Prevalence and types of extended spectrum β-lactamases among urinary Escherichia coli isolates in Moroccan community

This study was designed to characterize extended-spectrum-β-lactamases (ESBL) produced by Escherichia coli isolates causing community urinary tract infections over a 2-year period (2010 and 2011) in a Moroccan large geographical region. Molecular characterization was done by using PCR and sequencing of the β-lactamases genes and plasmid-mediated quinolone resistance determinants. Among 1174 isolates, 49 (4.1%) were ESBL producers. The blaCTx-M-15 (n = 31) was the most frequent ESBL gene detected, followed by blaCTx-M-1 (n = 5), blaSHV-12 (n = 6), blaPER-2 (n = 3), then blaTEM-3, blaTEM-20, blaTEM-158, blaSHV-27, blaSHV-28, blaSHV-36, blaSHV-125, blaCTx-M-14 and blaCTx-M-27 with one isolate for each. The non-ESBL genes detected were blaTEM-70 (n = 1), blaTEM-176 (n = 1), blaTEM-104 (n = 6), blaTEM-1 (n = 15) and blaOxA-1 (n = 12). Plasmid mediated AmpC β-lactamases genes; blaACT-5 (n = 1), blaDHA-1(n = 2) and blaCMY-2 (n = 4) were detected in seven isolates (14.2%). The blaOxA-48 (n = 1) and blaIMP-1 (n = 1) carbapenemases genes were detected among five carbapenem-resistant E. coli. Five isolates (10.2%) harboured qnr genes, qnrB1 (n = 3), qnrB2 (n = 1) and qnrS1 (n = 1) type were detected. Thirty isolates (61.2%) were positive for aac(6′)-Ib-cr gene. The class 1 integron was detected in twenty two (44.8%) isolates. Phylogenetic grouping revealed that 22 (44.8%) isolates belonged to group A, while 15 (30.6%), 11 (22.4%) and 1 (2%) belonged to B2, D and B1. Results of conjugation experiments indicated that blaCTx-M-15, blaTEM-1, blaOxA-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. The results of this work reports the genetic diversity of ESBL genes, with the CTX-M-15 enzyme being the most common among ESBL-producing E. coli in Moroccan community.