The incidence of drug-resistant community-acquired urinary tract infections (CA-UTI) continues to increase worldwide. In 1999 to 2000, a single lineage of uropathogenic Escherichia coli (UPEC) sequence type 69 (ST69) caused 51% of trimethoprim-sulfamethoxazole-resistant UTI in a Northern California university community. We compared the clonal distributions of UPEC and its impact on antimicrobial resistance prevalence in the same community during two periods separated by 17 years. We analyzed E. coli isolates from urine samples from patients with symptoms of UTI who visited a health service between September 2016 and May 2017 and compared them to UPEC isolates collected similarly between October 1999 and March 2000. Isolates were tested for antimicrobial drug susceptibility and genotyped by multilocus sequence typing. In 1999 to 2000, strains belonging to ST95, ST127, ST73, ST69, ST131, and ST10 caused 125 (56%) of 225 UTI cases, while the same STs caused 148 (64%) of 233 UTI cases in 2016 to 2017. The frequencies of ampicillin resistance and ciprofloxacin resistance rose from 24.4% to 41.6% (P < 0.001) and from 0.9% to 5.1% (P < 0.003), respectively. The six STs accounted for 78.6% and 72.7% of these increases, respectively. Prevalence of drug-resistant UTI in this community appears to be largely influenced by a small set of dominant UPEC STs circulating in the same community 17 years apart. Further research to determine the origin and reasons for persistence of these dominant genotypes is necessary to combat antimicrobial-resistant CA-UTI.
Keywords: Escherichia coli; molecular epidemiology; multilocus sequence typing; urinary tract infection; uropathogenic E. coli.
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