242. Carbapenem-Resistant Enterobacteriaceae: A Mixed-Methods Review of Epidemiology and Microbiology Practices in North and South Carolina
Session: Poster Abstract Session: Diagnostic Microbiology; Antimicrobial Sensitivities
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Background: Infections with carbapenem-resistant Enterobacteriaceae (CRE) have limited treatment options and high associated mortality. The microbiologic method for detecting CRE is not standardized, which may impair interpretation of surveillance data.

Methods: We conducted a retrospective cohort study of 23 community hospitals participating in the Duke Infection Control Outreach Network from 2008-2012.  Hospital microbiology personnel were surveyed regarding their current and historical methods for laboratory identification of CRE. We utilized the DICON surveillance database to abstract prospectively collected surveillance data of patients colonized or infected with CRE. We used Poisson regression to calculate incidence rate (IR) per 100,000 patient days (pt-d) and incidence rate ratios (IRR) to compare laboratory methods and identify time trends.

Results: A total of 55 patients with clinical cultures growing CRE were identified during 5.5 million patient days at study hospitals (median bed size=214); 33 (60%) patients had infection. Twelve (53%) hospitals identified one or more cases of CRE during the study period. Most common species were K. pneumoniae (n=34, 62%) and E. coli (n=16, 29%). The most common sites of CRE isolation were urine (56%) and sputum (9%). The majority of isolates were defined as healthcare-associated (71%), while 14% were hospital-acquired. The unadjusted rates of CRE increased from 0.18 to 1.34 per 100,000 pt-d over 5 years (IRR 7.7, 95% CI 1.7-35.4, p=0.009). 14 (61%) laboratories send suspected CRE to an external lab for verification, 6 (26%) perform a Modified Hodge test, and 3 (13%) perform local phenotypic testing only.  Hospitals (n=8, 35%) that adopted the 2010 CLSI MIC guidelines detected more CRE in 2011-12 than those that did not (IRR=2.81, 95% CI 0.82-9.64) but this difference was not statistically significant (p = 0.10).

Conclusion: Although CRE isolation was a rare event, the incidence of CRE significantly increased in community hospitals over the past 5 years.  Laboratory methods used to detect CRE in community hospitals were highly variable; only about a third used 2010 CLSI MIC guidelines. Further research to identify an ideal and practical lab method is needed so meaningful data can inform public health efforts.

Joshua T. Thaden, MD, PhD1, Sarah S. Lewis, MD1,2, Kevin C. Hazen, PhD3, Kirk Huslage, BSN, MS4, Rebekah W. Moehring, MD, MPH1,2, Luke F. Chen, MBBS, MPH, CIC, FRACP1,2, Daniel J. Sexton, MD, FIDSA1,2 and Deverick J. Anderson, MD, MPH1,2, (1)Division of Infectious Diseases, Duke University Medical Center, Durham, NC, (2)Duke Infection Control Outreach Network, Duke University Medical Center, Durham, NC, (3)Duke University Medical Center, Durham, NC, (4)Statewide Program for Infection Control and Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC


J. T. Thaden, None

S. S. Lewis, None

K. C. Hazen, None

K. Huslage, None

R. W. Moehring, None

L. F. Chen, Merck, Inc.: Grant Investigator, Research support
Optimer Pharmaceuticals: Investigator and Speaker's Bureau, Research grant and Speaker honorarium
Cubist Pharmaceuticals: Speaker's Bureau, Speaker honorarium

D. J. Sexton, None

D. J. Anderson, None

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