Development and validation of an in vitro resazurin-based susceptibility assay against Madurella mycetomatis

We here present an in vitro susceptibility assay for Madurella mycetomatis hyphae using resazurin for endpoint-reading. Using this assay, reproducible minimal inhibitory concentrations (MICs) were obtained for amphotericin B, itraconazole, voriconazole, posaconazole, terbinafine and micafungin. Results were comparable with XTT-based susceptibility assay. Lowest MICs were obtained for itraconazole and posaconazole (MIC50 of 0.016 μg/mL) followed by voriconazole (MIC50 of 0.063 μg/mL). Amphotericin B, micafungin, and terbinafine appeared much less effective.