In vitro action of combinations of antimicrobial agents and EDTA-tromethamine on Escherichia coli.
Combinations of EDTA-tromethamine and 7 antimicrobial agents [chloramphenicol, nalidixic acid, oxytetracycline, penicillin, polymyxin B, streptomycin, and triple sulfa (sulfamethazine, sulfapyridine, and sulfathiazole]) were tested for synergistic activities against Escherichia coli. Three in vitro tests were used including minimal inhibitory concentrations of the drugs, a 2-dimensional microtiter checkerboard technique, and bacterial inhibition studies. A strong synergistic inhibitory action was observed with combinations of EDTA-tromethamine plus penicillin and EDTA-tromethamine plus oxytetracycline. Combinations of EDTA-tromethamine plus chloramphenicol also had a synergistic action, but to a lesser extent than that with penicillin and oxytetracycline. When streptomycin or nalidixic acid was mixed with EDTA-tromethamine, a slight synergistic action was noticed. There was no synergistic effect recorded with combinations of EDTA-tromethamine and triple sulfa. Combinations of EDTA-tromethamine and polymyxin B had an antagonistic effect.
D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D004285:Dogs; D004357:Drug Synergism; D004492:Edetic Acid / Q000008:administration & dosage*; D004926:Escherichia coli / Q000187:drug effects*; D014325:Tromethamine / Q000008:administration & dosage*
D000900:Anti-Bacterial Agents; D014325:Tromethamine; D004492:Edetic Acid