Efficacy of Thunbergia alata asnd Senna didymobotrya Extracts Against Selected Bacteria Commonly Associated With Skin Infections in Kericho Referral Hospital, Kenya

Abstract

Bacterial infections are widely distributed and cause deadly infectious diseases such as skin, soft tissue and respiratory tract infections, meningitis, and tuberculosis. Bacterial infections are very common and can be acquired easily since bacteria are ubiquitous. The infections, however, have become a challenge to modern healthcare providers, due to the myriad of side effects of the costly conventional drugs. There is a need therefore to source for alternative remedies that are easily available, affordable, and effective. This study was carried out to determine the efficacy of Senna didymobotrya and Thunbergia alata crude plant extracts against Staphylococcus aureus,Streptococcus pyogenes and Pseudomonas aeruginosa in Kericho County. Leaves of the said plants were sourced from Bomet and Kabianga, dried, milled into powder and solvent extracted using Hexane, Dichloromethane: Methanol at a ratio of 1:1an Methanol. Phytochemicals present in each plant extract were evaluated using standard laboratory procedures. Antibacterial activity and Minimum Inhibitory Concentrations (MICs) and Minimum Bactericidal Concentration (MBC) were determined using the disc diffusion technique under sterile conditions. Discs impregnated with standard antibacterial drugs were used as a positive control. Leaves of S. didymobotrya and T. alata were found to be rich in alkaloids, flavonoids, terpenoids, glycosides and tannins irrespective of plant collection site, solvent of extraction or plant species. S. didymobotrya and T. alata plant extracts significantly inhibited the growth of the exposed microbes in the following order: S. aureus, ≥ S. pyogenes and ≥ P. aeruginosa bacteria in comparison with commercial antibiotics (penicillin, chloramphenicol, and erythromycin). The MIC values of the isolates ranged from 20×10-3 mg/ml to 4.8×10-3 mg/ml. However, inhibition by plant extracts showed re-growth of S. pyogenes after 36 hours, suggesting a bacteriostatic nature. These results suggest that S. didymobotrya and T. alata leaves contain significant amounts of alkaloids, flavonoids, terpenoids, glycosides and tannins. Hence can be used as traditional medicine to manage S. aureus,S. pyogenes and P. aeruginosa bacteria found on human skin.