The bacterium Staphylococcus aureus is among the most common causes of human infection requiring medical care across the lifespan, and among the most common causes of skin, bone, and bloodstream infections globally.1 It is also a pathogen of agricultural importance, particularly in dairy cows and poultry.2 S. aureus is generally a commensal organism, and it has been recovered in tests of asymptomatic nasal colonization from 23% to 41% of human populations in studies throughout the world.3–10 S. aureus is often part of the human skin and gut microbiome, and it is transmitted from person to person by direct contact. S. aureus can also spread between animals and humans.
S. aureus has been the target of antibiotic development since the 1930s, when sulfonamides were first introduced.11 However, well-documented resistance emerged to each new class of antibiotics that has been developed to combat this pathogen. Most notably, methicillin-resistant S. aureus (MRSA) strains are resistant to nearly all antibiotics related to penicillins, a large group of drugs that are known as ß-lactam antibiotics.1,12
S. aureus is a public health threat because it is spread from person to person inside and outside of the healthcare arena, causes thousands of fatal infections each year in the United States alone, and is an increasingly important cause of antimicrobial-resistant infections. However, the most important public health challenge of S. aureus lies in the fact that we have yet to develop adequate interventions to recognize and control the spread of virulent strains among humans and animals in order to prevent infections and to protect vulnerable populations. No vaccine exists to prevent S. aureus infections, and therefore approaches to infection prevention have focused on the interruption of transmission in healthcare facilities and less commonly in households and other community settings, decolonization of chronic carriers, and suppression of colonization prior to high-risk surgical procedures.
Although the vast majority of human infections caused by S. aureus are skin and soft tissue infections (SSTIs), the bacterium also causes invasive disease, particularly among individuals with certain risk factors. People at high risk of invasive infection include those with an intravenous catheter, chronic skin disease, recent surgery, hemodialysis, recent hospitalization, endotracheal intubation, or an immunocompromised state due to human immunodeficiency virus infection, immunosuppressive medications, or cancer. Patients with diabetes mellitus are also at elevated risk of S. aureus infection. S. aureus is a common cause of human surgical-site infections, bacteremia, osteomyelitis, joint infections, pneumonia, infective endocarditis, and abscesses in internal organs after dissemination in blood. It is a rare cause of urinary tract and central nervous system infections except those that occur after surgical procedures (Table 154-1).1 Infection is almost always preceded by asymptomatic colonization which is a risk factor for infection.15,16
TABLE 154-1COMMON S. AUREUS CLINICAL SYNDROMES