Emerging Cryptococcus gattii species complex infections in Guangxi, southern China.

The emergence and spread of cryptococcosis caused by theCryptococcus gattiispecies complex has become a major public concern worldwide.C.deuterogattii(VGIIa) outbreaks in the Pacific Northwest region demonstrate the expansion of this fungal infection to temperate climate regions. However, infections due to theC.gattiispecies complex in China have rarely been reported. In this study, we studied eleven clinical strains of theC.gattiispecies complex isolated from Guangxi, southern China. The genetic identity and variability of these isolates were analyzed via multi-locus sequence typing (MLST), and the phylogenetic relationships among these isolates and global isolates were evaluated. The mating type, physiological features and antifungal susceptibilities of these isolates were also characterized. Among the eleven isolates, six belonged toC.deuterogattii, while five belonged toC.gattii sensu stricto. TheC.deuterogattiistrains from Guangxi, southern China were genetically variable and clustered with different clinical isolates from Brazil. All strains wereMAT alpha, and threeC.deuterogattiiisolates (GX0104, GX0105 and GX0147) were able to undergo sexual reproduction. Moreover, most strains had capsule and were capable of melanin production when compared to the outbreak strain from Canada. Most isolates were susceptible to antifungal drugs; yet one of eleven immunocompetent patients died of cryptococcal meningitis caused byC.deuterogattii(GX0147). Our study indicated that the highly pathogenicC.deuterogattiimay be emerging in southern China, and effective nationwide surveillance ofC.gattiispecies complex infection is necessary. Author summary Cryptococcosis is a fatal systemic fungal disease caused byCryptococcus neoformans/gattiispecies complexes. As a former member of theC.neoformans,C.gattiihad been easily neglected before being elevated to species level. HumanC.gattiispecies complex infection was previously confined to the tropical and subtropical regions worldwide. However, in 1999, an outbreak ofC.gattiispecies complex occurred on Vancouver Island in Canada then expanded to the Pacific Northwest in the USA, causing over 200 infections. The highly virulent, highly pathogenic and more resistant to antifungal drugs of this species have become a therapeutic problem. To initiate a better understanding of the infection characteristics and pathogenicity ofC.gattiispecies complex in Guangxi, southern China, the current study aimed to characterize theC.gattiispecies complex isolates genetically and phenotypically. The ISHAM consensus MLST scheme was utilized to investigate the genetic structure ofC.gattiispecies complex and to correlate their geographic origin, clinical source, virulence factors and antifungal susceptibility. The authors expect that this work can support surveillance and encourage more research and public health initiatives to prevent and control the cryptococcosis cause byC.gattiispecies complex.