Comparative in vitro activity of the new oral cephalosporin cefixime

Cefixime was 8 to 10 times more active than cefaclor and augmentin against isolates of Escherichia coli, Klebsiella pneumoniae and Salmonella typhi, MIC90 values ranging from 0.06 to 0.25 micrograms/ml. However, none of these three drugs was particularly active against isolates of more resistant gram-negative bacilli such as Enterobacter, Serratia, Citrobacter, Acinetobacter, Providencia and Achromobacter spp. The lowest MIC values for gram-negative bacilli were seen with ciprofloxacin, except for isolates of Acinetobacter, 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 beta-lactam drugs, it does not appear to be useful for treatment of infections caused by more resistant gram-negative bacilli.