Abstract
1. The synergism of hetacillin and dicloxacillin in vitro was demonstrated in various gram-negative bacteria.
2. The combination effect was examined for bacteria growth curve of E. coil, Proteus morganii. When Dicloxacillin was combined with Hetacillin, the lag phase was prolonged by the ratios of combination (2: 1, 1: 1, 1: 2) of both antibiotics.
3. The enzymatic degradation of hetacillin by the crude penicillinase from Proteus morganii Kono was prevented in presence of Dicloxacillin. Dicloxacillin showed a competitive inhibition for Hetacillin degradation of penicillinase.
