Endolysin LysSte134_1 Reduces Staphylococcus Bacterial Load in Infected Wounds In Vivo

Staphylococcus aureus is an ESKAPE pathogen, defined by its ability to evade antibacterial treatment, and together with S. epidermidis is a leading Gram-positive cause of wound infection. The emergence of methicillin- and vancomycin-resistant strains further limits conventional antibiotic treatment. The staphylococcal endolysin LysSte134_1 was produced recombinantly, its proper folding confirmed by zymography, and its lytic activity demonstrated against planktonic cultures of both S. aureus and S. epidermidis. The combination of LysSte134_1 with 10% 1,3-propanediol and Zn²⁺ increased CFU reduction in both species relative to LysSte134_1 with Zn²⁺ alone. In a murine wound model, topical application of LysSte134_1 significantly reduced the bacterial burden in wound tissue, achieving a 2-3-log reduction in MRSA and below the detection limit for S. epidermidis. Treatment was accompanied by normalization of peripheral leukocyte counts and a shift in the serum cytokine profile from a sustained pro-inflammatory state with elevated IL-6, IL-17 and IL-10 toward levels comparable to non-infected controls. These results suggest the potential utility of LysSte134_1 as a component of topical antibacterial formulations and support further investigation in models of staphylococcal wound infection.