Correlation of genotype and in vitro susceptibilities of Cryptococcus gattii strains from the Pacific Northwest of the United States

Abstract

Cryptococcus gattii emerged in North America in 1999 as a human and veterinary pathogen on Vancouver Island, British Columbia. The emergent subtype, VGIIa, and the closely related subtype VGIIb can now be found in the United States in Washington, Oregon, and California. We performed multilocus sequence typing and antifungal susceptibility testing on 43 isolates of C. gattii from human patients in Oregon, Washington, California, and Idaho. In contrast to Vancouver Island, VGIIa was the most frequent but not the predominant subtype in the northwest United States. Antifungal susceptibility testing showed statistically significant differences in MICs between the subtypes. This is the first study to apply antifungal susceptibility testing to C. gattii isolates from the Pacific Northwest and the first to make direct comparisons between subtypes.