Efficacy of Ziziphus Mauritania stem bark extract against clinical isolate of multidrug resistant Pseudomonâs Aeroginosa and Methicillin resistant Staphylococcus Aureu

Abstract

This study investigated the antibacterial efficacy of Ziziphus mauritiana stem bark extracts against clinical isolates of multidrug-resistant (MDR) Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus (MRSA). The isolates were re-confirmed by sub-culturing into freshly prepared Cetrimide agar for Pseudomonas aeruginosa and Mannitol Salt Agar for Staphylococcus aureus. The MDR status of each of the isolates was also established. Stem bark of Z. mauritiana was obtained, identified, authenticated and subsequently extracted prior to phytoconstituents analysis. An Antibacterial susceptibility assay was conducted testing using agar well diffusion. The Phytoconstituents analysis revealed the presence of alkaloids, flavonoids, saponins, tannins, glycosides, phenols, and steroids, while anthraquinones were absent. Antibiotic susceptibility profiling confirmed multidrug resistance among the isolates, with P. aeruginosa resisting several antibiotics including levofloxacin, cefotaxime, sparfloxacin, and amoxicillin, while MRSA isolates exhibited resistance to cefoxitin with inhibition zones of 15 mm and 20 mm, confirming methicillin resistance. The antibacterial activity of the extracts demonstrated that the ethanolic extract exhibited greater efficacy against MRSA, producing zones of inhibition ranging from 10–26 mm across concentrations of 25–200 mg/mL, whereas the aqueous extract showed comparatively lower activity (0–24 mm).  Both extracts revealed no antibacterial activity against MDR P. aeruginosa. However, upon testing the MIC and MBC values of the extract against both extracts revealed bacterial growth inhibitory properties and bactericidal activity against same isolates. An MIC value of 12.5 mg/mL and MBC value of 25 mg/mL were recorded.  Both extracts exhibited moderate antibacterial activity against MRSA, although relatively high concentrations are required.