Activity of sulfamethoxazole trimethoprim against Bacteroides fragilis

The author tested parallely 35 Bacteroides fragilis strains by the agar diffusion method and disk technique. A notable discrepancy appears between these two procedures. No regression line can be constructe and the inhibition diameter measurement is unable to class the strain in "susceptible" or "resistant". A literature review on this theme shows that the dissociation between these two techniques were more frequent with anaerobic strains than aerobic for SMX + TMP as others antibiotics. The MIC determination by an agar dilution is the only able to these studies.