In vitro activity of ceftriaxone and amikacin against Pseudomonas aeruginosa.
Ceftriaxone and amikacin were combined at ratios of 1:1, 5:1, and 10:1 and tested in vitro against Pseudomonas aeruginosa. The activity was determined using the Steers-Foltz replicator and the agar dilution technique with Mueller-Hinton agar. Under all conditions tested, including those simulating severe infection (10(5) to 10(6) colony-forming units per spot), the organisms were more susceptible to the combination than to the single agents. With a conventional inoculum of 10(4) colony-forming units per spot, the combinations gave 97-100% coverage against P. aeruginosa. The increased activity of the combinations resulted in MIC90 values which were below the expected serum/plasma levels for significantly longer time periods than the MIC90 values observed with the individual agents.
Prosser
B L
BL
Chemotherapy Department, Hoffmann-La Roche Inc., Nutley, N.J.
Taylor
D B
DB
Cleeland
R
R
D000583:Amikacin / Q000494:pharmacology*; D002443:Ceftriaxone / Q000494:pharmacology*; D004357:Drug Synergism; D004359:Drug Therapy, Combination / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D011550:Pseudomonas aeruginosa / Q000187:drug effects*
D002443:Ceftriaxone; D000583:Amikacin