Phenotypic and Genotypic Investigation of Biofilm Formation in Clinical and Environmental Isolates of Acinetobacter baumannii

: Acinetobacter baumannii (A. baumannii) is an important opportunistic pathogen responsible for nosocomial infections worldwide at recent decades. Biofilm formation by A. baumannii leads to antibiotic resistance and survives on abiotic and biotic surfaces. In the present study we aimed to assess the ability of biofilm formation in clinical and environmental isolates of A. baumannii by phenotypic methods and to detect the presence of genes involving in the biofilm development; bap, ompA, csuE, abaI, and blaPER-1by PCR method. Totally 120 A. baumanniin isolates, 98 clinical, and 22 environmental were evaluated for biofilm formation using the modified Microtiter plate method, Congo red agar methods, and the existence of genes related to biofilm by standard PCR. The phenotypic results showed that the biofilm formation rate was 10.8% isolates that in environmental A. baumannii isolates were higher than clinical isolates. The abaI, csuE, and ompA genes were detected in all isolates with biofilm formation and the bap and blaPER-1genes were positive in 14.2% and 13.3% of A. baumannii isolates, respectively. The sequence of genes were submitted in NCBI. Based on our results, the Congo red agar method was significantly better than the Microtiter plate technique for phenotypic evaluation of biofilm formation in the A. baumannii. Our study indicates that abaI, csuE, and ompA genes were detected in all isolates unlike the bap and blaPER-1genes.