Antibacterial Activity of Neem (Azadirachta indica) Leaf Extracts Against Selected Clinical Isolates in Maiduguri, Borno State

The search for novel antimicrobial agents from plant sources has intensified globally due to the growing crisis of antibiotic resistance. Neem (Azadirachta indica) is a medicinal plant with documented pharmacological properties widely used in traditional medicine in North East Nigeria. This study evaluated the antibacterial activity of aqueous and ethanolic extracts of A. indica leaves against clinical isolates of E. coli, S. aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae obtained from clinical specimens at the University of Maiduguri Teaching Hospital, Borno State. Extraction was performed by cold maceration using distilled water and 70 percent ethanol as solvents. Antibacterial activity was determined by agar well diffusion method, and minimum inhibitory concentrations were established by broth microdilution. Phytochemical screening was conducted to identify bioactive constituents. Results demonstrated that ethanolic extracts produced significantly larger zones of inhibition than aqueous extracts across all test organisms. S. aureus showed the highest sensitivity (MIC: 6.25 mg/mL), while P. aeruginosa was least susceptible (MIC: 25 mg/mL). Phytochemical analysis revealed the presence of tannins, flavonoids, saponins, and terpenoids. These findings support the ethnomedicinal use of neem in North East Nigeria and indicate its potential as a source of novel antibacterial compounds. Further in vivo studies and toxicity assessments are recommended. Keywords: Azadirachta indica, neem, antibacterial activity, plant extracts, Maiduguri.