Low In Vitro Activity of Amphotericin B among Clinical Isolates of Aspergillus Spp. in a Subtropical Region of the Middle East: Species or Genome can be Effective?

Abstract

Background: Aspergillus genus is a group of opportunistic molds that can cause the different types of aspergillosis in various individuals especially those who are prone to immune deficiencies. Recently, the antifungal resistance has been increasingly reported among Aspergillus clinical isolates. The aim of the present study was to determine the in vitro antifungal susceptibility patterns of Aspergillus clinical isolates causing human infections in a subtropical region of the Middle East. Methods: The minimum inhibitory/effective concentrations (MICs/MECs) of 60 clinical Aspergillus strains including A. flavus (n=39), A. niger (n=11), A. fumigatus (n=6), A. tubingensis (n=3) and A. oryzae (n=1) were determined using the CLSI M38-A2 broth microdilution method. The antifungal agents tested were; amphotericin B, itraconazole, voriconazole, and caspofungin. The data were analyzed by using the Chi-square test in SPSS 20 software. Results: The MEC range of caspofungin was 0.007-4 μg/ml and the geometric mean (GM) was 0.45 μg/ml. The MIC ranges of itraconazole, voriconazole and amphotericin B were 0.031-4 μg/ml, 0.5-4 μg/ml and 1-4 μg/ml, respectively, and the GMs were 1.21 μg/ml, 2.51 μg/ml and 3.43 μg/ml, respectively. Conclusion: Caspofungin and amphotericin B was the most effective and least effective antifungal agent against all Aspergillus clinical isolates, respectively. A. flavus, A. niger and A. tubingensis were more susceptible to caspofungin, and A. fumigatus showed more susceptible to itraconazole.