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

Background:

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.

Objectives:

The aim of this study was to evaluate the in vitro and in vivo antistaphylococcal activity of recombinant lysostaphin.

Materials and Methods:

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.

Results:

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.

Conclusions:

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.

Cloning, Expression, and Purification of Recombinant Lysostaphin From Staphylococcus simulans

Background:

Staphylococcus aureus is one of the most common causes of nosocomial infections and its resistance to antibiotics is a global concern. Lysostaphin is an antimicrobial agent belonging to a major class of antimicrobial peptides and proteins known as the bacteriocins. It exhibits a high degree of anti-staphylococcal bacteriolytic activity.

Objectives:

In this study, high level of recombinant mature lysostaphin in Escherichia coli was produced by using pET32a expression vector.

Materials and Methods:

The S. simulans gene encoding lysostaphin was extracted, amplified by polymerase chain reaction (PCR), and sub-cloned in prokaryotic expression vector pET32a. E. coli BL21 (DE3) plysS were transformed with pET32a-lys and gene expression was induced by IPTG. The expressed protein was purified by affinity-chromatography using (Ni-NTA) resin.

Results:

PCR and sequencing results confirmed the successful cloning of the target gene into the vector. The expression of protein was induced by IPTG and high concentration of the recombinant protein was obtained via the purification process by affinity-chromatography.

Conclusions:

Our data showed that the recombinant mature lysostaphin protein produced by pET32a vector in E. coli system was very efficient.