Comparison of well diffusion, disc diffusion and broth dilution methods for antimicrobial activity of Andrographis paniculata herbal gel against acne-associated pathogen

Abstract

Aims: Acne is a common skin disease among teenagers and also affects other ages. It occurs when the oil and dead skin cells plug into the hair follicles and causing pimples or whitehead. Although antibiotics have been used for many years in treating acne, the widespread use of it has led to the development of bacterial resistant, which resulted in unsuccessful treatment. Thus, in this study, Andrographis paniculata (AP) herbal formulation gel is proposed in order to determine its effectiveness in treating acne. Three different methodologies were used to compare the antimicrobial effect of A. paniculata herbal gel against acne-associated pathogens. Methodology and results: Well diffusion, disc diffusion and broth dilution methods were applied to evaluate the antimicrobial effect of AP herbal gel at concentrations of 1.5% (w/w), 2.5% (w/w) and 5.0% (w/w) onto selected pathogens associated with acne which consisted of Staphylococcus epidermidis, Staphylococcus aureus, Propionibacterium acnes and Candida albicans. Among the three methods, broth dilution showed the best antimicrobial effect towards all microorganisms used. AP herbal gel at concentration 2.5% (w/w) showed the optimum antimicrobial effect of S. aureus and C. albicans, while 5.0% (w/w) exhibited the best antimicrobial activities for P. acnes and S. epidermidis. Conclusion, significance and impact of study: Broth dilution method appears to be a reliable method for the determination of antimicrobial effects for the pathogens tested. In addition, AP herbal formulation gel has great potential to treat acne effectively.