227. Effect of MALDI-TOF on the Time to Antibiotic De-escalation in Patients with Positive Blood Cultures: A Retrospective Study Using a Combined ICU Model
Session: Poster Abstract Session: Antimicrobial Stewardship in Clinical Practice
Friday, October 21, 2011
Room: Poster Hall B1
Handouts
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  • Background: 

    Matrix-assisted laser desorption ionization time of flight (MALDI-TOF) uses mass spectroscopy to create a bacterial species-specific spectral profile based proteins. MALDI-TOF enables identification of bacterial isolates within 30 minutes of initial blood culture positivity, potentially allowing earlier de-escalation of empiric antibiotic therapy. We examined the impact of MALDI-TOF identification on the theoretical time to initial de-escalation of antibiotic spectrum and costs.

    Methods: 

    Our clinical laboratory completed a validation of the MALDI-TOF Biotyper (Bruker Daltonics, Billerica MS) and Sepsityper Kit (Bruker) for the identification of bacterial and yeast isolates from positive blood cultures. The MALDI-TOF result was not available for clinical use. A retrospective chart review was performed for patients with positive cultures used in the validation study. Data collected included the time to identification using MALDI-TOF and traditional culture methods as well as start and stop times of all antibiotics. We calculated the reduction in empiric antibiotic duration and cost difference in patients undergoing de-escalation based on traditional blood culture results. Using average wholesale price, the potential cost of starting the de-escalated antibiotic therapy at the time of MALDI-TOF result was compared to actual antibiotic cost.

    Results: 

    110 positive blood cultures were included in the validation study from 1/4/2011 to 4/1/2011. Cultures positive for yeast, polymicrobial cultures, and specimens from patients from other institutions were not included yielding 58 total positive cultures.  MALDI-TOF correctly identified the bacterium present in 53 positive cultures. Forty-one patients were on empiric antibiotics, 27 of which underwent antibiotic de-escalation based on traditional identification.  

     

    Traditional

    MALDI-TOF

    Difference

    p value

    Empiric Antibiotic Duration (IQR, hrs)

    66.6 (44.4-87.5)

    15.5  (1.4-21.3)

    51.6 (41.8-71.6)

    <0.01

    Median Antibiotic Cost (USD)

    245.24

    88.48

    156.76

    <0.01

    Conclusion: 

    MALDI-TOF allows for rapid bacterial identification leading to a potentially significant reduction in the duration of empiric antibiotic therapy and cost for patients with positive blood cultures.


    Subject Category: J. Clinical practice issues

    Jasmeet Paul, MD1, David Milia, MD1, William Peppard, PharmD, BCPS2, Nathan Ledeboer, PhD, D(ABMM)3, Blake Buchan, PhD3 and Karen Brasel, MD, MPH1, (1)Division of Trauma/Critical Care, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, (2)Pharmacy Department, Froedtert Memorial Lutheran Hospital, Milwaukee, WI, (3)Department of Pathology, Medical College of Wisconsin, Milwaukee, WI

    Disclosures:

    J. Paul, None

    D. Milia, None

    W. Peppard, None

    N. Ledeboer, None

    B. Buchan, None

    K. Brasel, None

    Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.