Mohammad Abootaleb - Department of Biology, Qom Branch, Islamic Azad University, Qom, Iran.
Mohammad Reza Zolfaghari - Department of Biology, Qom Branch, Islamic Azad University, Qom, Iran
Nazila Arbab Soleimani - Department of Biology, Damghan Branch, Islamic Azad University, Semnan, Iran.
Nassim Ghorbanmehr - Department of Biotechnology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran.

Background: Microorganisms attach to various surfaces and they have manufactured biofilms by production polysaccharides like PSL in P.aeruginosa. synthesis of this kind of polysaccharide has done by PSL gene cluster. The aim of this study is consideration biofilm formation which is one of the major cause antibiotic resistance Methods: In this study, 100 P. aeruginosa were isolated with bacteriological and biochemical methods and pslA gene detection with PCR in all of the P. aeruginosa isolated from patients Then biofilm formation checked with microtiter plate method and it showed with SEM. Finally, expression of main attachment gene pslA in 6 strains could make moderate and strong biofilm were investigated by real-time PCR assay.Results:In this study, 100 P. aeruginosa were isolated that these strains showed High rates of MDR. The presence pslA gene in all of the pseudomonas isolated from patients was proven. Microtiter plate method showed 24 (24%) strains could make biofilm Among 100 strains that showed with SEM. The pslA expression in strains which making moderate and strong biofilms are more than other strains Conclusions: Hence, for bacterial biofilm treatment is recommended: Before antibiotics are prescribed, biofilm formation by bacteria should be investigated.

P. aeruginosa, microtiter plate, biofilm, Real time PCR, Scanning Electron Microscopy (SEM)