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Reporting of Unit-Specific, Culture Site-Specific Antimicrobial Susceptibility for Gram-Negative Bacteria: Identification of Significant Differences in Susceptibility, Intervention to Guide Empiric Therapy and Impact on Antimicrobial Consumption

Session: Poster Abstract Session: Diagnostic Microbiology: Bacterial Infections
Saturday, October 11, 2014
Room: The Pennsylvania Convention Center: IDExpo Hall BC
Background: Previous studies have described variances in antimicrobial susceptibility between patient care areas within the same institution. CLSI suggests consideration of segregating antibiogram results, including by patient location, specimen type, or clinical condition. However, the clinical impact of reporting antimicrobial susceptibility by combining unit and collection site-specific data is not well described. Our previous work using this novel antibiogram demonstrated significant differences in susceptibility results when combining unit and culture site specific data. Based on these data, we recommended cefepime (as good as a carbapenem) for ICU sepsis. We analyzed impact of this recommendation on antimicrobial consumption, and subsequent trends of selected gram-negative resistance patterns within high antimicrobial pressure units to aggregated hospital data.

Methods: All clinical isolates from 1/2010 - 12/2013 of gram negative organisms that were obtained from sterile site inpatient cultures at a large academic medical center were analyzed. Sterile sites included blood or lower respiratory tract. Differences between units for site-specific data were compared using Chi-square or Fisher’s exact test. We analyzed trends in susceptibility and also antimicrobial consumption per 1000 patient days before and after our recommendation (guiding clinicians to use cefepime as a carbapenem sparing agent given similar susceptibilities).

Results: Susceptibility results were statistically different between the hospital-wide results and ICU-specific, site-specific antibiogram results for all comparisons involving our 3 most commonly used b-lactams for all four years analyzed. Statistical difference was also observed when comparing specific ICUs to each other, and to aggregate results.  Although intial cefepime use did increase after our recommendation, utilization rebounded to baseline.

Conclusion: Reporting susceptibility by both unit- and collection site-specific data allows for increased insight into antimicrobial resistance. This method may be useful for therapeutic decisions for empiric therapy and increased knowledge of resistance patterns within specific patient care areas but dissemination of data must be sustained to impact prescribing practices.

Elizabeth Leung, PharmD, BCPS1, Michael Postelnick, RPh2, John Esterly, PharmD, BCPS AQ-ID3 and Marc Scheetz, PharmD, MSc, BCPS AQ-ID2,4, (1)Pharmacy, Northwestern Memorial Hospital, Chicago, IL, (2)Northwestern Memorial Hospital, Chicago, IL, (3)Pharmacy, Infectious Diseases, Northwestern Memorial Hospital, Chicago, IL, (4)Midwestern University, Downers Grove, IL


E. Leung, None

M. Postelnick, None

J. Esterly, None

M. Scheetz, None

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