Combined action of phosphomycin with streptomycin and gentamicin.

The combined action of phosphomycin with streptomycin and gentamicin against 41 strains of Gram-positive micrococci (S. aureus and Str. faecalis) and 87 strains of Gram-negative bacilli (including 38 strains of Pseudomonas) was evaluated. The combination of phosphomycin with streptomycin acted synergistically against 12 strains of Gram-positive micrococci, and the combination of phosphomycin with gentmicin against 10 strains. The combination of phosphomycin with streptomycin acted synergistically against 31% of strains (except Pseudomonas), and the combination of phosphomycin with gentamicin against 65% of strains. Only six of 38 Pseudomonas strains were acted synergistically by phosphamycin with streptomycin, and four by phosphomycin with gentamicin. The results indicate that the combination of phosphomycin with aminoglycoside antibiotics shows greater synergistic activity against Gram-negative strains than against Gram-positive micrococci.