An 11-year analysis of the prevalent uropathogens and the changing pattern of Escherichia coli antibiotic resistance in 38,530 community urinary tract infections, Dublin 1999-2009.

BACKGROUND

Knowledge of local antimicrobial resistance patterns is essential for evidence-based empirical antibiotic prescribing, and a cutoff point of 20% has been suggested as the level of resistance at which an agent should no longer be used empirically. We sought to identify the changing incidence of causative uropathogens over an 11-year period. We also examined the trends in antibiotic resistance encountered in both the pooled urine samples and those where the causative organism was Escherichia coli.

PATIENT AND METHODS

A retrospective analysis of the antimicrobial resistance within the positive community urine isolates over the 11-year period, 1999 to 2009, in a single Dublin teaching hospital was performed.

RESULTS

In total 38,530 positive urine samples processed at our laboratory originated in the community of which 23,838 (56.7%) had E. coli as the infecting organism. The prevalence of E. coli has been increasing in recent years in community UTIs with 70.4% of UTIs in the community caused by E.coli in 2009. Ampicillin and trimethoprim were the least-active agents against E. coli with mean 11-year resistance rates of 60.8 and 31.5%, respectively. Significant trends of increasing resistance over the 11-year period were identified for trimethoprim, co-amoxyclav, cefuroxime and gentamicin. Ciprofloxacin remains a reasonable empirical antibiotic choice in this community with an 11-year resistance rate of 10.6%. Higher antibiotic resistance rates were identified in the male population and in children.

CONCLUSION

Resistance rates to commonly prescribed antibiotics are increasing significantly. This data will enable evidence-based empirical prescribing which will ensure more effective treatment and lessen the emergence of resistant uropathogens in the community.