How long is mrsa contagious for?

Indefinitely: Unfortunately, MRSA can survive indefinitely on hosts. It can survive on non-host surfaces (ie: door knobs, light switches, commodes, tubs, phones, tables, etc.) for days, weeks, or months depending on environmental circumstances.

Always: Mrsa is a bacteria and can be spread through skin contact, so it is aways contagious.

MRSA: This strain of staphylococcus aureus may or may not produce infection. We are all colonized with staph, usually in our GI tract , but possibly on nasopharynx and skin. Once colonized, by direct contact with others who have this, you then have the potential to become infected, but this usually occurs only after experiencing some defect in the integument (skin and mucous membranes).

MRSA: Depends on your definition of "contagious". This organism is generally transferred person to person by direct hand contact, and then the other person may only become a carrier. Infection requires a break in the skin or soft tissues or introduction into an immune suppressed person.