This study included isolation and identification of different uropathogene (bacteria- yeasts) from catheterized patients suffering from complicated urinary tract infections, then detection the uropathogene ability to form biofilm as virulence factor responsible for initiation of infection and relationship between plasmids and antibiotics resistance . Study had been included the following steps: - First step: identification of uropathogene (bacteria- yeasts) obtained by swabs from 350 urine samples of catheterized patients. 339 sample (96.85%)were identified by culture as positive result while 11 sample (3.142%)were gave negative result. 221 samples (63.138%) were obtained from females and 118 sample (33.711%) from males. 339 isolate have been included 303 (89.380%)bacterial isolate and 36 (10.619%) yeast isolate. Results of biochemical tests and api 20 system for bacterial and yeasts isolates show that Proteus sp. ;Klebseilla sp, Pseudomonas spp.and Candida spp. which represent the main causative uropathiogen infect urinary system , cause complicated type of infection. - Second step: determination of bacterial and yeasts ability to form biofilm by using test tubes method , (306) isolates which represented (90.265%) which form biofilm were difference in thickness of formed layer. Pseudomonas spp. give thicker biofilm then E.coli, Candida spp., Proteus spp. and Klebseilla spp. respectively. - Third step: study the resistance of bacterial isolates towards different antibiotics that have been recommended for treating those patients it was found that higher percentage of resistance to penicillin, gentamycin , tetracyclin, chlormphnicol , and trimethoprim- sulfmethazxol then moderate resistance to ampcillin, nalidixic acid , cephotaxime, streptomycin , cephalexin and rifampicin and less resistance to ciprofloxacin that represent the most effective antibiotic against uropathogenic bacteria. Ketazole antibiotic was used against yeasts, which the Minimum inhibitory concentration of ketazole against 83% of C. albicans isolates was 128, the rest of the isolates was 64. - Fourth step: isolation of bacterial and yeasts DNA (chromosome + plasmids), results of DNA isolation showed that bacterial isolates(E.coli (RS1), P. mirabilis (RS2), K. pneumonia (RS3) and P. aeruginosa (RS4) have chromosome and plasmids vary in numbers and size according to isolate While yeasts(C13) isolate have only chromosome without plasmid . Results of curring show that: -Resistance to ampicillin , tetracycline, gentamycin, pencillin for all bacterial isolates carried on plasmid. - resistance to cephalexin by RS1 isolate, resistance to cephhotaxim by RS3 isolate and resistance to chlormphnicol by RS4 isolate carried on plasmid . while resistance to the rest once were carried on chromosome .