Characterization of Cryptococcus Neoformans Strains From Cases of Cryptococcal Meningitis in India

Abstract

Reports of clinical isolates of Cryptococcus neoformans often lack information on their mating types, molecular types, and in vitro antimycotic susceptibilities. This study compares these and other related characteristics of fifteen strains of C. neoformans obtained from cases of meningitis in different regions of India. PCR was used to determine the mating type and serotype of each strain, and Amplified Fragment Length Polymorphism was used for molecular typing of the strains. In vitro assays compared the proteinase and phospholipase activities of the strains, and the Clinical and Laboratory Standards Institute (CLSI) protocol was used to determine their minimal inhibitory concentrations (MICs) to amphotericin B (AMB), itraconazole, and fluconazole. All strains were identified as C. neoformans var. grubii (serotype A), possessed the alpha mating type, and belonged to molecular type VNII. Ten of the strains demonstrated strong proteolytic activity, and the remaining five were weakly proteolytic. Nine of the strains were positive for phospholipase. In vitro antifungal susceptibility tests, determined the MIC (µg/ml) values for AMB, itraconazole, and fluconazole to be 0.03-0.5, 0.002-03, and 2-4 µg/ml, respectively. Remarkedly, all 15 strains belonged to the relatively rare molecular type, VNII. This report is one of few studies to characterize clinical strains of C. neoformans from India.