Synergistic interaction in vitro with use of three antibiotics simultaneously against Pseudomonas maltophilia.
An abbreviated three-dimensional checkerboard titration method was devised to determine whether synergistic interaction of three antimicrobial agents could be found against multidrug-resistant bacteria. Pseudomonas maltophilia was used as the test organism because of its resistance to most commercially available antimicrobial agents, including those active against Pseudomonas aeruginosa. Three-dimensional isobolograms with concave surfaces were formed when synergy occurred. Triple combinations of gentamicin-carbenicillin-rifampin (mean fractional inhibitory concentration index, 0.32) and trimethoprim/sulfamethoxazole-carbenicillin-rifampin (mean fractional inhibitory concentration index, 0.18) were consistently synergistic against 14 clinical isolates of P. maltophilia.
D002228:Carbenicillin / Q000494:pharmacology*; D004357:Drug Synergism; D005839:Gentamicins / Q000494:pharmacology*; D011549:Pseudomonas; D012293:Rifampin / Q000494:pharmacology*; D013420:Sulfamethoxazole / Q000494:pharmacology; D013997:Time Factors; D014295:Trimethoprim / Q000494:pharmacology
D005839:Gentamicins; D014295:Trimethoprim; D002228:Carbenicillin; D013420:Sulfamethoxazole; D012293:Rifampin