MDRO guidelines draw fire on active surveillance issue

Others praise stepwise approach to aggressive measures

The prevention of multidrug-resistant organisms (MDROs) is a "national priority . . . that requires all health care facilities and agencies assume responsibility," the Centers for Disease Control and Prevention emphasizes in long-awaited new guidelines on the issue.

The new guidance, "Management of Multidrug-Resistant Organisms in Healthcare Settings," was developed by the CDC's Healthcare Infection Control Practices Advisory Committee (HICPAC). The full document has been posted on the web site of the CDC Division of Healthcare Quality Promotion at

"It is clearly a call to action," says Jane Siegel, MD, lead author of the guidelines as a CDC consultant and former member of HICPAC. "This is a national priority and it requires all health care settings to participate. That's not just the acute care hospital. It's long-term care facilities, home health. What is laid out are methods that have been shown to be effective to control MDROs."

Though some immediately questioned whether the plethora of recommendations and possible strategies created a guideline that is essentially flexible to a fault, the CDC chose not to mandate a single strategy such as active surveillance cultures (ACS) to detect the reservoir of MDROs in colonized patients.

"The guideline is not an edict of, 'You must do A, B, C in every institution,' but it is a call to action to assess the problem and affect a plan," Siegel says. "It is not saying that everyone admitted to an ICU or to an acute care hospital should have active surveillance cultures for MRSA [methicillin-resistant Staphylococcus aureus]. It is saying that an institution needs to define what the MDRO problem is. For some institutions, it will be MRSA; for some, it will be VRE [vancomycin-resistant enterococci]; for some, it will be gram negatives. It still supports the use of [ACS], but [the issue is] the application of active surveillance cultures."

The guidelines open with a sense of urgency not typical for CDC recommendations, including an unusually direct appeal for ICP support and administrative commitment. "Resources must be made available for infection prevention and control, including expert consultation, laboratory support, adherence monitoring, and data analysis," the guidelines state. "Infection prevention and control professionals have found that health care personnel (HCP) are more receptive and adherent to the recommended control measures when organizational leaders participate in efforts to reduce MDRO transmission."

The new guidelines call for hospitals and health care facilities to:

  • Carefully track infection rates and related data to monitor the impact of prevention efforts.
  • Ensure that staff use standard infection control practices and follow guidelines regarding the correct use of antibiotics.
  • Promote best practices with health education campaigns to increase adherence to established recommendations.
  • Design robust prevention programs customized to specific settings and local needs.

If those recommendations don't improve rates, health care facilities are to then reevaluate and implement more stringent measures, including screening of patients at high risk for carrying drug-resistant bacteria. (See recommendations.)

"One of the most controversial issues has been the role of active surveillance cultures, that is, screening at-risk patients for carriage of resistant organisms at the time of hospital admission," John Jernigan, MD, medical epidemiologist at the CDC, said at a press conference. "Some scientists think this practice should be used routinely in all health care settings to control certain pathogens, while others suggest that antimicrobial resistance can be controlled using other approaches. These new guidelines take into account this diversity of scientific opinion. The recommendations include the use of active surveillance cultures on certain resistant organisms in patients and populations when a reduction in infection rates does not occur using other measures."

In doing so, however, the CDC offers a somewhat chilly embrace of recommendations by its clinical colleagues in the Society of Healthcare Epidemiology of America (SHEA). SHEA called for bolder measures while the CDC document was still in draft form, creating a rift that has been seized on by patient safety advocates who question whether the CDC is being sufficiently aggressive to stem the rising tide of MDROs.1

"The CDC guideline discusses the SHEA guideline and rebuts the routine need for and scientific documentation of one of its key provisions — active identification and isolation of the full reservoir for spread," says Barry M. Farr, MD, MSc professor emeritus in the department of medicine at the University of Virginia Health System in Charlottesville. "The CDC guideline seems to suggest that this key measure cannot be recommended for routine use because it hasn't been shown effective in a randomized trial — without noting that none of its 87 recommendations apparently was studied or shown effective in a randomized trial."

Moreover, individual health care facilities seem to be allowed to "target" MDROs they believe should be controlled, creating a flexibility that actually could undermine the overall impact of the guidelines against major pathogens such as methicillin-resistant MRSA and VRE, Farr notes.

"The guideline doesn't seem to say in an unequivocal manner that important MDROs like MRSA and VRE must be controlled to a very low level in every health care facility, perhaps because this would interfere with an individual facility's flexibility and right to target — vs. not target — a particular pathogen," he says. "This flexibility, which was touted by the HICPAC authors in earlier drafts of the CDC guideline, seems a recipe for failure of control across the health care system — unless perhaps facilities are influenced to select effective measures by the rival SHEA guideline."

In a recent editorial published prior to the release of the CDC guidelines, Farr hammered home the point, arguing that the results of more than 100 studies in Europe, Australia, and the U.S. document control of MRSA by means of active detection and isolation.2

"Infection control professionals in U.S. hospitals tend to follow CDC guidelines, which have never explicitly recommended routine performance of active surveillance culture to identify colonized patients and isolation of all such patients in order to control nosocomial MRSA infection, as has been done in multiple nations that have controlled it to exceedingly low levels for decades," Farr wrote. "It should have been obvious for many years to infection control professionals and to CDC officials that isolation of only the small fraction of MRSA-colonized patients identified on the basis of clinical cultures (as has been done by most U.S. hospitals since 1983) and use of standard precautions (as has been done by most U.S. hospitals since 1996) have failed miserably to control nosocomial MRSA and VRE infections."

Conflicting finding, unresolved issues cited

The CDC concedes that the authors of several reports have concluded that ASC, in combination with use of contact precautions for colonized patients, contributed directly to the decline or eradication of the target MDROs.3,4 "However, not all studies have reached the same conclusion," the guidelines state. "Poor control of MRSA despite use of ASC has been described. A recent study failed to identify cross-transmission of MRSA or MSSA in a MICU during a 10-week period when ASC was obtained, despite the fact that culture results were not reported to the staff.5 The investigators suggest that the degree of cohorting and adherence to standard precautions might have been the important determinants of transmission prevention, rather than the use of ASC and contact precautions for MRSA-colonized patients."

In addition, a systematic review of the literature on the use of isolation measures to control health care-associated MRSA concluded that there is evidence that concerted efforts that include ASC and isolation can reduce MRSA even in endemic settings.6 "However, the authors also noted that methodological weaknesses and inadequate reporting in published research make it difficult to rule out plausible alternative explanations for reductions in MRSA acquisition associated with these interventions, and therefore concluded that the precise contribution of active surveillance and isolation alone is difficult to assess," the guidelines state.

If ACS is used, the most common strategy involves obtaining surveillance cultures from all patients admitted to units experiencing high rates of colonization/infection with the MDROs of interest, unless they are already known to be MDRO carriers. However, optimal timing and interval of ASC are not well defined, the CDC continues. In many reports, cultures were obtained at the time of admission to the hospital or intervention unit or at the time of transfer to or from designated units (e.g., ICU). In addition, some hospitals have chosen to obtain cultures on a periodic basis (e.g., weekly) to detect silent transmission. Others have based follow-up cultures on the presence of certain risk factors for MDRO colonization, such as antibiotic exposure, exposure to other MDRO colonized patients, or prolonged duration of stay in a high-risk unit. Though more research is needed to determine the circumstances under which ASC are most beneficial, their use should be considered in some settings, especially if other control measures have been ineffective, the CDC guidelines state.

"We know that there is a role for active surveillance cultures and that is an important tool, especially when you have an outbreak and ongoing transmission," Siegel says. "But it's not clear what the best approach is. As people are implementing more of [infection prevention] bundled practices there have been dramatic decreases in central line associated bacteremias caused by resistant organisms. So in some institutions, there may be a greater benefit to really concentrating on decreasing the infections by using these bundled practices and that will prevent the MRSA. The point of the guideline is that there are many different interventions that can be used. It is up to the institution to assess their situation and then determine what group of practices and interventions they want to implement and then of course to assess the effect of that and modify it."

Siegel emphasized the document is not just about MRSA, though that is the pathogen that is drawing national attention as it continues to spread in hospitals and emerges in the community. "The other message of this document is not just to focus on MRSA," she says. "We are seeing in the literature that institutions where the focus has been on MRSA have seen other resistant organisms emerge."

The CDC notes that any decision to use ASC as part of an infection prevention and control program will require additional support for successful implementation, including:

  1. personnel to obtain the appropriate cultures;
  2. microbiology laboratory personnel to process the cultures;
  3. mechanism for communicating results to caregivers;
  4. concurrent decisions about use of additional isolation measures triggered by a positive culture (e.g., Contact Precautions);
  5. mechanism for assuring adherence to the additional isolation measures.

Support for stepwise approach

Given the unresolved issues and the level of resources required, some ICPs argue that the CDC's flexible, stepwise approach is the right call on controlling MDROs.

"I am definitely not a proponent of routine active surveillance culturing because there are just too many unresolved issues," says Patti Grant, RN, BSN, CIC, an ICP at Medical City in Dallas. "I worked in two small hospitals for eight years, and we would never have had the resources to do such a thing."

There also is the concern that an emphasis on ACS as the principal infection control strategy may send the wrong message to health care workers, she adds.

"The bottom line is I don't want to go back to before standard precautions, where we teach health care workers not to worry unless there is a sign on the door," Grant says. "This whole active surveillance culturing thing comes dangerously close to that. Even with PCR technology, we are still telling people don't worry about it unless there is a sign on the door. I worry about that underlying message, which has kind of been hidden."

Overall, the new guidelines contain a lot of practical advice and are fairly impartial, she adds. "They say it several different ways throughout the document — the approaches to these individual pathogens need to be tailored to the specific needs of the population and the individual institution over time," Grant says. "I really like their stepwise approach. This document did the right thing with the science that we have at this particular time. And I think it is going to be a living document. It is something that is going to be updated as things progress."


  1. 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.
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