Clinical and microbiological characteristics of Cryptococcus gattii isolated from 7 hospitals in China

Background: Infection, even outbreak, caused by Cryptococcus gattii (C. gattii ) has been reported in Canada and the United States, but there were sparsely-reported cases of C. gattii in China. Our interest in occurrence, clinical manifestation, laboratory identification and molecular characterization of Chinese C. gattii strains leads us to this research.Methods: A total of 254 clinical isolates primarily identified as Cryptococcus neoformans (C. neoformans ) were collected. VITEK 2 compact, canavanine glycine bromothymol blue (CGB) agar and Bruker Biotyper matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) were used for strain identification. Multi-locus sequence typing (MLST) was performed for genotyping. Antifungal susceptibility test was carried out with commercial kits of both ATB fungus 3 and Yeast one. Clinical information of patients was reviewed retrospectively. Label-free proteome technique was used to quantitatively analyze the differential proteins of C. gattii. Results: Out of 254 clinical isolates, we identified eight strains as C. gattii. MLST showed genotype VGI accounted for the most (6 / 8), the other two strains were genotype VGII（VGIIa and VGIIb respectively）with 3 specific spectra of molecular weight about 4342, 8686, 9611 Dalton by MALDI-TOF MS. The minimal inhibitory concentrations (MICs) of Fluconazole with Yeast one was 2～4 times higher than that with ATB fungus 3. Higher MICs of antifungal agents were exhibited against VGII strains than against VGI strains. C. gattii genotype VGI and VGII possessed 418 and 774 specific proteins respectively. Comparative proteome analysis showed that 329 and 180 proteins were highly expressed in C. gattii VGI and VGII. The enrichment of differentially expressed proteins was directed to Golgi complex.Conclusions: Infection by C. gattii in China might have been underestimated because of initial mis-identification. Genotype VGI was predominant but VGII was more resistant to antifungal agents. There was significant difference in protein expression profile between VGI and VGII C. gattii.