Antimicrobial Activity of Moringa oleifera Leaf Extract Against Clinical Isolates of Bacterial Pathogens in Osun State

Increasing antibiotic resistance among clinical bacterial pathogens has stimulated global interest in plant-derived antimicrobials as alternative therapeutic options. This experimental laboratory study evaluated the in-vitro antimicrobial activity of ethanolic extracts of Moringa oleifera leaf against selected clinical bacterial isolates at Obafemi Awolowo University Teaching Hospitals Complex (OAUTH), Ile-Ife, Osun State, in the South West geopolitical zone of Nigeria. Ethanolic extracts were prepared from fresh Moringa oleifera leaves collected from Ile-Ife using cold maceration and rotary evaporation. Agar well diffusion was employed to test activity against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Salmonella typhi at concentrations of 25, 50, 100, 200, and 400 mg per mL. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using the broth dilution method. Significant inhibitory activity was demonstrated against S. aureus and E. coli at concentrations of 100 mg per mL and above. P. aeruginosa showed the least susceptibility. MIC values ranged from 50 to 200 mg per mL across tested organisms. Phytochemical screening revealed the presence of tannins, flavonoids, alkaloids, and saponins. These findings support further investigation of M. oleifera as a source of antimicrobial compounds for drug discovery. Keywords: Moringa oleifera, antimicrobial activity, plant extract, clinical isolates, antibiotic resistance.