Retracted: Single origin of three plasmids bearing blaCTX-M-15 from different Klebsiella pneumoniae clones

OBJECTIVES: To determine and compare the complete nucleotide sequences of plasmids carrying blaCTX-M-15 from three different Klebsiella pneumoniae clones. METHODS: IncFII-type plasmids pKP02022, pKP09085 and pKP007 were extracted from three K. pneumoniae strains. These strains belong to sequence types (STs) ST15, ST48 and ST23, respectively, and were isolated in Korea. Plasmids were sequenced using the 454 Genome Sequencer FLX system. RESULTS: The three plasmids, pKP02022 (203577 bp), pKP09085 (213019 bp) and pKP007 (246 176 bp), all exhibited a very similar structure, with a pKPN3-like backbone and a resistance region including blaOXA-1, aac(6')-Ib-cr and cat genes as well as blaCTX-M-15. They were also very similar to pUUH239.2, previously isolated in Sweden. Iron (III) uptake-related genes were found in pKP007 from the ST23 strain, which has been reported to be associated with liver abscesses. The resistance region contained several insertion sequences, such as IS26, which may play an important role in structural rearrangements of plasmids. CONCLUSIONS: The very similar structure of the three plasmids, extracted from different clones, suggests that the spread of CTX-M-producing K. pneumoniae isolates might result from the horizontal transfer of plasmids and subsequent integration and recombination.