Methicillin-resistant Staphylococcus Aureus (MRSA) is a type of staph bacteria that is resistant to certain antibiotics called beta-lactams. These antibiotics include methicillin and other more common antibiotics such as oxacillin, penicillin, and amoxicillin. In the community, most MRSA infections are skin infections. More severe or potentially life-threatening MRSA infections occur most frequently among patients in healthcare settings. Colonized refers to when a person carries the organism/bacteria but shows no clinical signs or symptoms of infection. For Staph aureus the most common body site colonized is the nose. While 25% to 30% of people are colonized in the nose with staph, less than 2% are colonized with MRSA.
Centers for Disease Control and Prevention (CDC)