MRSA or the methicillin-resistant-Staphylococcus-aureus is the name of bacteria that can resist common antibiotics like methicillin. The MRSA or the mercer disease is caused by the Staphylococcus aureus or simply the staph bacteria. As it is resistant to antibiotics, mercer disease is potentially dangerous. Overuse of antibiotics like penicillin or methicillin for minor infections is one of the causes of the development of mercer strain. The presence of antibiotics in food or water is the other cause as it builds immunity after prolonged use. Those working in medical facilities are the most vulnerable so are the children.