Prevalence and genotypic analysis of plasmid-mediated β-lactamases among urinary Klebsiella pneumoniae isolates in Moroccan community

Abstract

The aim of this study is to assess the prevalence and molecular characterization of the extended spectrum β-lactamases (ESBL)-producing Klebsiella pneumoniae isolated from community acquired urinary tract infections and collected in five Moroccan cities during a 2010 survey. In all, 34 (7.5%) of the 453 K. pneumoniae isolates studied were positive for an ESBL phenotype and 91.1% of these isolates were multidrug resistant. The bla(CTX-M-15) (n=31) was the most frequent ESBL genes detected, followed equally by bla(SHV-28) and bla(SHV-12) (n=3), then bla(TEM-3), bla(SHV-36), bla(SHV-110) and bla(CTX-M-1) with one isolate for each (n=1). Eight isolates co-expressed more than one ESBL with bla(CTX-M-15). The non-ESBL genes detected were bla(SHV-1), bla(SHV-11), bla(SHV-32), bla(SHV-26), bla(SHV-76), bla(TEM-1), bla(TEM-1b) and bla(OXA-1). Plasmid-mediated AmpC β-lactamase genes, bla(ACT-2), bla(DHA-1) and a new β-lacatamase named bla(EBC-1464), were detected in 11.7% of isolates. Fourteen (41.1%) isolates harbored qnr genes; qnrA6 (n=1), qnrB1 (n=8), qnrB2 (n=1) and qnrS1 (n=4) types were detected. Twenty-six isolates (76.4%) were positive for aac(6')-Ib-cr gene. Results of conjugation experiments indicated that bla(CTX-M-15), bla(TEM-1b), bla(OXA-1), aac(6')-Ib-cr and qnrB1 genes were co-transferred and that these genes were carried by a conjugative plasmid of high molecular weight. With the exception of qnrB1, all the antibiotic resistance genes were clustered in a 12-kb region. The results of this work report the genetic diversity of ESBL genes, with the CTX-M-15 enzyme being most common among ESBL-producing K. pneumoniae in Moroccan community. Furthermore, a major finding is that bla(EBC-1464) detection is a first in Morocco.