Antimicrobial activity of propolis against Streptococcus mutans

The ethanol extract of propolis (EEP) obtained from beehives of honeybee (Apis mellifera) was investigated for its antimicrobial activities against Streptococcus mutans isolated from dental caries. Agar well diffusion and minimum inhibitory concentration (MIC) determinations were the methods used in this study. The carious tooth was swabbed with a sterile cotton wool and immediately streaked on tryptic soy agar, incubated at 37°C for 48 - 72 h. S. mutans was characterized by standard cultural, morphological and biochemical methods. Several dilutions of EEP were made (0.5 - 32 μg/ml), while water and ethanol were used as controls. The EEP at concentrations of 4, 8, 16 and 32 μg/ml showed strong antimicrobial activity against S. mutans with inhibition zones of 10 ± 4, 12 ± 4, 20 ± 2 and 24 ± 2 mm, respectively. There were medium to maximum growth of S. mutans in the controls of ethanol and water. The results demonstrate that the ethanol extract of propolis has a strong antimicrobial activity and suggest that it may be useful in the treatment of dental caries caused majorly by S. mutans.Key words: Dental caries, antimicrobial activity, Apis mellifera, Streptococcus mutans, ethanol extract of propolis