Emergence of pan-resistance in KPC-2 carbapenemase-producing Klebsiella pneumoniae in Crete, Greece: A close call

Abstract

Objectives: KPC-2-producing Klebsiella pneumoniae (KPC-KP) ST258 has been rapidly expanding and is often associated with serious nosocomial infections. Last-line antibiotics such as colistin and tigecycline often remain the only treatment option.We describe here the evolving genetic background of KPC-KP isolates in Crete, Greece. Methods: We tested the antibiotic susceptibility of 34 clinical isolates from patients hospitalized in 2010 and 2013-14. Whole-genome sequences of these isolates were analysed for acquired resistance genes and gene mutations. Results: All KPC-KP isolates belonged to ST258 with the exception of one ST147 isolate. From 2014, 26% of isolates were non-susceptible to all antibiotics, compared with 0 of 11 isolates from 2010. Colistin resistance was associated with mutations in mgrB, which was present in 61% of isolates from 2014. Core-genome MLSTanalysis showed that pan-resistant isolates were closely related and appeared in two separate clusters. Conclusions: KPC-KP is rapidly evolving to pan-resistance in Crete. We identified molecular resistance markers for pan-resistant isolates and showed that core-genome MLST is a promising tool for molecular fingerprinting of KPC-KP ST258.