Comparative Antibacterial Effects of Selected Ethnomedicinal Plants on <em>Escherichia coli</em> and <em>Staphylococcus aureus</em> Isolated from Mastitic Cow Milk in West Arsi Zone, Ethiopia

Objective: The study aimed to evaluate the antimicrobial activity of selected medicinal plants, Datura stramonium (DS), Akokanthera schimperi (AS), and Balanites aegyptiaca (BA) against Escherichia coli(E. coli) and Staphylococcus aureus (S. aureus) isolated from mastitic cow milk in the West Arsi Zone, Ethiopia. These bacterial pathogens are known contributors to bovine mastitis and often exhibit multidrug resistance (MDR). Methods: A laboratory-based experimental study was conducted using clinical isolates and American Type Culture Collection (ATCC) standard strains of E. coli and S. aureus. Ethanolic extracts of the three medicinal plants were prepared and tested for antibacterial efficacy using the agar disc diffusion method at a concentration of 350 mg/mL. The diameter of inhibition zones was measured to assess the antimicrobial activity of each plant extract. Results: All three plant extracts exhibited antimicrobial activity against the tested bacterial strains. Akokanthera schimperi (AS) demonstrated the highest antibacterial effect, producing the largest zones of inhibition against both E. coli and S. aureus (18.8 ± 0.03 mm for E. coli, 16.1 ± 0.26 mm for S. aureus), followed by Datura stramonium (DS) (14.8 ± 0.05 mm and 12.1 ± 0.17 mm respectively for E. coli, and S. aureus) and Balanites aegyptiaca (BA) (11.6 ± 0.3 and 7.1 ± 0.12 for E. coli, and S. aureus respectively). The results varied depending on the plant species and the bacterial strain tested. Conclusion: The findings indicate that traditional medicinal plants, particularly Akokanthera schimperi (AS), possess promising antibacterial properties against major mastitis-causing pathogens, E. coli and S. aureus. These results support the potential integration of ethnoveterinary medicine (EVM) into mastitis management strategies. Further studies, including phytochemical analysis and in vivo efficacy testing, are recommended.