MRSA active surveillance: One size does not fit all

MRSA prevalence key to cost-effectiveness

States that pass laws requiring universal active surveillance cultures for methicillin-resistant Staphylococcus aureus (MRSA) may saddle some small, community hospitals with a practice that is not cost-effective, according to ongoing research in an upstate New York hospital group.

It appears in general that the cost-effectiveness of actively screening patients is in direct relationship to the prevalence of MRSA in the patient population. Thus requiring hospitals that see little or no MRSA to actively screen patients for it would not be cost-effective, according to data emerging from a study of 25 community hospitals that are member facilities in the Iroquois Healthcare Association in Clifton Park, NY.

"That's correct," says Carol Van Antwerpen, RN, CIC, a lead researcher on the project. "That is what our data suggest, and our hospitals probably represent the majority nationally. Something like 16% of [U.S.] hospitals are larger then 300 beds, and they are the ones that seem to be driving the MRSA issue. But the majority of the hospitals in the United States are community, nonteaching settings. That's why we think our results are kind of interesting because they do represent the majority of hospitals."

While the results are still being analyzed, preliminary findings indicate that "hospitals with high nosocomial MRSA (N-MRSA) rates would experience substantial cost savings through prevention of N-MRSA transmission by implementing selective culture screening. On the other hand, the cost savings of implementing selective culture screening to identify cases for hospitals experiencing a low incidence of N-MRSA case was not observed."1

Still, there appears to be little argument active surveillance can be cost-effective if there is sufficient prevalence of MRSA in the patient population. Indeed, another recent study at a 200-bed community hospital found that screening patients for MRSA in selected areas such as the intensive care unit can increase patient safety and save dollars even if there is relatively low prevalence of resistant staph in the patient population.

"We really don't have a high rate of MRSA relative to national levels, says Raymond Vautour, MD, chairman of infection control committee at Mount Nittany Medical Center in State College, PA." So we really didn't see a lot of infections, yet after implementing the [culture screening] program, we were still able to show that it was cost-effective."

Indeed, even in the setting of a community hospital with relatively low prevalence of MRSA (34% of staph isolates resistant), implementation of an active surveillance program for MRSA was shown to be a cost-effective strategy, reducing the risk of acquiring MRSA infection and avoiding associated excess cost of care, he found.2 Interestingly, a similar benefit was not found for screening for vancomycin resistant enterococci (VRE) because there was no significant prevalence of the pathogen in the patient population, he notes.

The MRSA screening protocol was implemented with the opening of a new 12-bed medical/surgical intensive care unit (M/SICU). Surveillance cultures (nares and open chronic wounds if present) were collected on admission, every seven days, and on discharge from the unit when length of stay was at least four days. Contact isolation precautions were instituted pending report of negative initial screening cultures. "They were presumed guilty," Vautour jokes.

During the protocol period (July 2004-July 2005), one patient acquired a MRSA infection (0.47 patients/1,000 patient days). In the one-year period preceding protocol implementation, five patients developed nosocomial infection related to MRSA in the critical care unit (3.3 infections/1,000 patient days). Using the pre-protocol rate of infection (3.3 infections/1,000 patient days) applied to patient days during the protocol period (2,117), an estimated six MRSA infections were averted.

"Looking at how many patient days we had in the years 2004-2005 and using that number as 3.3 infections per 1,000 days, we would have expected seven infections," he explains. "We saw one infection so we avoided six infections."

Using a published mean attributable cost associated with MRSA infection of $35,367, an estimated $212,000 in excess infection-associated cost was averted, he reports.3 The estimated direct cost (material and labor) for conducting the surveillance protocol was $40,000. "Even with those significant costs, we still showed that it was cost-effective," Vautour says.

While ICU screening yielded considerable bang for the buck, Vautour isn't sure the practice would be as cost-effective if taken beyond ICUs and high-risk groups. "We have not moved it to other units except a neonatal unit where babies are coming back from other hospitals," he says. "We do screening there, but we haven't moved it to other places. I guess that is the logical next step to see if it would be cost-effective in other settings."

Though the ongoing study in the New York hospital group found questionable benefit of screening in low prevalence populations, looking for MRSA in the ICUs might be cost-effective, Antwerpen says.

"The data would suggest in the facilities that have more nosocomial MRSA that do culture screening — those that were especially looking at the intensive care unit might have more cost benefit," she says. "It might be worthwhile. It did vary somewhat."

For example, the cost benefit of MRSA screening might vary by type of ICU, she notes, adding that another variable is whether the hospital is affiliated with a long-term care setting or other patient population that might serve as a reservoir for MRSA colonization. Each hospital must consider such factors as the nosocomial MRSA infection rate, the level of MRSA in the community, the costs of care and the costs of screening when considering whether to implement the strategy, she notes.

SHEA-APIC position paper expedited

The issue is important because at least two states already have considered laws requiring some version of active surveillance cultures. Legislation is expected to be reintroduced this year in Illinois that would require hospitals to screen all patients for MRSA in accordance with guidelines published by the Centers for Disease Control and Prevention. The CDC is expected to soon finalize new guidelines on multidrug-resistant pathogens that include use of active surveillance cultures if the institution is not decreasing MRSA rates or if it has no MRSA and is trying to prevent the pathogen from getting established.

Similar legislation was introduced in Maryland and failed, but likewise is expected to reintroduced in the near term. The issue has been complicated by the fact that the Society for Healthcare Epidemiology of America (SHEA) began advocating the practice while the CDC was delayed in a protracted review of its guidelines. While the CDC has been more cautious about advocating the practice, SHEA recommends culturing the nares of targeted patients on admission or periodically thereafter to detect and isolate the reservoir of resistant organisms.4 The SHEA guidelines recommend the practice so colonized patients can be placed in contact isolation rather than serving as an undetected source to spread the pathogens to other patients.

To provide vital input on the process before other states start considering MRSA surveillance laws, SHEA and the Association for Professionals in Infection Control and Epidemiology (APIC) were trying to expedite release of a joint-position paper as this issue of Hospital Infection Control went to press. There is some concern that MRSA legislation could start appearing state by state in much the same fashion as infection rate disclosure laws.

"It needs to get approval from both societies before it's published, but it's close," says Shannon Oriola, RN, CIC, COHN, chair of the APIC mandatory reporting task force. "Our hope at both SHEA and APIC is that the position paper will guide legislators considering sponsoring such legislation. So we are really trying to get it out. It specifically addresses whether you should legislate active surveillance of resistant bacteria. The question is if you are a state considering implementing it what are the considerations. It is a way to approach the issue."


  1. Antwerpen CV, Caffrey A, Clement E, et al. Cost-effectiveness assessment of potential financial savings from selective culture screening as a strategy to prevent nosocomial transmission of methicillin-resistant Staphylococcus aureus (MRSA) in 25 upstate New York hospitals. Abstract 5-40. Association for Professionals in Infection Control and Epidemiology. Tampa; June 11-15, 2006.
  2. Muto CA, Jernigan JA, Ostrowsky BE, et al. Special report: SHEA guideline for preventing nosocomial transmission of multidrug-resistant strains of Staphylococcus aureus and Enterococcus. Infect Control Hosp Epidemiol 2003; 24:362-386.
  3. Stetson MG, Vautour RJ. Abstract 5-39. Cost effectiveness of screening for methicillin resistant Staphylococcus aureus (MRSA) and vacomycin-resistant enterococcus (VRE) in an intensive care unit at a 200-bed community hospital with a low prevalence of these antibiotic-resistant organisms. Association for Professionals in Infection Control and Epidemiology. Tampa; June 11-15, 2006.
  4. Stone PW, Larson E, Kawar LN. A systematic audit of economic evidence linking nosocomial infections and infection control interventions: 1990-2000 Am J Infect Control 2002;30:145-52.