Similar to E. faecium, S. aureus can also cause infections on implanted medical devices and form biofilms that make treatment with antibiotics more difficult.[1] Additionally, approximately 25% of S. aureus strains secrete the TSST-1 exotoxin responsible for causing toxic shock syndrome.[13] Methicillin-resistant S. aureus, or MRSA, includes strains distinct from other strains of S. aureus in the fact that they have developed resistance to β-lactam antibiotics.