Background & Aims: Emergence of biofilm producing Proteus strains created a serious problem in the treatment of catheter-associated urinary tract infections. The aim of this research was to study biofilm production and plasmid pattern of proteus strains associated with Urinary tract infection. Methods: A total of 88 strains of Proteus were isolated from samples collected in hospitals of Kerman/ Iran during 2011-2012. The isolates were identified by routin microbiological tests and antibiotic sensitivity tests were carried out by disk diffusion and minimum inhibitory concentration (MIC) by E-test methods. Biofilm production was studied by microtiter plate method and confirmed by Scanning electron microscope. Plasmids from biofilm producing isolates were detected by alkaline lysis technique. Results: From 88 patients infected by proteus, 58% were female and 42% were male. The most and the least frequent age ranges were respectively 20-29 years old (77.39 %) and 60-69 years old. From all isolates, 40.69 % (n=59) showed the highest MIC range (16-320.05 µg/mL) to ceftriaxone whereas, 59% [n=41] exhibited the least MIC range to chloramphenicol (1-40.08 µg/mL). Biofilm production was positive for 17% (n=15) of the isolates and 6
(n=6) did not show any biofilm (P 0.05). Plasmid isolation from biofilm producing isolates revealed that stains number 87, 24 and 19 that produced strong biofilm all carried similar high molecular weight (M. Wt) plasmid. While strain 29 that showed strong biofilm did not have any plasmid. Conclusion: It can be concluded that the majority of isolates of Proteus were resistant to routine antibiotics and limited number of them could produce biofilm. Majority of the biofilm producing isolates contained a similar high M. Wt. plasmid.