Antibacterial assessment of antiseptic and herbal soaps available in Sri Lanka against selected skin pathogens

Antiseptic and herbal soaps labeled as antibacterial are widely available in Sri Lanka, yet their antimicrobial efficacy against skin pathogens is not well documented. This study aimed to evaluate the antibacterial activity of eight selected soap samples, including two widely available commercial brands, two doctor-prescribed antiseptic soaps, and four herbal soaps, against selected skin pathogens. Agar well diffusion and broth dilution assays were used to measure antibacterial activity and determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values. Test organisms included a common skin pathogen Staphylococcus aureus (ATCC 25923), as well as Pseudomonas aeruginosa (ATCC 27853) and Klebsiella pneumoniae (ATCC 700603) known to be associated with skin infections in immunocompromised people. Among these, only S. aureus revealed zones of inhibition (ZOI) in the agar diffusion assay against all tested soap samples. Antiseptic soaps prescribed by physicians exhibited maximum antibacterial activity with the highest ZOI (15 ± 1.0 mm), while herbal soaps revealed comparatively less activity, with the lowest zone of (9.2 ± 0.3 mm) at the concentration of 150 mg/mL. The MIC values for P. aeruginosa and K. pneumoniae ranged from 25 to 100 mg/mL, while those for S. aureus ranged from 12.5 to 50 mg/mL. In broth dilution tests, all soap samples demonstrated both bacteriostatic and bactericidal activity, indicating their potential role in controlling skin infections caused by these pathogens. However, Further studies are needed to evaluate their efficacy against a broader range of microorganisms responsible for skin-related infections.