The possibility of using Sansevieria aethiopica (Thunb) leaf extracts in combinations with gentamicin for the treatment of oral enterococcal infections

Sansevieria aethiopica (Thunb) has been reported to be used for the treatment of oral infections in Eastern Cape of South Africa. Based on ethnobotanical survey, the plant was selected for the possible synergistic effects of its acetone, ethanol and methanolic extracts with gentamicin on the planktonic and sessile cells of Enterococcus faecalisATCC 29212 and Enterococcus faecalis KZN. In vitro interactions between the plant extracts and gentamicin were studied using checkerboard macrodilution method and anti-biofilm activity of the iso-effective combinations was determined by semi-quantitative adherence assay. Acetone extract of S. aethiopica has the highest inhibitory activity. The minimum concentration of gentamicin that inhibited the two isolates was the same (0.016 mg/ml). Different iso-effective points were observed with fractional inhibitory concentration indexes ranged between 0.375 and 1.9313. Out of the iso-effective points observed only four were synergistic while one was addictive. The maximum biofilm reduction was observed when the two antibacterial agents were combined. We therefore suggest that the extracts of the plant at the test concentrations can be used in combination with gentamicin for oral hygiene.   Key words: Enterococcus faecalis, Sansevieria aethiopica, biofilm, planktonic cell, dental infection, medicinal plant.