• Calfee DP, Salgado CD, Classen D, Arias KM, Podgorny K, Anderson DJ, Burstin H, Coffin SE, Dubberke ER, Fraser V, Gerding DN, Griffin FA, Gross P, Kaye KS, Klompas M, Lo E, Marschall J, Mermel LA, Nicolle L, Pegues DA, Perl TM, Saint S, Weinstein RA, Wise R, Yokoe DS. Strategies to prevent transmission of methicillin-resistant Staphylococcus aureus in acute care hospitals. Infect Control Hosp Epidemiol 2008 Oct;29 Suppl 1:S62-80. PubMed

The effectiveness of active surveillance testing in the prevention of MRSA transmission is currently an area of controversy, and optimal implementation strategies (including timing and target populations) are unresolved. Several published studies of high-risk or high-prevalence populations (including those in outbreak situations) have shown an association between the use of active surveillance testing to identify and isolate MRSA-colonized patients and the effective control of MRSA transmission and/or infection (West et al., 2006; Huang et al., 2006; Safdar et al., 2006; Lucet et al., 2005). Two recent studies evaluated the impact of universal active surveillance testing performed at the time of hospital admission combined with administration of decolonization therapy to MRSA carriers and came to conflicting conclusions. One study used an observational cohort design and reported a significant reduction in hospital-associated MRSA disease after the introduction of active surveillance testing of all patients and decolonization of MRSA carriers (Robiscek et al., 2008). The other study used a crossover cohort design and found no significant changes in the incidence of nosocomial MRSA infection among surgical patients (Harbarth et al., 2008). There are several possible explanations for the differences in outcome observed in these 2 studies, including differences in study design, patient population, adherence to routine infection control measures, and adherence to decolonization therapy protocols. Of note, a multicenter, cluster-randomized trial investigating the impact of active surveillance testing on MRSA in ICUs has been performed, but the results have not yet been published (ClinicalTrials.gov identifier NCT00100386).

This was a very complex study. Preliminary analysis did not demonstrate a benefit from active surveillance testing during the 6-month study period under the specific study protocol. The authors have stated that those preliminary results should not be used to conclude that active surveillance testing is useless or that efforts to control MRSA are futile (Huskins, 2007). The final analysis and peer review of study methods, results, and conclusions are pending.

Because of conflicting results from these studies and the differences among acute care hospitals and their associated patient populations, a specific recommendation regarding universal screening for MRSA cannot be made. However, active surveillance testing as a single intervention in the absence of a multifaceted approach to MRSA transmission prevention (e.g., the basic measures described above) is unlikely to be uniformly effective across healthcare institutions. Active surveillance testing may, however, be useful in facilities that have implemented and optimized adherence to basic MRSA transmission prevention practices but continue to experience unacceptably high MRSA rates.

1. Implement an MRSA active surveillance testing program as part of a multifaceted strategy to control and prevent MRSA transmission when evidence suggests that there is ongoing transmission of MRSA despite effective implementation of basic practices (B-II).

   Assess MRSA transmission as the basis for determining if, when, and where active surveillance testing is to be used at an individual hospital. In general, active surveillance testing is considered appropriate in a facility where there is direct or indirect evidence of ongoing MRSA transmission despite adequate implementation of and adherence to basic practices. Although the use of serial active surveillance testing of hospital patients provides the most accurate measurement of MRSA transmission, other metrics may be used as surrogate markers for transmission when comprehensive active surveillance testing data are not available. Examples include the following:

   • A high or increasing prevalence or incidence of hospital-onset MRSA infection or colonization
   • An incidence of hospital-onset MRSA infection or colonization that is not decreasing despite the use of basic practices
   • An increasing proportion of hospital-onset S. aureus isolates that are resistant to methicillin
   • Identification of specific hospital units in which the colonization pressure (i.e., the prevalence rate of MRSA) is above the level associated with an increased risk of transmission (Merrer et al., 2000). (Such units may be identified with the use of point prevalence surveys.)
   • Identification of specific patient populations at high risk for MRSA colonization or infection

• Convene a multidisciplinary team to review the MRSA risk assessment and to plan and oversee the active surveillance testing program.
  • Because of the multidisciplinary nature of an active surveillance program, representatives from the microbiology laboratory, infection prevention and control personnel, nursing staff, medical staff, materials management, environmental services, and hospital administration should be involved in program development, implementation, and resource allocation. Careful consideration of the resources necessary for an active surveillance testing program is essential to ensure that the active surveillance testing program is implemented properly and that other important components of the hospital's infection control program are not disrupted.
  • Consultation with a trained individual who has expertise in MRSA transmission control and prevention may be useful for program development and assessment if such a person is not available within the hospital.
  • Pilot the program in one location before expanding to other locations. Select the pilot unit on the basis of the risk or prevalence of MRSA on the unit or the presence of motivated leadership and front-line personnel.
  • Expand the program to additional units once the pilot program has been evaluated and adjusted and initial goals have been met (e.g., more than 90% compliance with specimen acquisition).
• Select and identify the patient population(s) to be screened.
  • Determine which patients to screen (e.g., all patients versus high-risk patients or patients on high-risk units).
    • Use the MRSA risk assessment to determine whether all patients, patients admitted to specific high-risk units (e.g., the ICU), or high-risk patient populations (regardless of location) will be included in the screening program.
    • Patient-level risk factors for MRSA colonization (e.g., recent admission to a hospital or skilled nursing facility, long-term hemodialysis, and recent antimicrobial therapy) may also be used to determine inclusion in the screening program (Haley et al., 2007).
    • Consider available infrastructure and hospital-specific characteristics (size; staffing for infection prevention and control, laboratory, and nursing; patient population; and information technology support) when selecting the patient population(s) to be screened.
  • Develop and implement a system to identify and screen patients who meet the screening program criteria.
    • A reliable system for identification of all patients meeting the criteria for inclusion in the screening program is necessary for the success of the program.
    • Identification of patients who meet criteria for MRSA screening may be more difficult when patient-level risk factors, rather than patient care unit, are used to determine inclusion in the surveillance program. Take this into consideration during the planning stages of the screening program. Hospitals with well-developed electronic medical records and other computer databases may be able to identify such patients by use of a computer algorithm.
    • Consider developing and implementing a checklist to be completed at admission to assist in identifying patients to be screened for MRSA.
    • Determine how screening specimens will be ordered (e.g., protocol admission order set or individual patient order), who will initiate the order (e.g., physician or nurse) and who will obtain the specimens (e.g., unit-based nursing personnel or designated MRSA monitoring program personnel). These decisions will need to take into account relevant hospital policies, staffing, and infrastructure.
• Determine when to perform screening tests.
  • At a minimum, MRSA surveillance should be performed at admission to the hospital or to the specific unit in which surveillance is being performed.
  • To detect transmission while in the hospital, additional testing of patients with initial negative surveillance test results can be done either at regular intervals (e.g., weekly) or at discharge from the hospital or unit.
  • Testing at regular intervals has the potential to detect patients who have acquired MRSA during their hospitalization earlier than testing only at discharge and thus allows implementation of contact precautions to prevent further transmission.
  • When testing is to be performed at regular intervals, determine a specific day of the week when specimens will be collected. This will simplify the process and allow the microbiology laboratory to anticipate the increased volume of specimens and plan staffing and supplies accordingly.
• Determine the anatomic sites to include in screening program.
  • Identify the anatomic site(s) to be tested.
    • Anterior nares: The sensitivity of surveillance specimens obtained from a variety of sites has been evaluated in several settings and patient populations. Although testing of no single site will detect all MRSA-colonized persons, the anterior nares appear to be the most frequently positive site, with sensitivity ranging from 73% to 93% (Manian et al., 2002; Sanford et al., 1994; Cox et al., 1995; Lucet et al., 2003; Eveillard et al., 2006; Rohr et al., 2004; Girou et al., 1998). Because of this and the accessibility of the site, the anterior nares are generally considered to be the primary site for sampling in MRSA screening programs.
    • Collection of samples from other sites, such as wounds, foreign body (e.g., gastrostomy or tracheostomy tube) exit sites, the throat, the perianal area, and/or the umbilicus (in neonates) (Rosenthal et al., 2006) will allow identification of additional colonized patients who would not be identified by testing of nasal specimens alone.
• Determine laboratory methods and assess resource requirements.
  • Identify the screening test method to be used.
  • MRSA can be detected using culture-based methods or molecular diagnostic testing methods, such as polymerase chain reaction (PCR). Many factors must be considered when determining which laboratory method(s) will be used in an MRSA screening program. These factors include but are not limited to the following:
    • Performance characteristics of the test (e.g., sensitivity and specificity)
    • Turnaround time
    • Capabilities of the laboratory (whether an in-house or reference laboratory) that will be providing the service
    • Number of specimens that will be processed
    • Facility-specific cost-benefit calculations
  • A detailed discussion of the various laboratory methods for MRSA detection is beyond the scope of this document, but some of the key features of the most common methods are discussed below.
    • Culture-based methods: Culture-based techniques have been used in the majority of MRSA screening programs. Numerous microbiological media and techniques have been described for use in the detection of MRSA colonization. One of the more commonly used selective media is mannitol salt agar with or without antimicrobial (e.g., oxacillin or cefoxitin) supplementation to increase specificity for methicillin-resistant organisms. Additional enrichment steps, such as overnight incubation in trypticase soy broth, can further increase the yield of standard culture-based methods (Safdar et al., 2003). The time required for detection of MRSA by use of most culture-based techniques is approximately 48 hours. More recently, several chromogenic agar media have been developed that allow more rapid detection of MRSA, usually within 24 hours. Studies using established collections of isolates and clinical specimens have shown that these chromogenic media rival or outperform more conventional microbiological techniques (Diederen et al., 2005; Diederen et al., 2006; Flayhart et al., 2005; Stoakeset al., 2006; Perry et al., 2004; Han et al., 2007; Louie et al., 2006; Ben Nsira, Dupuis, & Leclerq, 2006; Smyth & Kahlmeter, 2005).
    • Molecular testing methods: In recent years, there have been advances in molecular diagnostic testing methods, such as real-time PCR, for detection of MRSA colonization. At least 2 PCR assays for direct   detection of MRSA in nasal specimens have been approved for use. These PCR assays have been shown to be highly sensitive (90% to 100%) and specific (91.7% to 98.4%), compared with standard culture-based methods (Huletsky et al., 2005; Warren et al., 2004; Bishop et al., 2006; Drews et al., 2006). Although it is more costly than culture-based techniques, one potential advantage of this technology is its ability to provide a result less than 2 hours from the time of specimen collection, although in actual practice the turnaround time may be longer because of batching of samples. Although at least 1 uncontrolled study (Cunningham et al., 2007) and a mathematical model (Bootsma, Diekmann, & Bonten, 2006) have suggested that rapid testing may allow for more effective use of isolation precautions and enhanced prevention of MRSA transmission, a recently published cluster-randomized crossover trial of universal screening in general wards failed to identify a difference in MRSA acquisition rates with the use of rapid testing, compared with the use of a culture-based method (Jeyaratman et al., 2008). These data suggest that the clinical and economic benefits of rapid testing may vary among individual hospitals and settings.
• Clarify how to manage patients while awaiting the results of screening tests.
  • Before implementing a screening program, a decision should be made as to how a patient will be managed while waiting for the result of the admission MRSA screening test. There are 2 common approaches:
    • Await the screening test result and implement contact precautions only if the test result is positive.
    • Place the patient under empirical contact precautions until a negative admission screening test result is documented.
  • Implementing contact precautions at the time of receipt of a positive screening test result is a reasonable initial approach. Although empirical contact precautions minimize the risk of MRSA transmission from unrecognized sources and have been shown to contribute to effective control of MRSA (Safdar et al., 2006), logistical difficulties are associated with this approach. Empirical use of contact precautions substantially increases the need for single rooms and the amount of supplies needed to practice contact precautions. When only a small proportion of screened patients are colonized with MRSA and single rooms are of limited quantity, a large number of patients whose screening test results are negative will need to be moved so that their single room can be used for another patient. These room reassignments and the necessary cleaning before the vacated room can be reoccupied can slow down patient flow within the hospital. The empirical use of contact precautions for all tested patients while awaiting test results may be most feasible in hospitals in which a relatively large proportion of patient rooms are single rooms and in individual hospital units, such as many ICUs, in which each patient is in an individual room or bay. Despite its potential logistical difficulties, this approach should be considered if transmission continues despite introduction of a screening program in which contact precautions are implemented only after a positive MRSA screening test result is obtained.
• Assess the availability of single rooms and, if needed, plan for cohorting colonized or infected patients.
  • When developing a screening program, address the availability of single rooms for MRSA-positive patients, including cohorting persons colonized or infected with the same organism, when single rooms are not available. Consider the following:
    • Prioritize MRSA-positive patients who are at greater risk for transmission (e.g., those with draining wounds) for a single room.
    • Ensure that patients who are known or suspected to have other indications for isolation precautions (e.g., colonization or infection with other multidrug-resistant organisms, influenza, or tuberculosis) are not cohorted with MRSA-positive patients.
    • Cohorting does not eliminate the need for full compliance with hand hygiene and other basic prevention recommendations.
• Assess the availability of personal protective equipment and other supplies.
  • Ensure that gowns, gloves, and hand-hygiene products (e.g., alcohol-based hand rubs, soap, and paper towels) are consistently available to healthcare personnel. The screening program will not be effective if healthcare personnel are not able to comply with contact precautions because of a lack of supplies.
    • Cooperation among the purchasing department, laundry/linen service (if reusable gowns are selected), and unit-based personnel is imperative.
    • Infection prevention and control experts, particularly those familiar with the use of active surveillance, can serve as a resource to help hospitals estimate the number of patients likely to be found to be colonized with MRSA and, thus, the amount of supplies needed.
• Assess compliance with the screening protocol.
  • Monitor compliance with the screening and contact precautions protocols, because suboptimal compliance will prevent the surveillance program from providing its maximal benefit. The monitoring program should ensure that the following measures are taken:
    • Screening tests are collected and processed according to protocol.
    • Infection prevention and control personnel are notified of positive results within the proper time frame.
    • The clinical personnel caring for the patient are notified of positive results within the proper time frame.

Active Surveillance Testing for MRSA among Healthcare Personnel

Screening of healthcare personnel for MRSA is not routinely recommended in settings of endemicity unless they have been epidemiologically linked to new MRSA cases. Screening of healthcare personnel for MRSA should be considered in an outbreak setting.

1. Screen healthcare personnel for MRSA infection or colonization only if they are epidemiologically linked to a cluster of MRSA infections (B-III).
   • Healthcare personnel can become transiently or persistently colonized with MRSA, and this has been determined to be the source of several outbreaks in hospitals. Molecular testing (e.g., pulse-field gel electrophoresis) to establish clonality of MRSA isolates has been useful in such situations (Bertin et al., 2006; Stein et al., 2006; Meier et al., 1996; Wang et al., 2001, Blok et al., 2003).

Routine Bathing with Chlorhexidine

Recent studies have demonstrated that the use of chlorhexidine for routine cleansing of adult ICU patients may decrease the incidence of patient acquisition of MRSA (Climo et al., 2007) and vancomycin-resistant Enterococcus (Vernon et al., 2006) and may reduce the incidence of catheter-associated bloodstream infections (Bleasdale et al., 2007). The effect of chlorhexidine on transmission of bacterial pathogens is likely due to a reduction in the burden of organisms on the skin of colonized or infected patients, with a subsequent reduction in contamination of environmental surfaces and the hands of healthcare workers (Vernon et al., 2006). The use of chlorhexidine for routine patient cleansing outside of the adult ICU setting has not been studied.

1. Routinely bathe adult ICU patients with chlorhexidine (B-III).
   • Use chlorhexidine rather than regular soap and water or other nonmedicated cleansing regimens for routine patient cleansing.
   • A variety of chlorhexidine products that could be used for patient bathing are available. These include single-use bottles of aqueous chlorhexidine that can be added to a basin of water and 2% chlorhexidine-impregnated cloths. It should be noted that the use of undiluted 4% aqueous chlorhexidine solution for skin cleansing has been associated with a relatively high rate of reversible adverse skin effects (e.g., skin fissures, itching, and burning of the skin) (Wendt et al., 2007).
   • When using chlorhexidine, the manufacturer's recommendations should be followed. Care must be taken to avoid contact with the eyes and middle ear (e.g., in patients with perforated tympanic membranes). Chlorhexidine is in US Food and Drug Administration Pregnancy Category C.

MRSA Decolonization Therapy for MRSA-Colonized Persons

MRSA decolonization therapy can be defined as the administration of topical antimicrobial or antiseptic agents, with or without systemic antimicrobial therapy, to MRSA-colonized persons for the purpose of eradicating or suppressing the carrier state. The use of MRSA decolonization therapy in conjunction with active surveillance testing may be a useful adjunctive measure for prevention of MRSA transmission within a hospital. For example, one group of investigators observed a 52% reduction in incident cases of MRSA colonization or infection among adult ICU patients after the introduction of a decolonization regimen for all MRSA-colonized patients (Ridenour et al., 2007). Decolonization therapy has also been a component of several successful MRSA outbreak control programs (Saiman et al., 2003; Nambiar, Herwaldt, & Singh, 2003; Hitomi et al., 2000).

Decolonization therapy has also been used in certain patient populations in an attempt to reduce the risk of subsequent S. aureus infection among colonized persons. These populations have included patients undergoing dialysis (Herwaldt, 1998), patients with recurrent S. aureus infections, and patients undergoing certain surgical procedures (Kluytmans et al., 1996). Further discussion of this topic is beyond the scope of this document.

1. Provide decolonization therapy to MRSA-colonized patients in conjunction with an active surveillance testing program (B-III).
   • The optimal decolonization therapy regimen has not been determined. Most experience has been with the use of 2% mupirocin administered intranasally with or without chlorhexidine bathing. In the previously mentioned study that observed a reduction in incident cases of MRSA colonization or infection after the introduction of decolonization therapy, the decolonization regimen consisted of intranasal administration of 2% mupirocin twice daily for 5 days and chlorhexidine baths for 7 days (Ridenour et al., 2007). In that study, bed baths were performed after adding a 4-oz bottle of 4% chlorhexidine gluconate to a 6-qt basin of warm water.
   • Complications of decolonization therapy are relatively uncommon; however, hospital personnel involved in the decolonization therapy program should be familiar with potential adverse effects, such as development of resistance to the agents used (e.g., mupirocin) and drug-related toxicities.

Unresolved Issues

There are a number of unresolved issues related to MRSA and its transmission. A full discussion of these issues is beyond the scope of this document, but a brief mention of some of these important topics is worthwhile. For example, the impact of antimicrobial stewardship efforts on the risk of MRSA infection and transmission has not been clearly defined. Also, further study of the epidemiology and prevention of MRSA transmission among family members and other close contacts of persons colonized or infected with MRSA is needed. Additionally, the emergence of community-associated MRSA has further complicated the epidemiology of MRSA in healthcare facilities and has generated new questions related to MRSA transmission prevention in hospitals. One such topic that requires further study is the approach to detection of carriers of community-associated MRSA. Current approaches that are largely based on the epidemiology of hospital-associated MRSA may be suboptimal, given differences in risk factors for colonization and the presence of some evidence that suggests that there are differences in the predominant sites of colonization, compared with hospital-associated MRSA. Differences in antimicrobial susceptibility and virulence between typical hospital-associated MRSA and community-associated MRSA suggest that the phenotypic characteristics (e.g., antimicrobial susceptibility) of MRSA isolates from individual patients may need to be considered when it becomes necessary to cohort patients with MRSA colonization or infection. These and other aspects of MRSA transmission and control require further investigation.

Definitions:

Quality of Evidence*

1. Evidence from >1 properly randomized, controlled trial
2. Evidence from >1 well-designed clinical trial without randomization, from cohort or case-controlled analytic studies (preferably from >1 center), from multiple time-series studies, or from dramatic results of uncontrolled experiments
3. Evidence from opinions of respected authorities based on clinical experience, descriptive studies, or reports of expert committees

Strength of Recommendation*

1. Good evidence to support a recommendation for use
2. Moderate evidence to support a recommendation for use
3. Poor evidence to support a recommendation

*Adapted from the Canadian Task Force on the Periodic Health Examination.

References open in a new window

• Calfee DP, Salgado CD, Classen D, Arias KM, Podgorny K, Anderson DJ, Burstin H, Coffin SE, Dubberke ER, Fraser V, Gerding DN, Griffin FA, Gross P, Kaye KS, Klompas M, Lo E, Marschall J, Mermel LA, Nicolle L, Pegues DA, Perl TM, Saint S, Weinstein RA, Wise R, Yokoe DS. Strategies to prevent transmission of methicillin-resistant Staphylococcus aureus in acute care hospitals. Infect Control Hosp Epidemiol 2008 Oct;29 Suppl 1:S62-80. PubMed

Electronic copies: Available from the Society for Healthcare Epidemiology of America (SHEA) Web site.

Print copies: Available from the Reprints Coordinator, University of Chicago Press, 1427 E. 60th St., Chicago, IL 60637 (reprints@press.uchicago.edu) or contact the journal office (iche@press.uchicago.edu).

• Improving patient safety through infection control: a new healthcare imperative. Infect Control Hosp Epidemiol 2008;29:S3–S11. Electronic copies: Available from the Society for Healthcare Epidemiology of America (SHEA) Web site.
• A compendium of strategies to prevent healthcare-associated infections in acute care hospitals. Executive summary. Infect Control Hosp Epidemiol 2008;29:S12–S21. Electronic copies: Available from the Society for Healthcare Epidemiology of America (SHEA) Web site.

Print copies: Available from the Reprints Coordinator, University of Chicago Press, 1427 E. 60th St., Chicago, IL 60637 (reprints@press.uchicago.edu) or contact the journal office (iche@press.uchicago.edu).

Performance measures and a urinary catheter reminder form (in appendix) are available in the original guideline document.

Electronic copies: Available in English and Spanish from the Society for Healthcare Epidemiology of America (SHEA) Web site.

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