Anti-biofilm Chemical Treatment Using Polyphosphate Molecules

Objectives: Bacteria in periodontal disease are found in organized structures known as biofilms, typically consisting of bacterial cells surrounded with extracellular matrix. These structures protect bacteria from various antimicrobial agents, leaving mechanical debridement as the most commonly used treatment today. Polyphosphate molecules have been previously suggested for anti-biofilm treatment, and were shown to act synergistically with antibiotics. In this study, we examined the effect of polyphosphates on periodontal biofilm and shed light over its possible mechanisms of action.
Methods: Multi species biofilm consists of Actinomyces naslundii, Streptococuss Sanguis, Fusobacterium nucleatum and Porphyromonas gingivalis was grown on hydroxyapetite discs in-vitro. The biofilm was treated with hexamethapohosphate (HMP) and compared with antibiotics (positive control), PBS (negative control) and combination of antibiotics and HMP. Biofilm structure and Bactericidal effect was tested using SYTO9-PI staining and confocal microscopy, flow cytometry and blood agar cultures. The effect of the treatments on the biofilm extracellular matrix (ECM) was done using ConA and Dextran florescent staining and confocal microscopy.
Results: Antibiotics treatment led to significant reduction in bacterial viability within the biofilm compared with negative control. Strikingly, HMP showed an impressive ability to disrupt the biofilm with a synergistic effect when combined with antibiotics (reduction of 75% and 90% of biofilm biomass respectively). This phenomenon was not evident in the antibiotics or negative control groups. Interestingly, HMP was found to have limited to none bactericidal effect, both on each bacterium alone or on a multi-species biofilm. However, the HMP did show a clear ability to dissociate the ECM of the biofilm.
Conclusions: HMP has a remarkable ability to remove biofilm from the HA surfaces. This effect is not associated with bactericidal ability, but rather from the ability to disassociate biofilm`s extracellular matrix. HMP may serve as chemical therapy with great potential as an effective chemical treatment for periodontitis.