Screening the in vitro susceptibility of posaconazole in clinical isolates of Candida spp. and Aspergillus spp. and analyzing the sequence of ERG11 or CYP51A in non-wild-type isolates from China.

The present study was to determine the in vitro activity of posaconazole (POS) against 385 Candida and 268 Aspergillus clinical isolates from China. We found that POS was active against 85.5% Candida and 94.4% Aspergillus isolates. Non-wild-type (non-WT) phenotype was found in a subset of Candida albicans (15.4%), Candida tropicalis (11.9%), Aspergillus fumigatus (4.1%), and Aspergillus flavus (17.4%) isolates. Cross-resistance to POS and other triazoles was seen. Gene sequencing showed that 4 C. albicans, 1 C. tropicalis, and 9 A. fumigatus isolates with cross-resistance to POS and other triazoles had mutations in ERG11 or CYP51A. In conclusion, POS has potent in vitro activity against most of Candida and Aspergillus isolates from China. Non-WT phenotype and those with cross-resistance to POS and other triazoles exist, frequently driven by mutations of ERG11 in Candida spp. and CYP51A in Aspergillus spp.