Isolation of Cryptococcus gattii serotype B from detritus of Eucalyptus trees in Colombia.

Abstract

Introduction. Cryptococcus gattii serotype B has been associated with several species of trees in tropical and subtropical regions. Serotype B has been found to be the second most frequently isolated from patients in Colombia, but it has not been isolated from the environment. Therefore, a study was designed to sample plant material from a forest in the province of Cundinamarca, with the aim of establishing the presence and distribution of the C. neoformans complex, specially serotype B. In addition, isolates were evaluated for several phenotypic characteristics associated with virulence.
Methodology. During February and March, 2003, 4 separate sample collections were made. One hundred sixty-seven samples were collected from detritus of eucalyptus and 28 samples from other species of trees. All were processed using the conventional procedure and plated on selective media. The following parameters were measured: cellular and capsular sizes in the filtrates, growth at 37 degrees C, virulence in a mouse animal model system, and mating type as detected by PCR.
Results. Cryptococcus gattii serotype B was isolated from 46 eucalyptus samples (27.5%). The cellular size in the filtrates ranged from 3.10 to 4.15 microm and the capsular size from 0.30 and 0.46 microm. The 46 isolates grew at 37 degrees C, but none of them caused the death in the animals during 70-day observation period. All isolates were of mating type a.
Conclusions. This constitutes the first report of the isolation of serotype B, mating type a, from eucalyptus detritus in Colombia.