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Identification of the perfect state of Cryptococcus neoformans from 195 clinical isolates including 84 from AIDS
N Madrenys1, C De Vroey, C Raes-Wuytack
1Department of Microbiology, Autonomous University of Barcelona, Spain.
Abstract:
Filobasidiella neoformans is the teleomorphic state of Cryptococcus neoformans and it is a heterothalic. The purpose of this study was to establish the proportions of each mating types (a, alpha) from among 195 strains of C. neoformans isolated from clinical material. The culture medium used was sunflower agar. Cultures were incubated at 20-22 degrees C for 15 days and observed periodically for one month. Non-reactive strains were mated several times with different reactive strains. Under these conditions 96.8% of the strains were found to be reactors. Among both varieties of C. neoformans, mating type alpha was found to have the highest frequency of 95% in the variety neoformans and 84% in the variety gattii. These results showed a higher reactivity in comparison with other investigators. This difference could be due to the medium used or to repeated mating with different reactive tested strains.
Insights
This study investigated mating types in Cryptococcus neoformans, finding that 96.8% of clinical strains were reactive. Mating type alpha was predominant in both C. neoformans varieties.
Area of Science:
- Medical Mycology
- Fungal Genetics
Background:
- Filobasidiella neoformans is the teleomorphic state of Cryptococcus neoformans.
- Cryptococcus neoformans is a significant human pathogen, and understanding its mating types is crucial for epidemiological and genetic studies.
Purpose of the Study:
- To determine the proportions of mating types (a and alpha) among 195 clinical isolates of Cryptococcus neoformans.
- To assess the reactivity of these clinical strains under specific culture conditions.
Main Methods:
- 195 clinical isolates of Cryptococcus neoformans were cultured on sunflower agar.
- Cultures were incubated at 20-22°C for 15 days and observed for one month.
- Non-reactive strains were repeatedly mated with known reactive strains to confirm mating type.
Main Results:
- 96.8% of the tested Cryptococcus neoformans strains exhibited mating activity.
- Mating type alpha was the most frequent, found in 95% of the C. neoformans var. neoformans strains and 84% of the C. neoformans var. gattii strains.
- The observed reactivity was higher than reported in previous studies, potentially due to the sunflower agar medium or repeated mating protocols.
Conclusions:
- The study highlights a high prevalence of mating-reactive strains and a strong predominance of mating type alpha in clinical isolates of Cryptococcus neoformans.
- The findings suggest that mating type alpha is the dominant mating type in both major varieties of this fungus.
- The enhanced reactivity observed may be attributed to methodological differences, including the specific culture medium and mating strategies employed.