AUTHOR=Liu Wentian , Dong Huiyue , Yan Tingting , Liu Xuchun , Cheng Jing , Liu Congcong , Zhang Songxuan , Feng Xiang , Liu Luxin , Wang Zhenya , Qin Shangshang 

TITLE=Molecular Characterization of blaIMP–4-Carrying Enterobacterales in Henan Province of China

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.626160

DOI=10.3389/fmicb.2021.626160

ISSN=1664-302X

ABSTRACT=<p>Carbapenem-resistant <italic>Enterobacterales</italic> (CRE) pose a serious threat to clinical management and public health. We investigated the molecular characteristics of 12 IMP-4 metallo-β-lactamase-producing strains, namely, 5 <italic>Enterobacter cloacae</italic>, 3 <italic>Escherichia coli</italic>, 2 <italic>Klebsiella pneumoniae</italic>, and 2 <italic>Citrobacter freundii</italic>. These strains were collected from a tertiary teaching hospital in Zhengzhou from 2013 to 2015. The minimum inhibitory concentration (MIC) results showed that each <italic>bla</italic><sub><italic>IMP</italic></sub><sub>–</sub><sub>4</sub>-positive isolate was multidrug-resistant (MDR) but susceptible to colistin. All of the <italic>E. coli</italic> belonged to ST167, two <italic>C. freundii</italic> isolates belonged to ST396, and diverse ST types were identified in <italic>E. cloacae</italic> and <italic>K. pneumoniae</italic>. S1-PFGE, Southern blotting, and PCR-based replicon typing assays showed that the <italic>bla</italic><sub><italic>IMP</italic></sub><sub>–</sub><sub>4</sub>-carrying plasmids ranged from ∼52 to ∼360 kb and belonged to FII, FIB, HI2/HI2A, and N types. N plasmids were the predominant type (8/12, 66.7%). Plasmid stability testing indicated that the <italic>bla</italic><sub><italic>IMP</italic></sub><sub>–</sub><sub>4</sub>-carrying N-type plasmid is more stable than the other types of plasmids. Conjugative assays revealed that three of the <italic>bla</italic><sub><italic>IMP</italic></sub><sub>–</sub><sub>4</sub>-carrying N plasmids were transferrable. Complete sequence analysis of a representative N type (pIMP-ECL14–57) revealed that it was nearly identical to pIMP-FJ1503 (KU051710) (99% nucleotide identity and query coverage), an N-type <italic>bla</italic><sub><italic>IMP</italic></sub><sub>–</sub><sub>4</sub>-carrying epidemic plasmid in a <italic>C. freundii</italic> strain. PCR mapping indicated that a transposon-like structure [IS<italic>6100-mobC-intron (K1.pn.I3)-bla</italic><sub><italic>IMP</italic></sub><sub>–</sub><sub>4</sub><italic>-IntI1-</italic>IS<italic>26</italic>] was highly conserved in all of the N plasmids. IS<italic>26</italic> involved recombination events that resulted in variable structures of this transposon-like module in FII and FIB plasmids. The <italic>bla</italic><sub><italic>IMP</italic></sub><sub>–</sub><sub>4</sub> gene was captured by a <italic>sul1</italic>-type integron In1589 on HI2/HI2A plasmid pIMP-ECL-13–46.</p>