Carbapenem-resistant Klebsiella pneumoniae cause important healthcare-associated infections worldwide. An outbreak of ST11 OXA-48-producing K. pneumoniae isolates (OXA-48-Kp) occurred in Tzaneio Hospital in 2012 and was contained until 2014, when OXA-48-Kp reemerged. The present study involved 19 bloodstream infection (BSI) OXA-48-Kp recovered from 19 ICU patients hospitalized between August 2014 and July 2016. MICs were determined by broth microdilution. β-lactamase genes were detected by PCR. All isolates were typed by PFGE/MLST and 10 representative isolates by next generation sequencing (NGS). Of the 19 study patients, nine had previous hospitalizations and 10 carried OXA-48-Kp prior to BSI isolations; median time from ICU admission to BSI was 29 days. Four OXA-48-Kp belonged to PFGE profile A (ST147) and were pandrug-resistant (PDR), while 15 isolates exhibited PFGE profile B (ST101) and were extensively drug-resistant. NGS resistome analysis detected genes justifying resistances, except for tigecycline and fosfomycin. Insertional inactivation of mgrB (distinct per clone) conferred colistin resistance in all 19 isolates. NGS SNPs analysis validated the clonal relatedness of the ST147 and ST101 strains and revealed possible presence of two index ST147 strains and microevolution of ST101 strains. Distinct, but highly related, IncL OXA-48-encoding plasmid lineages were identified; plasmids of the ST147 strains were identical with that of ST11 OXA-48-Kp causing the 2012 outbreak. In conclusion, biclonal circulation of OXA-48-Kp and, alarmingly, emergence of a PDR clone are reported. These observations, along with the challenging phenotypic detection of OXA-48 producers and the high reported transmissibility of blaOXA-48, necessitate intensive efforts to prevent their further spread.
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