This study investigates the potential synergistic effect of Cranberry (Vaccinium oxycoccos) extract and Amoxicillin-Clavulanic acid in enhancing antibacterial effectiveness and combating resistance. The main objectives of this study are do determine the MIC and FIC values for Amoxicillin-Clavulanic Acid and Vaccinium oxycoccos extract on different bacterial strains, and therefore to evaluate the synergistic effect of compounds combined. Vaccinium oxycoccos extract is rich in proanthocyanidins, phenolic acids, anthocyanins, vitamin C, and triterpene compounds, and has demonstrated antibacterial, antifungal, and anti-inflammatory properties. This study specifically evaluates its potential to inhibit biofilm formation by gram-negative bacteria. Amoxicillin, a semi-synthetic penicillin, is combined with Clavulanic acid, a β-lactamase inhibitor, to treat various bacterial infections. However, the rising antimicrobial resistance challenges the efficacy of this antibiotic combination. The effectiveness of combining antibiotics and natural substances in inhibiting bacterial growth can vary among different bacteria. This research emphasizes the importance of personalized treatment for each bacterial strain to effectively combat antibiotic-resistant infections.