Detection of an Escherichia coli Sequence Type 167 Strain with Two Tandem Copies of blaNDM-1 in the Chromosome.
New Delhi metallo-β-lactamase-1 (NDM-1)-producing Enterobacteriaceae has disseminated rapidly throughout the world and poses an urgent threat to public health. Previous studies confirmed that the blaNDM-1gene is typically carried in plasmids but rarely in chromosome. We discovered a multidrug-resistant Escherichia coli strain Y5, originating from a urine sample and containing the blaNDM-1gene, which did not transfer by either conjugation or electrotransformation. We confirmed the possibility of its chromosome location by S1-pulsed-field gel electrophoresis (PFGE) and XbaI-PFGE, followed by Southern blotting. To determine the genomic background of blaNDM-1, the genome of Y5 was completely sequenced and compared to other reference genomes. The results of our study revealed that this isolate consists of a 4.8-Mbp chromosome and three plasmids, it is an epidemic clone of sequence type (ST) 167, and it shows 99% identity with Escherichia coli 6409 (GenBank accession no. CP010371), which lacks the same blaNDM-1gene-surrounding structure as Y5. The blaNDM-1gene is embedded in the chromosome along with two tandem copies of an insertion sequence common region 1 (ISCR1) element (sul1-ARR-3-cat-blaNDM-1-bleo-ISCR1), which appears intact in the plasmid from Proteus mirabilis (GenBank accession no. KP662515). The genomic context indicates that the ISCR1 element mediated the blaNDM-1transposition from a single source plasmid to the chromosome. Our study is the first report of an Enterobacteriaceae strain harboring a chromosomally integrated blaNDM-1, which directly reveals the vertical spreading pattern of the gene. Close surveillance is urgently needed to monitor the emergence and potential spread of ST167 strains that harbor blaNDM-1.
State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
Ping
P
Shen
Department of Clinical Laboratory, Yantai Yuhuangding Hospital Affiliated with the School of Medicine, Qingdao University, Yantai, Qingdao, China.
Maoli
M
Yi
Department of Clinical Laboratory, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
Ying
Y
Fu
Department of Clinical Laboratory, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
Zhi
Z
Ruan
Department of Infectious Diseases, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
Xiaoxing
X
Du
Department of Infectious Diseases, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China yvys119@163.com scottxie@mail.hz.zj.cn.
Yunsong
Y
Yu
Department of Clinical Laboratory, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China yvys119@163.com scottxie@mail.hz.zj.cn.
Xinyou
X
Xie
D000328:Adult; D002876:Chromosomes, Bacterial; D004926:Escherichia coli / Q000145:classification / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology*; D005260:Female; D006801:Humans; D058889:Molecular Typing; D010957:Plasmids / Q000032:analysis; D017422:Sequence Analysis, DNA; D014556:Urine / Q000382:microbiology; D001618:beta-Lactamases / Q000235:genetics*
D001618:beta-Lactamases; C552864:beta-lactamase NDM-1
Enterobacteriaceae; ISCR1; New Delhi metallo-β-lactamase-1; chromosome