A novel plasmid carrying blaCTX-M-15 identified in commensal Escherichia coli from healthy pregnant women in Ibadan, Nigeria

The aim of this study was to investigate the molecular characteristics of commensal Escherichia coli producing extended-spectrum β-lactamases and showing fluoroquinolone resistance circulating in a healthy population in Ibadan, Nigeria. In total, 101 faecal samples from healthy pregnant women on the day of admission to hospital were collected and plated on eosin-methylene blue agar supplemented with cefotaxime. Genotyping demonstrated the presence of the blaCTX-M-15 gene in all of the cefotaxime-resistant isolates (n = 32), and there was circulation of prevalent clones. The aac(6′)-Ib-cr, qnrS1, qepA1 and qnrB1 genes were identified in several strains. A novel plasmid supporting the spread of the blaCTX-M-15, blaTEM-1 and qnrS1 genes was identified in these isolates by complete DNA sequencing.