Antibiotic Resistance in Staphylococcus aureus: Effects of Quorum Sensing Inhibition and DNA Fragmentation

Antimicrobial resistance (AMR) is a global crisis, causing 2.8 million infections and 35,000 deaths annually. Staphylococcus aureus is mainly responsible for causing these challenging infections through biofilm formation and the action of efflux pumps. A limited number of studies on Hop ( Humulus lupulus ) have shown its potential to inhibit quorum sensing in pathogenic bacteria. Therefore, a novel treatment approach was used in this study, which investigated Hop’s β-acids , particularly the combination of colupulone and nupupulone, as well as in combination with fluoroquinolone antibiotics ciprofloxacin and ofloxacin. As ciprofloxacin remains a highly effective antibiotic against Staphylococcus aureus but resistance can develop, and ofloxacin exhibits naturally higher resistance in S. aureus , this study hypothesized that combining Hop (containing colupulone & n+adlupulone) with the two antibiotics separately would result in a greater reduction in biofilm growth of S. aureus compared to their individual potency levels. Antimicrobial activity was assessed through use of disk diffusion assays and minimum inhibitory concentration for biofilms for multiple concentrations. Our data demonstrate that Hop-derived β-acids possess direct antimicrobial activity and, when combined with the fluoroquinolone antibiotics, exhibit additive or synergistic effects by acting on different targets in Staphylococcus aureus , offering a promising natural-conventional hybrid approach to addressing antimicrobial resistance.