Studies on the combined action of phosphonomycin with streptomycin, penicillin G and ampicillin.

Using the serial dilution method in solid media, sensitivity of isolated strains of S. aureus and E. coli to phosphonomycin, streptomycin, penicillin G and ampicillin, and the effect of combined action of phosphonomycin with these antibiotics were studied. Against S. aureus strains, phosphonomycin in combination with penicillin G showed synergistic action more often than in combination with streptomycin. On the other hand, against E. coli strains the combination of phosphonomycin with streptomycin and ampicillin was similarly synergistic. The findings suggest the possibility of clinical applications of combined therapy with phosphonomycin and antibiotics of the beta-lactam and aminoglycoside groups.