Antibacterial effects of BB-Cl-Amidine against multidrug-resistant Gram-positive pathogens via membrane disruption

The escalating prevalence of multidrug-resistant (MDR) gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and linezolid-resistant Enterococcus faecalis, highlights the critical demand for new antibacterial agents that target resistance pathways. BB-Cl-Amidine is originally considered as a peptidyl arginine deiminase inhibitor and till now, its potential antimicrobial activity has not been explored. This study sought to evaluate the antibacterial effectiveness and underlying mechanisms of BB-Cl-Amidine against MDR gram-positive pathogens. The results showed that BB-Cl-Amidine exhibited potent antibacterial activity with minimum inhibitory concentration (MIC) values ranging from 25 μM to 50 μM against MRSA, E. faecalis and various of Gram-positive bacteria clinical isolates. At sub-MIC concentrations, BB-Cl-Amidine significantly reduced biofilm formation in both S. aureus and E. faecalis. Moreover, the increased permeability and depolarizing membrane potential of S. aureus was found by BB-Cl-Amidine. The antibacterial activity of BB-Cl-Amidine can be neutralized by cardiolipin (CL) and phosphatidylglycerol (PG). Furthermore, BB-Cl-Amidine exposure resulted in the abnormal expression of functional proteins correlated with the cell membranes and phospholipid metabolas. In summary, the potential antibacterial and anti-biofilm activities of BB-Cl-Amidine are demonstrated via membrane disruption, offering a promising scaffold for combating MDR Gram-positive infections.