Environmental isolates of Cryptococcus neoformans var. gattii serotype B from Argentina
Introduction: Infections by Cryptococcus neoformans var. gattii occur mainly in tropical or subtropical regions in association with the distribution of eucalyptus trees (frequent habitat of this yeast). These infections affect mainly immunocompetent patients and are associated with severe neurologic sequelae. In Argentina, human infections by C. neoformans var. gattii have occasionally been reported since 1984. We described the first two autochthonous environmental isolates in 2003. The aim of our work was to find out if C. neoformans var. gattii is part of the microflora present in the tree hollows of the parks of Buenos Aires city. Methods: In the spring of 2001 and 2002, samples were collected with swabs rubbing the inner hollow of Eucalyptus spp. and other trees, which were identified at the collection moment. Samples were swabbed directly onto cafeic acid with antibiotic agar, incubated at 28 ÂºC and observed daily for a week. Isolates were recovered from cafeic acid medium showing characteristic colonies of the species that allowed differentiation from other microorganisms of the sample. Identification was performed using carbohydrates fermentation, assimilation of nitrogen and carbon sources and urease and phenoloxidase detection. Strain variety was determined with canavanine-glicine- bromotimol blue agar medium (CGB). Serotype was established by slide agglutination with specifics antiserums produced in our laboratory. Results: Twenty environmental isolates of C. neoformans var. gattii serotype B, were isolated from four city parks. Genotypic characterization using AP- PCR with (GACA)4 and (GTG)5 aleatory primer and the minisatelite specific core sequence of the wild-type phage M13, showed band profiles of VGI genetic type. These strains were isolated from the following trees: Acacia visca (1), Cipresus sempervirens (1), Eucalyptus sp. (3), Cedrus deodara (6), Ulmus campestrus (1), Tipuana tipa (6), and no identified (2). Conclusion: The recovery of these isolates from natural sources demonstrates that C. neoformans var. gattii is present in the Buenos Aires city environment and it is not necessarily associated with Eucalyptus spp. These findings may explain the sporadic association of this yeast to human infections in Argentina.
Full conference title:
15th Annual Focus on Fungal Infections