JAC 49/2 pp. 367-371

Co-amoxiclav is widely used in France to treat different infectious diseases, in particular community-acquired otitis, sinusitis and pneumonia, and occasionally urinary tract infections (UTIs). While the mechanisms of resistance to co-amoxiclav have been well defined, particularly in Escherchia coli, the influence of co-amoxiclav treatment on the in vivo selection of E. coli resistant to co-amoxiclav has never clearly been demonstrated; however, ampicillin– sulbactam has been shown to select for resistance in E. coli responsible for various nosocomial infections. In order to prove that co-amoxiclav treatment can be a risk factor for selecting co-amoxiclav-resistant E. coli in vivo, we conducted a study of patients who had a bacteriologically confirmed E. coli UTI, and for whom the history of co-amoxiclav consumption in the month before the reported infection was documented. The -lactam susceptibility of the urinary E. coli isolates of patients who had been given co-amoxiclav in the month before diagnosing the infection was compared with that of the urinary E. coli isolates of patients who had not been given co-amoxiclav. We also determined the frequency of co-amoxiclav-resistant isolates in the faeces of patients treated with amoxicillin or co-amoxiclav for the reported UTI, and compared it with that for patients treated with other antibiotics, such as third-generation cephalosporins or fluoroquinolones.