Antibacterial Potential of Eucalyptus globulus, Allium sativum and Azadirachta indica oils Against Salmonella typhi, Staphylococcus aureus and Escherichia coli, Mekelle, Ethiopia

Abstract

Medicinal plants are vital for their antimicrobial compounds, and address concerns over synthetic drug side effects and they combat infections and antibiotic resistance. Ethiopia's rich herbal tradition spotlights Eucalyptus, Garlic, and Neem for their antimicrobial efficacy. These plants offer potent compounds effective against various pathogens. Amid global antibiotic resistance, exploring local plant remedies is crucial for cost-effective infectious disease solutions.  This in-vitro study, conducted in Mekelle city from August to November 2019, evaluates the antibacterial efficacy of Eucalyptus globulus, Allium sativum, and Azadirachta indica extracts against Salmonella typhi, Staphylococcus aureus, and Escherichia coli. Extraction involved maceration with ethanol or distilled water, followed by filtration. Bacterial strains were cultured in Nutrient broth and standardized using McFarland standard, and disc diffusion method assessed antibacterial activity. Study variables included extract types, concentrations, bacterial strains, and solvent types. Data were analyzed using SPSS®, employing descriptive and analytic statistics including ANOVA, with statistical significance set at P ≤ 0.05. The research aimed to determine the efficacy of plant extracts as alternative antimicrobial agents. Ethanol outperformed distilled water in extracting crude oil from E. globulus, A. indica, and A. sativum, with significantly higher yields ranging from 3.3% to 15.5%. Antibacterial activity against E. coli, S. typhi, and S. aureus varied between ethanol and distilled water extracts, with ethanol generally exhibiting larger zones of inhibition. E. globulus showed significant inhibition against all bacteria with ethanol, whereas A. indica demonstrated minimal effects regardless of solvent. These findings underscore the promising role of medicinal plants in combating infectious diseases and antibiotic resistance. Further optimization of extraction processes, clinical suitability assessments, and mechanistic studies should be conducted to enhance the efficacy and understanding of plant-based antimicrobial treatments.