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Evaluation of Empirical Regimens Including Antistaphylococal Beta-lactam Antibiotics versus Vancomycin Monotherapy on Outcomes of Patients with Methicillin-Susceptible Staphylococcus aureus (MSSA) Bacteremia

Session: Poster Abstract Session: Bacteremia: Staphylococcal Bacteremia
Friday, October 10, 2014
Room: The Pennsylvania Convention Center: IDExpo Hall BC
Posters
  • ID Week Poster-final.pdf (268.8 kB)
  • Background: Little is known about the outcomes of patients who are initiated on vancomycin as empiric monotherapy relative to antistaphyloccal BL therapy for MSSA BSIs.  The purpose of this study was to evaluate outcomes of patients with MSSA BSIs who were treated with vancomycin monotherapy empirically compared to those who also received an antistaphylococcal BL.

    Methods: This was a single-center retrospective study of patients with MSSA BSIs from Apr 2008-Dec 2013.  Inclusion criteria were: receipt of ≥48 hours of empiric therapy; ≥1 positive blood culture with MSSA; 1st positive culture drawn within 24 hours of starting empiric antibiotics.  Exclusion criteria consisted of: use of anti-MRSA therapy for concomitant infection; polymicrobial BSI; use of other agents active against MSSA.  The primary endpoint was clinical failure, a composite of 30-day mortality and persistent BSI ≥7 days. Logistic regression was performed to determine factors associated with the endpoint.

    Results: 339 charts of patients with S. aureus BSI were screened and 75 of these patients were included in the final analysis.

     

    Table 1. Study Results

    Variable

    Vancomycin monotherapy

    (N=20)

    Empiric BL

    (N=75)

    P-Value

    Demographics

    Male

    55%

    69.1%

    0.23

    Intensive Care Unit

    55%

    47.2%

    0.55

    Age, mean ± SD

    53.2 ± 14.5

    54.9 ± 15.7

    0.67

    BL allergy

    25%

    3.6%

    0.005

    Acute Physiology and Chronic Health Evaluation II (APACHE II), mean ± SD

    19.9 ± 10.3

    21.4 ± 10.0

    0.55

    Charlson Index, mean ± SD

    4.4 ± 2.8

    4.3 ±3.1

    0.9

    Primary Outcome

    Clinical failure

    35%

    23.6%

    0.33

    30-day mortality

    20%

    16.3%

    0.71

    BSI ≥7 days

    20%

    7.2%

    0.11

    Factors Related to Clinical Failure

    Variable

    Odds Ratio [95% Confidence Interval])

    Vancomycin monotherapy

    2.98 [0.78-11.38]

    Age

    1.05 [0.99-1.12]

    APACHE II

    1.12 [1.03-1.21]

    Charlson Index

    0.94 [0.71-1.24]

    On multivariate analysis, only APACHE-II score was associated with clinical failure.  

    Conclusion: This study does not show a significantly increased risk of clinical failure in patients who are treated with vancomycin monotherapy empirically. The lack of significant differences between groups may be due to insufficient power to detect a difference; therefore, a larger study evaluating the influence of empiric antibiotic choice for MSSA BSI is warranted.

    Adrienne Terico, PharmD, Temple University Hospital, Philadelphia, PA, Kevin Haynes, PharmD, MSCE, University of Pennsylvania School of Medicine, Philadelphia, PA and Jason Gallagher, PharmD, FCCP, BCPS, Temple University, Philadelphia, PA

    Disclosures:

    A. Terico, None

    K. Haynes, None

    J. Gallagher, Cubist: Consultant, Consulting fee
    Optimer: Scientific Advisor and Speaker's Bureau, Consulting fee and Speaker honorarium
    Astellas: Speaker's Bureau, Speaker honorarium
    Forest: Scientific Advisor and Speaker's Bureau, Consulting fee and Speaker honorarium
    Pfizer: Scientific Advisor, Consulting fee

    Findings in the abstracts are embargoed until 12:01 a.m. EDT, Oct. 8th with the exception of research findings presented at the IDWeek press conferences.

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