From the Division of Adult Infectious Diseases, University of Colorado Denver, Aurora, CO, and the Department of Veterans Affairs, Eastern Colorado Healthcare System, Denver, CO.
Abstract
Objective: To review the published literature on methicillin-resistant Staphylococcus aureus (MRSA) infections among patients recently discharged from hospital, with a focus on possible prevention measures.
Methods: Literature review.
Results: MRSA is a major cause of post-discharge infections. Risk factors for post-discharge MRSA include colonization, dependent ambulatory status, duration of hospitalization > 5 days, discharge to a long-term care facility, presence of a central venous catheter (CVC), presence of a non-CVC invasive device, a chronic wound in the post-discharge period, hemodialysis, systemic corticosteroids, and receiving anti-MRSA antimicrobial agents. Potential approaches to control include prevention of incident colonization during hospital stay, removal of nonessential CVCs and other devices, good wound debridement and care, and antimicrobial stewardship. Hand hygiene and environmental cleaning are horizontal measures that are also recommended. Decolonization may be useful in selected cases.
Conclusion: Post-discharge MRSA infections are an important and underestimated source of morbidity and mortality. The future research agenda should include identification of post-discharge patients who are most likely to benefit from decolonization strategies, and testing those strategies.
Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of morbidity and mortality due to infections of the bloodstream, lung, surgical sites, bone, and skin and soft tissues. The mortality associated with S. aureus bloodstream infections is 14% to 45% [1–4]. A bloodstream infection caused by MRSA is associated with a twofold increased mortality as compared to one caused by methicillin-sensitive S. aureus [5]. MRSA pneumonia carries a mortality of 8%, which increases to 39% when bacteremia is also present [6]. S. aureus bloodstream infection also carries a high risk of functional disability, with 65% of patients in a recent series requiring nursing home care in the recovery period [7]. In 2011 there were more than 11,000 deaths due to invasive MRSA infection in the United States [8]. Clearly S. aureus , and particularly MRSA, is a pathogen of major clinical significance.
Methicillin resistance was described in 1961, soon after methicillin became available in the 1950s. Prevalence of MRSA remained low until the 1980s, when it rapidly increased in health care settings. The predominant health care–associated strain in the United States is USA100, a member of clonal complex 5. Community-acquired MRSA infection has garnered much attention since it was recognized in 1996 [9]. The predominant community-associated strain has been USA300, a member of clonal complex 8 [10]. Following its emergence in the community, USA300 became a significant health care–associated pathogen as well [11]. The larger share of MRSA disease remains health care–associated [8]. The most recent data from the Center for Disease Control and Prevention Active Bacterial Core Surveillance system indicate that 77.6% of invasive MRSA infection is health care–associated, resulting in 9127 deaths in 2011 [8].
This article reviews the published literature on MRSA infections among patients recently discharged from hospital, with a focus on possible prevention measures.
MRSA Epidemiologic Categories
Epidemiologic investigations of MRSA categorize infections according to the presumed acquisition site, ie, in the community or in a health care setting. Older literature refers to nosocomial MRSA infection, which is now commonly referred to as hospital-onset health care–associated (HO-HCA) MRSA. A common definition of HO-HCA MRSA infection is an infection with the first positive culture on hospital day 4 or later [12]. Community-onset health care–associated MRSA (CO-HCA MRSA) is defined as infection that is diagnosed in the outpatient setting, or prior to day 4 of hospitalization, in a patient with recent health care exposure, eg, hospitalization within the past year, hemodialysis, surgery, or presence of a central venous catheter at time of presentation to the hospital [12]. Community-associated MRSA (CA-MSRSA) is infection in patients who do not meet criteria for either type of health care associated MRSA. Post-discharge MRSA infections would be included in the CO-HCA MRSA group.
