During the first few hours of incubation, imipenem induced large lemon-shaped cells while the turbidity increased without substantial changes in culture viability. Despite the low MIC (0.2 mg/l) of imipenem for the five strains included in our study, the MBC remained relatively high (4.4 mg/l). Phase-contrast microscopy, killing-curves and turbidimetric growth-curves were used in a comparative study of the antibacterial effects of a new carbapenem, meropenem (SM 7338) and imipenem on five strains of Proteus mirabilis.
