Invasive Mucormycosis (zygomycosis) in the Pre-Covid-19 and COVID-19 Eras: A Comparative Retrospective Study at a Tertiary Care Center in Chennai

Introduction: In India, the incidence of mucormycosis is high among patients with uncontrolled diabetes mellitus, with a prevalence of approximately 0.02-9.5 cases per 100,000 persons. There was a localized epidemic of mucormycosis during the second wave of Coronavirus disease-2019 (COVID-19), which could be attributed to the indiscriminate use of steroids and lapses in infection control practices, both in the hospital and at home. Treatment of mucormycosis is challenging because it is highly invasive and intrinsically resistant to some of the antifungal agents. In this study, we aimed to compare the prevalence, clinical presentations, and antifungal susceptibility pattern of mucormycosis between the pre-COVID-19 era and COVID-19 eras. Materials and Methods: This single-center retrospective study included patients admitted during the pre-COVID-19 era and COVID-19 era at a tertiary care center in Chennai. The samples were subjected to culture techniques, and the positive isolates were tested for antifungal susceptibility to amphotericin B, itraconazole, posaconazole, voriconazole, and isavuconazole via the microbroth dilution method, according to the CLSI M38-A2 guidelines. Results: Among the 365 samples received at the laboratory during the pre-COVID-19 era, 52 were positive for mucormycosis. During the COVID-19 era, out of the 886 samples received, 174 were positive for mucormycosis. The incidence of mucormycosis was high during the COVID-19 era. Although most of the risk factors and clinical presentations were similar during the pre-COVID-19 and COVID-19 eras, clinical complications were more common during the pre-COVID-19 era. The mean minimum inhibitory concentration (MIC) of amphotericin B was higher during the pre-COVID-19 era than during the COVID-19 era. Furthermore, the mean MIC of posaconazole was higher during the COVID-19 era than during the pre-COVID-19 era. This may be attributable to the increased usage of posaconazole during the COVID-19 era. Due to its low MIC value, newer azoles such as isavuconazole can be considered a good therapeutic option for future resistant infections. Conclusion: Early diagnosis and timely management of mucormycosis with appropriate antifungals, on the basis of antifunal susceptibility tests, may help improve the patient outcomes and prevent the development of resistance.