Staphylococcus aureus Infections Epidemiology, Pathophysiology, Clinical Manifestations and Management
Staphylococcus aureus is a major human pathogen that causes a wide range of clinical infections. Age is a powerful determinant of SAB incidence, with the highest rates of infection occurring at either extreme of life.
Studies consistently demonstrate high rates in the first year of life, a low incidence through young adulthood, and a gradual rise in incidence with advancing age. HIV and hemodialysis patients are also at a greatly increased risk. This review comprehensively covers the epidemiology, pathophysiology, clinical manifestations, and management of each of these clinical entities. Staphylococcus aureus is both a commensal bacterium and a human pathogen. Approximately 30% of the human population is colonized with S. Aureus.
The primary defense against S. aureus infection is the neutrophil response. When S. aureus enters the skin, neutrophils and macrophages migrate to the site of infection. S. aureus evades this response in a multitude of ways, including blocking chemotaxis of leukocytes, sequestering host antibodies, hiding from detection via polysaccharide capsule or biofilm formation, and resisting destruction after ingestion by phagocytes.
There are many different primary clinical foci or manifestations of S. Aureus infections. The common primary sources of infection are vascular catheter-related infections, SSTIs, pleuropulmonary infections, and osteoarticular infections.
S. aureus causes a variety of SSTIs, ranging from benign (e.g., impetigo and uncomplicated cellulitis) to immediately life-threatening. It is the most common pathogen isolated from surgical site infections (SSIs), cutaneous abscesses, and purulent cellulitis. SSIs occur after 2 to 5% of all surgeries, although there is considerable heterogeneity depending on the type of procedure, population studied, comorbid illnesses, the experience of the surgeon, setting, and antimicrobial prophylaxis utilized. Impetigo is the most common bacterial skin infection in children. While the hallmark infection of S. aureus SSTI is generally regarded as a cutaneous abscess. Necrotizing fasciitis is another cutaneous syndrome caused by S. aureus. The management of skin infection is different according to the disease and it includes local topical antibiotics until prolonged courses of antibiotics.
Osteomyelitis is an infection of bone resulting in its inflammatory destruction, bone necrosis, and new bone formation. S. aureus is the predominant cause of OM in all of these categories and is identified in 30 to 60% of cases. The management of OM caused by S. aureus requires prolonged courses of antibiotics.
Clinical infections with S. aureus will likely remain both common and serious and it needs full care and attention.