Molecular characterization and in vitro antifungal susceptibility of 80 clinical isolates of mucormycetes in Delhi, India

Mucormycosis is a highly aggressive disease which is usually fatal in immunocompromised patients. The species of mucormycetes show significant differences in susceptibility to amphotericin B, azoles and terbinafine. The precise species level identification for this fungal group could be achieved by internal transcribed-spacer (ITS) region sequencing. Herein, we present the largest series of antifungal susceptibility data of molecularly characterised isolates of mucormycetes reported so far from India. Eighty isolates originating from 71 patients comprised 50 (62.5%) from pulmonary cases, 15 (19%) from rhino-orbital-cerebral, 13 (16.2%) from cutaneous and 2 (2.5%) from disseminated mucormycosis. ITS and D1/D2 regions sequencing of the isolates identified, Rhizopus arrhizus var. delemar (n=25), R. arrhizus var. arrhizus (n=15), R. microsporus (n=17), R. stolonifer (n=3), Syncephalastrum racemosum (n=11), Apophysomyces elegans (n=2), A. variabilis (n=2), Lichtheimia ramosa (n=3) and Mucor circinelloides f. lusitanicus (n=2). Amplified fragment length polymorphism analysis was done to genotype Rhizopus isolates and revealed 5 clusters of R. arrhizus, which were well separated from R. microsporus. Amphotericin B was the most potent antifungal followed by posaconazole, itraconazole and isavuconazole. Etest and CLSI MICs of amphotericin B showed 87% agreement. Overall, the commonest underlying condition was uncontrolled diabetes mellitus. Records of 54 patients revealed fatalities in 28 cases.