Sistemática molecular de Trichosporon spp. baseada em genes ribossomais e sua correlação com fatores de virulência e epidemiologia / Molecular systematics of Trichosporon spp. based on ribosomal genes and its correlation with virulence factors and epidemiology

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

25/11/2009

RESUMO

Yeasts of the genus Trichosporon appear as emerging pathogens with high rates of morbidity and mortality in immunocompromised patients and is becoming increasingly widespread. The significant increase of invasive tricosporonose and the controversial identification of this kind imply an epidemiological deficit which in turn complicates the understanding of the natural history of these infections, leading to delays in diagnosis and, consequently, appropriate antifungal therapy. The present study aimed to evaluate the epidemiological aspects related to human colonization and infection by Trichosporon spp. through phenotypic and genotypic methods and its correlation with virulence factors in vitro. We evaluated 112 isolates from skin of healthy individuals and 26 isolates from urine (22) and catheter (4) identified by the phenotypic method. Among the colonizing isolates (112) the following species were identified: T. cutaneum (29.46%), T. asteroides (20.53%), T. ovoides (15.17%), T. inkin (10.71%), T. mucoid (8.92%) and T. asahii (6.25%). Among the isolates from urine and catheter the species identified were T. asahii the most species isolated (n = 23; 76.66%), followed by T. inkin (n = 5; 16.66%) and T. asteroides (n = 2, 6.6%). For the genotypic identification of yeasts Trichosporon, the ITS and IGS regions of ribosomal DNAwere used. After phylogenetic analysis, the region that better discriminates the species is IGS, and the gold standard for our investigation was based in that region. In isolates from urine and catheter the T. asahii was the predominant species, being identified in 22 isolates (84.6%), followed by two T. inkin (7.69%). T. coremiiforme and T. debeurmannium were isolated in one sample each (3.84%). When comparing the data obtained by molecular and phenotypic identifications it was observed that only in 30% of the isolates (21/70), the phenotypic identification was able to correctly identify isolates of Trichosporon spp. The polymorphism of the sequences of T. asahii, was analyzed according to the classification of genotypes. Bayesian analysis classified the 062 isolate belonging to genotype 3, the isolated 002 belonging to genotype 4 and no isolate belonging to genotypes 5, 6 and 7. Likewise we cannot say with which genotype 1 or 2, the remainder of the isolates most closely because of the large polytomous and low posterior probability of the branches. Evaluated as virulence factors of production of exoenzymes (proteinase, phospholipase and DNase) and index of adhesion of these isolates and it was observed that there are two distinct patterns: isolates colonizing lowexoenzymes and loosely adhering, and isolated from urine and catheter pronounced production of exoenzymes and high rate of adherence.

ASSUNTO(S)

trichosporon spp fatores de virulência filogenética trichosporonose microbiologia

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