Evaluation of different antibiotic actions combined with rifampicin. In vitro synergism against Pseudomonas and Proteus.

Associations of penicillin, streptomycin, tetracycline and polymyxin B with rifampicin were tested for synergism against Pseudomonas and Proteus pathological strains. The combination of rifampicin and polymyxin B was clearly synergistic for all strains as it was evaluated by isobolograms and killing curvesmthe bactericidal action of this association, without any cross-resistance between its components, may eradicate gram-negative bacteria infections with marked polyvalent drug resistances.