Anti-staphylococcal activity and cytocompatibility of lysostaphin

Objective. To study the antibacterial activity of lysostaphin against staphylococci various species, as well as its effect on the viability of Vero cells. Materials and Methods. Lysostaphin was obtained by genetic engineering. Purification of the protein was carried out on SP-sepharose, the purity was determined by electrophoresis in PAGE by Lamley. The susceptibility to lysostaphin of 9 species 175 strains of staphylococci was studied. Identification was performed by MALDI-TOF MS, antibiotic susceptibility by EUCAST (v. 11.0). The MIC of lysostaphin was studied by the method of serial dilutions with concentrations between 0.015 and 512 mg/l. For 72 hours, the viability of Vero cells with lysostaphin at concentrations of 0.5-32.0 mg/l was determined by the MTT method with counting of living cells according to their growth curve. The results were analyzed by ANOVA followed by Dunnett's test. Results. A kinetic study of S. aureus growth in the presence of revealed an inhibitory effect of endopeptidase (MIC 0.06 mg/l). Lysostaphin was characterized by pronounced activity against clinical methicillinsensitive S. aureus. The MIC ranged between 0.03 and 0.5 mg/l and the MIC50/90 was 0.125/0.5 mg/l. For methicillin-resistant S. aureus MIC50/90 0.25/0.5 mg/l. The MIC50 for MRSE was 2 times higher than for MSSE – 1 mg/l. The maximum MIC value was determined against isolates of S. warneri and S. hominis – 64 mg/l, the lowest for S. saprophyticus – 0.5 mg/l. MIC50 of lysostaphin against MRSA was 4 times lower than that of vancomycin, MIC90 was 3 times lower. Differences in viable cells depending on the concentration of lysostaphin were not found. Conclusions. Significant activity of lysostaphin against staphylococci was revealed, which is several times higher than vancomycin against MRSA. Lysostaphin was also effective against methicillin-resistant S. aureus. The high anti-staphylococcal activity and cytocompatibility of lysostaphin are promising for its further study in the prevention and treatment of staphylococcal orthopedic infections.