Background: Salmonella infection remains endemic in northern Nigeria, with rising antimicrobial resistance. While Acacia nilotica has been widely studied, research has focused mainly on bark and roots.
Aims: this study provides novel clinical evidence on the antibacterial activity of its leaf extracts against Salmonella isolates from patients in Kano.
Methods: Four hundred stool samples from patients screened for typhoid were enriched in Selenite F broth and cultured on selective media. Presumptive Salmonella isolates were identified phenotypically by morphology, Gram staining, and biochemical profiling. Leaves of A. nilotica were extracted with water and ethanol. Phytochemical screening was performed, and antibacterial activity was assessed by agar diffusion at graded concentrations. MIC and MBC were determined by broth dilution.
Result; Fourteen isolates (3.5%) were identified as Salmonella phenotpically. Phytochemical analysis revealed abundant tannins, alkaloids, saponins, steroids, and glycosides. Both extracts exhibited concentration-dependent inhibition against a subset of isolates, with ethanol showing higher activity (zones up to 20 mm at 50 mg/mL) than water. MICs ranged from 25–50 mg/mL, and MBCs were typically 50 mg/mL for susceptible isolates. Activity was substantially lower than ciprofloxacin.
Conclusion: A. nilotica leaves possess measurable but modest anti-Salmonella activity. While weaker than reports for bark and roots, the leaf-based approach offers sustainability and safety advantages. Further molecular identification is warranted, with tannins, alkaloids, and saponins prioritized for bioassay-guided isolation.