Drug resistance

SCCmec

Electrical engineering

Asymptomatic carrier

Pathology

Staphylococcal infections

Disease

Antibiotics

Bacteria

Biology

Microbiology

Gene

Engineering

Infection control

Intensive care medicine

Pathogen

Methicillin-resistant Staphylococcus aureus

Leukocidin

Staphylococcus aureus

Genetics

Virulence

Medicine

Transmission (telecommunications)

Antibiotic resistance

Nature Reviews Disease Primers

Since the 1960s, methicillin-resistant Staphylococcus aureus (MRSA) has emerged, disseminated globally and become a leading cause of bacterial infections in both health-care and community settings. However, there is marked geographical variation in MRSA burden owing to several factors, including differences in local infection control practices and pathogen-specific characteristics of the circulating clones. Different MRSA clones have resulted from the independent acquisition of staphylococcal cassette chromosome mec (SCCmec), which contains genes encoding proteins that render the bacterium resistant to most β-lactam antibiotics (such as methicillin), by several S. aureus clones. The success of MRSA is a consequence of the extensive arsenal of virulence factors produced by S. aureus combined with β-lactam resistance and, for most clones, resistance to other antibiotic classes. Clinical manifestations of MRSA range from asymptomatic colonization of the nasal mucosa to mild skin and soft tissue infections to fulminant invasive disease with high mortality. Although treatment options for MRSA are limited, several new antimicrobials are under development. An understanding of colonization dynamics, routes of transmission, risk factors for progression to infection and conditions that promote the emergence of resistance will enable optimization of strategies to effectively control MRSA. Vaccine candidates are also under development and could become an effective prevention measure. Staphylococcus aureus is a common commensal bacterium in the nasal mucosa. Several strains have acquired resistance to methicillin (methicillin-resistant S. aureus, MRSA) and most β-lactam antibiotics; such drug resistance, in addition to the intrinsic high virulence potential of S. aureus, makes MRSA an important source of health-care-associated and community-associated infections.