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 Klebsiella pneumoniae 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 beta-lactamases (ESBL), plasmid-mediated AmpC beta-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 bla(OXA-48) and 2 were positive for bla(NDM-1). All carbapenemase-producing K. pneumoniae were also ESBL producers and the bla(CTX-M-15) was the most frequent ESBL gene detected (n = 9), bla(CTX-M-28) and bla(SHV-28) were also encountered in one isolate each. The K. pneumoniae isolates carried also non-ESBL genes bla(TEM-1) (n = 9), bla(SHV-1) (n = 8) and bla(OXA-1) (n = 3). Five isolates harbored qnr genes, qnrS1 (n = 3) and qnrB1 (n = 2) variants. Six isolates were positive for aac(6'-1b-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 bla(OXA-48) + bla(CTX-M-15), bla(OXA-48) + bla(CTX-M-28), bla(NDM-1) + bla(CTX-M-15) + bla(OXA-1), + qnrS1 + aac(6'-1b-cr and bla(NDM-1) + bla(CTX-M-15) + bla(TEM-1) + qnrB1 + aac(6'-1b-cr genes were co-transferred and that these genes were carried by a conjugative plasmid of high molecular weight. (C) 2015 Published by Elsevier B.V.