AUTHOR=Liu Na , Tang Biao , Wang Hui , Chen Xiangyang , Wen Peipei , Wang Zhaorui , Chen Xu , Guo Xiaobing , Gou Jianjun , Song Yinsen 

TITLE=Coexistence of a novel NDM-1-encoding MDR plasmid and an IMP-4-encoding IncN-IncU hybrid plasmid in a clinical isolate of Citrobacter freundii BC73

JOURNAL=Frontiers in Microbiology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1388651

DOI=10.3389/fmicb.2024.1388651

ISSN=1664-302X

ABSTRACT=<sec id="sec1"><title>Objectives</title><p>To investigate the genetic characteristics and transmission mechanism of the NDM-1-, IMP-4-, and SHV-12-producing multidrug-resistant (MDR) clinical isolate, <italic>Citrobacter freundii</italic> BC73.</p></sec><sec id="sec2"><title>Methods</title><p><italic>C. freundii</italic> BC73 was isolated from a urine specimen of a urological patient diagnosed with bladder cancer at a Chinese teaching hospital. Antimicrobial susceptibility testing was carried out using DL-120E susceptibility cards and DL-96A system. Whole genome sequencing (WGS) of the isolate was performed using the Illumina and Oxford Nanopore platforms to analyze the genetic context of drug resistance genes and plasmid characteristics. The phylogenetic tree was constructed and visualized by KSNP3.0 software and iTOL5.0 online database.</p></sec><sec id="sec3"><title>Results</title><p><italic>C. freundii</italic> isolate BC73 co-carrying <italic>bla</italic><sub>NDM-1</sub>, <italic>bla</italic><sub>IMP-4</sub> and <italic>bla</italic><sub>SHV-12</sub> were multidrug-resistant. <italic>bla</italic><sub>NDM-1</sub> and <italic>bla</italic><sub>IMP-4</sub> were located on a novel IncFIB-like plasmid, pCFBC1, and an IncN-IncU hybrid plasmid, pCFBC2, respectively. The transferability of <italic>bla</italic><sub>NDM-1</sub> and <italic>bla</italic><sub>IMP-4</sub> from <italic>C. freundii</italic> BC73 to <italic>E. coli</italic> J53 was successfully demonstrated. The genetic context of the <italic>bla</italic><sub>NDM-1</sub> and <italic>bla</italic><sub>IMP-4</sub> genes were IS<italic>CR27</italic>-<italic>groEL</italic>-<italic>∆groES</italic>-<italic>cutA</italic>-<italic>dsbD</italic>-<italic>trpF</italic>-<italic>ble</italic><sub>MBL</sub>-<italic>bla</italic><sub>NDM-1</sub>-∆IS<italic>Aba125</italic>-IS3000 and <italic>intI1</italic>-<italic>bla</italic><sub>IMP-4</sub>-<italic>Kl.pn.13</italic>-<italic>mobC</italic>-IS<italic>6100</italic>, respectively. Additionally, two extensive transposition units (MGE1 in pCFBC1, MGE2 in pCFBC2) were identified and numerous antimicrobial resistance genes were discovered on it.</p></sec><sec id="sec4"><title>Conclusion</title><p>To our knowledge, our study represents the first characterization of a ST22 <italic>C. freundii</italic> isolate co-harboring <italic>bla</italic><sub>NDM-1</sub>, <italic>bla</italic><sub>IMP-4</sub>, and <italic>bla</italic><sub>SHV-12</sub>, obtained from a urine sample. The dissemination of this MDR isolate should be of close concern in future clinical surveillance.</p></sec>