St.aureus is well documented as a human opportunistic pathogen. Some of the more serious infections of St.aureus are bacteremia, pneumonia, osteomyelitis,meningitis, acute endocarditis and toxic shock syndrome. Food poisoning is often attributed to staphylococcal enterotoxin. Methicillin-resistant St.aureus is one of the most frequent nosocomial pathogens in the world.
At the other hand St. aureus is a relatively hardly microorganism that colonizes the skin and the mucous membranes of approximately 30% of normal humans.