Review Question - QID 8610

PVL is a cytotoxin that defines CA-MRSA and is not typical of hospital-acquired MRSA. PVL has the ability to lyse white blood cells and cause tissue necrosis, allowing for rapid progression of abscess formation. Beta-lactamase is an enzyme that breaks the beta-lactam bond of penicillin and is present in most strains of Staphylococcus aureus today. Synthetic penicillins such as methicillin are resistant to the effects of beta-lactamase. MRSA and CA-MRSA carry the mecA gene, which encodes a penicillin-binding protein with a very low affinity for beta-lactam antibiotics, resulting in methicillin resistance. SCCmec mobile genetic units carry the mecA gene with additional genetic elements that together yield the multidrug-resistant strains found in healthcare environments. SCCmec type IV is specific to CA-MRSA and lacks these additional genetic elements, resulting in less multidrug resistance.