2005 Volume 68 Issue 3_4 Pages 241-252
We examined the ability to form biofilm of 74 clinical isolates of black-pigmented Gram-negative anaerobic rods isolated from periodontitis lesions based on their capacity to produce viscous materials in culture media as most biofilm-forming bacteria do. Two strains, designated as OD 1-2 and OD 1-16, were obtained and identified as Prevotell intermedia by using the API-ZYM system, 16 S rRNA sequencing and DNA-DNA hybridization. Scanning electron microscopy revealed that both strains had dense meshwork-like structures around their cells which are typical cell surface structures for biofilm-forming bacteria. Chemical analyses of the viscous material isolated from culture supernatants of strain OD 1-16 showed that they contained neutral sugars (791.7μg/mg), uronic acid (27.7μg/mg), and amino-sugar (13.7μg/mg), with mannose constituting 82% of the polysaccharide. As compared to strain ATCC 25611, which was a type strain for Prevotell intermedia and was non-producing of EPS, strain OD 1-16 showed higher activities for inducing abscess formation in mice. Further, strain OD 1-16, but not ATCC 25611, showed resistance against phagocytosis by human neutrophils. Combining this with findings from our previous studies, these results suggest that Prevotella intermedia might achieve the capacity to produce large amounts of exopolysaccharide, consisting primarily of mannose, and that they might play a key role in the development of biofilm infections in the oral cavity.
