An estimated 30,800 fewer invasive methicillin-resistant Staphylococcus aureus infections occurred in the U.S. in 2011 compared with 2005, according to a study.
MRSA is one of the most common antimicrobial-resistant pathogens causing infections, especially in the skin and soft tissues, according to background information in the study, which was published Sept. 16 on the website of JAMA Internal Medicine.
Raymund Dantes, MD, MPH, of the CDC, and colleagues estimated that 80,461 invasive MRSA infections occurred nationally in 2011. Of those, 48,353 were healthcare-associated community-onset infections, 16,560 were community-associated infections and 14,156 were hospital-onset infections.
Hospital-onset infections were classified as those with a positive culture obtained after three days of hospitalization; healthcare-associated community-onset infections as those with a positive culture obtained as an outpatient within three days of hospitalization in a patient with a documented healthcare risk factor; and community-associated infections as those with a positive culture obtained as an outpatient or within three days of hospitalization in a patient without documentation of a healthcare risk factor.
The authors noted the category of healthcare-associated community-onset infections comprised mostly recently discharged patients, long-term care residents and dialysis patients.
Since 2005, national estimated incidence rates have decreased 54.2% for hospital-onset infections, 27.7% for healthcare-associated community onset infections and 5% for community-onset infections.
The large decrease in hospital-onset invasive MRSA infections between 2005 and 2011 is highly encouraging and may be attributable to increased awareness and implementation of local and nationwide infection prevention measures in many healthcare settings, the authors wrote, including those targeting intravascular catheter-related infections and healthcare transmission of multidrug-resistant organisms.
With national survey data indicating the number of hospitalizations and average length of stay were stable between 2007 and 2010, the authors noted, length of stay likely was not a factor in the reduction in hospital-onset MRSA.
The moderate decrease of healthcare-associated community-onset infections could be attributable to decreased transmission in hospital settings or prevention efforts outside of the acute care hospital, the authors wrote.
Among nondialysis cases with prior hospitalization, nearly two-thirds developed their infections within three months of hospitalization. This suggests a higher risk of invasive MRSA in the weeks following hospitalization. Invasive devices that remain placed during the postdischarge period, progression from colonization to clinical infection and breakdowns in host defense and skin integrity during hospitalization may account for this increased risk.
Although the decreases in infection rates are encouraging, invasive MRSA infections with onset in the community or outpatient setting remain problematic and represent the majority of invasive MRSA infections, the authors wrote. Future research is needed to understand the progression of colonization and non-invasive MRSA infection to invasive infection in outpatient settings. Future prevention efforts should target both community and healthcare transmission, especially among patients with recent hospitalization.
Study abstract: http://archinte.jamanetwork.com/article.aspx?articleid=1738718.