Background: The empiric treatment of extrahospitalary urinary infections must keep in mind the patterns of susceptibility of the potentially causative bacteria. The consumption of antibiotics is one of the most important causes of change in the susceptibility of the bacteria. The recent introduction of fluorquinolones and the widespread use of those antibiotics makes knowledge of new patterns of sensitivity necessary in order to determine whether there are changing sensitive pattern among the different geographic zones.
Methods: During a period of two weeks randomly chosen 379 strains of Escherichia coli isolated from extrahospitalary bacteria were collected in 11 laboratories in 4 health areas in Madrid. Sensitivity to 11 antibiotics, including four of the quinolone group was determined by the agar dilution method. The existence of significant differences of sensitivity among the different areas was analyzed by the chi 2 test.
Results: The prevalence of sensitivity to ampicillin and cotrimoxazol was 42 and 73% respectively. Nineteen percent of the strains were resistant to amoxycillin/clavulanic acid. No strain was found to be resistant to cefotaxime. Four percent of the sample studied was not sensitive to the new fluorquinolones and almost 10% were resistant to nalidixic acid latter having decreased sensitivity to the fluorquinolones. No significant differences were observed in sensitivity among the areas, except with amoxycillin/clavulanic acid and cotrimoxazole.
Conclusions: The high prevalence of the resistance of E. coli to ampicillin recently leads to the recommendation of its use in empiric treatments of urinary infections. In the zone in Madrid studied a high prevalence of resistance and decreased sensitivity of E. coli to fluoroquinolones was observed. It is therefore advisable to moderate their use to thereby prolong use over time.