The epidemiology of methicillin-resistant Staphylococcus aureus colonisation and infection.

Methicillin-resistant Staphylococcus aureus (MRSA) is an increasingly common nosocomial pathogen in health care facilities throughout the world. Overall, approximately two-thirds of nosocomial cases and outbreaks have occurred in critical care units. Major risk factors for colonisation and infection in nursing homes include age, underlying conditions, nasal colonisation and the presence of indwelling devices such as catheters, tracheostomies and nasogastric tubes. In general, patients with MRSA infections in an acute care facility are more likely to have had a prolonged hospital stay, to have received prior antibiotics and to have severe underlying disease, than patients infected with methicillin-susceptible S. aureus. Risk factors for MRSA bacteraemia include: a higher frequency of severe underlying disease, poorer underlying prognosis, prior antibiotic therapy, prolonged hospitalisation, intravascular catheterisation, and intensive care unit location. Risk factors for developing MRSA postoperative wound infections include: prior antimicrobial therapy, prolonged hospitalisation and severity of underlying disease. Little data are available to identify specific risk factors for colonisation or infection of burn wounds by MRSA.