Efficacy of cefmenoxime in experimental Escherichia coli bacteremia and meningitis.

Cefmenoxime, a new semisynthetic cephalosporin structurally similar to cefotaxime, was evaluated for its activities in vitro and in vivo against a K1 Escherichia coli strain in comparison with activities of cefotaxime and ampicillin. In vitro the MICs and MBCs of both cefmenoxime and cefotaxime were the same, 1/16th and 1/32nd those of ampicillin, respectively. The efficacies of cefmenoxime and cefotaxime against experimentally induced E. coli bacteremia and meningitis in newborn rats were similar and significantly better than that of ampicillin as judged by bactericidal titers of blood and cerebrospinal fluid, rapidity of clearance of bacteria from blood and cerebrospinal fluid, and incidence of meningitis in animals with bacteremias. The efficacy of cefmenoxime or cefotaxime measured by impact on mortality was influenced by the size of bacterial populations. The mortality was significantly greater in rats with bacterial counts before therapy of greater than or equal to 10(6) CFU/ml of blood than in animals with lower counts. Overall, the in vivo efficacy of cefmenoxime was similar to that of cefotaxime; thus it could be useful in the therapy of neonatal E. coli infection.