Impact of Blue Light on Nafcillin Resistance in Staphylococcus aureus: The Role of AbcA Efflux Pump

Staphylococcus aureus , including methicillin-resistant strains (MRSA), is a major cause of microbial infections. The rise of antibiotic-resistant strains has prompted efforts to explore alternative strategies to enhance antibiotic efficacy. Antimicrobial blue light (aBL), known for its antimicrobial properties, is a promising approach, although its mechanism remains incompletely understood. This study investigated the effect of aBL on the AbcA efflux pump, which contributes to nafcillin’s mild-resistance in S. aureus. We found that the ΔabcA strain exhibited higher sensitivity to aBL than the wild-type strain, suggesting that the presence of AbcA plays a key role in modulating aBL’s antibacterial effects. In addition, WT showed higher viability reduction under co-treatment with aBL and nafcillin compared to either treatment alone, with a reduction of over 2log CFU/mL in each strain. These findings provide new insights on mechanism of aBL and its potential synergistic effect with antibiotics, offering a promising strategy to address antibiotic resistance.