Defects in energy metabolism increase the susceptibility of and its small colony variants (SCVs) to and lugdunin.

Unlabelled: Lugdunin, produced by , exhibits potent antimicrobial activity against a broad range of Gram-positive bacteria, including . This study aims to elucidate the mechanisms underlying the susceptibility of to lugdunin by screening a transposon-based mutant library generated using the lugdunin-susceptible strain HG001. We identified four . mutants with mutations in , , , and , which are involved in ATP and GTP synthesis, and displayed increased susceptibility to . Further tests using synthetic lugdunin confirmed that energy generation defects make more susceptible to lugdunin. Moreover, these mutants displayed small colony variant (SCV) phenotypes, a slow-growing form of characterized by altered metabolism, revealing the critical role of energy metabolism in 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 to antibiotics, presenting a promising avenue for combating SCV-related infections.

Importance: The rise of antimicrobial resistance in , particularly small colony variants (SCVs), poses a significant clinical challenge due to their persistence and reduced susceptibility to antibiotics. produces lugdunin, a potent antimicrobial compound that inhibits 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 .