Phenotypic Antibacterial Resistance Profiles of Azadirachta indica and Calotropis procera Fresh Leaf Extracts Against Multidrug-Resistant Pathogens

Antibiotic resistance remains a global public health crisis, exacerbated by the rise of multidrug-resistant (MDR) and extensively drug-resistant bacteria. This study investigated the antibacterial activity and resistance mechanisms of Azadirachta indica (neem) and Calotropis procera (apple of Sodom), two plants traditionally used for their medicinal properties. Both plants contain bioactive compounds with broad antimicrobial effects, yet their genotypic profiles related to resistance mechanisms remain underexplored. We assessed the phenotypic resistance profiles of A. indica and C. procera leaf extracts using a combination of agar disc diffusion, minimal inhibitory concentration assays, and advanced bacterial identification techniques. Fresh leaves were collected from the Kashere community, Gombe State, Nigeria, and extracts were prepared using methanol and n-hexane. The antibacterial activities of the extracts were tested against several MDR bacterial strains, including Pseudomonas aeruginosa, Proteus mirabilis, Salmonella enterica, Klebsiella pneumoniae, and Aeromonas hydrophila. Biochemical and morphological characterization of the bacterial isolates revealed significant resistance to a wide array of antibiotics, with the highest resistance observed in P. aeruginosa. The plant extracts exhibited promising antibacterial properties, particularly against resistant strains, with variable inhibition zones. The results indicated that A. indica and C. procera bacteria are resistant to beta-lactams, aminoglycosides, and fluoroquinolones, but are more susceptible to plant extracts, suggesting potential natural alternatives.