244. Reporting of Unit-Specific, Culture Site-Specific Antimicrobial Susceptibility for Gram-Negative Bacteria: Identification of Significant Differences in Susceptibility and Impact on Empiric Antimicrobial Choice
Session: Poster Abstract Session: Diagnostic Microbiology; Antimicrobial Sensitivities
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
  • IDSA2013-ELeung-rev2-pc.pdf (253.2 kB)
  • Background: Previous studies have described variances in antimicrobial susceptibility between patient care areas within the same institution as well as lack of data regarding questionable utility of accounting for anatomical site of specimen collection in antibiogram reporting. Recently, the Clinical and Laboratory Standards Institute (CLSI) has acknowledged increasing interest in 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 has not been previously described. We compared selected gram-negative resistance patterns within high antimicrobial pressure units to aggregated hospital data using this novel method.

    Methods: All clinical isolates from 1/2011-1/2012 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. One isolate per patient per location per source was obtained; however we included multiple isolates per patient if the susceptibility profile had changed. Differences between units for site-specific data were compared using Chi-square or Fisher’s exact test.

    Results: 297 BAL and 522 blood isolates were analyzed in 2010, and 295 BAL and 424 blood isolates were analyzed in 2011. 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. Statistical difference was also observed when comparing specific ICUs to each other, and to aggregate results.

    Conclusion: Reporting susceptibility by both unit- and collection site-specific data allows for increased insight into antimicrobial resistance at an institution. This method may be useful for therapeutic decisions for empiric therapy of suspected infections and increased knowledge of resistance patterns within specific patient care areas. Specialized antibiograms as we have described may be useful to prevent empiric escalation to carbapenems, if unwarranted. Future work should focus on analysis of clinical outcomes of this novel method of reporting susceptibility.

    Elizabeth Leung, PharmD, BCPS, Pharmacy, Northwestern Memorial Hospital, Chicago, IL and Michael Postelnick, RPh, Northwestern Memorial Hospital, Chicago, IL


    E. Leung, None

    M. Postelnick, None

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