Expansion of KPC-producing Klebsiella pneumoniae with various mgrB mutations giving rise to colistin resistance: the role of ISL3 on plasmids.

mcr-1 has been reported as the first plasmid-encoded gene conferring colistin resistance. In KPC-producing Klebsiella pneumoniae (KPC-KP), however, colistin resistance is rapidly emerging through other mechanisms. Resistance is frequently due to disruption of the mgrB gene by insertion sequences, e.g. ISL3. The aim of this study was to investigate the expansion of mgrB-mutated KPC-KP isolates. In addition, the localisation and targets of ISL3 sequences within the core and accessory genome of common KPC-KP lineages were identified. A total of 29 clinical K. pneumoniae isolates collected from Italian patients were randomly selected. Whole genome sequences were analysed for resistance genes, plasmids and insertion sequences. In addition, 27 colistin-resistant KPC-KP isolates from a previous study from Crete (Greece) were assessed. Clonal expansion of KPC-KP isolates with various mutations in mgrB among all lineages was observed. In two Italian MLST ST512 isolates and eight Greek ST258 isolates, an identical copy of ISL3 was inserted in mgrB nucleotide position 133. ISL3, a transposable restriction-modification system of 8154 nucleotides, was located on pKpQIL-like plasmids and may transpose into the chromosome. In four isolates, chromosomal integration of ISL3 in diverse inner membrane proteins other than mgrB was identified. Colistin resistance is most often explained by clonal expansion of isolates with mutated mgrB. pKpQIL-like plasmids, which are omnipresent in KPC-KP, carry insertion sequences such as ISL3 that have mgrB as a target hotspot for transposition. Transposition of insertion sequences from plasmids and subsequent clonal expansion may contribute to the emerging colistin resistance in KPC-KP.

Giordano C ，Barnini S ，Tsioutis C ，Chlebowicz MA ，Scoulica EV ，Gikas A ，Rossen JW ，Friedrich AW ，Bathoorn E ... -  《-》

An Update of the Evolving Epidemic of blaKPC Carrying Klebsiella pneumoniae in Sicily, Italy, 2014: Emergence of Multiple Non-ST258 Clones.

Bonura C ，Giuffrè M ，Aleo A ，Fasciana T ，Di Bernardo F ，Stampone T ，Giammanco A ，MDR-GN Working Group ，Palma DM ，Mammina C ... -  《PLoS One》

Characterization of ST258 Colistin-Resistant, blaKPC-Producing Klebsiella pneumoniae in a Greek Hospital.

Mavroidi A ，Katsiari M ，Likousi S ，Palla E ，Roussou Z ，Nikolaou C ，Maguina A ，Platsouka ED ... -  《-》

In vivo emergence of colistin resistance in Klebsiella pneumoniae producing KPC-type carbapenemases mediated by insertional inactivation of the PhoQ/PhoP mgrB regulator.

Cannatelli A ，D'Andrea MM ，Giani T ，Di Pilato V ，Arena F ，Ambretti S ，Gaibani P ，Rossolini GM ... -  《-》

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

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. 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. 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 MLST analysis showed that pan-resistant isolates were closely related and appeared in two separate clusters. 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.

Bathoorn E ，Tsioutis C ，da Silva Voorham JM ，Scoulica EV ，Ioannidou E ，Zhou K ，Rossen JW ，Gikas A ，Friedrich AW ，Grundmann H ... -  《-》