The localisation and genetic organisation of blaCTX-M-15 were studied in 37 CTX-M-15-producing Klebsiella pneumoniae isolates collected from 2005 to 2008 within the Barcelona metropolitan area. Polymerase chain reaction (PCR)-based replicon typing and Southern hybridisations were used to identify the blaCTX-M-15 location. The genetic environment was analysed by PCR mapping and sequencing, and transferability of blaCTX-M-15 was evaluated by conjugation and transformation assays. The majority of the 37 isolates carried blaCTX-M-15 in a plasmid location, frequently associated with the aac(6')-Ib-cr gene. Plasmids encoding blaCTX-M-15 carried three distinct replicons, i.e. IncFII, IncR and IncFIIk, the latter two not having been described previously in association with blaCTX-M-15. Several of these plasmids were not self-transferable. Furthermore, in all isolates belonging to sequence type ST-1, blaCTX-M-15 was found integrated into the K. pneumoniae chromosome. In all the studied isolates, the mobile element ISEcp1 was found upstream of blaCTX-M-15, whereas IS26 was found inserted within ISEcp1 in several isolates, in previously unreported positions. In conclusion, these findings indicate that among K. pneumoniae strains isolated in the Barcelona metropolitan area, blaCTX-M-15 is associated with diverse genetic elements, including the IncR and IncFIIk replicons, as reported for the first time here, and the chromosome.
Bibliographical noteFunding Information:
Funding: This work was supported by Fondo de Investigación Sanitaria (PI050289), Ministerio de Sanidad y Consumo, Instituto de Salud Carlos III – FEDER (Spanish Network for Research in Infectious Diseases) (REIPI RD06/0008) and the Office of Research and Development, Medical Research Service, Department of Veterans Affairs (JRJ).
- Klebsiella pneumoniae