ANTIBACTERIAL EFFICACY OF NEEM (AZADIRACHTA INDICA) LEAF EXTRACT AGAINST SALMONELLA TYPHI AND SHIGELLA SPECIES ASSOCIATED WITH TYPHOID FEVER
Abstract
The increasing prevalence of antibiotic resistance among enteric pathogens such as Salmonella Typhi and Shigella has heightened the need for alternative therapeutic agents derived from medicinal plants. This study evaluated the antibacterial efficacy of neem (Azadirachta indica) leaf extract against Salmonella Typhi and Shigella species associated with typhoid fever. The specific objectives were to isolate and identify Salmonella Typhi and Shigella spp. from clinical or environmental samples, prepare neem leaf extracts using standard solvent extraction techniques, and determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the extracts. Fresh neem leaves were collected, dried, powdered, and subjected to extraction using methanol, ethanol, and aqueous solvents. The extracts were analyzed for phytochemical constituents using qualitative and quantitative methods, while antibacterial activity was assessed in vitro through the agar well diffusion method. Phytochemical screening revealed the presence of alkaloids, flavonoids, tannins, saponins, phenols, glycosides, terpenoids, and steroids, with methanolic and ethanolic extracts showing broader profiles compared to aqueous extracts. Quantitative analysis indicated that saponins (13.2%) and flavonoids (11.6%) were the most abundant compounds, followed by phenols (9.5%), tannins (8.4%), and alkaloids (5.8%). Extraction efficiency varied with solvents, with methanol yielding 12.4%, ethanol 10.8%, and aqueous extract 7.6%. Antibacterial assays demonstrated concentration-dependent inhibition, with inhibition zones of 25.0 mm for S. Typhi and 23.9 mm for Shigella at 400 mg/ml, comparable to streptomycin and approximately 80% as effective as ciprofloxacin. The MIC was 200 mg/ml, while the MBC was 400 mg/ml. This study concludes that neem leaves contain abundant bioactive compounds with significant antibacterial potential against enteric pathogens, supporting their use as a complementary therapy in the management of typhoid fever and shigellosis.
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