Antimicrobial Activity and Phytochemical Characterisation of Neem (Azadirachta indica) Extracts Against Multidrug-Resistant Clinical Isolates in Sokoto State

Azadirachta indica, commonly known as neem, has documented broad-spectrum biological activity, yet systematic studies evaluating its antimicrobial efficacy against multidrug-resistant (MDR) clinical pathogens in northern Nigerian populations have not been reported. This study evaluates the antimicrobial activity and phytochemical composition of neem leaf, stem bark, and root extracts against MDR clinical isolates from Usmanu Danfodiyo University Teaching Hospital, Sokoto State, North West Nigeria. MDR isolates of Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Candida albicans were selected based on confirmed resistance to at least three antibiotic classes. Ethanolic, methanolic, and aqueous extracts were prepared by maceration and evaluated by agar well diffusion, broth microdilution MIC determination, and time-kill kinetics. Phytochemical screening identified saponins, flavonoids, terpenoids, and alkaloids as major constituents. Ethanolic stem bark extract demonstrated the strongest antibacterial activity with MIC values of 0.625 mg/ml against MRSA and 1.25 mg/ml against MDR Klebsiella. Time-kill analysis confirmed bactericidal action at 4x MIC within 8 hours for MRSA. Activity against Candida albicans was moderate. Synergy with conventional antibiotics was demonstrated for the neem-ciprofloxacin combination against Pseudomonas. The study provides quantified evidence of neem antimicrobial potential against northern Nigerian MDR pathogens and recommends preclinical pharmacokinetic evaluation. Keywords: Azadirachta indica, antimicrobial activity, MDR pathogens, Sokoto State, phytochemistry