[Phenotypes of resistance in community urinary tract isolates of Escherichia coli: therapeutic implications].

Background And Objective: Urinary tract infectious (UTI) are very frequent in the community and are managed through empirical treatment guidelines. The knowledge of patterns of susceptibility of patients at the time of establishing an empirical treatment is fundamental to avoid therapeutic failures. The aim of this study was to know the pattern of resistance to betalactams and other antimicrobials used in the treatment of non-complicated urinary infections in the area 11 of Madrid.

Patients And Method: Retrospective study of susceptibility of Escherichia coli isolated in cultures of urine of outpatients of area 11 of Madrid during a period of 12 months.

Results: We found high rates of resistance to ampicillin and trimethoprim-sulfamethoxazole (57 and 29%, respectively). We observed high rates of resistance to cefuroxime (24%) and amoxicillin-clavulanic acid (27%). Resistance to ciprofloxacine was 16%. Resistance to phosphomicin and nitrofurantoin was very low (5 and 4%). Most frequent resistance association was ampicillin + cephalothin (20,2%). The mechanisms of resistance having more clinical relevance was the production and hyper-production of betalactamase.

Conclusions: Changes were detected as to the pattern of susceptibility of certain antimicrobials frequently used in the empirical treatment of UTI such as cefuroxime and amoxicillin-clavulanic acid. It is important to support a condition of active surveillance for the evolution of resistances.