In vitro activity of taurolidine gel on bacteria associated with periodontitis

The purpose of this in vitro study was to determine the antimicrobial activity of two different taurolidine gel formulations in comparison with minocycline microspheres. Three percent taurolidine gel (TLG3) and 2 % taurolidine gel (TLG2) were compared to minocycline microspheres (MINO) against single bacterial species and a 12-species-mixture. The antimicrobial activity was proven by determination of minimal inhibitory concentrations (MICs), killing assays, after exposure of the antimicrobials as well as within a biofilm. The MICs against the single species were between 0.5 and 2 mg/ml of taurolidine. MICs of the used mixed microbiota were 1.5 mg/ml (TLG3) and 4 mg/ml (TLG2). Fusobacterium nucleatum and Porphyromonas gingivalis were completely killed by 10 % TLG3 and TLG2 (equivalent to 3 and 2 mg/ml taurolidine) after 6 h. The mixture of 12 species was not completely killed by any of the test substances. Taurolidine gels showed a post-antimicrobial activity, however being less than that of MINO. On biofilms, taurolidine gels reduced concentration dependently the colony forming unit (CFU) counts (multi-species biofilms by 3.63 log10 after 100 % (30 mg/ml) of TLG3), reductions were 2.12 log10 after MINO (1000 mu g/ml minocycline). Taurolidine gel formulations exert antimicrobial activity against bacteria associated with periodontal disease. Nevertheless, a complete elimination of biofilms seems to be impossible and underlines the importance of mechanical removal of biofilms prior to application of the antimicrobial. Taurolidine gels may represent a potential alternative for adjunctive topical antimicrobial treatment in periodontitis and infectious peri-implant diseases.