Synergistic antibacterial and antibiofilm activity of N-acetylcysteine combined with niosomal recombinant lysostaphin against MRSA Staphylococcus aureus.

Abstract

Wound infections significantly impair healing and often result in chronic wounds, burdening healthcare systems substantially. The principal pathogen in such infections is Staphylococcus aureus (S. aureus), which forms biofilms that resist host defences and conventional therapies. To overcome these challenges, recombinant lysostaphin (rLyso) was encapsulated in niosomes using thin-film hydration and evaluated with N-acetylcysteine (NAC) against standard and clinical S. aureus strains. Antibacterial and antibiofilm activities were assessed by determining the minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC), complemented by fluorescence and confocal microscopy. Cytotoxicity was assessed in L929 fibroblasts, and in vivo efficacy was investigated in BALB/c mouse wound models. The NAC/niosomal rLyso formulation exhibited the most potent antibacterial and antibiofilm effects, significantly lowering the MIC values (standard: 1250/5.9 μg/ml; clinical: 1250/2 μg/ml) and achieving notable biofilm eradication (MBEC: standard: 5000/23.6 μg/ml; clinical: 1250/2 μg/ml). Cytotoxicity assays confirmed high bio-compatibility, with nearly 100% cell viability at MIC, while NAC alone was highly toxic. The combination of two agents achieved full bacterial clearance in vivo and accelerated wound healing. These findings suggest that NAC combined with niosomal rLyso synergistically disrupts S. aureus biofilms, enhances antimicrobial activity, and promotes wound repair, making it a promising therapeutic strategy against resistant staphylococcal infections.