Methicillin-resistant Staphylococcus aureus (MRSA) is a group of Staphylococcus aureus strains that are resistant to β-lactam antibiotics. The β-lactam group is a broad-spectrum group of antibiotics that includes several widely used drugs, including methicillin, oxacillin, and cephalosporins. Therefore, MRSA is responsible for several difficult-to-treat infections in humans. It caused more than 100,000 deaths worldwide attributable to antimicrobial resistance in 2019. Strains unable to resist these antibiotics are classified as methicillin-susceptible S. aureus, or MSSA.