Abstract:
Bacterial infections are distributed worldwide and cause deadly
infectious bacterial diseases such as skin, soft tissue and respiratory tract
infections, meningitis, and tuberculosis. Bacterial infections are very
common and can be easily acquired since bacteria are ubiquitous. It has
challenged modern healthcare providers; conventional drugs are costly
and have side effects. Therefore, alternative remedies that are easily
available, affordable, and effective are needed. This study was carried
out to determine the antimicrobial activity of Senna didymobotrya and
Thunbergia alata crude plant extracts against Staphylococcus aureus,
Streptococcus pyogenes and pseudomonas aeruginosa common in
Kericho County. Plant leaves of the two plants were sourced from two
sites (Bomet and Kabianga), dried, milled into powder and solvent
extracted using hexane, dichloromethane: methanol ratio (1:1) and
methanol. Phytochemicals present in each plant extract were evaluated
using standard laboratory procedures. Antimicrobial sensitivity testing,
Minimum Inhibitory Concentrations (MICs) and Minimum Bactericidal
Concentration (MBC) were determined. Discs impregnated with
standard antibacterial drugs were used as positive control. Leaves of T.
alata and Senna didymobotrya collected from Bomet contained 7.41%
and 10.4% while those from Kabianga contained 8.07% and 17.71% of
extracts respectively, suggesting that site conditions do not influence the
percentage of extracts. Leave extracts 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. S.
didymobotrya and T. alata plant extracts significantly inhibited growth
of the exposed microbes in the following order: S. aureus, ≥S. pyogenes
and≥ P. aeruginosa bacteria in comparison with commercial antibiotics
(penicillin, chloromphenical, and erythromycin). The MIC values of the
isolates ranged from 20×10-3 mg/ml to 4.8 ×10-3 mg/ml. However,
bacterial inhibition by plant extracts showed re-growth of S. pyogenes
after 36 hours, suggesting 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.
