Susceptibility of Selected Multi-Drug Resistant Clinical Isolates to Different Leaf Extracts of Senna alata

Abstract

The present study evaluated the antibacterial effects of the methanolic, ethanolic and aqueous extracts of Senna alata leaves. The extracts were tested using agar well diffusion method against selected clinical isolates: Salmonella typhi, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Klebsiella pneumoniae. Antibiogram profile of the isolates deduced by disc diffusion method confirmed that the methanolic extract inhibited the growth of all tested organisms except for Klebsiella pneumoniae, which also showed no sensitivity to the ethanolic extract. There was no inhibition observed for the aqueous extract against all the tested organisms, indicating that the methanolic extract of the plant was more potent than the aqueous extract. Inhibitory activities were observed for gentamicin, ofloxacin and erythromycin against Staphylococcus aureus and Escherichia coli. No inhibitory activity was observed in all the antibiotics against Pseudomonas aeruginosa. In Klebsiella pneumoniae, inhibition was only observed in ofloxacin. The activity of both the methanolic and ethanolic extract of Senna alata was optimal under different concentrations, but gradually diminished as the concentration was adjusted. The activity of the plant extracts against the selected bacteria is an indication of the presence of broad spectrum bioactive compounds which could be explored in the therapy of bacterial infections.

Keywords

• antibiotic resistance
• minimum inhibitory concentration
• minimum bactericidal concentration