Post-COVID-19 rhino-orbito-cerebral mucormycosis-A clinico-mycological study from North India

Abstract

The second wave of coronavirus disease 2019 (COVID-19), during the early 2021, lead to a devastating outbreak of mucormycosis in India. This study aimed to determine the aetiology, clinical features, comorbidities, and risk factors of rhino-orbito-cerebral mucormycosis (ROCM) and antifungal susceptibility pattern for the isolates. The study included all suspected cases of ROCM in post-COVID-19 patients attending the hospital from May to December 2021. A total of 70 patients were diagnosed with mucormycosis during the study period. The commonest presentations were rhino-orbital and rhino-orbito-cerebral in 35.7% of cases each. Diabetes mellitus was the commonest associated risk factor in 95.7% of all patients, while 78.5% of the patients were treated with corticosteroids in the recent past, and 25.7% presented with active COVID-19 pneumonia. The commonest isolate was Rhizopus arrhizus n = 14, followed by Aspergillus flavus n = 16, A. fumigatus n = 4, A. niger n = 3, Fusarium oxysporumn = 1, and Apophysomyces variabilisn = 1. Fungal species identification was done by phenotypic methods for all the isolates and DNA sequence analysis of 18 isolates, and antifungal susceptibility testing of 30 isolates was performed by commercially prepared HiMIC plate (HiMedia, Mumbai, India) using broth microdilution for amphotericin B, isavuconazole, itraconazole, voriconazole, and posaconazole. The MIC50 and MIC90 of amphotericin B for R. arrhizus strains were 0.25 and 4 μg/ml, respectively; and the MIC50 and MIC90 results for itraconazole, posaconazole, and isavuconazole were 8 and 8, 2 and 2, and 2 and 8 μg/ml, respectively. In vitro data showed that amphotericin B was the most effective antifungal against most species. The commercially available ready-to-use minimum inhibitory concentration plates are user-friendly for performing antifungal susceptibility, which may be useful in choosing appropriate regimens and monitoring emerging resistance.

Keywords: COVID-19-associated mucormycosis; amphotericin B; mucormycosis; rhino-orbito-cerebral mucormycosis, antifungal susceptibility.