Comparison of Escherichia coli susceptibility to cephalothin, cefazolin, ceforanide, and cefamandole

Twenty-seven Escherichia coli test strains that were not susceptible to cephalothin were tested for susceptibility to cefazolin, cefamandole, and ceforanide. By zone-size criteria (≥ 18 mm), 67% of E. coli were susceptible to cefazolin and cefamandole, and 93% were susceptible to ceforanide. By microtiter assay (MIC ≤ 8 μg/ml), 88% were susceptible to cefazolin and cefamandole, and 94% were susceptible to ceforanide. The results support susceptibility testing of E. coli with specific first- or second-generation cephalosporins rather than with class agents.