mayoclinic.com/health/mrsa/DS00735
www.webmd.com/.../understanding-mrsa-methicillin-res... MRSA infection is caused by Staphylococcus aureus bacteria — often called "staph." MRSA stands for methicillin-resistant Staphylococcus aureus. It's a strain of staph that's resistant to the broad-spectrum antibiotics commonly used to treat it. Though most MRSA infections aren't serious, some can be life-threatening.Staph infections, including MRSA, occur most frequently among persons in hospitals and healthcare facilities (such as nursing homes and dialysis centers) who have weakened immune systems.