Antimicrobial Activity of Lannea welwitschii Stem Bark Against Wound Pathogens

Infection of wound with resistant bacteria often causes discomfort, delay in wound healing, wound dehiscence, gas gangrene in prolonged hospitalization, and increased cost of treatment. Lannea welwitschii (Hiern) Engl. is used in traditional medicine in South West Nigeria for treating wounds and other infections without scientific proof of efficacy. The in vitro antimicrobial activities of both aqueous and ethanol extracts of the stem bark of the plant were investigated against bacterial agents isolated from wound infections using agar diffusion method. The plant extracts exhibited definite antimicrobial activity, which was more in the ethanol extract than the aqueous extract. The antimicrobial activity is broad spectrum. The plant extracts inhibited Enterococcus faecalis, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus aureus, and some Escherichia coli that are resistant to more than four antibiotics including pefloxacin. The inhibitory activity was more against S. aureus compared with other bacteria. The extract is bacteriostatic at 1.57 mg/ml and bactericidal at 3.13 mg/ml. There was 2log unit reduction in the number of viable cells of S. aureus in 2 h, and total killing at 4 h of incubation. The antimicrobial properties of the plant can be attributed to the presence of saponins, flavonoides, anthraquinones and tannins in the extracts. The antimicrobial activities exhibited by this medicinal plant justify its use in the treatment of wounds.Keywords: Lannea welwitschii, traditional medicine, wounds, antimicrobial activity, plants extrac