The authors wrote that they could not say why the infection rates have dropped, "a number of factors might have contributed, including the dissemination of MRSA prevention practices in many U.S. hospitals."
Eight of the sites demonstrated a decrease, six of which were statistically significant, but one site experienced a significant increase over the period.
A subset analysis limited just to bloodstream infections showed a 34% decrease in all hospital-onset cases and a 20% decrease in health-care associated or community onset cases. The authors wrote that "much of the estimated reduction in these infections might have been due to the dissemination of inpatient central line-associated BSI prevention efforts rather than MRSA-specific prevention efforts," specifically, the Michigan Keystone ICU project and the Pittsburgh Regional Health Initiative Project.
The only group that did not see a consistent decline was that isolated for patients undergoing dialysis, a category in which most of the decline occurred in 2008.
In an accompanying editorial, Eli Perencevich, MD and Daniel Diekema, MD of the University of Iowa Carver College of Medicine suggest the decline in infections began earlier than specific MRSA prevention campaigns, "and such interventions still have not been implemented in many U.S. hospitals.
"Therefore, the observed declines in MRSA reported may instead be the result of general infection control efforts such as wider adoption of alcohol-based hand rubs, improved hand hygiene compliance, efforts targeted at eliminating central line-associated bloodstream infections and enhanced antimicrobial stewardship programs."
The authors also note that "natural biological trends," such as the emergence and disappearance of bacteria clones, "are likely to override the best-laid attempts at infection control of all staph infections, not just MRSA.
Also, they wrote, robust surveillance systems are lacking for additional metropolitan areas, and even those are only tracking MRSA as a sole pathogen. "Continued surveillance for S aureus and the other important healthcare-associated pathogens (eg, Enterobacteriaceae, Pseudomonas, Acinetocbacter, Candida)" is essential for informing and targeting infection prevention efforts.