Antibacterial and Antibiofilm Effects of Virgin Coconut and Virgin Olive Oils on Streptococcus sobrinus and Lactobacillus casei
Background: To determine the effect of virgin coconut and virgin olive oils on the growth of Streptococcus sobrinus and Lactobacillus casei using Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC), to observe the effects of these oils on the morphology of Streptococcus sobrinus and Lactobacillus casei, to investigate the ant adherence and antibiofilm effects of these oils towards Streptococcus sobrinus and Lactobacillus casei in single- and dual-species biofilms.
Materials and method: Broth microdilution technique was implemented to determine the MIC of the oils in a 96-wells microtiter plate, followed by MBC using the sub-cultured method. Chlorhexidine (0.12% CHX) and broth served as positive and negative controls respectively. All specimens that exhibited MIC were examined under a Transmission Electron Microscope. Both oils at MIC and subMIC were also tested for antiadherence and antibiofilm properties.
Results: Virgin coconut oil showed higher antibacterial activities against Streptococcus sobrinus and Lactobacillus casei compared to virgin olive oil but were not statistically significant (p=0.40 and p=0.34, respectively). Both oils were bactericidal at 100% concentration. Significant cytological changes in cell morphology were observed in both bacteria after exposure to both oils. Virgin olive oil showed higher antiadherence activity while virgin coconut oil exerted higher antibiofilm activity.
Conclusions: Virgin coconut and virgin olive oils are as effective as chlorhexidine as an alternative mouthwash. The effectiveness of virgin olive oil is at the initiation stage of plaque formation as it has superior antiadherence activity. However, once the plaque has formed, the use of virgin coconut oil as a mouthwash is advocated as it has more superior antibiofilm activity.