IncN ST7 epidemic plasmid carrying blaIMP-4 in Enterobacteriaceae isolates with epidemiological links to multiple geographical areas in China.
To characterize blaIMP-4-carrying plasmids originating from inpatients in Hong Kong.



Sixteen blaIMP-4-carrying plasmids identified among Enterobacteriaceae (nine Escherichia coli, four Klebsiella pneumoniae, two Citrobacter freundii and one Enterobacter cloacae) recovered from 15 patients were characterized. The isolates, collected during January 2010 to December 2013, were retrospectively investigated by plasmid sequencing, molecular and fitness studies.



The blaIMP-4-carrying plasmids belonged to the IncN ST7 lineage (∼50 kb). Twelve of the 16 plasmids were epidemiologically linked to seven different regions in China. Alignment of the complete plasmid sequences showed identical plasmid backbones and two highly similar resistance regions, each carrying one of two resistance genes (blaIMP-4and qnrS1). The blaIMP-4was detected in a class 1 integron (containing blaIMP-4and intron Kl.pn.13) that is part of an IS6100-IS26 transposon-like structure. The nine E. coli carrying the epidemic plasmid belonged to multiple multilocus STs (six ST542, one ST131, one ST657 and one ST3177). Fitness assays performed on E. coli J53 recipients showed that the presence of the epidemic plasmid did not have a significant biological cost.



This study identified a blaIMP-4-carrying IncN ST7 plasmid disseminated among multiple enterobacterial species originating from patients with epidemiological links to different regions in China.
Carol Yu Center for Infection and Department of Microbiology, University of Hong Kong, Hong Kong, People's Republic of China.|Department of Microbiology, Queen Mary Hospital, Hospital Authority, Hong Kong, People's Republic of China.
Ya
Y
Wang
Carol Yu Center for Infection and Department of Microbiology, University of Hong Kong, Hong Kong, People's Republic of China.|Department of Microbiology, Queen Mary Hospital, Hospital Authority, Hong Kong, People's Republic of China.
Wai-U
WU
Lo
Department of Clinical Pathology, Prince of Wales Hospital, Hospital Authority, Hong Kong, People's Republic of China.
Raymond Wai-Man
RW
Lai
Department of Clinical Pathology, Kwong Wah Hospital, Hospital Authority, Hong Kong, People's Republic of China.
Cindy Wing-Sze
CW
Tse
Department of Clinical Pathology, Pamela Youde Nethersole Eastern Hospital, Hospital Authority, Hong Kong, People's Republic of China.
Rodney Allan
RA
Lee
Department of Clinical Pathology, Tseung Kwan O Hospital, Hospital Authority, Hong Kong, People's Republic of China.
Wei-Kwang
WK
Luk
Carol Yu Center for Infection and Department of Microbiology, University of Hong Kong, Hong Kong, People's Republic of China.|Department of Microbiology, Queen Mary Hospital, Hospital Authority, Hong Kong, People's Republic of China.
Vincent Chi-Chung
VC
Cheng
Department of Clinical Pathology, Tuen Mun Hospital, Hospital Authority, Hong Kong, People's Republic of China.
Tak-Lun
TL
Que
Carol Yu Center for Infection and Department of Microbiology, University of Hong Kong, Hong Kong, People's Republic of China.|Department of Microbiology, Queen Mary Hospital, Hospital Authority, Hong Kong, People's Republic of China.
Kin-Hung
KH
Chow
Carol Yu Center for Infection and Department of Microbiology, University of Hong Kong, Hong Kong, People's Republic of China plho@hkucc.hku.hk.|Department of Microbiology, Queen Mary Hospital, Hospital Authority, Hong Kong, People's Republic of China.
Pak-Leung
PL
Ho
D000368:Aged; D000369:Aged, 80 and over; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology*; D004755:Enterobacteriaceae / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000453:epidemiology / Q000382:microbiology*; D005260:Female; D022761:Gene Transfer, Horizontal; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D010957:Plasmids / Q000032:analysis* / Q000145:classification; D012189:Retrospective Studies; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D019371:Topography, Medical