The research frontier

Methicillin resistance is conferred by the mecA (or mecC) gene, carried on a mobile staphylococcal cassette chromosome. The gene encodes an altered penicillin-binding protein (PBP2a) with low affinity for nearly all β-lactam antibiotics, so penicillins, cephalosporins, and carbapenems are ineffective.

Long-acting lipoglycopeptides (dalbavancin, oritavancin) allow single-dose treatment of skin infections and are being studied for bacteremia. Anti-PBP2a cephalosporins such as ceftaroline and ceftobiprole expand the β-lactam toolbox. Phage therapy and monoclonal antibodies remain investigational.

No licensed S. aureus vaccine exists yet, but several multi-antigen candidates targeting capsule polysaccharides, clumping factor, and manganese-transport proteins are in mid- to late-phase trials, particularly for prevention of surgical-site infection.

CDC's Emerging Infections Program tracks invasive MRSA across ten U.S. sites; the European CDC runs comparable surveillance through EARS-Net. Whole-genome sequencing is increasingly used to detect outbreaks and trace transmission within hospitals.