Activity of combinations of ceftazidime, imipenem and pefloxacin against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa

The chequerboard technique was used to look for synergistic combinations of ceftazidime, imipenem and pefloxacin. The synergistic combinations were used in vivo in mice experimentally infected with Escherichia coli, Salmonella typhimurium and Pseudomonas aeruginosa. In vitro ceftazidime/imipenem, ceftazidime/pefloxacin and pefloxacin/imipenem combinations showed synergistic effects against Staphylococcus aureus and S. typhimurium and additive effects against P. aeruginosa. Only the ceftazidime/pefloxacin combination was synergistic against E coli while the ceftazidime/imipenem and pefloxacin/imipenem combinations resulted in additive effects. In vivo, combination of ceftazidime/imipenem against E coli infection and the pefloxacin/imipenem combination against S. typhimurium infection were protective. (C) 2003 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.