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 (greater than or equal to 18 mm), 67% of E coli were susceptible to cefazolin and cefamandole, and 93% were susceptible to ceforanide. By microtiter assay (MIC less than or equal to 8 micrograms/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.