Antimicrobial resistance of uropathogens among outpatients, 2000-2004

A retrospective study based on the electronic database of a university hospital was carried out to investigate the prevalence of etiological agents and their susceptibilities to antibiotics, among adult outpatients (> 18 years old) with urinary tract infections. Nine hundred and fifty- seven positive urine cultures were identified between January 2000 and December 2004. Escherichia coli, Proteus mirabilis and Klebsiella sp were the three principal bacterial etiological agents. Trimethoprim- sulfamethoxazole presented the highest prevalence of bacterial resistance ( 46.9%), followed by cefalotin (46.7%), nalidixic acid (27.6%) and nitrofurantoin ( 22.3%). Over the study period, nalidixic acid presented annual increases of 5.9% in the rate of bacterial resistance (p = 0.02). Ciprofloxacin also showed an increasing trend, of 3.3% per year (p = 0.07). This study demonstrated that the antibiotics that are widely recommended for empirical treatment of urinary tract infection in adults presented high rates of bacterial resistance among the population studied.