Detection and characterization of OXA-48-producing Klebsiella pneumoniae originated in Bulgaria

We report the identification of OXA-48-producing Klebsiella pneumoniae, causing peritonitis in a cancer patient admitted to the Oncology Hospital in Sofia. The isolate had reduced susceptibility to carbapenems but remained susceptible to extended-spectrum cephalosporins. PCR and sequencing confirmed the presence of bla(OXA-48) gene flanked by two intact copies of IS1999 on truncated Delta Tn1999.1. This transposon was located on unusual non-typeable 29-kb plasmid that could be transferred only by transformation. Multilocus sequence typing (MLST) indicated the presence of the sequence type ST530. This is the first documented infection due to OXA-48-producing Enterobacteriaceae strain in Bulgaria.