Molecular characterisation of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella spp. isolates at a tertiary-care centre in Lebanon

The prevalence of blaCTX-M, blaTEM and blaSHV genes among extended-spectrum β-lactamase (ESBL)-producing clinical isolates of Escherichia coli (n = 50) and Klebsiella spp. (n = 50) from Lebanon was 96%, 57% and 67%, and 40%, 82% and 84%, respectively. Genotyping revealed that the clonal diversity was unrelated to the presence of bla genes. Sequence analysis of 16 selected isolates identified the blaCTX-M-15, blaTEM-1, blaOXA-1 and six blaSHV genes, as well as the gene encoding the quinolone-modifying enzyme AAC(6′)-Ib-cr. The genes encoding CTX-M-15 and AAC(6′)-Ib-cr were carried on a 90-kb plasmid of the pC15–1a or pCTX-15 type, which transferred both ESBL production and quinolone resistance from donors to transconjugants.