Outbreak of KPC-2-Producing Klebsiella pneumoniae ST76 Isolates in an Intensive Care Unit and Neurosurgery Unit

Background: The aim of this study was to investigate the characteristics of carbapenem-resistant Klebsiella pneumoniae (CRKP) ST76 isolates collected during an outbreak in a hospital's intensive care unit and neurosurgery unit. Methods: Seventeen separate clinical isolates of CRKP were collected from patients from March 2016 to February 2017. Bacterial isolates were identified, and antimicrobial susceptibility testing was conducted using the VITEK-2 compact system. Isolates containing antibiotic resistance genes were characterized by polymerase chain reaction and DNA sequencing. Clonal relatedness was assessed by multilocus sequence typing and pulsed-field gel electrophoresis. Conjugation experiments were performed to determine the transferability of plasmids with antibiotic resistance. The genomic features and mobile genetic elements of ST76 CRKP were detected by whole genome sequencing. Results: ST76 KPC-2-producing CRKP prevailed in our hospital, causing an outbreak. The strains also carried bla(SHV-1), bla(CTX-M-15), bla(TEM-1), qnrB, and acc(6 ')Ib-cr resistance genes. Plasmids from 17.7% of the isolated strains bearing these resistance genes could be transferred into the recipient Escherichia coli J53 through conjugation. Sequencing results showed that the KP4 genome mainly consisted of a circular chromosome and three antibiotic resistance plasmids. The plasmid carrying the bla(KPC-2) gene was located on a 437 kb IncFIB (pQil) plasmid with Tn1721-bla(KPC-2)-Delta T3 gene structure. Genes conferring resistance against aminoglycosides, quinolones, fluoroquinolones, beta-lactamase, phenicols, sulfonamides, and trimethoprims and the presence of virulence-associated genes related to iron acquisition or adhesins were determined. Conclusion: This is the first report of the whole genome sequence of a KPC-2-producing K. pneumoniae ST76 isolate. This work provides a basis for understanding antibiotic resistance and resistant plasmid transmission. Relevant departments should implement infection control and prevention measures to reduce the incidence of nosocomial infections.