Home Feature Who should you screen for MRSA?

Who should you screen for MRSA?

May 2008

Published in the May 2008 issue of Today’s Hospitalist

WHEN EVANSTON NORTHWESTERN HEALTHCARE system launched a universal screening program to detect patients colonized with methicillin-resistant Staphylococcus aureus (MRSA) on admission, the idea seemed radical. The program was costly, and no other hospital in the U.S. was doing anything remotely similar.

While active screening programs in countries like Denmark have helped contain MRSA rates, they have not received the seal of approval from the CDC or professional societies. But three years later, while Evanston Northwestern Healthcare’s MRSA screening program is still far from the norm, it no longer seems so extreme. A few smaller hospital systems are swabbing the noses of all incoming patients to look for MRSA colonization, as are all 153 Veterans Affairs hospitals around the country.

And there’s more activity on the horizon. Several states have passed laws requiring hospitals to do some type of MRSA screening, and more than 20 other states are debating infection control legislation. New practice guidelines are in the works, and health care payers, quality improvement organizations and hospital accrediting bodies are all debating the pros and cons of universal surveillance.

When it comes to the debate about whether active surveillance is essential to control the spread of hospital-acquired MRSA, William R. Jarvis, MD, a consultant and leading expert on inpatient infection control, says that the U.S. has reached a “tipping point.” While the screening issue continues to polarize the infectious diseases community, the question may no longer be whether to screen at all for MRSA, but who and how to screen.

Differing conclusions
The screening debate heated up earlier this year when two studies published a week apart reached strikingly different conclusions. The first study, which appeared in the March 12, 2008, Journal of the American Medical Association (JAMA), found that screening patients on admission to the surgical wards of a Swiss hospital did little to reduce MRSA infection rates.

But a second study, published in the March 18, 2008, Annals of Internal Medicine, found that a three-stage intervention at three hospitals slashed MRSA rates by 70%. The study, which was conducted at Evanston Northwestern Healthcare, screened all patients, not just those on surgical wards. It also used concurrent interventions like decolonizing carriers with topical mupirocin and chlorhexidine baths (as did the Swiss study), and giving providers feedback on how well they met screening guidelines.

The studies seem to stake out opposing positions on MRSA screening, but their results are anything but clear cut. While the JAMA study seems to weaken the case for screening, for example, screening proponents claim that those results actually help bolster the case for screening all patients and isolating carriers of MRSA. They say that the intervention didn’t work in the Swiss surgical wards because screening wasn’t broad enough to identify all inpatient carriers.

And while the Annals study makes a strong case for universal MRSA screening, an accompanying editorial pointed out that more research is needed to tease out which components of the multiple interventions at Evanston Northwestern Healthcare were most important. The editorial went on to say that while the study’s reduction in infection rates was impressive, adopting universal screening based on those results “would be premature.”

Some consensus
While hospitals may not be ready to commit to universal screening, infectious diseases experts say there is growing consensus that at the very least, more active surveillance is warranted, particularly in hospitals where the superbug is a problem.

“My personal opinion is that it is very useful for hospitals to perform a point prevalence study “such as screening ICU patients once or twice a year “to get a handle on the numbers,” says Susan S. Huang, MD, assistant professor of infectious diseases and medical director of infection control at University of California, Irvine.

Prevalence studies may be particularly helpful, she adds, in tertiary care centers or large hospitals with a lot of ICU beds. “In those settings, it’s a good idea to screen and isolate, or at least to demonstrate that MRSA is not a problem in your facility,” says Dr. Huang. “The question that hospitals are asking now is the right one: Does my hospital, which may be small and in a seemingly unaffected area where we don’t see a lot of MRSA infection, need to screen?”

No one-size-fits-all
Dr. Huang says targeted screening, which focuses on high-risk populations, may be right for many hospitals. Screening targets may include medical or surgical patients in the ICU; individuals who are immunocompromised or on hemodialysis; patients coming from nursing homes; and patients with previous histories of MRSA.

A study that Dr. Huang performed at Brigham and Women’s Hospital in Boston and published in the Oct. 15, 2006, issue of Clinical Infectious Diseases found that screening all ICU patients resulted in “large and statistically significant reductions in the incidence of MRSA bacteremia” across the entire hospital.

According to Dr. Huang, researchers reduced MRSA infection rates hospital-wide by actively screening everyone in the ICU “not all patients. The initiative may have produced benefits that extended beyond the ICU, she says, in part because the proportion of ICU beds to all beds at Brigham and Women’s is so high. And while universal screening wasn’t necessary, Dr. Huang adds, active surveillance of high-risk populations was critical to the study’s success.

At Evanston Northwestern Healthcare, by contrast, where ICUs don’t account for a high portion of patient rooms, MRSA rates didn’t budge until universal screening was introduced. According to Lance R. Peterson, MD, the epidemiologist who spearheaded the program and who was the lead author of the Annals study, only about one-quarter of the patients found to be colonized with MRSA would have been detected with ICU-only surveillance.

Plus, Dr. Peterson points out, the more complicated you make the protocol to screen patients, the fewer doctors and nurses will remember to swab. Because his goal was to find 100% of MRSA carriers, it was logistically simpler to swab everybody on admission.

“Our number of transmissions went from 1,300 before we were doing surveillance to about 80 after,” Dr. Peterson says. “The reduction occurred quickly, and the rates are still going down after two years.”

Smaller-scale efforts
While large teaching centers have led the way on large-scale screening efforts, some community hospitals are getting into the act on a smaller scale. They are tailoring surveillance efforts to local infection rates and patient populations.

In Western New York, for instance, where the 40- physician Endion Hospitalist System serves three hospitals and two long-term care facilities, MRSA rates “are really, really ugly,” says the group’s president and CEO, John Brach, MD, a practicing hospitalist. “People are now contracting MRSA from what would have previously been considered casual health care contacts in physician centers and outpatient diagnostic centers.”

Two of the hospitals where Endion physicians work have started limited surveillance programs: United Memorial Medical Center in Batavia, N.Y., which launched a screening program two years ago, and Mercy Hospital of Buffalo, a tertiary facility that began targeted screening this year.

The 110-bed United, which has many private rooms, takes a decidedly low-tech approach, screening only for patients who have a history of MRSA or those who are chronic carriers, relying on medical records and patients’ history and physical. “They definitely have been successful at controlling the hospital threat,” Dr. Brach says.

At Mercy, high-risk patients “defined as the elderly and individuals from nursing homes “are getting nasal swabs. If they are found to be carriers, they’re either isolated or put with other patients who test positive.

The hospitalists at Mercy do some swabbing and are still working out swabbing logistics, according to Dr. Brach. “There’s been some discussion: Should it be nurses’ responsibility or physicians?'” he says.

Not surprisingly, there has been some pushback from medical staff. “They’re fearful about identifying patients who are colonized, who will then be permanently labeled,” he explains. “No other patients will want to be in the room with these people.”

But while Dr. Brach says that neither hospital has plans to expand screening to low-risk patients, “that may change with time.” Although screening efforts in both hospitals are somewhat limited, he believes they are cost effective and will lay the groundwork for figuring out how to control other major community threats, including increasingly virulent strains of C. difficile and VRE.

“It absolutely will lead to better control of them all,” says Dr. Brach. “We’re just in the infancy of identifying basic, low-cost opportunities to control these bugs in our community.”

Out of time?
Even the most passionate advocates of universal screening acknowledge that screening alone is not the answer for MRSA or any other type of infectious disease.

They say that screening has to be coupled with tried-and-true, evidence-based infection control practices, from compulsive hand hygiene to contact isolation (including gowns and gloves) and environmental cleaning.

Experts at the CDC “think that a narrow strategy is unlikely to work,” explains John Jernigan, MD, one of the agency’s top MRSA experts. “We think hospitals are going to have to implement a multifaceted, comprehensive strategy that attacks the problem from several different angles.”

Part of the problem, Dr. Jernigan adds, is that it is difficult to say what the best combination of interventions is for any given facility. The best strategy, including what precise role active surveillance should play, may differ among hospitals due to different settings and patient populations. “It’s an area in which the level of evidence is not as crystal clear as we would like it to be,” he explains.

But while infection control experts may wish they had more definitive evidence on screening, they may have run out of time. Not only are legislatures now focused on inpatient infections, but there is some discussion that the Centers for Medicare and Medicaid Services (CMS) may add MRSA to its list of preventable inpatient complications that it will no longer pay for. In addition, the Joint Commission’s proposed list of 2009 national patient safety goals may include a focus on MRSA, including active surveillance testing.

Says Dr. Jarvis, who consults for the Association for Professionals in Infection Control and Epidemiology: “The public is basically saying, ‘If you don’t do it, we will make you.’ ”

Good health care and good business
Some hospitals are not waiting to be forced to implement MRSA screening “or for all of the evidence to come in on a public health threat that regularly makes headlines.

The Nashville-based Hospital Corporation of America (HCA), for instance, with its 170 hospitals across the country, has come to view MRSA control as not only good health care, but good PR and good business.

A corporate initiative kicked off last year includes active surveillance of all high-risk patients on admission to any hospital in the system. Hospitals are not billing payers for that surveillance, according to Betsy Blair, vice president of quality and risk for HCA’s Richmond Health System.

While the company does not yet have data on its MRSA transmission rates, Ms. Blair notes that, on average, 10% of the swabs are coming back positive for MRSA at the six HCA hospitals around Richmond that she oversees.

“We did get some complaining at first,” she says, adding that the hospitals are still struggling with how to get doctors to improve their hand hygiene. (Spot checks show that nurses are doing better than physicians.)

Still, identifying and isolating patients with MRSA is “the right thing to do,” says Ms. Blair. “It’s a national health care concern, so it’s a performance expectation for our staff.”

Deborah Gesensway is a freelance writer reporting on U.S. health care from Toronto, Canada.

Beyond identification: how to treat carriers

TO LAY PEOPLE “and that includes patients, payers and hospital administrators “universal MRSA screening may seem like the obvious thing to do. Nasal swabs aren’t invasive, and faster testing methods, from relatively inexpensive clinical culturing to more expensive but quicker PCR testing, are now on the market.

The reality, however, is that deciding what to do with patients in whom MRSA is detected can be tricky. Many infectious diseases experts, including those who have studied the natural history of S. aureus, say there’s a big difference between being “colonized” and developing an illness.

It’s true that asymptomatic chronic carriers are more likely to develop illness and to “shed” it into the environment, infecting others. Among hospitalized patients, one estimate has the percentage of colonized people who develop full-blown MRSA infections averaging about 15% over the following six to eight months. (Other estimates run as high as 33% over the course of a year among commercially insured patients at a tertiary care center.)

That’s why there’s a problem “treating all carriers as if they are at equal risk of spreading the disease,” says Suzanne Bradley, MD, professor of internal medicine, infectious diseases and geriatrics at the University of Michigan. “In nursing homes, we have detected MRSA colonization, but no illness, in the same patient over a four-year period. Do you want to isolate that person for four years?”

Dr. Bradley points out that isolation can have grave effects for patients. “There are good data that people who stay in isolation are at greater risk of depression,” she says. “They get pressure ulcers and have more falls.” There can also be psychological consequences, including depression, anxiety and anger, from labeling “well” people as disease carriers.

Moreover, Dr. Bradley cautions, people who believe that universal screening by nasal swabs will pick up all MRSA carriers do not understand the organism; some carry MRSA in their pharynx, throat, rectum or wounds, but not in their nose. Another obstacle: Patients on antibiotics may not have their MRSA detected.

Still another objection raised about universal screening has to do with what Daniel Diekema, MD, hospital epidemiologist and associate professor of infectious diseases at the University of Iowa, calls “MRSA exceptionalism.”

Is MRSA so different a “threat to our patients,” he asks, “that we need to focus our energies on it specifically, even if this means that we have to cut back in some other area?” Or, “does one approach it as one of many threats that exist in the hospital?”

Although MRSA is clearly what Dr. Diekema calls “an ongoing global epidemic,” he points out that the latest CDC survey found that MRSA accounts for 8% of hospital-acquired bacterial infections. “That means that organisms other than MRSA account for 92% of hospital-acquired bacterial infections.”

According to Richard P. Wenzel, MD, professor and chair of internal medicine at Virginia Commonwealth University in Richmond and one of the nation’s leading infectious diseases experts on antibiotic resistance, universal screening may reduce MRSA, but it may not catch other infections.

“I want to see an infection control program reduce all infections” in a hospital, Dr. Wenzel says. “The goal should be to reduce all bloodstream infections, not just a subset.”