Caracterização fenotípica de isolados de Cryptococcus gattii

Abstract

Cryptococcus neoformans was described as human pathogen in 1894. Since then, studies about fungal aspects as biology, taxonomy, ecology and epidemiology have been developed with great importance to medicine and the environment. The fungus was recently classified in two separated species, C. neoformans (serotypes A, D and AD) and C. gattii (serotypes B and C) each one with well defined genetic and morphological features as well as ecology and epidemiology aspects. C. neoformans occurs mainly in immunocompromised hosts, especially those infected by HIV. In the other hand, C. gattii infects mainly immunocompetents individuals to all lifetimes. The main factors determining the cryptococcosys pathogenesis have relations with the host defenses state, the size of particle and strain virulence, this last for four main features: the polyssacharide capsule, the melanin production, the mating types (MAT and MATa) and thermotolerance. The fungus has a transitory life cycle between haploid yeast form and dykariotic filamentous forms. The sexual cycles includes a mixture of genetic parental genes that form progenies containing the genetic characteristics of both. The asexual cycle occurs through a process know as haploid fruiting. The species are heterothallic with two mating types MAT and MATa. Phenotypic characterization studies, including the species identification, serotype and mating type have a great importance for conductions of profound studies because of the close relation between the ecological variants features and its development cycle and multiplication, especially in Brazilian regions North and Northeast where serotype B is the most prevalent cause of meningitis in ordinary hosts. This work used the CGB techniques for methabolic analysis (species identification), where 28 strains were positive, characterizing C. gattii and two were negative, characterizing C. neoformans. The serotyping results, make among agglutination test reveals 28 strains of serotype B and two of serotype A. The mating type was realized by PCR technique and all strains were MAT.