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Updated: Aug 5, 2026
Automated Measurement of Cryptococcal Species Polysaccharide Capsule and Cell Body
Published on: January 11, 2018
Comparative analysis of environmental and clinical populations of Cryptococcus neoformans
Anastasia P Litvintseva1, Lori Kestenbaum, Rytas Vilgalys
1Department of Molecular Genetics and Microbiology, Duke University Medical Center, Box 3020, Durham, NC 27710, USA. litvi001@mc.duke.edu
Abstract:
Cryptococcus neoformans is a major, global cause of meningoencephalitis in immunocompromised patients. Despite advances in the molecular epidemiology of C. neoformans, its population structure and mode of reproduction are not well understood. In the environment, it is associated with avian guano or vegetation. We collected nearly 800 environmental isolates from three locations in the United States (viz., North Carolina, California, and Texas) and compared them with one another and with clinical isolates from North Carolina. As expected, they consisted of the most prevalent serotypes, serotypes A and D, as well as serotype AD hybrids. The majority of environmental isolates were obtained from pigeon excreta. All environmental and clinical isolates of serotype A or D had the MATalpha mating-type allele. However, the AD hybrids included MATa alleles typical of serotypes A and D. Using an amplified fragment length polymorphism fingerprinting technique with two primer pairs, we identified 12 genotypes among the isolates of serotype A. Six of these genotypes were present in both the clinical and the environmental populations. However, one of the most prevalent environmental genotypes was absent from the clinical samples, and two other genotypes were isolated only from patients. The combined molecular data suggest that this environmental population of C. neoformans is predominantly clonal, although there was evidence for recent or past recombination.
Insights
This study investigated the population structure of Cryptococcus neoformans, a fungus causing serious infections. Environmental and clinical isolates suggest a predominantly clonal population with some evidence of recombination.
Area of Science:
- Mycology
- Infectious Diseases
- Molecular Epidemiology
Background:
- Cryptococcus neoformans is a significant cause of meningoencephalitis in immunocompromised individuals globally.
- Understanding its population structure and reproductive modes is crucial despite advances in molecular epidemiology.
- The fungus is environmentally associated with avian guano and vegetation.
Purpose of the Study:
- To investigate the population structure and reproductive modes of Cryptococcus neoformans.
- To compare environmental and clinical isolates of C. neoformans from the United States.
- To identify genotypes and their distribution in environmental and clinical settings.
Main Methods:
- Collected nearly 800 environmental isolates from North Carolina, California, and Texas.
- Compared environmental isolates with clinical isolates from North Carolina.
- Utilized amplified fragment length polymorphism (AFLP) fingerprinting with two primer pairs to identify genotypes.
Main Results:
- Environmental and clinical isolates included prevalent serotypes A, D, and AD hybrids, with most environmental isolates from pigeon excreta.
- All serotype A or D isolates possessed the MATalpha mating-type allele; AD hybrids contained MATa alleles.
- AFLP analysis revealed 12 genotypes for serotype A, with six shared between environmental and clinical populations. One prevalent environmental genotype was absent in clinical samples, and two genotypes were exclusively clinical.
Conclusions:
- The environmental population of Cryptococcus neoformans appears predominantly clonal.
- Evidence suggests recent or past recombination events within the C. neoformans population.
- Distinct genotypes exist in environmental and clinical settings, highlighting potential sources and transmission dynamics.
