Molecular Characteristics and Antimicrobial Susceptibility Profiles of -Producing Isolated from a Teaching Hospital in Shanghai, China.

INTRODUCTION

Carbapenem-Resistant Enterobacteriaceae (CRE) has posed a significant threat to humans.The aim of this study was to investigate the molecular characteristics of -producing in a university-affiliated tertiary hospital.

METHODS

Polymerase chain reaction (PCR) and BLAST+ software were used to detect the prevalence of in and . Whole-genome sequencing was performed for the -harboring clinical isolates. Antimicrobial resistance genes, MLSTs, KPC-carrying plasmid typing and genetic environment of 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 . The minimal inhibitory concentrations of the common antimicrobial agents were determined using the broth microdilution method.

RESULTS

The prevalence of in 424 clinical isolates and 1636 strains from GenBank database were 2.2% (45/2060) whereas the detection rate of in from the GenBank database was 29.8% (415/1394). The -harboring conjugants exhibited resistance to multiple β-lactams, except for cefepime-zidebactam and ceftazidime-avibactam. All -carring isolates were susceptible to tigecycline and polymyxin B. ST131 was the dominant sequence type of -carring , accounting for 40.0% (18/45). Most of the -producing ST131 (89.5%,17/19) belonged to clade C ST131 lineage. Genetic environment analysis revealed that 57.8% (26/45) of gene was linked to Tn-associated structure IS-IS. IncN was the most common plasmid type in KPC-producing whereas IncFII was the dominant plasmid type in KPC-producing

CONCLUSION

The detection rate of was lower in compared with e. The dominant sequence and plasmid types of -harboring isolates differed between and . Further studies about the role of the defense system in acquisition of KPC-plasmids in will be performed to provide new insights into the low prevalence of .