ABSTRACT
Introduction: Carbapenem-Resistant Enterobacteriaceae (CRE) has posed a significant threat to humans.The aim of this study was to investigate the molecular characteristics of blaKPC-producing Escherichia coli in a university-affiliated tertiary hospital. Methods: Polymerase chain reaction (PCR) and BLAST+ software were used to detect the prevalence of blaKPC in E. coli and Klebsiella pneumoniae. Whole-genome sequencing was performed for the blaKPC-harboring clinical E. coli isolates. Antimicrobial resistance genes, MLSTs, KPC-carrying plasmid typing and genetic environment of blaKPC were analyzed. A maximum likelihood core single nucleotide polymorphism (SNP)-based phylogeny tree was constructed to determine the evolutionary relationships within this ST131 collection. Conjugation experiments were performed to determine the mobilization of blaKPC. The minimal inhibitory concentrations of the common antimicrobial agents were determined using the broth microdilution method. Results: The prevalence of blaKPC in 424 clinical E. coli isolates and 1636 E. coli strains from GenBank database were 2.2% (45/2060) whereas the detection rate of blaKPC in K. pneumoniae from the GenBank database was 29.8% (415/1394). The blaKPC-harboring conjugants exhibited resistance to multiple ß-lactams, except for cefepime-zidebactam and ceftazidime-avibactam. All blaKPC-carring E. coli isolates were susceptible to tigecycline and polymyxin B. ST131 was the dominant sequence type of blaKPC-carring E. coli, accounting for 40.0% (18/45). Most of the blaKPC-producing ST131 E. coli (89.5%,17/19) belonged to clade C ST131 lineage. Genetic environment analysis revealed that 57.8% (26/45) of blaKPC gene was linked to Tn4401-associated structure ISKpn6-blaKPC-ISKpn7. IncN was the most common plasmid type in KPC-producing E. coli whereas IncFII was the dominant plasmid type in KPC-producing K. pneumoniae. Conclusion: The detection rate of blaKPC was lower in E. coli compared with K. pneumoniae. The dominant sequence and plasmid types of blaKPC-harboring isolates differed between E. coli and K. pneumoniae. Further studies about the role of the defense system in acquisition of KPC-plasmids in E. coli will be performed to provide new insights into the low prevalence of blaKPC.
