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Variation in Definitions and Isolation Procedures for Multidrug-Resistant Gram-Negative Bacteria: A Survey of the Society for Healthcare Epidemiology of America Research Network

  • Marci Drees (a1), Lisa Pineles (a2), Anthony D. Harris (a2) and Daniel J. Morgan (a2) (a3)

To assess definitions, experience, and infection control practices for multidrug-resistant gram-negative bacteria (MDR-GNB), including Enterobacteriaceae, Acinetobacter, and Pseudomonas species, in acute care hospitals.


Cross-sectional survey.


US and international members of the Society for Healthcare Epidemiology of America (SHEA) Research Network.


Online survey that included definitions, infection control procedures, and microbiology capability related to MDR-GNB and other MDR bacteria.


From November 2012 through February 2013, 66 of 170 SHEA Research Network members responded (39% response rate), representing 26 states and 15 countries. More than 80% of facilities reported experience with each MDR-GNB isolate, and 78% had encountered GNB resistant to all antibiotics except colistin (62% Acinetobacter, 59% Pseudomonas, and 52% Enterobacteriaceae species). Participants varied regarding their definitions of “multidrug resistant,” with 14 unique definitions for Acinetobacter, 18 for Pseudomonas, and 22 for Enterobacteriaceae species. Substantial variation also existed in isolation practices. Although isolation was commonly used for methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and carbapenem-resistant Enterobacteriaceae (CRE), approximately 20% of facilities did not isolate for MDR Pseudomonas or Acinetobacter. The majority of those that isolated MDR organisms also removed isolation using a wide variety of criteria.


Facilities vary significantly in their approach to preventing MDR-GNB transmission. Although practices for MRSA and VRE are relatively standardized, emerging pathogens CRE and other MDR-GNB have highly varied definitions and management. This confusion makes communication difficult, and varied use of isolation may contribute to emergence of these organisms. Public health agencies need to promote standard definitions and management to enable broader initiatives to limit emergence of MDR-GNB.

Corresponding author
Christiana Care Health System, 4755 Ogletown-Stanton Road, Suite 2E70, PO Box 6001, Newark, DE 19718 (
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Infection Control & Hospital Epidemiology
  • ISSN: 0899-823X
  • EISSN: 1559-6834
  • URL: /core/journals/infection-control-and-hospital-epidemiology
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