Methicillin-resistant Staphylococcus aureus, commonly known as MRSA, refers to strains of Staphylococcus aureus that are resistant to methicillin and other β-lactam antibiotics, including penicillins, oxacillin, most cephalosporins, and carbapenems. Staphylococcus aureus can normally be present on the skin and in the nose without causing symptoms. MRSA can cause infections when the bacteria enter tissues. These infections commonly affect the skin and soft tissues but can also cause conditions such as pneumonia, bloodstream infections, and sepsis.

MRSA resistance is associated with the mecA gene, which produces a protein called penicillin-binding protein 2a (PBP2a). This protein allows S. aureus to continue producing its cell wall in the presence of β-lactam antibiotics. MRSA can occur in healthcare settings, communities, and in association with animals (livestock‑associated MRSA). It can spread through contact between people and through contaminated surfaces, wounds, equipment, or shared personal items.

MRSA can be identified through laboratory testing of blood, urine, sputum, or other body-fluid samples. PCR can detect MRSA‑associated genes (such as mecA); some laboratories also use tests that detect PBP2a protein. Treatment depends on the location and severity of the infection and the antibiotics to which the bacterial strain is susceptible. Measures such as regular handwashing, keeping wounds clean and covered, and avoiding shared personal items can help reduce the spread of MRSA.

Disclaimer: This information is for general educational purposes only and does not replace professional medical advice, diagnosis, or treatment. Consult a qualified healthcare professional for advice about any health concern.