In-vitro effects of a combination of antipseudomonal antibiotics against multi-drug resistant Pseudomonas aeruginosa

We evaluated the in-vitro effects of various combinations of five types of widely used antipseudomonal antibiotics (piperacillin, meropenem, ceftazidi me, aztreonam and amikacin) against six Pseudomonas aeruginosa strains that were resistant to each of these antibiotics. Among two-drug combinations, the combinations of two beta-lactam antibiotics inhibited growth of one to three P.aeruginosa strains, while those of one beta-tactam antibiotic and a mikacin inhibited growth of two to four strains. Among three-drug combinati ons, the combinations of three beta-lactam antibiotics inhibited growth of four to five strains, and those of two beta-lactam antibiotics and amikacin inhibited growth of five strains. These results suggest the potential usef ulness of a combination of two beta-lactam antibiotics and amikacin or that of three beta-lactam antibiotics in treating multi-drug resistant P.aerugi nosa infections.