Abstract
Lugdunin, produced by Staphylococcus lugdunensis, exhibits potent antimicrobial activity against a broad range of Gram-positive bacteria, including Staphylococcus aureus. This study aims to elucidate the mechanisms underlying the susceptibility of S. aureus to lugdunin by screening a transposon-based mutant library generated using the lugdunin-susceptible S. aureus strain HG001. We identified four S. aureus mutants with mutations in ctaA, hemY, qoxA, and guaB, which are involved in ATP and GTP synthesis, and displayed increased susceptibility to S. lugdunensis. Further tests using synthetic lugdunin confirmed that energy generation defects make S. aureus more susceptible to lugdunin. Moreover, these mutants displayed small colony variant (SCV) phenotypes, a slow-growing form of S. aureus characterized by altered metabolism, revealing the critical role of energy metabolism in S. aureus defense mechanisms. Furthermore, we observed that clinical SCV isolates exhibited greater susceptibility to lugdunin compared to their parental strains. Additionally, lugdunin treatment enhanced SCV susceptibility to commonly used antibiotics, including oxacillin and vancomycin, suggesting a synergistic effect between lugdunin and antibiotics. This study highlights the role of lugdunin in sensitizing energy-compromised S. aureus to antibiotics, presenting a promising avenue for combating SCV-related infections. IMPORTANCE: The rise of antimicrobial resistance in Staphylococcus aureus, particularly small colony variants (SCVs), poses a significant clinical challenge due to their persistence and reduced susceptibility to antibiotics. Staphylococcus lugdunensis produces lugdunin, a potent antimicrobial compound that inhibits S. aureus growth. This study reveals that energy metabolism-deficient mutants and clinical SCVs exhibit increased susceptibility to lugdunin, underscoring the role of energy metabolism in bacterial defense. Furthermore, lugdunin enhances SCV susceptibility to antibiotics oxacillin and vancomycin, suggesting a potential strategy to overcome antibiotic resistance. By elucidating the link between energy metabolism and susceptibility to antimicrobial compounds, this study highlights lugdunin as a promising candidate for combating SCV-associated infections and antibiotic-resistant S. aureus.