Antibacterial Activity of Ziziphus Spina-Christi Leaf Extract and Its Effect on Gene Expression of Some Virulence Factors of Some Pathogenic Bacteria

Given the increasing frequency of antibiotic-resistant bacteria, other antimicrobial therapies have to be looked at. The antibacterial activity of Ziziphus spina-christi leaf extract against Staphylococcus aureus and Klebsiella pneumoniae is evaluated in this work using disk diffusion, least inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). The results indicated a concentration-dependent inhibitory effect as S. aureus had larger inhibition zones (18 mm at 100 mg/mL) than K. pneumoniae (14 mm at 100 mg/mL). MIC and MBC values helped to further confirm S. aureus's (MIC = 16 mg/mL, MBC = 32 mg/mL) better sensitivity in relation to K. pneumoniae (MIC = 32 mg/mL, MBC = 64 mg/mL). Gene expression findings indicate that the agrA gene, a vital regulator of quorum sensing and pathogenicity, was greatly downregulated in S. aureus with a 65% drop at 100 mg/mL (p < 0.001). Likewise, the highest dosage produced a 50% reduction in fimH expression in K. pneumoniae, a component of adhesion and biofilm development. These findings suggest that since the extract reduces pathogenicity in addition to suppressing bacterial growth, it is a suitable choice for antimicrobial therapy. Structural changes in their cell walls most likely explain the different sensitivity of the two bacterial species; K. pneumoniae exhibits stronger resistance due to its outer membrane barrier. Further investigation on the effects of the extract on additional illnesses, its synergistic effects with other antibiotics, and its in vivo efficacy will help to assess its possible clinical usage.