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Genotypic diversity in clinical and environmental isolates of Cryptococcus neoformans from India using multilocus
Anupam Prakash1, Gandhi Sundar1, Brijesh Sharma2
1Department of Medical Mycology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India.
Background:
Cryptococcus neoformans is the leading cause of cryptococcal meningitis in HIV/AIDS patients. As infections in humans are predominantly caused by the inhalation of basidiospores from environmental sources, therefore, analysing the population structure of both clinical and environmental populations of C neoformans can increase our understanding of the molecular epidemiology of cryptococcosis.
Objective:
To investigate the genotypic diversity and antifungal susceptibility profile of a large collection of C neoformans isolates (n = 523) from clinical and environmental sources in India between 2001 and 2014.
Materials And Methods:
Cryptococcus neoformans isolates were genotyped by AFLP, microsatellite typing (MLMT) and MLST. In vitro antifungal susceptibility for standard antifungals was undertaken using CLSI M27-A3.
Results:
All isolates were C neoformans, AFLP1/VNI and exhibited mating-type MATα. MLMT revealed that the majority of isolates belonged to microsatellite cluster (MC) MC3 (49%), followed by MC1 (35%), and the remaining isolates fell in 11 other MC types. Interestingly, two-thirds of clinical isolates were genotype MC3 and only 17% of them were MC1, whereas majority of environmental strains were MC1 (54%) followed by MC3 (16%). Overall, MLST assigned 5 sequence types (STs) among all isolates and ST93 was the most common (n = 76.7%), which was equally distributed in both HIV-positive and HIV-negative patients. Geometric mean MICs revealed that isolates in MC1 were significantly less (P < .05) susceptible to amphotericin B, 5-flucytosine, itraconazole, posaconazole and isavuconazole than isolates in MC3.
Conclusions:
The study shows a good correlation between MLMT and MLST genotyping methods. Further, environmental isolates were genetically more diverse than clinical isolates.
Insights
Cryptococcus neoformans molecular epidemiology was studied in India. Environmental isolates showed greater genetic diversity than clinical ones, with distinct microsatellite profiles influencing antifungal susceptibility.
Area of Science:
- Medical Mycology
- Molecular Epidemiology
- Antimicrobial Resistance
Background:
- Cryptococcus neoformans is a primary cause of cryptococcal meningitis in HIV/AIDS patients.
- Infections typically arise from inhaled environmental basidiospores.
- Analyzing clinical and environmental C. neoformans populations enhances understanding of cryptococcosis epidemiology.
Purpose of the Study:
- To investigate genotypic diversity and antifungal susceptibility of C. neoformans isolates from India (2001-2014).
- To analyze 523 clinical and environmental C. neoformans isolates.
Main Methods:
- Genotyping using Amplified Fragment Length Polymorphism (AFLP), Microsatellite-Length Multiplex Typing (MLMT), and Multilocus Sequence Typing (MLST).
- In vitro antifungal susceptibility testing following CLSI M27-A3 guidelines.
Main Results:
- All isolates were C. neoformans, AFLP1/VNI, mating-type MATα.
- MLMT identified MC3 (49%) and MC1 (35%) as dominant microsatellite clusters.
- Clinical isolates predominantly belonged to MC3, while environmental isolates favored MC1.
- MC1 isolates showed significantly lower susceptibility to multiple antifungals compared to MC3 isolates.
Conclusions:
- MLMT and MLST genotyping methods demonstrated good correlation.
- Environmental C. neoformans isolates exhibited greater genetic diversity than clinical isolates.
- Genotypic variations correlate with differential antifungal susceptibility profiles.
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