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A recent report analyzing data from 2005 through 2008 of nine metropolitan areas in the U.S. indicates healthcare-associated (HA) invasive methicillin-resistant Staphylococcus aureus (MRSA) infections have decreased among patients with infections that began in the community or in the hospital, according to a study in JAMA (JAMA. 2010;304[6]:641-648).
An estimated 1.7 million HA infections are associated annually with 99,000 deaths in U.S. hospitals, according to the study.
The CDC's Alexander J. Kallen, MD, MPH, and colleagues used a population-based surveillance system to evaluate the incidence of invasive HA-MRSA infections covering a population of approximately 15 million persons.
Reported laboratory-identified episodes of invasive MRSA infections were evaluated and classified based on the setting of the positive culture and the presence healthcare exposures. HA infections made up 82 percent of the total.
 Overall, the participating surveillances sites reported 21,503 cases of invasive MRSA infections for the years 2005 through 2008, with 17,508 cases either hospital-onset or HA community-onset. Most HA infections (15,458) involved a positive blood culture and were classified as a bloodstream infection.
"The modeled incidence, adjusted for age and race, of hospital-onset invasive MRSA infections significantly decreased 9.4 percent per year from 2005 through 2008; while there was a significant 5.7 percent decrease per year in the modeled incidence of HA community-onset infections. This would equate to about a 28 percent decrease in all hospital-onset invasive MRSA infections and about a 17 percent decrease in all invasive HA community-onset infections over the 4-year period," the authors wrote.
A subset analysis limited to blood stream infections demonstrated a larger decrease in the modeled yearly incidence rates of both hospital-onset (-11.2 percent) and HA community-onset (-6.6 percent) BSIs, equating to about a 34 percent decrease in all hospital-onset MRSA BSIs and about a 20 percent decrease in all HA community-onset BSIs over the 4-year period.
"Taken together with data from more than 600 intensive care units nationwide, these findings suggest that there is a real decrease in MRSA infection rates among patients in U.S. hospitals. As highlighted in the recently finalized HHS Action Plan to Prevent HA Infections, prevention of invasive MRSA infections is a national priority," the authors concluded.
Battling Infection
While the news is welcome, the researchers have yet to attribute the reduction to any particular MRSA prevention practices.
Tobi B. Karchmer, medical director for BD Diagnostics, told ADVANCE common infection prevention and control programs being implemented range from basic activities (e.g., hand hygiene, appropriate utilization of isolation precautions and environmental cleaning); to active surveillance (i.e., actively seeking to detect MRSA colonized patients and utilize contact precautions, including gowns, gloves and occasionally private rooms, for both colonized and infected patients).
Additionally, some institutions have also implemented decolonization with mupirocin or chlorhexidine baths to decrease the risk of MRSA infections rates in individual patients as well as potentially decreasing transmission.
According to Karchmer, these practices have been proven in studies from Drs. Lance Peterson and Ari Robicsek from NorthShore University HealthSystem (Evanston, IL) and Dr. Keith Ramsey from Pitt County Memorial Hospital (Greenville, NC).
NorthShore University HealthSystem tested all patients upon admission for MRSA for 4 years. Study results found 406 potential MRSA infections were avoided, corresponding with $8.8 million of excess cost avoided. NorthShore University HealthSystem avoided 72 potential deaths from invasive MRSA in these 4 years, Karchmer related.
A study conducted by Pitt County Memorial Hospital found active surveillance testing of patients for MRSA combined with a comprehensive infection prevention and control program reduced MRSA device-related HA infections by at least half, he added.
Additional Threats
While any progress is encouraging, the study authors caution the work is far from done. "Although these data suggest progress has occurred in preventing HA MRSA infections, more challenges remain. Increasing adherence to existing recommendations and addressing MRSA transmission and prevention beyond inpatient settings are challenges that will require further effort and investigation if eliminating the goal of preventable health care-associated invasive MRSA infections is to be attained," the authors noted.
Indeed, HA infections have not been eliminated or even reduced to acceptable levels in all areas of healthcare, Karchmer pointed out. The study recorded the decline was not recognized in all geographic areas studied.
Additionally, there are a number of other resistant organisms already established as problems or which are beginning to become a problem in healthcare institutions, such as extended-spectrum beta lacatamase containing Gram-negative bacilli and Klebsiella pneumoniae Carbapenemase containing Gram-negative rods, and vancomycin-resistant enterococci. Clostridium difficile infections are also increasing in incidence and severity in the U.S., Karchmer noted.
Ultimately, it is important to have an infection control foundation in place including hand hygiene, an understanding of how infections occur and a system for measuring infections, Karchmer stressed. "These components are the core of any infection prevention program."
In addition to this foundation, Karchmer noted, if MRSA HA infections remain a problem at an institution then additional activities should be implemented including but not limited to active surveillance testing.
Kerri Hatt (khatt@advanceweb.com) is managing editor of ADVANCE.
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