Rational design of short hybrid Cecropin B/Aurein 1.2 peptide analogues: in vitro synergistic anti-MRSA and anti-biofilm activities

Background The increasing prevalence of methicillin-resistant Staphylococcus aureus (MRSA) and the limited efficacy of conventional antibiotics necessitate the development of novel antimicrobial agents. This study aimed to design short hybrid antimicrobial peptides derived from Cecropin B and Aurein 1.2 and evaluate their anti-MRSA, antibiofilm, synergistic, and safety properties. Methods Two hybrid peptide analogues (Cec-Aur 1 and 2) were rationally designed using bioinformatics tools and assessed for structural and physicochemical characteristics. The antimicrobial activities were evaluated against these analogues, five clinical MRSA isolates and the reference strain MRSA ATCC 33591 using MIC and MBC assays. For one analogue with best efficiency, synergistic activity with oxacillin was determined by checkerboard analysis. Time-kill kinetics, biofilm inhibition, hemolytic activity, cytotoxicity on HEK-293 and HDF cell lines, and in vivo efficacy in a murine MRSA wound infection model were also investigated. Results Among the designed analogues, Cec-Aur 1 demonstrated moderate antibacterial activity, with geometric mean MIC and MBC values of 215 and 430 µg/mL, respectively. Cec-Aur 1 exhibited rapid bactericidal activity and significantly reduced bacterial viability in a concentration-dependent manner. Synergistic interactions with oxacillin were observed in several MRSA isolates, with fractional inhibitory concentration index values as low as 0.025 and up to a 64-fold reduction in oxacillin MIC. Cec-Aur 1 also effectively inhibited biofilm formation in a dose-dependent manner. Hemolysis remained negligible at MIC and MBC concentrations, while cell viability exceeded 80% in both HEK-293 and HDF cell lines. In the murine wound infection model, Cec-Aur 1 reduced bacterial burden by more than 93% and promoted wound healing compared with untreated controls. Conclusions The rationally designed hybrid peptide Cec-Aur 1 exhibited potent anti-MRSA, antibiofilm, and synergistic activities with minimal toxicity. These findings highlight Cec-Aur 1 as a promising candidate for the development of alternative therapies against multidrug-resistant S. aureus infections.