In vitro activity of thienamycin.

The in vitro activity of thienamycin was determined simultaneously in Müller-Hinton broth and peptone broth. Minimum inhibitory and bactericidal concentrations were compared to those of 4 aminoglycosides and 3 cefalosporins. The activity of thienamycin against gram-negative aerobic bacterial was influenced by the media. Peptone broth gave the lowest MICs and MBCs. Concentrations less than or equal to 8 mcg thienamycin/ml peptone broth inhibited 354 out of 382 strains tested.