Antibiotic resistance and trend of urinary pathogens in general outpatients from a major urban city

ABSTRACT

OBJECTIVE: We assessed the antimicrobial resistance patterns of pathogens responsible for urinary tract infections (UTI) in outpatients in São Paulo, Brazil, as well as the Escherichia coli antimicrobial resistance trend. MATERIALS AND METHODS: Outpatients urine cultures were collected from January 2000 to December 2003. Statistical analysis considered positive results for one bacterial species with colony count > 100,000 CFU/mL. Stratification was done on age group and gender. Statistical tests used included chi-square and the chi-square test for trend to evaluate differences between susceptibility rates among age groups and ordering in the E. coli resistance rates per year, respectively. RESULTS: There were 37,261 positive results with Enterobacteriaceae isolated in 32,530 (87.3 percent) and Gram-positive cocci in 2,570 (6.9 percent) cultures. E. coli had the highest prevalence (71.6 percent). Susceptibility tests were performed in 31,716 cultures. E. coli had elevated resistance rates (> 30 percent) to ampicillin, trimethoprim-sulfamethoxazole, and tetracycline. Significant differences between age groups and ordering among years were observed. CONCLUSIONS: The use of trimethoprim-sulfamethoxazole is precluded in the population studied due to elevated resistance rates (> 30 percent) among most prevalent pathogens. Significant resistance rate differences among age groups and years were observed, particularly for fluoroquinolones. Fluoroquinolones should be used with caution. Nitrofurantoin should be used as empirical therapy for primary, non-complicated urinary tract infections.