Occurrence of OXA-48 and NDM-1 carbapenemase-producing Klebsiella pneumoniae in a Moroccan university hospital in Casablanca, Morocco.

The purpose of this investigation was to determine the prevalence and the characteristics of carbapenemase-producing Klebsiellapneumoniae isolates recovered from various clinical specimens in the university hospital of Casablanca, in Morocco. We conducted a prospective study on a total of 166 K. pneumoniae isolates collected from June to August 2011. The strains suspected to carry carbapenemase showed reduced susceptibility to imipenem or ertapenem. The PCR and a sequencing strategy were used to identify carbapenemases, expended spectrum β-lactamases (ESBL), plasmid-mediated AmpC β-lactamases, plasmid mediated quinolone resistance and aminoglycoside resistance determinants. The clonal relationships between isolates were analyzed by pulsed field gel electrophoresis (PFGE). Among the 166 K. pneumoniae isolates studied, 11 (6%) were carbapenemases producers, 9 of which harbored blaOXA-48 and 2 were positive for blaNDM-1. All carbapenemase-producing K. pneumoniae were also ESBL producers and the blaCTX-M-15 was the most frequent ESBL gene detected (n=9), blaCTX-M-28 and blaSHV-28 were also encountered in one isolate each. The K.pneumoniae isolates carried also non-ESBL genes blaTEM-1 (n=9), blaSHV-1 (n=8) and blaOXA-1 (n=3). Five isolates harbored qnr genes, qnrS1 (n=3) and qnrB1 (n=2) variants. Six isolates were positive for aac(6')-Ib-cr gene and two for aac(3)-II gene. The class 1 integron was detected in five isolates. PFGE has revealed the presence of a clonal dissemination in our hospital. The results of conjugation experiments indicated that blaOXA-48+blaCTX-M-15, blaOXA-48+blaCTX-M-28, blaNDM-1+blaCTX-M-15+blaTEM-1+blaOXA-1+qnrS1+aac(6')-Ib-cr and blaNDM-1+blaCTX-M-15+blaTEM-1+qnrB1+aac(6')-Ib-cr genes were co-transferred and that these genes were carried by a conjugative plasmid of high molecular weight.