title: Pseudomonas aeruginosa: in vitro susceptibility to antimicrobial drugs, single and combined, with and without defibrinated human blood.
abstract: Twelve clinical isolates of Pseudomonas aeruginosa of distinct pyocin type varied in susceptibility to 14 of 17 antimicrobial drugs. The 2 x MIC concentrations of 16 antimicrobial drugs combined with 55% (v/v) of fresh, defibrinated human blood yielded additive effects. Additive effects were noted with blood plus the MIC concentrations of all drugs tested except cefoperazone, gentamicin, and netilmicin. Blood combined with subinhibitory (1/2 MIC) concentrations of aztreonam, ceftazidime, ciprofloxacin, fleroxacin, imipenem, and tobramycin, respectively, yielded additive effects; indifferent effects were observed with the remaining 10 blood plus 1/2 MIC drug combinations. The following drug combinations additively augmented the antibacterial activity of 65% (v/v) of human blood against two selected isolates of P. aeruginosa: tobramycin (1 microgram/ml) plus the MIC or 2 x MIC concentrations of azlocillin, aztreonam, ceftazidime, ciprofloxacin, imipenem, norfloxacin, ofloxacin, piperacillin, and ticarcillin, respectively. Imipenem (8 micrograms/ml) combined with ceftazidime, cefoperazone, and piperacillin, but not aztreonam, enhanced the bactericidal activity of human blood. Rifampin (2 micrograms/ml) plus tobramycin (0.5-1 microgram/ml) combined with 8 or 16 micrograms/ml of azlocillin, aztreonam, cefoperazone, ceftazidime, imipenem, and piperacillin, respectively, enhanced blood-mediated killing of three representative multiple-drug-resistant P. aeruginosa isolates. Additional effective triple-drug combinations with human blood were rifampin + tobramycin + polymyxin B, rifampin + ciprofloxacin + imipenem, and rifampin + amikacin + imipenem. Ciprofloxacin (2 micrograms/ml) was the most potent intraphagocytic bactericidal drug of 16 tested agents (greater than or equal to 2 x MBC concentrations) against P. aeruginosa control strain ATCC 27853.
authors.affiliation: Institut für Medizinische Mikrobiologie und Hygiene, Universität desSaarlandes, Homburg, FRG.
authors.forename: W H
authors.initials: WH
authors.lastname: Traub
authors.forename: M
authors.initials: M
authors.lastname: Spohr
authors.forename: D
authors.initials: D
authors.lastname: Bauer
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001770:Blood Bactericidal Activity; D004338:Drug Combinations; D005342:Fibrinolysis; D006801:Humans; D008826:Microbial Sensitivity Tests; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D004338:Drug Combinations