Abstract

Background: There is an increasing demand to identify naturally occurring plantderived substances with antimicrobial activity as alternatives to conventional antibiotics. Miswak, obtained from the Arak plant (Salvadora persica), is traditionally used by Muslim communities as a natural oral hygiene product to clean teeth and maintain dental health. Objective: This study aimed to assess in vitro the antibacterial activity of different concentrations of ethanolic extracts of S. persica Linn. against bacterial strains associated with dental caries using the agar well diffusion method. Methodology: A cross-sectional study was conducted in Shendi town, Sudan, between January and March 2025, at the Microbiology Laboratory, Faculty of Medical Laboratory Sciences, Shendi University. A total of 50 oral swabs were collected from patients suffering from dental caries. Bacterial isolates were identified using Gram staining and biochemical tests. The ethanolic extract of S. persica was tested at concentrations of 100%, 50%, 25%, 12.5%, and 6.25% (v/v). Results: Among the 50 isolates, the identified bacteria were: Staphylococcus aureus (20%), Streptococcus pyogenes (2%), Streptococcus group C or G (4%), undifferentiated Gramnegative bacilli (2%), Streptococcus viridans (52%), and Staphylococcus epidermidis (18%). The ethanolic extract of S. persica showed no antibacterial activity against any of the tested bacterial strains. However, a consistent zone of inhibition of approximately 7 mm was observed for all extracts and all bacterial strains using the agar well diffusion method. This value is considered negligible and does not represent a true antibacterial effect, especially since the well diameter itself was 6 mm, meaning the actual inhibition halo around the well is only 0.5 mm per side, which is generally classified as indicating resistance according to standard criteria. The observed zone likely represents a diffusion artefact of the solvent rather than a true antibacterial effect, indicating resistance across all tested strains. Conclusion: The ethanolic extract of S. persica demonstrated no significant antibacterial effect against the bacterial isolates associated with dental caries, indicating resistance across all tested strains.

Keywords

antimicrobial, salvadora persica, streptococcus, streptococcus viridans, herbal medicine