Antimicrobial resistance is a public health concern. Understanding any role that urban seagulls may have as a reservoir of resistant bacteria could be important for reducing transmission. This study investigated fecal Escherichia coli isolates from seagulls (herring gulls and lesser black-backed gulls) to determine the prevalence of extended-spectrum cephalosporin-resistant (ESC-R) and fluoroquinolone-resistant E. coli among gull species from two cities (Taunton and Birmingham) in the United Kingdom (UK). We characterized the genetic background and carriage of plasmid-mediated resistance genes in extended-spectrum β-lactamase (ESBL)-producing E. coli obtained from these birds. Sixty ESC-R E. coli isolates were obtained from 39 seagulls (39/78, 50%), of which 28 (28/60, 46.7%) were positive for plasmid-mediated CTX-M and/or AmpC β-lactamase resistance genes. Among these, blaCTX-M-15, blaCTX-M-14, and blaCMY-2 predominated. Three isolates belonging to the B2-ST131 clone were detected, of which two harbored blaCTX-M-15 (typed to C2/H30Rx) and one harbored blaCTX-M-27 and was typed to C1/H30-R (recently described as the C1-M27 sublineage). The plasmid-mediated quinolone resistance (PMQR) gene carriage prevalence (11.7%) consisted of aac(6')-Ib-cr and qnrB genes. No carbapenem or colistin resistance genes were detected. Urban seagulls in the UK are colonized and can spread major antimicrobial-resistant E. coli isolates harboring ESBL and PMQR determinants, including clinically important strains such as the pandemic clone B2-ST131 and the C1-M27 subclade. This is the first report of ST131-C1-M27 subclade in wildlife in the UK and in seagulls worldwide.
Keywords: AmpC; B2-ST131; C1-M27; ESBLs; Escherichia coli; Larus spp; PMQR.