Antimicrobial activity of Warburgia ugandensis against oral pathogenic microorganisms

Background: Oral diseases such as bleeding gums, toothache, oral mucosal lesions, dental diseases and periodontal diseases affect the quality of life of people. Medicinal plants have been found to be effective against oral pathogens. This study was performed to determine the effect of Warburgia ugandensis against selected oral pathogenic microorganisms. Methods: Plants were collected from their natural habitats, dried and processed at CTMDR, KEMRI. Aqueous, methanol and methanol:dichloromethane (1:1) extracts were then prepared. The crude extracts were then screened for antimicrobial activity against Methicillin-resistant S. aureus (MRSA), Staphylococcus aureus, Streptococcus mutans and Candida albicans. Disc diffusion, minimum inhibitory concentration and minimum bactericidal concentration bioassays were performed at CMR, KEMRI. Sulfamethoxazole/trimethoprim (SXT) and fluconazole were used as positive controls for the disc diffusion and gentamicin for MIC bioassay. Results: The methanol:dichloromethane (MeOH:DCM) extracts of W. ugandensis exhibited good antimicrobial activity. The methanol: dichloromethane extracts of W. ugandensis leaves and stem bark demonstrated an average inhibition zone of 18.00±0.00mm and 16.50±0.70711mm against MRSA. The MIC values demonstrated by the MeOH:DCM extracts of W. ugandensis leaves and stem bark were 6.25mg/ml and 0.390625mg/ml. The MBC values for W. ugandensis leaves and stem bark MeOH:DCM extracts were 12.5mg/ml and 0.78125mg/ml. SXT inhibited the growth of S. aureus and S. mutans but showed no inhibition towards MRSA. Conclusion: It is evident that the antimicrobial activity elicited by W. ugandensis supports its use in the treatment or prevention of oral infections. W. ugandensis can also be used in the eradication of antibiotic resistant bacteria such as MRSA.