In Vitro and in Vivo Antistaphylococcal Activity Determination of the New Recombinant Lysostaphin Protein

Bacterial infection by antibiotic-resistant Staphylococcus aureus strains is a worldwide concern and the development of novel antistaphylococcal agents is acutely needed. Lysostaphin, an example of such novel agents, is a bacteriocin secreted by S. simulans to kill S. aureus through proteolysis of the Staphylococcus cell wall. The aim of this study was to evaluate the in vitro and in vivo antistaphylococcal activity of recombinant lysostaphin. The in vitro study of the recombinant lysostaphin activity against S. aureus was determined by turbidimetric assay. For in vivo investigation, two groups of rats were inoculated with 1.4 × 109 CFU S. aureus. Five days after the nasal instillation of S. aureus, treatment in one of the groups was performed with a single dose (200 μg/dose) of recombinant lysostaphin formulated in Eucerin-based cream. Recombinant lysostaphin at 100 μg/mL concentration showed a significant decrease of the optical density compared to the control samples. The in vivo study demonstrated that a single dose (200 μg/dose) of recombinant lysostaphin cream significantly reduced nasal colonization in all the treated animals compared to the untreated ones. These results demonstrated that the recombinant lysostaphin produced in this study was able to kill nasal S. aureus in rats. It can be recommended for human clinical trial studies.