Evaluation of the Antibacterial and Drug Potentiating Activity of Dysphania ambrosioides Ethanol Extract Against MDR Strains

The discovery of penicillin by Alexander Fleming in 1928 marked the beginning of the antibiotic era but also led to the development of resistant bacterial strains. Bacterial resistance, worsened by the improper use of antibiotics, has become a growing concern. Phytotherapy, particularly using medicinal plants, emerges as a promising alternative for treating resistant infections. Dysphania ambrosioides (L.) Mosyakin & Clemants, commonly known as "mastruz," has shown significant therapeutic potential and is the focus of this study to evaluate its effect against multidrug-resistant bacterial strains. The leaves of D. ambrosioides were collected, and an ethanolic extract (EEDA) was prepared from 250 g of dried leaves. Antibacterial activity was assessed using standard strains (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) and resistant clinical isolates. The Minimum Inhibitory Concentration (MIC) was determined by microdilution in 96-well plates. The potentiating effect of EEDA was evaluated by combining it with gentamicin, norfloxacin, and oxacillin, using serial microdilutions and resazurin analysis. EEDA showed a significant potentiating effect when combined with gentamicin for P. aeruginosa, reducing the MIC. However, with norfloxacin and oxacillin, the effect was antagonistic. For E. coli, the combination with gentamicin also reduced the MIC, though not statistically significant. For S. aureus, there was no change in MIC with gentamicin and norfloxacin, and the combination with oxacillin showed an antagonistic effect. Phytochemical analysis revealed flavonoids and other secondary metabolites in EEDA, suggesting these compounds may influence antimicrobial activity. These results underscore the importance of investigating interactions between natural compounds and antibiotics to develop more effective therapeutic strategies.