The in Vitro Antibacterial Activity of a Multiherbal Formula used in Yemeni Traditional Medicine for Topical Treatment of Impetigo

Impetigo – a contagious superficial pyogenic infection caused by specific strains of Staphylococcus aureus and Streptococcus pyogenes– is spreading among preschool and young school age children in Yemen especially in late summer. A number of indigenous multiherbal formulas have been appreciated in Yemeni traditional medicine and claimed to be useful for the treatment of impetigo. The present study was aimed at evaluating the antibacterial activity of an empirically applied indigenous aqueous multiherbal formula for the treatment of impetigo. Different amounts (25µL 50µL, and 100µL equivalent to 5mg, 10mg, and 20mg of the dried extract) of the aqueous extracts of an indigenous multiherbal formula -composed of a mixture of equal quantities of leaves from Meriandra benghalensis Benth., Ruta chalepensis L., and Thymus laevigatus L. and of these individual components, as well as of 80% ethanol extracts of the aforementioned plant materials individually and as a mixture of them, designated as alcoholic multiherbal formula were tested for antibacterial activity by using a modified agar diffusion assay [1, 2] against the pathogenic Staphylococcus aureus strains (1), (2), (3), and Streptococcus pyogenes strains (1) & (2) isolated from patients with impetigo. Indigenous aqueous multiherbal formula was found ineffective against all tested bacteria. On the other hand only the high concentration (100µL equivalent to 20mg of the dried extract) of the aqueous extracts of R. chalepensis, and T. laevigatus showed antibacterial activity approaching as well as exceeding those exhibited by the positive controls against pathogenic Streptococcus pyogenes strain 1. One or more of the tested concentrations (equivalent to 5. 10, and 20mg extracts) of the 80% ethanol extracts of the alcoholic multiherbal formula as well as of two of its individual components (R. chalepensis, and T. laevigatus) demonstrated antibacterial effect similar or higher than those produced by the positive controls against the tested pathogenic bacteria. Consequently the antibacterial activity demonstrated by the 80% ethanol extracts of Ruta chalepensis leaves, and Thymus laevigatus leaves suggest these components could be utilized as an alcoholic multiherbal formula or individually as alcoholic extracts for the treatment of impetigo instead of the ineffective indigenous aqueous multiherbal formula.

Acknowledgements: the authors thank Dr. Saeed Shibani, Director of the Central Laboratory- Sana'a, Yemen- for providing laboratory facilities. The authors also wish to thank Dr. Huda Al-Shami for isolating pathogenic bacteria from the patients and her persistent help.

References: 1. Bauer, A.W. et al. (1996), Am. J. Clin. Path. 45: 493–496. 2. Wilkins, T.D. et al. (1972), Chemotherapy 1:451–496.