Efficacy of imipenem in experimental group B streptococcal bacteremia and meningitis

We evaluated the activity of imipenem (N-formimidoyl thienamycin) against a type III group B streptococcal strain in vitro and in vivo. The minimal inhibitory and bactericidal concentrations of imipenem were 15 mg/l. In vivo studies using an infant rat model of group B streptococcal bacteremia and meningitis revealed that imipenem was highly effective. This was shown by (1) rapid bacterial clearance from the blood and cerebrospinal fluid; (2) rapid sterilization of the blood and cerebrospinal fluid; (3) prevention of the development of meningitis in bacteremic animals, and (4) reduction in mortality. Even 10 mg/kg of imipenem produced the mean serum bactericidal titers > 1:100 and cerebrospinal fluid bactericidal titers ≥ 1:16 at 1-2 h after subcutaneous administration. These findings suggest that the activity of imipenem is bactericidal in vitro and in vivo and may be an effective regimen against group B streptococci in this experimental model of bacteremia and meningitis.