The combination of cloxacillin, thioridazine and tetracycline protects mice against Staphylococcus aureus peritonitis by inhibiting α-Hemolysin-induced MAPK/NF-κB/NLRP3 activation.

Staphylococcus aureus (S. aureus) infection is difficult to fight, previous experimental reports have demonstrated thioridazine (TZ) and tetracycline (TC) is an inhibitor of S. aureus efflux pump NorA and autolysin Atl, respectively, here, by means of molecular docking and molecular dynamics simulation, we observed that thioridazine (TZ) and tetracycline (TC) blocked the binding of substrates to NorA and Atl, respectively, and reduced their activities, and our antibacterial susceptibility test and three-dimensional checkerboard method showed that the three-drug combination of antibiotic cloxacillin (CXN), TZ and TC had a synergistic anti-Staphylococcal activity in vitro, and α-Hemolysin tests and scanning electron microscopy showed that the three-drug combination and the subinhibitory concentration of the combination significantly inhibited the secretion of α-hemolysin relative to the number of membrane-derived vesicles produced by S. aureus. Whereas Western blot and pharmacological inhibition assays showed that the three-drug combination significantly inhibited the expression of MAPK/NF-κB/NLRP3 proteins in macrophages induced with S. aureus α-hemolysin. In vivo, the drug combination significantly reduced bacterial colony-forming unit counts in the viscera of a mouse peritonitis model of S. aureus infection, therapy reduced the primary inflammatory pathology and the bacteria-stimulated release of cytokines such as IL-1β and TNF-α, and inhibited the expression of MAPK/NF-κB/NLRP3 proteins in peritoneal macrophages. Thus, the combination of efflux pump inhibitor, autolysis inhibitor and antibiotic, is a novel anti-Staphylococcal and anti-inflammatory strategy who owning good antibacterial activity and significant inhibiting staphylococcal α-hemolysin and inflammation.