Sequence type ST131 and ST10 complex (ST617) predominant among CTX-M-15-producing Escherichia coli isolates from Nigeria

Abstract

Of 109 clinical Escherichia coli isolates from two major tertiary hospitals in Lagos (University Teaching Hospital and the National Orthopaedic Hospital Igbobi), 14 (12.8%) extended-spectrum beta-lactamse (ESBL) producers were characterized using PCR and sequencing, ERIC-PCR and multilocus sequence typing. All ESBL-producing isolates encoded only the CTX-M-15 gene. Clonal group ST131 (35.7%) was the predominant ST, followed by ST617 (28.6%). Isolated cases of other sequence types were also observed. Plasmid-mediated quinolone resistance genes qnrA, qnrB1 and aac-(6')-lb-cr were detected among these ESBL isolates of different clonal groups. This is the first description of the clonality of CTX-M-15-producing E. coli from Nigeria. The presence of diverse clonal lineages shows the continuing potential for genetic diversification and emergence of new epidemic strains.