sites in Gorgan, North of Iran. A. fumigatus is the most prevalent and most resistant isolate in the studied area. History of previous agriculture activity and use of pesticides in the proximity of sampling sites may have affected the rate of ITC resistance.