http://www.cdc.gov/ncidod/dhqp/ar_mrsa.html
National Center for Infectious Diseases, Centers for Disease Control and Prevention
Methicillin-resistant Staphylococcus aureus (MRSA) is a type of bacteria resistant to certain antibiotics. "Staph" infections occur most frequently among persons in hospitals and healthcare facilities (such as nursing homes and dialysis centers) who have weakened immune systems.