Assessment of antimicrobial susceptibility of Enterococcus faecalis isolated from chronic periodontitis in biofilm versus planktonic phase.

Background: Enterococci are often associated with chronic and recurrent infectious diseases because of their antimicrobial resistance. The aim of this study is to assess antimicrobial susceptibility of Enterococcus faecalis in chronic periodontitis.Methods: Antimicrobial susceptibility was determined on 23 E. faecalis strains isolated from patients with chronic periodontitis. Ampicillin, erythromycin, gentamicin, tetracycline, triclosan, and vancomycin were prepared in two-fold serial dilution up to 8,192 μg/mL. Enterococcal biofilm was established by a biofilm device and observed by confocal laser microscopy and scanning electron microscopy. The minimum inhibitory concentration (MIC), minimum biofilm inhibitory concentration, and minimum biofilm eradication concentration were determined by spectrophotometer at optical density650.Results: A few patches of monolayer early biofilm were observed on the surfaces of biofilm device pegs. The colony-forming units of biofilm per peg were 1.2 × 103 to 1.7 × 104 an...