AUTHOR=Shi Jiping , Zhu Hong , Liu Chang , Xie Hui , Li Chuchu , Cao Xiaoli , Shen Han 

TITLE=Epidemiological and genomic characteristics of global mcr-positive Escherichia coli isolates

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.1105401

DOI=10.3389/fmicb.2022.1105401

ISSN=1664-302X

ABSTRACT=<sec><title>Objective</title><p>The worldwide dissemination of colistin-resistant <italic>Escherichia coli</italic> (<italic>E. coli</italic>) endangers public health. This study aimed to better understand the global genomic epidemiology of <italic>E. coli</italic> isolates carrying mobilized colistin resistance (<italic>mcr</italic>) genes, providing information to assist in infection and prevention.</p></sec><sec><title>Methods</title><p><italic>Escherichia coli</italic> genomes were downloaded from NCBI, and <italic>mcr</italic> was detected using BLASTP. Per software was used to extract information on hosts, resources, collection data, and countries of origin from GenBank. Sequence types (STs), prevalence of plasmids, antimicrobial resistance genes (ARG), and virulence factors (VF) in these genomes were analyzed. Statistical analyses were performed to assess the relationships between <italic>mcr</italic>, ARGs, plasmids, and STs.</p></sec><sec><title>Results</title><p>In total, 778 <italic>mcr</italic>-positive isolates were identified. Four <italic>mcr</italic> variants were detected, with <italic>mcr</italic>-1 (86.1%) being the most widespread, followed by <italic>mcr</italic>-9 (5.7%), <italic>mcr</italic>-5 (4.4%), and <italic>mcr</italic>-3 (3.0%). Multiple ARGs were identified, with <italic>bla</italic><sub>CTX–M</sub> (53.3%), <italic>fosA</italic> (28.8%), <italic>qnr</italic> (26.1%), <italic>bla</italic><sub><italic>NDM</italic></sub> (19.8%), and <italic>aac (6’)-Ib-cr</italic> (14.5%) being the most common. Overall, 239 distinct STs were identified, of which ST10 (13.8%) was the most prevalent. A total of 113 different VFs were found, <italic>terC</italic> (99.9%) and <italic>gad</italic> (83.0%) were most frequently detected. Twenty types of plasmids were identified; IncFIB (64.1%), IncX (42.3%), and IncX (42.3%) were the most common replicons. IncI2 and IncX4 were frequently detected in <italic>mcr</italic>-1-positive isolates, whereas IncFII, IncI1-I, and IncHI2 were dominant plasmids in <italic>mcr</italic>-3, <italic>mcr</italic>-5, and <italic>mcr</italic>-9-positive isolates, respectively. A higher frequency of ARGs and VFs was observed among ST156 and ST131 isolates.</p></sec><sec><title>Conclusion</title><p>Our data indicated that more than half of the <italic>mcr</italic>-positive <italic>E. coli</italic> strains carried endemic ARGs and VFs. ST10 and ST156 isolates deserved further attention, given the rapid transmission of ST10 and the convergence of ARGs and VFs in ST156.</p></sec>