[Study of antibiotic multiresistance of Escherichia coli from urine cultures].

Background And Objective: The appearance of resistance in urinary tract infections caused by Escherichia coli constitutes an important therapeutic problem that requires the study of its evolution throughout time in order to establish a suitable empirical treatment. Our objective was to test the antimicrobial sensitivity of E. coli isolations in urine cultures performed in our area.

Material And Method: 5,247 isolates of E. coli from hospital and ambulatory urine cultures of patients in the area of Segovia were retrospectively analyzed. The antibiotic sensitivity of these isolations was studied for 4 years (2000-2005). Moreover, 6 phenotype patterns of resistance to betalactams were analyzed: natural, penicillinase, increased penicillinase, IRT, increased AMPc and BLEE and the difference in sensitivity between BLEE producing and non-producing stocks regarding nitrofurantoin, phosphomicin, ciprofloxacin, gentamicin, and trimetoprim-sulfametoxazol.

Results: 57% of isolates were resistant to ampicillin, 23% to ciprofloxacin and 31% to trimetroprim-sulfametoxazol. 48% were penicillinase producer, 6.6% increased penicillinase producer, 1.2% IRT producer, 1.1% AMPc producer and 2.2% were BLEE producer. As far as the origin of the sample is concerned, significant differences were not found. The percentages of co-resistance to ciprofloxacin and trimetoprim-sulfametoxazol were greater in BLEE producer stocks than in non-producers ones. We observed a gradual increase in the expression of this resistance mechanism throughout the studied period.

Conclusions: Ampicillin, ciprofloxacin and trimetoprim-sulfametoxazol are not suitable for the empirical treatment of uncomplicated urinary infections. Research on sensitivity is essential in order to establish correct empirical treatments.