Cryptococcus neoformans strains and infection in apparently immunocompetent patients, China

To determine the population structure of the cryptococcosis agents in China, we analyzed the genotype of 120 Cryptococcus neoformans and 9 Cryptococcus grattii strains isolated from 1980 through 2006 from cryptococcosis patients residing in 16 provinces of mainland China. A total of 71% (91/129) of the clinical strains isolated from 1985 through 2006 were from patients without any apparent risk factors. Only 8.5% (11/129) were from AIDS patients; the remaining 20.5% (27/129) were from patients with underlying diseases other than HIV infection. One hundred twenty of the 129 isolates were C. neoformans serotype A, mating type MAT alpha strains that exhibited an identical M13-based VNI subtype, which was distinguishable from the reference VNI molecular type. The 9 remaining isolates were serotype B, MATa strains of C. gattii and portrayed a typical VGI molecular type. Data analyzed from multilocus sequences showed no variation and that these Chinese C. neoformans isolates belong to a cluster that has phylogenetically diverged from the VNI reference strain. Our finding that most cryptococcosis patients in China had no apparent risk factor is in stark contrast with reports from other countries.