Genomic and antimicrobial resistance characteristics of non-O1/non-O139Vibrio cholerae isolated in Ningbo City
WANG Shanshan1, YUAN Xinru2, LIU Yanqing1, WU Aihua1, YE Shuo3, WENG Xingbei1
1. The First Affiliated Hospital of Ningbo University, Ningbo, Zhejiang 315010, China; 2. Shanghai Pulmonary Hospital, Shanghai 200082, China; 3. Ningbo Center for Disease Control and Prevention, Ningbo, Zhejiang 315010, China
Abstract：Objective To analyze the genomic characteristics and antimicrobial resistance profiles of non-O1/non-O139Vibrio cholerae (NOVC) isolated in Ningbo City, Zhejiang Province, so as to provide evidence for the prevention and control of Vibrio cholerae infections. Methods Stool and blood specimens from diarrhea and bacteremia cases were collected from The First Affiliated Hospital of Ningbo University from January 2022 to November 2024, for the isolation and identification of NOVC. Antimicrobial susceptibility testing was performed to evaluate the resistance of NOVC against 12 kinds of antimicrobial agents. Whole genome sequencing was performed to analyze core genome multilocus sequence typing (cgMLST), antimicrobial resistance genes and virulence genes of NOVC. Crystal violet staining method was used to detect the biofilm formation capacity of the strains. Results A total of 11 specimens from diarrhea and bacteremia cases were collected in Ningbo City from 2022 to 2024, and 11 strains were isolated, all of which were NOVC, with 11 different STs detected. All 11 NOVC strains were susceptible to cefoperazone/sulbactam, piperacillin/tazobactam, ceftazidime, cefepime, meropenem, ciprofloxacin, levofloxacin, amikacin, doxycycline and tigecycline, while 2 strains were resistant to trimethoprim/sulfamethoxazole. All strains carried the β-lactam resistance gene php2, the tetracycline resistance gene tet34, and the efflux pump-related resistance gene norm. Virulence gene prediction results revealed that none of the 11 NOVC strains carried ctxA, while all carried hlyA, vgrG, vas and hapA. One strain showed strong biofilm formation ability, 2 strains showed moderate ability, and the remaining strains showed relatively weak ability. Conclusions The NOVC strains isolated in Ningbo City showed genetic diversity and susceptibility to commonly used antimicrobial agents, with the absence of the classical virulence gene ctxA, but the presence of multiple other virulence genes. Biofilm formation ability exhibited heterogeneity among strains. It is necessary to continuously strengthen surveillance of antimicrobial resistance, transmission characteristics and potential pathogenic risks.
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