A genus of Gram-positive facultatively anaerobic cocci including Staphylococcus aureus that includes several that infect humans.

S. aureus is a common commensal bacterium. However, it can cause infections in the bloodstream, skin- and soft tissue, as well as other body sites. It is also an important cause of infections associated with implants and medical devices.

Methicillin-resistant S. aureus (MRSA) is an important cause of hospital-acquired infections (HAIs) and community-acquired MRSA infections have also been detected. Methicillin resistance is generally associated with the presence of the mecA gene, part of a mobile genetic element known as the staphylococcal cassette chromosome mec (SCCmec).

S. aureus can be multidrug-resistant and MRSA can be resistant to multiple classes of antibiotics too. It is categorized by WHO as a ‘priority 2 (high)’ pathogen for R&D of new antibiotics.