Susceptibility of Escherichia coli to the amoxycillin-clavulanate combination: which recommendations should be used to provide relevant information to clinicians?

This study compared MIC distributions of amoxycillin-clavulanate obtained with NCCLS and French (Comité de l'Antibiogramme de la Société Française de Microbiologie; CA-SFM) methodologies for Escherichia coli isolates from urine that were non-susceptible to amoxycillin-clavulanate by the disk diffusion method. With the NCCLS and CA-SFM methods, 74% and 13%, respectively, of these isolates were susceptible to amoxycillin-clavulanate. Therefore, the apparent relatively poor efficacy of amoxycillin-clavulanate against E. coli in French hospitals probably reflects a methodological difference rather than a localised resistance problem. This implies that amoxycillin-clavulanate could be used as an alternative to fluoroquinolones for treatment of E. coli urinary tract infections. Susceptibility tests for amoxycillin-clavulanate should be standardised worldwide.