Abstract
IMP-26 was a rare IMP variant with more carbapenem-hydrolyzing activities, which was increasingly reported now in China. This study characterized a transferable multidrug resistance plasmid harboring blaIMP-26 from one Enterobacter cloacae bloodstream isolate in Shanghai and investigated the genetic environment of resistance genes. The isolate was subjected to antimicrobial susceptibility testing and multilocus sequence typing using broth microdilution method, Etest and PCR. The plasmid was analyzed through conjugation experiments, S1-nuclease pulsed-field gel electrophoresis and hybridization. Whole genome sequencing and sequence analysis was conducted for further investigation of the plasmid. E. cloacae RJ702, belonging to ST528 and carrying blaIMP-26, blaDHA-1, qnrB4 and fosA5, was resistant to almost all β-lactams, but susceptible to quinolones and tigecycline. The transconjugant inherited the multidrug resistance. The resistance genes were located on a 329,420-bp IncHI2 conjugative plasmid pIMP26 (ST1 subtype), which contained trhK/trhV, tra, parA and stbA family operon. The blaIMP-26 was arranged following intI1. The blaDHA-1 and qnrB4 cluster was the downstream of ISCR1, same as that in p505108-MDR. The fosA5 cassette was mediated by IS4. This was the first report on complete nucleotide of a blaIMP-26-carrying plasmid in E. cloacae in China. Plasmid pIMP26 hosted high phylogenetic mosaicism, transferability and plasticity.
Highlights
Extended and overuse of antibiotics have potentiated globally rapid emergence and spread of carbapenem-resistant Enterobacterales (CRE), posing a serious threat to clinical therapy and infection control[1,2,3]
RJ702 was initially identified as E. cloacae or E. asburiae by MALDI
RJ702 was precisely identified as E. cloacae subsp. cloacae
Summary
Extended and overuse of antibiotics have potentiated globally rapid emergence and spread of carbapenem-resistant Enterobacterales (CRE), posing a serious threat to clinical therapy and infection control[1,2,3]. IMP-26 was first reported as an IMP-4 variant in Singapore in 2010 from a clinical carbapenem-resistant P. aeruginosa isolate by Koh TH et al.[12]. The emergence of IMP-producing E. cloacae has been extensively reported as a challenge to clinical therapy because of its rapid worldwide transmission[14,16,18]. Considering the higher carbapenem-hydrolyzing activities and emerging reports in China of IMP-26, we subsequently analyzed the transferability and full nucleotide sequence of the corresponding multi-drug-resistance plasmid pIMP26 in this study, which carried several important resistance determinants, such as blaIMP-26, blaDHA-1, aacA4, qnrB4 and fosA5, conferring resistance to carbapenems, cephalosporins, aminoglycoside and fosfomycin, respectively
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