In-Vitro Effect of Natural Honey on the Growth of Streptococcus sanguinis

  Streptococcus sanguinis (S. sanguinis) is one of the effective bacteria in the formation of caries and periodontal diseases which are caused by dental plaque. Currently, the use of natural honey (NH) is considered as a method of reducing S. sanguinis and S. mutans in saliva, which results in reducing the dental plaque. The purpose of this study was to evaluate the effects of NH on the growth of S. sanguinis and to compare its effects with that of Ciprofloxacin and Penicillin antibiotics in vitro.  
In this experimental study, the effect of NH against S. sanguinis was investigated according to the growth inhibition zone in the disk diffusion method by measuring the inhibition zone around the disks which were dipped in the case and control groups. The agar well diffusion method was used as well. The results were analyzed using analysis of variance (ANOVA). In case of the presence of a significant difference, post-hoc Scheffe test was used as a supplementary test.
In the disk diffusion method, the average inhibition zone was 21 mm for Ciprofloxacin, 10.35 mm for Penicillin, and 17.77 mm for NH (P<0.001). In the agar well diffusion method, the average inhibition zone was 17.68 mm for Ciprofloxacin, 15.83 mm for NH, and 8.06 mm for Penicillin (P<0.01).  
It seems that NH is effective against S. sanguinis in vitro. Nevertheless, its inhibition zone in the agar well diffusion and the disk diffusion methods is smaller than that formed by Ciprofloxacin and larger than that formed by Penicillin.