The in vitro effect of manuka honeys on growth and adherence of oral bacteria

Honey has been used since ancient times and more recently, for the healing of wounds and against infectious diseases. The aim of our study was to investigate the effect of two manuka honeys showing different potencies of their antibacterial activity, on potentially pathogenic oral bacteria.The antimicrobial activity was examined by determining the MIC and MBC using the macro dilution broth technique. The effect on the adherence was tested on growing cells of Streptococcus mutans on a glass surface and on a multi-species biofilm grown on saliva-coated hydroxyapatite discs.As expected, the antibacterial activity of manuka (with higher potency of antibacterial activity) was the most important. The two tested honeys weakly inhibited the adherence of S.mutans cells to a glass surface at sub-MIC concentration.Manuka showed a total inhibition of multi-species biofilm at the concentration of 200 μg/ml manuka inhibited biofilm formation weakly at the concentration of 200 μg/ml but firmly at the concentration of 500 μg/ml.Our findings suggest that manuka honeys might be able to reduce oral pathogens within dental plaque. These two honeys appear to be able to control dental biofilm deposit.