Effectiveness of Dioscorea hispida Dennst as antibacterial and antibiofilm agent

Abstract

Aims: Antimicrobial resistance (AMR) is a growing threat to public health, where treatments using conventional drugs are becoming ineffective. One viable but underexplored alternative is through the use of Dioscorea hispida, a wild plant that exhibits antimicrobial properties. This study aims to explore D. hispida effectiveness as an antibacterial and antibiofilm agent against selected pathogenic and non-pathogenic bacteria. Methodology and results: Different concentrations of D. hispida crude extracts (0 - 2.5 mg/mL) were tested against the growth of planktonic bacterial cells over 24 h incubation, and the half maximal effective concentration (EC50) obtained was used in the antibiofilm test over 24 and 48 h. All bacteria treated with D. hispida showed significant (P<0.05) reduction in planktonic cell and biofilm densities against the negative control starting at 0.3 mg/mL. However, in comparison to the antibiotic, only certain bacteria were significantly affected by D. hispida, implying the plant has a 'moderate' biocidal activity in general. Furthermore, Atomic Force Microscopy imaging of S. aureus biofilm with D. hispida revealed increased height and width of cell clusters despite reduction in volume compared to the negative control, suggesting unique biofilm resistance behaviour against the plant. Conclusion, significance and impact of study: This study demonstrated D. hispida capability as a natural antimicrobial and antibiofilm agent. The plant could complement current antimicrobials to maximise killing efficiency and minimise occurrences of resistance. Unique biofilm behaviour against D. hispida also warrants further investigation on the effect of biocides towards biofilm structure. Overall, this research provides new insights into a traditional plant-based antimicrobial activity in combating infectious diseases and AMR.