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MRSA Surveillance

Active Bacterial Core surveillance (ABCs)

ABC icon ABCs is an active laboratory- and population-based surveillance system for invasive bacterial pathogens of public health importance. For each case of invasive disease in the surveillance population, a case report with basic demographic information is completed and bacterial isolates are sent to CDC and other reference laboratories for additional laboratory evaluation. ABCs also provides an infrastructure for further public health research, including special studies aiming at identifying risk factors for disease, post-licensure evaluation of vaccine efficacy, and monitoring effectiveness of prevention policies. At this time, ABCs conducts surveillance for six pathogens: group A and group B Streptococcus (GAS, GBS), Haemophilus influenzae, Neisseria meningitidis, Streptococcus pneumoniae, and methicillin-resistant Staphylococcus aureus (MRSA).

Prevalence of S. aureus and MRSA colonization

In 2003-2004, approximately 29% (78.9 million persons) and 1.5% (4.1 million persons) of the U.S. population was colonized in the nose with S. aureus and MRSA respectively. (Gorwitz RJ et al. Journal of Infectious Diseases. 2008;197:1226-34.)

Burden of S. aureus and MRSA infections

In 2005, there were an estimated 478,000 hospitalizations with a diagnosis of S. aureus infection in U.S. hospitals. Of these approximately 278,000 hospitalizations were related to MRSA. This includes people admitted to the hospital for treatment of an infection that was acquired or occurred outside the hospital. (Klein E et al. Emerging Infectious Diseases. 2007;13:1840-6.)

In Hospitals

The proportion of healthcare-associated staphylococcal infections that are due to MRSA has been increasing: 2% of S. aureus infections in U.S. intensive-care units were MRSA in 1974, 22% in 1995, and 64% in 2004. (Klevens RM et al. Clinical Infectious Diseases 2006;42:389-91)
More recent evaluations have documented a stabilization of this trend, with only 56% of device-associated infections with S. aureus reported as MRSA in 2006-2007 (Hidron AI et al. Infect Control Hosp Epidemiol 2008;29:996-1011)
The most recent estimates of the incidence of healthcare-associated infections with MRSA show decreases in these infections in the U.S.

Incidence of MRSA central line-associated bloodstream infections reported from hundreds of different intensive care units have decreased 50-70% between 2001 and 2007 (Burton D, et. al JAMA. 2009;301(7):727-736)
A separate system tracking MRSA bloodstream infections from all types of hospitalized patients demonstrated a 34% decrease in incidence of these infections among hospitalized patients between 2005 and 2008 (Kallen A, et. al., JAMA, 2010 in press).

Invasive Infections

In 2005, about 94,000 persons developed their first invasive (i.e., serious) MRSA infection, of which approximately 19,000 died. Of these infections, about 86% are healthcare-associated and 14% are community-associated. (Klevens et al. Journal of the American Medical Association 2007;298(15):1763-1771 [PDF 229KB/9 pages]
National estimates of the number of invasive MRSA infections are performed yearly by Active Bacterial Core surveillance (ABCs).

Skin and Soft Tissue Infections in the Community

In 2005, there were an estimated 14 million outpatient (i.e., physician offices, emergency and outpatient departments) healthcare visits for suspected S. aureus skin and soft tissue infections in the United States. (Hersh AL et al. Arch Intern Med. 2008;168:1585-91.)
In 2004, approximately 76% of purulent (i.e., containing pus) skin and soft tissue infections (SSTIs) in adults seen in 11 emergency departments were caused by S. aureus. Of these infections 78% were caused by MRSA and overall MRSA caused 59% of all SSTIs. (Moran GJ et al. New England Journal of Medicine. 2006; 355:666-74.)

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