Staphylococcus aureus, is a bacteria that about 30% of people carry in their noses. Most of the time, staph does not cause any harm; however, sometimes staph causes infections. Staphylococcus is common cause of microbial keratitis. S. aureus infections are common in people with frequent skin injury. Localised and difuse otitis externa due to S. aureus has also been described. In healthcare settings, these infections can be serious or fatal, including: bacteremia or sepsis, pneumonia, endocarditis or osteomyelitis.