Genotypic analysis of uropathogenic Escherichia coli to understand factors that impact the prevalence of ß-lactam-resistant urinary tract infections in a community

Abstract Objective To determine the contribution of specific uropathogenic Escherichia coli (UPEC) lineages, drug-resistance genes, and plasmid incompatibility/replicon (Inc) groups to the prevalence of β-lactam-resistant urinary tract infections (UTIs) in a university community. Methods Urine samples were consecutively collected and cultured over a two-year period from patients presenting to a university health center with symptoms of UTI. Isolated UPEC were subtyped by MLST and fimH typing, and tested by PCR and sequencing for s-lactamase genes and plasmid Inc groups. Results Among 273 UPEC isolates, 85 (31%) were ampicillin-resistant (AMP-R) and 188 (69%) were susceptible to all s-lactam drugs (AMP-S). Six lineages accounted for two-thirds of the isolates ST95 (21%), ST69 (11%), ST420 (11%), ST73 (10%), ST127 (8%), and ST404 (3%). ST69 and ST404 were associated with AMP-R (P = 0.003, P = 0.0005), while ST420 and ST127 were associated with AMP-S (P  TEM was the most common s-lactamase gene, identified in 81 (95%) AMP-R isolates. IncFIB, IncFIA, and IncB/O type plasmids were the most common types identified, and were associated with s-lactam resistance (P  Conclusions These observations indicate that the prevalence of β-lactam-resistant UTIs in this community was largely determined by a limited set of circulating UPEC STs and sublineages, carrying TEM s-lactamase genes that were likely encoded on one of three Inc type plasmids.