Cefixime was 8 to 10 times more active than cefaclor and augmentin against isolates ofEscherichia coli, Klebsiella pneumoniae andSalmonella typhi, MIC90 values ranging from 0.06 to 0.25 µg/ml. However, none of these three drugs was particularly active against isolates of more resistant gram-negative bacilli such asEnterobacter, Serratia, Citrobacter, Acinetobacter, Providencia andAchromobacter spp. The lowest MIC values for gram-negative bacilli were seen with ciprofloxacin, except for isolates ofAcinetobacter, where cotrimoxazole was the most active of the five drugs studied. Augmentin and ciprofloxacin exhibited the lowest MICs for isolates of streptococci and corynebacteria. Although cefixime may be among the most active oral betalactam drugs, it does not appear to be useful for treatment of infections caused by more resistant gram-negative bacilli.