The MOST appropriate action to take for a patient infected with MRSA (Methicillin-Resistant Staphylococcus Aureus) is:
Use contact precautions and place this sign on the door.
MRSA is typically spread through direct contact with infected wounds or contaminated surfaces, so appropriate measures include using contact precautions, such as wearing gloves and gowns when handling the patient or their belongings, and informing others through signage. Reversed isolation is not applicable here, and respirators are not typically required unless the patient has a respiratory infection causing droplet transmission. General personal protective equipment (PPE) is important, but the specific emphasis should be on contact precautions.