In vitro double and triple synergistic activities of Polymyxin B, imipenem, and rifampin against multidrug-resistant Acinetobacter baumannii.
Eight unrelated clinical Acinetobacter baumannii isolates resistant to all commonly used antibiotics were subjected to three-dimensional checkerboard microtiter plate dilution and time-kill studies at one-fourth of their MICs of polymyxin B, imipenem, and rifampin. Synergy was demonstrated with combinations of polymyxin B and imipenem, polymyxin B and rifampin, and polymyxin B, imipenem, and rifampin. Double combinations of polymyxin B and imipenem and of polymyxin B and rifampin were bactericidal for seven of eight isolates, and triple combinations were bactericidal for all isolates within 24 h. Future clinical studies using double and triple therapy with these antibacterials may provide an effective option against potentially lethal infection due to multiresistant Acinetobacter baumannii.
Yoon
Jimmy
J
Infectious Disease Section, New York Hospital Queens, Flushing, Department of Microbiology, Weill Medical College of Cornell University, New York, New York, USA.
Urban
Carl
C
Terzian
Christian
C
Mariano
Noriel
N
Rahal
James J
JJ
D000151:Acinetobacter Infections / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000187:drug effects*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000904:Antibiotics, Antitubercular / Q000494:pharmacology*; D015169:Colony Count, Microbial; D024901:Drug Resistance, Multiple, Bacterial; D004357:Drug Synergism; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D015378:Imipenem / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D011112:Polymyxin B / Q000494:pharmacology*; D012293:Rifampin / Q000494:pharmacology*; D013845:Thienamycins / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D000904:Antibiotics, Antitubercular; D013845:Thienamycins; D015378:Imipenem; D011112:Polymyxin B; D012293:Rifampin