[Bacteriological studies on the therapy of bacillus pyocyaneus infections].

The effect of combined antibiotics was studied in 25 strains of Pseudomonas aeruginosa by serial diluting tests. A synergistic effect was stated in 15 strains with oxacillin plus ampicillin, and in 7 strains with carbenicillin plus ampicillin. In these examinations, the quantities of antibiotics needed each time were within the highest admissible level of therapuetic concentrations. A constant rate of the optimum single concentrations could not be observed. On principle, the inhibitory tobramycin concentrations (0.06 - 1 gamma/ml) were lower than the corresponding concentrations of gentamycin (0.25 - 2gamma/ml); tobramycin was more effective than gentamycin also in 6 strains resistant to carbenicillin, tobramycin only had a synergistic effect - in five of these six strains - when very high ampicillin concentrations (i.e. 250-500 gamma/ml) were used.