In vitro antifungal susceptibility of clinical species belonging to Aspergillus genus and Rhizopus oryzae

Abstract

Objective: Among filamentous fungal pathogens, Aspergillus spp. and zygomycetes account for highest rates of morbidity and mortality among immunocompromised patients. Recently developed antifungal drugs offer the potential to improve management and therapeutic outcomes of fungal infections. The aim of this study was to analyse the in vitro activities of voriconazole, itraconazole, amphotericin B and caspofungin against clinical isolates of Aspergillus spp. and Rhizopus oryzae.

Material and methods: The in vitro antifungal susceptibility of 54 isolates belonging to different clinical isolates of Aspergillus spp. and R. oryzae was tested for four antifungal agents using a microdilution reference method (CLSI, M38-A2). All isolates were identified by typical colony and microscopic characteristics, and also characterized by molecular methods.

Results: Caspofungin (MEC range: 0.008-0.25 and MEC50: 0.0023μg/mL) was the most active drug in vitro against Aspergillus spp., followed by voriconazole (MIC range: 0.031-8 and MIC50: 0.5μg/mL), itraconazole (MIC range: 0.031-16 and MIC50: 0.25μg/mL), and amphotericin B (MIC range: 0.125-4 and MIC50: 0.5μg/mL), in order of decreasing activity. The caspofungin, voriconazole, and itraconazole demonstrated poor in vitro activity against R. oryzae isolates evaluated, followed by amphotericin B.

Conclusion: This study demonstrates that caspofungin had good antifungal activity and azole agents had better activity than amphotericin B against Aspergillus species. Although, azole drugs are considered ineffective against R. oryzae. This result is just from a small scale in vitro susceptibility study and we did not take other factors into consideration.

Keywords: Antifungal susceptibility; Aspergillus spp.; Clinical specimens; Des spécimens cliniques; Rhizopus oryzae; Sensibilité aux antifongiques.