AUTHOR=Wang Jing , Huang Xin-Yi , Xia Ying-Bi , Guo Ze-Wen , Ma Zhen-Bao , Yi Meng-Ying , Lv Lu-Chao , Lu Pei-Lan , Yan Jie-Cong , Huang Jia-Wei , Zeng Zhen-Ling , Liu Jian-Hua 

TITLE=Clonal Spread of Escherichia coli ST93 Carrying mcr-1-Harboring IncN1-IncHI2/ST3 Plasmid Among Companion Animals, China

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.02989

DOI=10.3389/fmicb.2018.02989

ISSN=1664-302X

ABSTRACT=<p>The purpose of this study was to investigate the occurrence of plasmid-mediated colistin resistance gene <italic>mcr-1</italic> in Enterobacteriaceae isolates from companion animals in Guangzhou, China. Enterobacteriaceae isolated from 180 samples collected from cats and dogs were screened for <italic>mcr-1</italic> by PCR and sequencing. MCR-1-producing isolates were further characterized by multilocus sequence typing and pulsed-field gel electrophoresis (PFGE). Plasmid characterization was performed by conjugation, replicon typing, S1-PFGE, and Southern blot hybridization. Plasmid pHN6DS2 as a representative IncN1-IncHI2/ST3 plasmid from ST93 <italic>E. coli</italic> was fully sequenced. pHN6DS2-like plasmids were screened by PCR-mapping and sequencing. The <italic>mcr-1</italic> gene was detected in 6.25% (8/128) <italic>Escherichia coli</italic> isolates, of which, five belonged to <italic>E. coli</italic> ST93 and had identical PFGE patterns, resistance profiles and resistance genes. <italic>mcr-1</italic> genes were located on ∼244.4 kb plasmids (<italic>n</italic> = 6), ∼70 kb plasmids, and ∼60 kb plasmids, respectively. Among them, five <italic>mcr-1</italic>-carrying plasmids were successfully transferred to recipient by conjugation experiments, and were classified as IncN1-IncHI2/ST3 (∼244.4 kb, <italic>n</italic> = 4, all obtained from <italic>E. coli</italic> ST93), and IncI2 (∼70 kb, <italic>n</italic> = 1), respectively. Plasmid pHN6DS2 contained a typical IncHI2-type backbone, with IncN1 segment (Δ<italic>repA-</italic>Iterons I-<italic>gshB</italic>-ΔIS<italic>1294</italic>) inserted into the multiresistance region, and was similar to other <italic>mcr-1</italic>-carrying IncHI2/ST3 plasmids from Enterobacteriaceae isolates of various origins in China. The remaining five <italic>mcr-1</italic>-bearing plasmids with sizes of ∼244.4 kb were identified to be pHN6DS2-like plasmids. In conclusion, clonal spread of ST93 <italic>E. coli</italic> isolates was occurred in companion animals in Guangzhou, China.</p>