MRSA as a cause of lung infection including airway infection, community-acquired pneumonia and hospital-acquired pneumonia

Staphylococcus aureus has been recognised as a cause of community-acquired pneumonia, albeit uncommon, and an important cause of healthcare-associated (HA) pneumonia, including ventilator-associated pneumonia. Resistance of S. aureus to methicillin developed shortly after its introduction into clinical practice. Since then, methicillin-resistant S. aureus (MRSA) has predominantly been a feature of hospital-acquired, or latterly HA, infections as the boundaries became more blurred between the community and hospital environments. However, more recently true community-acquired (CA)-MRSA infections have been detected and are becoming increasingly common, especially in the USA. Europe has not been immune to the development of MRSA in healthcare settings and although the prevalence of CA-MRSA is currently relatively low, there is the risk of wider spread. These new CA-MRSA strains appear to behave differently to HA-MRSA strains. Although predominantly causing skin and soft tissue infections, mainly as boils and abscesses requiring drainage, life threatening invasive infections including necrotising pneumonia can also occur. This article summarises the pathogenesis and clinical presentations of MRSA-related lung infections.