Objectives: Genomic and phenotypic characterization of resistance mechanisms to carbapenems and colistin in Klebsiella pneumoniae strains isolated from the Shaare Zedek Medical Center (Jerusalem, Israel).
Results: The 15 K. pneumoniae isolates studied present a high level of resistance to the antibiotics tested. Microbiological tests revealed production of carbapenemase enzymes by all isolates. ABI SOLiD sequencing of K. pneumoniae genomes generated between 5,033,665 and 8,876,861 million reads per genome. The genomic study revealed that carbapenem resistance was mediated by production of the KPC-3 enzyme in 13 isolates and NDM-1 enzyme in the remaining 2 isolates. In addition, colistin resistance was induced either by a missense mutation in the mgrB gene or inactivation of mgrB by an IS5-like insertion sequence. The mobile genetic element, transposon Tn4401, was identified in all genomes harboring the blaKPC gene. The 15 K. pneumoniae strains were assigned to 4 different sequence types, including ST16, ST76, ST258, and ST512.
Conclusion: In this study, we report the usefulness of whole-genome sequencing in detection of antibiotic resistance mechanisms and in highlighting the emergence of the carbapenem and colistin-resistant K. pneumoniae clone ST512 in Israeli hospitals.
Keywords: carbapenemases; colistin resistance; whole genome sequencing.