Molecular Characterization of blaIMP4-Carrying Enterobacterales in Henan Province of China

W Liu, H Dong, T Yan, X Liu, J Cheng, C Liu… - Frontiers in …, 2021 - frontiersin.org
W Liu, H Dong, T Yan, X Liu, J Cheng, C Liu, S Zhang, X Feng, L Liu, Z Wang, S Qin
Frontiers in Microbiology, 2021frontiersin.org
Carbapenem-resistant Enterobacterales (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 Enterobacter cloacae, 3 Escherichia coli,
2 Klebsiella pneumoniae, and 2 Citrobacter freundii. These strains were collected from a
tertiary teaching hospital in Zhengzhou from 2013 to 2015. The minimum inhibitory
concentration (MIC) results showed that each bla IMP–4-positive isolate was multidrug …
Carbapenem-resistant Enterobacterales (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 Enterobacter cloacae, 3 Escherichia coli, 2 Klebsiella pneumoniae, and 2 Citrobacter freundii. These strains were collected from a tertiary teaching hospital in Zhengzhou from 2013 to 2015. The minimum inhibitory concentration (MIC) results showed that each blaIMP4-positive isolate was multidrug-resistant (MDR) but susceptible to colistin. All of the E. coli belonged to ST167, two C. freundii isolates belonged to ST396, and diverse ST types were identified in E. cloacae and K. pneumoniae. S1-PFGE, Southern blotting, and PCR-based replicon typing assays showed that the blaIMP4-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 blaIMP4-carrying N-type plasmid is more stable than the other types of plasmids. Conjugative assays revealed that three of the blaIMP4-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 blaIMP4-carrying epidemic plasmid in a C. freundii strain. PCR mapping indicated that a transposon-like structure [IS6100-mobC-intron (K1.pn.I3)-blaIMP4-IntI1-IS26] was highly conserved in all of the N plasmids. IS26 involved recombination events that resulted in variable structures of this transposon-like module in FII and FIB plasmids. The blaIMP4 gene was captured by a sul1-type integron In1589 on HI2/HI2A plasmid pIMP-ECL-13–46.
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