Outbreak of Klebsiella pneumoniae carbapenemase-producing Klebsiella aerogenes strains in atertiary hospital in China

Abstract

Purpose: This study aimed to evaluate the molecular characteristics and prevalence of clinical carbapenem-resistant Klebsiella aerogenes (CRKA), collected during an outbreak in a Chinese tertiary hospital. Methods: Antimicrobial susceptibility test, using 17 antibiotics, was performed on 14 CRKA isolates. The strains were examined for the presence of β-lactamase genes by PCR, and efflux pump phenotype was determined by efflux pump inhibition test. Presence of outermembrane porins was examined. Clonal relatedness among the isolates was investigated by pulsed-field gel electrophoresis (PFGE). S1 nuclease-PFGE and plasmid incompatibility group analysis were performed to determine plasmids, and the genetic environment of blaKPC-2 was analyzed. Epidemiological data were collected via chart review. Results: The 14 CRKA isolates were all resistant to carbapenems; five distinct groups (PFGE types A-E) were observed. All 14 isolates carried the blaKPC-2 gene. S1 nuclease- PFGE indicated the size of blaKPC-2-carrying plasmids to range from 20 kb to 200 kb, and the 14 plasmids belonged to various incompatibility groups. The most frequent genetic environment of blaKPC-2 was Tn1721- blaKPC-2-ΔTn3-IS26. PFGE type A group, including 11 KPC- 2-producing clinical isolates, was primarily responsible for dissemination. Conclusion: Our findings suggest both transposons and vertical transmission to contribute to the transformation of blaKPC-2. The results strongly suggest strict implementation of infection control of CRKA, in healthcare facilities.