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Ho C, Lau A, Cimon K, et al. Screening, Isolation, and Decolonization Strategies for Vancomycin-Resistant Enterococci or Extended Spectrum Beta-Lactamase Producing Organisms: A Systematic Review of the Clinical Evidence and Health Services Impact [Internet]. Ottawa (ON): Canadian Agency for Drugs and Technologies in Health; 2012 Sep.

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Screening, Isolation, and Decolonization Strategies for Vancomycin-Resistant Enterococci or Extended Spectrum Beta-Lactamase Producing Organisms: A Systematic Review of the Clinical Evidence and Health Services Impact [Internet].

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1CONTEXT AND POLICY ISSUES

Bacterial resistance to antibiotics is an increasing problem in Canada and worldwide.14 Vancomycin-resistant enterococci (VRE) are strains of Enterococcus faecium or Enterococcus faecalis that contain genes conferring resistance to vancomycin.5,6 Escherichia coli (E. coli), Klebsiella pneumonia (K. pneumonia), and other gram-negative bacteria may produce enzymes known as extended spectrum beta-lactamases (ESBLs). These have the ability to break down beta lactam antibiotics such as penicillin, ampicillin, and cephalosporins.7,8 The presence and growth (colonization) of VRE and ESBL organisms in the gastrointestinal tract is a source of infection for the carrier, and a reservoir for the transmission of VRE and ESBL-producing organisms to other persons.9,10 In a cohort of patients admitted to an acute rehabilitation hospital, who did not have a history of antibacterial-resistant infections, admission swabs were positive for methicillin-resistant Staphylococcus aureus (MRSA) or VRE in 16% of the population.20 Results from the Canadian Nosocomial Infection Surveillance Program showed that from 1999 to 2005, the rate of VRE detection and VRE infection increased from 0.37 to 1.32 cases and from 0.02 to 0.05 cases respectively, per 1,000 patients admitted to hospital.11 The laboratory-based Canadian Ward Surveillance Study in 2008 found that ESBL-producing E. coli were identified in all Canadian geographic regions, and that 4.9% of E. coli isolates were ESBL producers.12 In one study, the rate of colonization with ESBL-producing organisms among high-risk hospitalized patients increased from 1.33% in 2000 to 3.21% in 2005.21 The number of blood stream infections caused by ESBL-producing organisms also increased from nine cases in 2001 to 40 cases in 2005.21

Among patients with enterococcal bloodstream infections, bacteria that were resistant to vancomycin were shown in two meta-analyses to be directly associated with increased mortality compared with bacteria that were susceptible to vancomycin.22,23 It is noteworthy that the meta-analyses were systematic reviews (SRs) of cohort studies, most of them with inadequate sample size, and most studies were conducted before the availability of newer antimicrobials against VRE.

Prevention and control measures for VRE and ESBL-producing organisms include a screening process to identify patients colonized with antibiotic-resistant organisms (AROs), and isolation of the carriers. Decolonization is not typically performed for patients with VRE or ESBL colonization.

Hospital infection prevention and control strategies and guidelines for AROs have been developed in some Canadian jurisdictions,1316 and these include non-specific control measures such as the appropriate use of antimicrobials like vancomycin, and implementing an antimicrobial stewardship program that promotes the appropriate selection, dose, route and duration of antimicrobial therapy. The non-specific guidelines also include performing environmental cleaning, implementing bundled practices to prevent procedure-associated infections such as central line-associated blood stream infections, and education of hospital staff concerning procedures such as hand washing with an antiseptic agent. Organism-specific guidance includes routine screening for VRE and gram-negative isolates for ESBL production, and contact isolation of patients infected with VRE or ESBL-producing organisms.2426 The relative contribution of specific versus non-specific measures is unknown, especially as compliance with non-specific measures would be expected to vary between institutions.

In one example of organism-specific guidance, the Ontario Provincial Infectious Diseases Advisory Committee (PIDAC)16 recommended, among other things, that:

  • “Each health care setting should have a prevention and control program for AROs.” (p.27)
  • “Screening for risk factors for MRSA, VRE and CRE should include a screening tool that is applied to all clients/patients/residents admitted to the health care facility.” (p. 27)
  • “Every effort should be made to try to determine the source of new cases of MRSA, VRE, and CRE. Every new case should warrant an investigation.” (p. 27)
  • “During an outbreak, all client/patient/resident contacts with common risk factors should be actively screened.” (p. 27)
  • “Hand hygiene must be performed by all staff before and after each contact with a client/patient/resident or contact with environmental surfaces near the client/patient/resident.” (p. 24)
  • “VRE, CRE or ESBL decolonization is not effective and is not recommended.” (p. 27)
  • additional precautions such as contact precautions are required for MRSA and VRE.16

These recommendations were based on relevant citations and expert opinions, and were not specific to any particular health care setting. However, some of these specific recommendations remain controversial, with some Canadian hospitals discontinuing screening for VRE colonization or isolating patients with VRE, arguing that the increased resources required for containment are not commensurate with the increased patient risk from VRE.27

AROs such as VRE and ESBL-producing organisms increase the use of hospital resources due to extended hospital stays, laboratory tests, physician consultations, and the cost of infection prevention and control measures to prevent the further spread of these pathogens.19 However, both morbidity caused by infection and screening and control strategies contribute to this increased resource use. Additionally, AROs are commonly detected in the intensive care unit (ICU) where antimicrobial selection pressure is higher and exposure to broad-spectrum antimicrobials is more common.19 The health care impact of antimicrobial resistance cannot be limited to the hospital perspective, as significant portions of clinical care are provided in other facilities.28

The objective of this study is to conduct an SR of the clinical evidence for screening, isolation, and decolonization strategies for VRE and ESBL-producing organisms. The health services impact of these strategies will be discussed. In the face of increasing rates of multidrug resistant (MDR) infections in Canada, the findings from this report may be used to update guidelines in Canadian jurisdictions.

Copyright © CADTH (September 2012)

You are permitted to make copies of this document for non-commercial purposes provided it is not modified when reproduced and appropriate credit is given to CADTH.

Bookshelf ID: NBK174615
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