Association of in-vitro production of virulence factors and the antifungal susceptibility pattern of Mucormycetes (zygomycetes) isolated from clinical samples at a tertiary care center, Chennai.

Background: Mucormycosis is a serious fungal infection caused by the class mucormycetes. Individuals with risk factors associated with mucormycosis have a chance of producing virulence factors. This study was undertaken to understand the association between the production of various virulence factors and the antifungal susceptibility pattern as it aids in providing effective treatment, especially in a hospital-based setup. Methods: A total of 54 isolates belonging to the order Mucorales received in the Mycology division, Sri Ramachandra Institute of Higher Education and Research, Porur, Chennai were considered for the study. Phenotypic confirmation of the isolates was done by performing Lactophenol cotton blue (LPCB) wet mount and also by studying the colony morphology on Sabouraud’s dextrose agar. The production of virulence factors such as lipase, phospholipase, amylase, and hemolysin was detected using standard phenotypic methods with Mucor racemosus ATCC (American Type Culture Collection) 42647 as the control strain. Antifungal susceptibility patterns of all mucormycetes isolates to amphotericin B, itraconazole, voriconazole, posaconazole, and isavuconazole were evaluated as per the Clinical Laboratory Standards Institute (CLSI) M38-A2 guidelines. Results: The distribution of the isolates was Rhizopus sp (45), Rhizomucor sp (4), Mucor sp (2), Lichtheimia sp (1), and Apophysomyces variabilis (2). The mean MIC values are as follows: Amphotericin B (0.91 µg/ml), Itraconazole (12.58 µg/ml), Posaconazole (11.28 µg/ml), Voriconazole (12.95 µg/ml), and Isavuconazole (1.71 µg/ml). All the highly resistant strains produced virulence factors, and few isolates that showed low MIC had also produced virulence factors indicating even if it has low MIC it could be a virulent strain. Conclusion: The study's findings characterize the relationship between virulence factors and antifungal resistance and advance the understanding of the pathogenesis of mucormycetes. These findings may also suggest new therapeutic approaches in light of the potential role of the virulence mechanism in treatment efficacy.