In vitro action of combinations of antimicrobial agents and EDTA-tromethamine on Escherichia coli [Dogs]

• Published in: American journal of veterinary research Vol. 44; no. 6; p. 1154
• Main Authors: Wooley, R.E, Jones, M.S, Gilbert, J.P, Shotts, E.B. Jr
• Format: Journal Article
• Language: English
• Published: United States 01.06.1983
• Subjects: Animals; Anti-Bacterial Agents - administration & dosage; Dogs; Drug Synergism; Edetic Acid - administration & dosage; Escherichia coli - drug effects; Tromethamine - administration & dosage
• ISSN: 0002-9645; 1943-5681

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.