[Aetiology and bacterial resistance in urinary infections of outpatients]

Knowledge of the etiological agents of infections of the urinary tract and of the map of the antimicrobial sensitivity of each geographic zone is a practice recommended for improving the use of antibiotics and for facilitating the choice of empirical treatment. The aim of this study is to provide up-to-date information on the pathogen flora of outpatients urinary infections in our health area and their sensitivity to antimicrobials, based on the urinary cultivations carried out in the Microbiology laboratory of the Solchaga Outpatient Surgery during the last four years.

Between 1996 and 1999, we carried out 92,816 urinary cultivations of outpatients. The urine specimens were sown on plaques with chocolate agar and MacKonkey agar with calibrated loop. The antibiogram was carried out using the Kirby-Bauer method.

The percentage of positive urinary cultivations was 17%. Gram-negative bacilli represented 88.9% of the isolations, Gram-positive cocci 11% and yeasts 0.1%. Escherichia coli was the most frequently isolated germ (71%). The sensitivity studies show that amoxycillin-clavulanic acid, first generation cephalosporins and fosfomycin maintain a sensitivity above 80%.

Up-to-date knowledge of the most common pathogen flora and their sensitivity to antimicrobials makes it possible for a more suitable selection to be made of the antibiotic treatment when the sensitivity pattern of the responsible germ is unavailable. In the light of the results we can conclude that amoxycillin-clavulanic acid, first generation cephalosporins and fosfomycin show a good activity in vitro, and should be considered as empirical treatments for infections of the urinary tract.