A Comparative Study of the Antibacterial Activity of Piliostigma reticulatum Bark Extract with Some Antibiotics

Aqueous and ethanolic extracts of Piliostigma reticulatum, a herb widely used for the treatment of diarrhea in southwest Nigeria, was challenged with clinical isolates of Escherichia coli, Shigella dysenteriae, Salmonella typhimurium, Staphylococcus aureus and Pseudomonas aeruginosa. The ethanol extract exhibited the highest activity against the test organisms with zones of inhibition ranging from 16.0 – 20.0 mm, followed by the hot aqueous extract and the cold aqueous extracts, with zones of inhibition ranging between 8.0 – 10.0 mm and 4.0 – 7.0 mm respectively. The Minimum Inhibitory Concentration (MIC) ranged between 0.025 – 0.25% w/v and photochemical analysis showed that the plant possesses saponins, tanins, phenolics, phlobatinins and glycosides. A comparative analysis of the extract with some conventional antibiotics namely; Chloramphenicol, Ampicillin and Tetracycline showed that there was significant difference in the antibacterial activity of the bark extract and the antibiotic standard (P<0.05).