AUTHOR=Wang Qiqi , Cai Xuan , Li Yun , Zhao Jianhong , Liu Zhiyong , Jiang Yan , Meng Ling , Li Yanming , Pan Shiyang , Ai Xiaoman , Zhang Fang , Li Ruoyu , Zheng Bo , Wan Zhe , Liu Wei 

TITLE=Molecular identification, antifungal susceptibility, and resistance mechanisms of pathogenic yeasts from the China antifungal resistance surveillance trial (CARST-fungi) study

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.1006375

DOI=10.3389/fmicb.2022.1006375

ISSN=1664-302X

ABSTRACT=<p>To have a comprehensive understanding of epidemiology and antifungal susceptibilities in pathogenic yeasts, the China Antifungal Resistance Surveillance Trial (CARST-fungi) study was conducted. All yeast isolates were identified by ribosomal DNA sequencing. Antifungal susceptibilities were performed using CLSI M27-A4 broth microdilution method. Sequence and expression level of resistant-related genes in resistant/non-wide-type (NWT) <italic>Candida</italic> isolates were analyzed. Totally 269 nonduplicate yeast isolates from 261 patients were collected. About half of the yeast isolates (127, 47.2%) were recovered from blood, followed by ascetic fluid (46, 17.1%). <italic>C. albicans</italic> remained the most prevalent (120, 44.6%), followed by <italic>C. parapsilosis</italic> complex (50, 18.6%), <italic>C. tropicalis</italic> (40, 14.9%), and <italic>C. glabrata</italic> (36, 13.4%). Fourteen (11.7%) <italic>C. albicans</italic> isolates and 1 (2.0%) <italic>C. parapsilosis</italic> isolate were resistant/NWT to triazoles. Only 42.5% (17/40) <italic>C. tropicalis</italic> were susceptible/WT to all the triazoles, with 19 (47.5%) isolates NWT to posaconazole and 8 (20%) cross-resistant to triazoles. Among <italic>C. glabrata</italic>, 20 (55.6%) and 8 (22.2%) isolates were resistant/NWT to voriconazole and posaconazole, respectively, and 4 (10.3%) isolates were cross-resistant to triazoles. Isavuconazole was the most active triazole against common <italic>Candida</italic> isolates. Except for 2 isolates of <italic>C. glabrata</italic> cross-resistant to echinocandins which were also NWT to POS and defined as multidrug-resistant, echinocandins exhibit good activity against common <italic>Candida</italic> species. All isolates were WT to AMB. For less common species, <italic>Rhodotorula mucilaginosa</italic> exhibited high MICs to echinocandins and FLC, and 1 isolate of <italic>Trichosporon asahii</italic> showed high MICs to all the antifungals except AMB. Among triazole-resistant <italic>Candida</italic> isolates, <italic>ERG11</italic> mutations were detected in 10/14 <italic>C. albicans</italic> and 6/23 <italic>C. tropicalis</italic>, while 21/23 <italic>C. tropicalis</italic> showed <italic>MDR1</italic> overexpression. Overexpression of <italic>CDR1</italic>, <italic>CDR2</italic>, and <italic>SNQ2</italic> exhibited in 14, 13, and 8 of 25 triazole-resistant <italic>C. glabrata</italic> isolates, with 5 isolates harboring <italic>PDR1</italic> mutations and 2 echinocandins-resistant isolates harboring S663P mutation in <italic>FKS2</italic>. Overall, the CARST-fungi study demonstrated that although <italic>C. albicans</italic> remain the most predominant species, non-<italic>C. albicans</italic> species accounted for a high proportion. Triazole-resistance is notable among <italic>C. tropicalis</italic> and <italic>C. glabrata</italic>. Multidrug-resistant isolates of <italic>C. glabrata</italic> and less common yeast have been emerging.</p>