Mucormycosis: Microbiological insights, diagnostic advances, and emerging trends with special reference to Tamil Nadu

Abstract

Mucormycosis is a rapidly progressive and life-threatening fungal infection caused by fungi of the order Mucorales, characterized by angioinvasion, thrombosis, and extensive tissue necrosis. India carries the highest global burden of the disease, with incidence rates estimated to be 70-80 times higher than those reported in developed countries. During the second wave of the COVID-19 pandemic, a significant surge in COVID-19-associated mucormycosis was observed, particularly in Tamil Nadu, which emerged as one of the most severely affected states. Uncontrolled diabetes mellitus, especially when associated with prolonged or inappropriate corticosteroid therapy, remains the most important predisposing factor, while COVID-19-related immune dysregulation further increases susceptibility. Rhizopus arrhizus is the most commonly isolated pathogen, although newer species are increasingly being reported. The infection usually begins through inhalation of fungal spores, followed by rapid tissue invasion and vascular involvement, processes that are intensified in diabetic ketoacidosis due to elevated free iron levels. Early diagnosis using microscopy, histopathology, culture, and molecular techniques, along with prompt antifungal therapy such as Amphotericin B, is essential for improving survival and reducing mortality.