Background & Aim: Excessive use of antibiotics has significantly increased resistance to common antibiotics in the treatment of urinary tract infections. In the present study, antimicrobial efficacy of chitosan nanoparticles and peptide IDR-1018 was evaluated against P. aeruginosa isolates. Methods: In the present study, 20 resistant and 20 sensitive P. aeruginosa isolates to imipenem were collected from patients with urinary tract infections. The ability of biofilm formation and the presence of three genes involved in biofilm production including algD, pslD and pelF in the isolates were determined by crystal violet and PCR methods, respectively. The anti-bacterial effect of imipenem, antimicrobial peptide IDR-1018 and chitosan nanoparticles was evaluated by determining the MIC by microdilution broth method. Results: The ability of biofilm formation in the isolates was weak (10%), moderate (35%) and strong (55%). The frequency of presence of three genes related to biofilm formation including algD, pslD and pelF was 90%, 80% and 75%, respectively. MIC values for the isolates were 16-168 μ, g/ml for imipenem, 40 and 80 μ, g/ml for peptide IDR-1018, 750 and 375 μ, g/ml for chitosan nanoparticles, respectively. Conclusion: Finding alternative approaches such as antimicrobial peptides and nanoparticles can be effective in treatment of P. aeruginosa infections. The results of our study showed that peptide IDR-1018 and chitosan nanoparticles alone or in combination with imipenem can be considered as a treatment strategy.