AUTHOR=Chen Junzhu , Hu Niya , Xu Hongzhi , Liu Qiong , Yu Xiaomin , Zhang Yuping , Huang Yongcheng , Tan Junjun , Huang Xiaotian , Zeng Lingbing 

TITLE=Molecular Epidemiology, Antifungal Susceptibility, and Virulence Evaluation of Candida Isolates Causing Invasive Infection in a Tertiary Care Teaching Hospital

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=11

YEAR=2021

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2021.721439

DOI=10.3389/fcimb.2021.721439

ISSN=2235-2988

ABSTRACT=<sec><title>Background</title><p>The incidence of invasive candidiasis is increasing worldwide. However, the epidemiology, antifungal susceptibility, and virulence of <italic>Candida</italic> spp. in most hospitals remain unclear. This study aimed to evaluate invasive candidiasis in a tertiary care hospital in Nanchang City, China.</p></sec><sec><title>Methods</title><p>MALDI-TOF MS and 18S rDNA ITS sequencing were used to identify <italic>Candida</italic> strains. Randomly amplified polymorphic DNA analysis was used for molecular typing; biofilm production, caseinase, and hemolysin activities were used to evaluate virulence. The Sensititre™ YeastOne YO10 panel was used to examine antifungal susceptibility. Mutations in <italic>ERG11</italic> and the hotspot regions of <italic>FKS1</italic> of drug-resistant strains were sequenced to evaluate the possible mechanisms of antifungal resistance.</p></sec><sec><title>Results</title><p>We obtained 110 <italic>Candida</italic> strains, which included 40 <italic>Candida albicans</italic> (36.36%), 37 C. <italic>parapsilosis</italic> (33.64%), 21 C. <italic>tropicalis</italic> (19.09%), 9 C. <italic>glabrata</italic> (8.18%), 2 C. <italic>rugose</italic> (1.82%), and 1 C. <italic>haemulonii</italic> (0.91%) isolates. At a limiting point of 0.80, <italic>C</italic>. <italic>albicans</italic> isolates could be grouped into five clusters, <italic>C</italic>. <italic>parapsilosis</italic> and <italic>C</italic>. <italic>tropicalis</italic> isolates into seven clusters, and <italic>C</italic>. <italic>glabrata</italic> isolates into only one cluster comprising six strains by RAPD typing. Antifungal susceptibility testing revealed that the isolates showed the greatest overall resistance against fluconazole (6.36%), followed by voriconazole (4.55%). All <italic>C</italic>. <italic>albicans</italic> and <italic>C</italic>. <italic>parapsilosis</italic> isolates exhibited 100% susceptibility to echinocandins (i.e., anidulafungin, caspofungin, and micafungin), whereas one <italic>C</italic>. <italic>glabrata</italic> strain was resistant to echinocandins. The most common amino acid substitutions noted in our study was 132aa (Y132H, Y132F) in the azole-resistant strains. No missense mutation was identified in the hotpot regions of <italic>FKS1</italic>. Comparison of the selected virulence factors detectable in a laboratory environment, such as biofilm, caseinase, and hemolysin production, revealed that most <italic>Candida</italic> isolates were caseinase and hemolysin producers with a strong activity (Pz &lt; 0.69). Furthermore, <italic>C. parapsilosis</italic> had greater total biofilm biomass (average Abs<sub>620</sub> = 0.712) than <italic>C. albicans</italic> (average Abs<sub>620</sub> = 0.214, p &lt; 0.01) or <italic>C. tropicalis</italic> (average Abs<sub>620</sub> = 0.450, <italic>p</italic> &lt; 0.05), although all <italic>C. glabrata</italic> strains were either low- or no-biofilm producers. The virulence level of the isolates from different specimen sources or clusters showed no obvious correlation. Interesting, 75% of the <italic>C. albicans</italic> from cluster F demonstrated azole resistance, whereas two azole-resistant <italic>C. tropicalis</italic> strains belonged to the cluster Y.</p></sec><sec><title>Conclusion</title><p>This study provides vital information regarding the epidemiology, pathogenicity, and antifungal susceptibility of <italic>Candida</italic> spp. in patients admitted to Nanchang City Hospital.</p></sec>