MRSA as a cause of community-acquired pneumonia.

S taphylococcus aureus is a species of bacterium that can cause a broad variety of infections, ranging from minor skin infections to severe pneumonia and sepsis. The genetic adaptation of S. aureus has led to a multidrug-resistant pathogen, meticillin-resistant S. aureus (MRSA) after the introduction of meticillin (previously methicillin) into clinical practice in the 1960s [1]. MRSA is resistant to b-lactam antibiotics, including penicillin and cephalosporins. Resistance is mediated by penicillin binding protein 2a, a penicillin binding protein encoded by the mecA gene that permits growth in the presence of meticillin. The mecA gene is situated in the staphylococcal cassette chromosome SCCmec. Initially, MRSA was only a nosocomial pathogen, i.e. healthcare-associated MRSA. It is associated with severe invasive disease [2] and tends to have multidrug resistance. It carries SCC chromosome type II (SCCmec type II) [3].