**2. Strains of** *S. aureus*

Although *S. aureus* is normally a commensal part of the human microbiota, its role sometime as opportunistic pathogen, which causes several diseases in skin as abscesses, sinusitis as respiratory diseases, and food poisoning. Pathogenic strains regularly promote infections by causing virulence causes including strong protein toxins and the creation of a cell-surface protein that attaches to and deactivates antibodies. The enhancement of antibiotic-resistant types of *Staphylococcus aureus*, such as methicillin-resistant *Staphylococcus aureus* (MRSA), is a worldwide scientific problem. Even though there are wide investigation and expansion, no *S. aureus* vaccine has been approved. There are now 32 species and the genus Staphylococcus has eight subspecies, numerous of which specially inhabit the human body, although *Staphylococcus aureus* and *Staphylococcus epidermidis* are the two most explained and examined strains.
