Hospital-acquired MRSA infections decline between 2005 and 2008

Infections with the deadly methicillin-resistant Staphylococcus aureus (MRSA) bacteria contracted in hospitals and other healthcare settings have declined 28% over a 4-year period, according to a new Centers for Disease Control and Prevention (CDC) study of about 15 million people. The study was published in the Aug. 11 issue of the Journal of the American Medical Association, HealthDay News reported.

CDC researchers report that rates of “invasive” MRSA infections that had their onset in hospitals or other healthcare facilities declined an average 9% annually from 2005 through 2008. Invasive MRSA infections are those that are found in a normally sterile body site, such as the bloodstream.

According to the study, invasive MRSA infections that were associated with healthcare settings, but began in the community, declined by about 6% annually, for a total decrease of 17% over the 4-year period.

“While we don’t know for sure what caused these rates to go down, we’re hopeful and encouraged that the aggressive infection control programs that many hospitals have instituted are having an impact,” said lead author Alexander J. Kallen, MD, MPH, medical officer in the division of Healthcare Quality Promotion for CDC.

For the study, Dr. Kallen and colleagues evaluated a CDC population-based surveillance system of MRSA infections that covers 9 U.S. metropolitan areas. After evaluating all reports of laboratory-identified episodes of invasive MRSA infections, they limited their analysis to infections that began in hospitals or those that began in the community but were associated with a healthcare setting. MRSA infections associated with healthcare settings made up 82% of the total infections. The researchers did not evaluate community-acquired MRSA infections.

A subset analysis of only bloodstream infections showed even greater decreases: a 34% drop in hospital-onset infections and an approximate 20% decrease in community-onset infections over the 4-year period.

The authors of an editorial accompanying the study said that while the findings are encouraging, government surveillance systems should be expanded to more geographical areas and should include all Staphylococcus aureus infections and other healthcare-associated pathogens.

“Even if MRSA causes half of all Staph infections, that means other strains of S. aureus are causing the other half, and we need to focus on these infections as well,” said co-author Daniel J. Diekema, MD, director of the division of infectious diseases at the University of Iowa Carver College of Medicine. Dr Diekema said broadening the surveillance requires more funding. “But we think it will be well worth it in the long run,” he said.

Daniel J. Sexton, MD, director of the Duke Infection Control Outreach Network, Durham, N.C., a collaboration between Duke University Medical Center and 39 community hospitals in 4 states, said the findings confirm what recent smaller studies have shown.

“We were aware from our own data, as well as other regional data presented at meetings, that MRSA rates have dropped dramatically,” he said. “But this population-based study is important because it shows that the decline is occurring across broad geographical regions.

“It’s unlikely that any one type of intervention is the reason for the decline, because rates have dropped all across these areas, where people are doing all kinds of different things,” he added.