Program Schedule

What Defines Carbapenem-Resistant Enterobacteriaceae (CRE) in a Low Prevalence State? Oregon, 2010 2013

Session: Poster Abstract Session: Public Health
Saturday, October 11, 2014
Room: The Pennsylvania Convention Center: IDExpo Hall BC
  • CRE poster-FINAL.pdf (2.9 MB)
  • Background: Preventing the spread of carbapenem-resistant Enterobacteriaceae (CRE) is important to public health because of high infection-related morbidity, mortality, and cost. Carbapenemase producing (CP)-CRE are most concerning because of their rapid global dissemination.  In 2013, CRE in Oregon were defined as Enterobacteriaceae with non-susceptibility to ≥1 carbapenem, including ertapenem, and resistance to any 3rdgeneration cephalosporin. Review of surveillance data raised concerns of poor definition specificity for CP-CRE creating burden for laboratories and public health investigators. 

    Methods: We analyzed all CRE isolates reported in Oregon 12/2010—10/2013. We reviewed surveillance data from other states and published literature, focusing on CRE minimal inhibitory concentration breakpoints.

    Results: Of our 125 unique isolates, 75 (60%) were Enterobacter cloacae, 13 (10%) Enterobacter aerogenes, 11 (9%) Escherichia coli, 11 (9%) Klebsiella pneumoniae, and 14 (11%) were other species. Non-susceptibility only to ertapenem was demonstrated by 66 (53%), of which 47 (72%) were E. cloacae. Of the 34 isolates non-susceptible to multiple carbapenems, 18 (53%) were E. cloacae, 5 (15%) E. aerogenes, 4 (12%) E. coli, and 6 (18%) K. pneumoniae. Ninety-nine (81%) isolates were resistant to all 3rd generation cephalosporins tested. Three were CP-CRE; all were K. pneumoniae producing K. pneumoniae carbapenemases.

    Review of literature and other states’ data confirmed carbapenemases were present in E. cloacae. Excluding ertapenem from the definition for laboratories using the updated Clinical Laboratory Standard Institute (CLSI) breakpoints did not greatly reduce sensitivity for the most common carbapenemases. Finally, retaining the cephalosporin-resistance requirement enhanced specificity. The new definition decreased the number of cases to investigate by 57%, without missing any CP-CRE.

    Conclusion: We modified our case definition to increase CP-CRE specificity, without losing sensitivity, thus decreasing investigation burden. For laboratories using current CLSI breakpoints, the new definition includes all Enterobacteriaceae, removes ertapenem, and requires resistance to all 3rd generation cephalosporins tested.

    P. Maureen Cassidy, MPH1, Christopher Pfeiffer, MD, MHS2, Genevieve L. Buser, MDCM, MSHP1 and Zintars G. Beldavs, MS1, (1)Acute & Communicable Disease Prevention, Oregon Health Authority, Portland, OR, (2)Portland VA Medical Center, Portland, OR


    P. M. Cassidy, None

    C. Pfeiffer, None

    G. L. Buser, None

    Z. G. Beldavs, None

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