MRSA drops in ICUs, but BSI battle awaits in wards
IP interventions credited for declining infections
Infection prevention efforts appear to be making a dramatic difference in hospital intensive care units, which are reporting declining rates of methicillin-resistant Staphylococcus aureus (MRSA) central line-associated bloodstream infections (BSIs), the Centers for Disease Control and Prevention reports.
The CDC reported that MRSA central line- associated BSI incidence has declined in recent years in all major adult ICU types and has remained stable in pediatric ICUs.1 Overall, 33,587 central line–associated BSIs were reported from 1684 ICUs. Declines in MRSA central line–associated BSI incidence ranged from 51.5% in nonteaching-affiliated medical-surgical ICUs to 69.2% in surgical ICUs. Although the overall proportion of S. aureus central line-associated BSIs due to MRSA increased 25.8% in the 1997-2007 period, overall MRSA central line-associated BSI incidence decreased 49.6% over the period, the CDC reported.
"The overall decline in incidence stands in sharp contrast to trends in percent MRSA, which give an incomplete picture of changes in the magnitude of the MRSA problem over time and may have led to a misperception that the MRSA central line-associated BSI problem in ICUs has been increasing," the authors noted. It's a bit of an "apples-and-oranges" comparison, but essentially, the researchers are saying that looking at the rising percent of MRSA among all staph infections does not tell the whole story.
"The incidence measure of MRSA, which we focused on for this analysis is a measure of actual risk — meaning the rate of disease for a certain number of patients who are exposed to central lines for a certain amount of time," explains lead author Deron C. Burton, MD, JD, MPH, a medical epidemiologist in the CDC division of healthcare quality promotion. "The percent of MRSA is really answering a different question, which is: If you have a health care-associated infection that is caused by Staph aureus, what is the likelihood that the particular staph will be MRSA? In our study, we saw that the proportion of staph bloodstream infections that are in fact caused by MRSA has actually [increased] over the study period. That is the percent MRSA [measure]. But in fact, the numbers — the risk, the rate of infections — has gone down dramatically for all Staph aureus infection, including both MRSA and methicillin-susceptible S. aureus [MSSA]."
No specifics, but IP efforts credited
Indeed, declines in the incidence rates of MSSA and total central line-associated BSIs in all major non-neonatal ICU types studied suggest that general central line-associated BSI prevention efforts are succeeding and may have contributed to the observed MRSA trends, Burton and colleagues concluded. Such prevention efforts, as we have reported, include a checklist for central line insertion that has virtually eliminated catheter-related bloodstream infections in some participating sites. Originally developed at Johns Hopkins, could we be seeing the bountiful results of this expanding program and similar prevention efforts in ICUs?
"We were not able to assess specifically which interventions are having the most impact or being used most commonly," Burton says. "That information isn't reported to us through our surveillance system."
Still, the CDC arrived at the general conclusion that infection prevention efforts must be playing a key role, though the study includes a few caveats about the findings. "In the literature, there have been reports of success on the local scale or among groups of hospitals in [reducing] these infections using these prevention strategies," Burton says. "Taking all of that together, it seems most plausible to us that some of these interventions — or perhaps all of them — are having in the aggregate a substantial impact and causing these declines."
In an interesting caveat, the CDC noted that reports of high rates of MRSA have prompted calls for mandatory screening or reporting in efforts to reduce MRSA infections in health care. "Concerns have been raised that the enactment of state laws requiring health care facilities to report rates of health care-associated infections to state agencies, the public, or both provides a disincentive for facilities to conduct thorough [HAI] surveillance and to accurately report health care-associated infections that are identified," the CDC investigators observed. "The trend analysis presented in this article was not designed to examine the potential impact of public reporting laws on [HAIs], but it is unlikely that the observed trends in central line-associated BSI incidence can be explained by such impacts."
Nevertheless, as increasing numbers of states implement mandatory public reporting requirements for HAIs, evaluating the impact of such requirements on health care-associated infection surveillance practices and reporting to the CDC will be critical, the researchers concluded.
"We are confident that the results that we demonstrated in this analysis aren't being driven by mandatory public reporting laws, primarily because the majority of the time period covered preceded implementation of public reporting laws nationally," Burton says. "We believe that declines were happening prior to implementation of those strategies. But it may be — and other evidence may show — that those additional measures are continuing to accelerate the decline — or perhaps not."
In raising the issue of infection rate disclosure laws, the CDC seems to beg the question of whether such measures are really needed if ICUs are reporting these declines in their absence. Burton declined comment on that aspect, saying the paper is not an attempt to establish CDC "policy." An infection preventionist who looked at the findings was less diplomatic.
"The reduction of MRSA in ICUs didn't come about because of legislation," says Susan Kraska, RN, CIC, an IP at Memorial Hospital of South Bend, IN. "It came about because IPs have been working their tails off. Because things are being looked at more closely, many IPs who didn't have support from their organizations have begun to get opportunities for resources and training to implement a lot of the strategies we know work."
William Jarvis, MD, a former leading CDC hospital outbreak investigator now in private consulting, agreed that the results reflect improved infection prevention in ICUs. "I think it shows we are making tremendous progress — which is wonderful — in controlling CVC BSIs," he says. "It shows that more and more pressure is being exerted on intensive care units to include an insertion bundle, a maintenance [protocol], the use of checklists — standardized practices of what we know work."
That said, Jarvis provides a reality check on the findings: Most MRSA infections do not occur in ICUs. "We are making a big deal out of controlling MRSA in the ICU when in fact, MRSA BSIs in the ICU are a drop in the bucket for MRSA," he says. "To say we are controlling MRSA because we are controlling it in the ICU, where we have [applied] interventions such as active surveillance testing, it's easier to do contact isolation and monitor [compliance] and we have had those [aforementioned] BSI interventions. The fact remains — and CDC can't address it because they don't have the data — 70% of BSIs occur outside the ICU. What are we doing with those?"
Burton concedes the point, but says the study still focused on a very important subset of patients. "A relatively small portion — something probably substantially less than half — are in this category of bloodstream infections specifically, associated with central lines specifically, and in ICUs specifically," he says. "So, those three sort of narrowing factors that were key in this analysis do wind up representing a relatively small portion of the overall MRSA problem. However, we think this is a very important subset, even if it is a relatively small one, because intensive care unit patients are particularly vulnerable. They are at particular high risk for infection and for severe complications of those infections."
CDC surveillance is expanding to other areas and, "in the future, we'll be able to look more broadly [at MRSA]," Burton adds.
There appears to be plenty left to find, despite the gains in the ICUs. Jarvis conducted an MRSA prevalence study in 2007 for the Association for Professionals in Infection Control and Epidemiology. The one-day "snapshot" study found that 46 out of every 1,000 patients in participating facilities of all stripes and sizes were colonized or infected with MRSA. Thus, the real challenge to reduce MRSA BSIs remains on the hospital wards, not the ICUs, he says.
"Obviously, if CMS and insurance companies stop paying for them we are going to have to address them," Jarvis says. "It's a much bigger problem than addressing them in the ICU where you have a small number of staff that you have to train and monitor. Now you have a huge hospital staff you have to train and monitor [on the wards]."
As a result, hospitals may end up forming IV teams specifically trained to insert and handle central lines on the wards. "Outside the ICU, I think we are going to see a reversal of what happened over the last 10 to 15 years," Jarvis says. "I know as I go around the country and talk at meetings, I hear that IV teams are being cut. I think that is going to be reversed, because I just don't see how we are going to be able to apply the checklist and the education and the process and outcome monitoring hospitalwide."
Reference
- Burton DC, Edwards JR, Horan TC, et al. Methicillin-resistant Staphylococcus aureus central line-associated bloodstream infections in U.S. intensive care units, 1997-2007. JAMA 2009; 301(7):727-736.
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