Staphylococcus aureus can be peacefully present on the surface of the human skin and in the nasal cavity, but it is also one of the main pathogens causing human infection, which can cause mild skin or soft tissue infections, and can also cause deadly infections such as bacteremia, arthritis, pneumonia, toxic shock syndrome which are high-profile medical problems in many parts of the world. In 1961, the world’s first case of methicillin-resistant S. aureus (MRSA) appeared in the United Kingdom and was subsequently reported around the world.

After acquiring the mecA gene, S. aureus became MRSA which can translate penicillin-binding protein 2a (PBP 2a) to obtain anti-methicillin and anti-β-lactam antibiotics. Infections obtained from patients in healthcare institutions have been a typical manifestation of MRSA infections, and their infections are often associated with health-related risk factors such as long-term hospitalization, surgery, hemodialysis, intubation or other indwelling devices. These MRSA belong to healthcare-associated MRSA, HA-MRSA. However, MRSA continued to expand its ecological niche until the 1990s when infections caused by MRSA were rarely observed in the community. Since then, Australia and the United States have reported for the first time an increase in the incidence of MRSA infections caused by community-associated MRSA (CA-MRSA). The outbreak broke out among poor Aboriginal communities, schoolchildren, prison inmates, soldiers, athletes and men who have sex with men. CA-MRSA mainly causes skin and soft tissue infections ranging from sputum to necrotizing fasciitis. In addition, cases of severe invasive CA-MRSA infections such as necrotizing pneumonia are noteworthy because these infections are associated with a mortality rate of up to 75%. Recently, MRSA has been found to cause co-infection of livestock and humans in several countries. This MRSA is called livestock-associated MRSA (LA-MRSA), and a survey released by the European Food Safety Authority (EFSA) showed MRSA in pig farms in 17 EU member states.