Infections caused by a strain of Staphylococcus aureus that is non-susceptible to the action of the antibiotic, methicillin. The mechanism of resistance usually involves modification of normal or the presence of acquired penicillin binding proteins. The disease is methicillin-resistant staphylococcus aureus infectious disease (MONDO_0100073, a Monarch Disease Ontology id). Also known as: MRSA.