Effect of Oxantel on Oral Bacterial Synergistic Polymicrobial Biofilm Formation

Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia exist in a polymicrobial biofilm strongly associated with chronic periodontitis disease progression. These species rely on complex anaerobic respiration of amino acids and synergistic interactions to proliferate. The anthelmintic drug Oxantel has previously been shown to inhibit fumarate reductase (Frd) activity in some bacteria and inhibit P. gingivalis homotypic biofilm formation. Objectives: To determine synergistic interactions and polymicrobial biofilm formation by these bacteria and determine the effect of Oxantel. Methods: To determine homotypic and polymicrobial biofilm formation flow cell and static systems were employed. The biofilms were imaged by confocal scanning laser microscopy and SEM. Bacterial interactions were determined using a range of transcriptomic, metabolomics and proteome approaches on co-cultured bacteria. Results: P. gingivalis and T. denticola responded metabolically to each other by altering gene transcription which resulted in synergistic growth. T. denticola gene products of the glycine catabolic pathways were significantly up-regulated during co-culture with P. gingivalis. T. denticola rapidly metabolized this amino acid and free glycine production by P. gingivalis was stimulated by T. denticola. In a flow cell all three species attached and grew synergistically as a polymicrobial biofilm. Oxantel directly inhibited P. gingivalis Frd activity and planktonic growth of P. gingivalis and T. forsythia, but had no effect on T. denticola. Oxantel disrupted the development of polymicrobial biofilms composed of P. gingivalis, T. forsythia and T. denticola in a concentration dependent manner. In these biofilms all three species were inhibited to a similar degree demonstrating dependence of T. denticola on the other species. In a murine alveolar bone loss model of periodontitis Oxantel addition to the drinking water of P. gingivalis-infected mice eliminated bone loss. Conclusion: Oxantel disrupts pathogenic polymicrobial biofilm formation and have efficacy in the treatment of chronic periodontitis.