Cryptococcus gattii VGI and Cryptococcus neoformans VNI Associated with Wood Decay in Ficus Hollow Trees in Rio de Janeiro, Brazil

Aim: Considering the geographic expansion of Cryptococcus gattii, the aim of this study was to investigate hollows of living trees as a reservoir of C. gattii in Rio de Janeiro, Brazil.
Place and Duration of the Study: In an urban quarter of Rio de Janeiro city, 80 samples of decaying wood were collected. In addition, 85 decaying wood samples were collected in the wild rainforest. The samples were analyzed at the Mycology Laboratory, Evandro Chagas Clinical Research Institute, Oswaldo Cruz Foundation, from 2008-2010.
Methodology: Samples were collected by scraping the inner decaying wood of the hollows of the trunks of each tree. Pathogenic Cryptococcus species were identified by: brown colonies on niger seed agar (NSA) medium, thermotolerance at 35ºC, cycloheximide sensitivity, carbon and nitrogen assimilation tests performed by 32-Vitek System (Vitek ICB, bioMeriux, Durham, EUA). Canavanine-glycine-bromothymol blue medium (CGB) was used to determine the species of the isolates and the genotypes were determined by restriction fragment length polymorphism of URA5 gene.
Results: After plating the samples on NSA, 584 colonies were obtained from the urban quarter. C. gattii VGI was identified in 98% of colonies, followed by C. neoformans VNI 2%. The positivity of the urban area was 7.8%. The concentrations of the fungi in hollows of ficus trees ranged from 50 to 56,250 colony-forming units per gram of sample (CFU/g).
Conclusions: For the first time in Rio de Janeiro C. gattii VGI was isolated in a hollow of living tree.