Molecular characterization of OXA-48-like-producing Enterobacteriaceae in the Czech Republic: evidence for horizontal transfer of pOXA-48-like plasmids

The aim of this study was to characterize the first cases and outbreaks of OXA-48-like-producing Enterobacteriaceae recovered from hospital settings in the Czech Republic. From 2013 to 2015, 22 Klebsiella pneumoniae isolates, 3 Escherichia coli isolates, and 1 Enterobacter cloacae isolate producing OXA-48-like carbapenemases were isolated from 20 patients. Four of the patients were colonized or infected by two or three different OXA-48-like producers. The K. pneumoniae isolates were classified into nine sequence types (STs), with ST101 being predominant (n = 8). The E. coli isolates were of different STs, while the E. cloacae isolate belonged to ST109. Twenty-four isolates carried bla(OXA-48), while two isolates carried bla(OXA-181) or bla(OXA-232). Almost all isolates (n = 22) carried bla(OXA-48)-positive plasmids of a similar size (similar to 60 kb), except the two isolates producing OXA-181 or OXA-232. In an ST45 K. pneumoniae isolate and an ST38 E. coli isolate, S1 nuclease profiling plus hybridization indicated a chromosomal location of bla(OXA-48). Sequencing showed that the majority of bla(OXA-48)-carrying plasmids exhibited high degrees of identity with the pOXA-48-like plasmid pE71T. Additionally, two novel pE71T derivatives, pOXA48_ 30715 and pOXA-48_30891, were observed. The bla(OXA-181)-carrying plasmid was identical to the IncX3 plasmid pOXA181_EC14828, while the bla(OXA-232)-carrying plasmid was a ColE2-type plasmid, being a novel derivative of pOXA-232. Finally, sequencing data showed that the ST45 K. pneumoniae and ST38 E. coli isolates harbored the IS1R-based composite transposon Tn6237 containing bla(OXA-48) integrated into their chromosomes. These findings underlined that the horizontal transfer of pOXA-48-like plasmids has played a major role in the dissemination of bla(OXA-48) in the Czech Republic. In combination with the difficulties with their detection, OXA-48 producers constitute an important public threat.