Re: MRSA nasal swab test?
Humans commonly house staphyloccocus aureus in the nasal cavities. It is a sort of home for these little guys, probably because the environmental conditions are perfect for them there. Commonly, when a person is being admitted to the hospital for surgery or for a short term stay, the laboratory will do an MRSA screen to determine if the patient is housing this oxacillin-resistant strain in their nose. Of course, MRSA is a superbug and very difficult to treat should it become a problem with infection on the patient.
So, all that to say, that you probably do not carry the oxacillin resistant strain of Staph. aureus in your nose and thus obtained the infection in some other way, not through self-infection.