High-throughput method to test antimicrobial gels against a multispecies oral biofilm

Periodontitis, characterized by the damage of the periodontium can eventually lead to tooth loss. Moreover, severe forms of periodontitis are associated with several systemic disorders. The evolution of the disease is linked to the pathogenic switch of the oral microbiota comprising of commensal colonizers and anaerobic pathogens. Treatment with antimicrobial gels has the potential to help eradicate periodontal pathogens. Testing antibacterial gels against in vitro biofilm models is complicated. Recovery of detached and sessile bacteria from in vitro biofilms treated with gel formulations using conventional methods (microtiter plates, -slides, flow cells etc.,) may prove arduous. To overcome this challenge, we optimised a simple method using the principle of the Calgary Biofilm Device (CBD) for testing antimicrobial gels against multispecies oral biofilms. First, we established three-species oral biofilms consisting of two periodontal pathogens (Porphyromonas gingivalis, Treponema denticola) and a primary colonizer of the dental plaque (Streptococcus gordonii) on the surface of pegs. Next, a protocol to test gels against oral biofilms was implemented using commercially available gels with different active products. This method enables the analysis of the composition of biofilm and detached/planktonic cells to measure the effect of topical gel formulations/antibacterial gels for the treatment of periodontitis. However, the method is not restricted to oral biofilms and can be adapted for other biofilm-related studies.