AUTHOR=Bi Ruru , Kong Ziyan , Qian Huimin , Jiang Fei , Kang Haiquan , Gu Bing , Ma Ping 

TITLE=High Prevalence of blaNDM Variants Among Carbapenem-Resistant Escherichia coli in Northern Jiangsu Province, China

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.02704

DOI=10.3389/fmicb.2018.02704

ISSN=1664-302X

ABSTRACT=<p>The continuous emergence of carbapenem-resistant <italic>Escherichia coli</italic> (CRECO) presents a great challenge to public health. New Delhi metallo-lactamase (NDM) variants are widely disseminated in China, so the research on the prevalence and transmission of diverse <italic>bla</italic><sub>NDM</sub> variants is urgently needed. In the present study, 54 CRECO isolates were collected from 1,185 <italic>Escherichia coli</italic> isolates in five hospitals in Northern Jiangsu Province, China from September 2015 to August 2016. Antimicrobial susceptibility tests, PCR detection of resistance determinants, multi-locus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) were performed to characterize these strains. Plasmid conjugation experiments were carried out to determine the transferability of resistant genes from selected isolates. PCR-based replicon typing (PBRT), S1 nuclease-PFGE, and Southern blotting were conducted for plasmid profiling. Carbapenemase genes were detectable in all CRECO isolates, among which thirty-one CRECO isolates were found to carry <italic>bla</italic><sub>NDM−5</sub> (54.7%), while, <italic>bla</italic><sub>NDM−1</sub>, <italic>bla</italic><sub>NDM−7</sub>, <italic>bla</italic><sub>NDM−4</sub>, <italic>bla</italic><sub>NDM−9</sub>, and <italic>bla</italic><sub>KPC−2</sub> were identified in 14, five, two, one, and one isolates, respectively. MLST results revealed 15 different STs and four new STs were first reported to be linked with NDM-producing isolates. PFGE typing showed that no more than two isolates with the same ST appeared to the same band pattern except three ST410 isolates. Twenty-six selected NDM-producing isolates were successfully transferred to <italic>E. coli</italic> J53 by conjugation experiments. Notably, 50.0% (13/26) of <italic>bl</italic>a<sub>NDM</sub> variants were found to be carried by ~55 kb IncX3 plasmid. Our study reported a high prevalence of <italic>bl</italic>a<sub>NDM</sub> variants, especially <italic>bla</italic><sub>NDM−5</sub>, in Northern Jiangsu province, China. Diverse <italic>bla</italic><sub>NDM</sub> variants were mainly carried by ~55 kb IncX3 plasmids, suggesting that the fast evolution and high transferability of this kind of plasmid promote the high prevalence of <italic>bla</italic><sub>NDM</sub> variants. Therefore, large-scale surveillance and effective infection control measures are also urgently needed to prevent diverse <italic>bla</italic><sub>NDM</sub> variants from becoming epidemic in the future.</p>