الفهرس | Only 14 pages are availabe for public view |
Abstract Combination therapy is used to widen the antimicrobial spectrum, minimize toxicity and prevent the emergence of resistant mutants. Antimicrobial synergy resulting from antibiotic combination therapy is often important in the treatment of serious bacterial infections. The purpose of the present study is to determine the in-vitro activities of aminoglycosides (amikacin) in combination with third-generation cephalosporins (cefoperazone), antipseudomonal pencillins (piperacillin – tazobactem), carbapenems(meropenem),fluoroquinolones(ciprofloxacin) and polymixins (colistin) against MDR isolates of pseudomonas spp. And P. aeruginosa ATCC 27853 that was used as a quality control strain throughout the study. The effects of these antibiotic combinations were examined by two methods (disk diffusion, and checkerboard).Fractional inhibitory concentration indices were calculated for all isolates with all combinations. Use of the disk diffusion method revealed that amikacin in combination with the β-lactams and ciprofloxacin exhibited synergy against 70% of isolates, whereas the combinations of amikacin and colistin displayed synergic effects against 80% of isolates .Using the checkerboard method , all of the combinations exhibited synergic effects against all the isolates. No antagonism was found with these combinations. The result of this study indicates that synergism may occur between aminoglycosides, β-lactams and fluoroquinolones although the strains are resistant to the individual antibiotics. Key Words: Antimicrobial combinations, Checkerboard titration method, β-lactams Aminoglycosides |