Ceftriaxone therapy of group B streptococcal bacteraemia and meningitis in infant rats

The efficacy of ceftriaxone against group B streptococci was studied in vitro and in vivo with an infant rat model of group B streptococci bacteraemia and meningitis. Twenty-four strains demonstrated minimal inhibitory concentrations of ceftriaxone of 0 . 05-0 . 1 mg/l and minimal bactericidal concentrations of 0 . 1-0 . 4 mg/l. Four strains were selected to induce bacteraemia and meningitis in infant rats by intraperitoneal inoculation. All 45 bacteraemic animals with or without meningitis that were treated with ceftriaxone 2 mg/kg/dose every eight hours for five doses survived, while all 12 control animals died (P less than 0 . 001). When recultured 54 h after the last dose of ceftriaxone, both CSF and blood remained sterile in all treated animals. These results indicate group B streptococci to be sensitive to ceftriazone in vitro and that, in the low dosage used, ceftriaxone effectively eradicates group B streptococcal bacteraemia and meningitis in infant rats.