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[Characterization of Cryptococcus neoformans strains isolated from patients with acquired immunodeficiency syndrome
D Garza-Garza1, J L Buendía-Uribe, E Martínez-Cruz
1Departamento de Microbiología, Instituto Politécnico Nacional, Mexico.
Abstract:
In Mexico cryptococosis ranks third in frequency among the mycoses ocurring as complications in AIDS patients. Neither the prevalence of the two varieties of C. neoformans in these patients nor the morphological and physiological changes suffered by these strains in AIDS patients are known. A total of 60 isolates were obtained from patients with AIDS from the Hospital de Infectología, Centro Médico "La Raza" IMSS. The identity of each isolate was established by: growth at 37 degrees C, colony and microscopic characteristics, urease and phenoloxidase activity, carbon sources assimilation. The canavanine glycine-bromothymol blue agar was used to distinguish C. neoformans var. neoformans and C. neoformans var. gattii. Pathogenicity in mice was also tested. Fifty one isolates of C. neoformans var. neoformans and nine of C. neoformans var. gattii were identified. All strains grew well at 37 degrees C, urease and phenoloxidase were positive, the morphology and the auxanographic profile were variable. C. neoformans var. neoformans was more virulent in mouse than C. neoformans var. gattii. This study has confirmed the presence of the two varieties of C. neoformans in Mexico with 85% prevalence of var. neoformans and 15% of var. gattii in AIDS patients. This frequency was higher than in reports from other countries.
Insights
Cryptococcosis is a significant fungal infection in Mexican AIDS patients. This study identified both Cryptococcus neoformans varieties, with C. neoformans var. neoformans being more prevalent and virulent.
Area of Science:
- Medical Mycology
- Infectious Diseases
- Immunocompromised Hosts
Background:
- Cryptococcosis is a leading mycosis in AIDS patients in Mexico.
- The prevalence and characteristics of Cryptococcus neoformans varieties in this population were previously unknown.
Purpose of the Study:
- To determine the prevalence of Cryptococcus neoformans varieties in Mexican AIDS patients.
- To characterize the morphological and physiological traits of these fungal strains.
- To assess the pathogenicity of different varieties in a murine model.
Main Methods:
- Sixty Cryptococcus neoformans isolates were obtained from AIDS patients.
- Identification involved phenotypic tests (growth at 37°C, urease, phenoloxidase, carbon assimilation) and CGB agar.
- Pathogenicity was evaluated in a mouse model.
Main Results:
- Fifty-one isolates were identified as C. neoformans var. neoformans and nine as C. neoformans var. gattii.
- All strains exhibited positive urease and phenoloxidase activity; morphology and auxanogram profiles varied.
- C. neoformans var. neoformans demonstrated higher virulence in mice compared to C. neoformans var. gattii.
Conclusions:
- This study confirms the presence of both C. neoformans varieties in Mexico.
- C. neoformans var. neoformans (85%) was more prevalent than C. neoformans var. gattii (15%) in Mexican AIDS patients.
- The observed prevalence rates exceed those reported in other countries.