Aim: In this study, we aimed to investigate in-vitro susceptibility of Pseudomonas aeruginosa and Acinetobacter strains against various antibiotics.

Material and method: Susceptibility of 169 P. aeruginosa and 31 Acinetobacter strains which isolated from various clinical samples were investigated using disc diffusion method according to NCCLS (M2-A6) guidelines.

Results: The susceptibility ratio of Pseudomonas aeruginosa and Acinetobacter isolates were found to be; ceftazidim 77% and 10%, gentamicin 38% and 13%, piperacillin 44% and 0%, ticarcilline/clavulanic acide 44% and 10%, amikacin 83% and 52%, aztreonam 19% and 48%, cefepime 62% and 46%, ciprofloxacin 82% and 13%, imipenem 96% and 74%, meropenem 95% and 68%, respectively.

Conclusion: It was concluded that P. aeruginosa and Acinetobacter strains were significantly resistant to antipseudomonal antibiotics, but carbapenem susceptibility of these strain was very high.