Characterization of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae isolates from the community in Morocco

Of 803 community Escherichia coli (n = 767) and Klebsiella pneumoniae (n = 36) isolates collected from patients with urinary tract infections in three Moroccan cities, 10 E. coli (1.3%) and 2 K. pneumoniae (5.6 %) isolates were shown to produce extended-spectrum β-lactamases (ESBLs). PFGE revealed that the E. coli isolates comprised seven distinct genotypes. The presence of plasmids in the 12 isolates was revealed by conjugation experiments of plasmids from these Enterobacteriaceae strains with E. coli K(12)J(5), with further isolation of the plasmids in the transconjugants. Subsequent nucleotide sequencing indicated that the plasmids encoded the bla(CTX-M), bla(OXA), bla(TEM) and bla(SHV) genes, including genes for CTX-M-15 (n = 11), OXA-1 (n = 11), TEM-1b (n = 4), SHV-5 (n = 1) and SHV-1 (n = 2). Identification of plasmid-mediated quinolone-resistance genes was performed by PCR. The aac(6')Ib-cr variant was detected in all strains, and two strains co-expressed qnrS1, bla(CTX-M-15) and bla(OXA-1) genes. The presence of ESBLs in the Enterobacteriaceae strains studied was probably due to the dissemination of resistance plasmids with the predominant genotype of bla(CTX-M-15.).