1222. Risk Factors and Outcomes for Daptomycin Non-Susceptible Methicillin-Resistant Staphylococcus aureus Bloodstream Infections
Session: Poster Abstract Session: Healthcare Epidemiology: MSSA, MRSA and Other Gram Positive Infections
Friday, October 5, 2018
Room: S Poster Hall
Posters
  • risk factors and outcomes of DNS MRSA1.pdf (865.9 kB)
  • Background:

    Daptomycin (dap) has been approved and successfully used for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. However, reports of daptomycin non-susceptible (DNS) MRSA strains have emerged over the recent years. This study describes the clinical characteristics of patients with DNS MRSA bloodstream infections (BSIs) with the objective of identifying risk factors and outcomes.

    Methods:

    This is a retrospective case-control study in a tertiary healthcare system in southeast Michigan. Cases included 34 patients with DNS MRSA BSI between 9/24/2005 and 3/31/2018. Cases were matched with controls with MRSA BSI based on age, source of BSI, and time-period of BSI in a 1:1 ratio. Charts were reviewed for clinical and laboratory data. Vancomycin (van) and dap minimum inhibitory concentrations (MICs) were determined by E-test. DNS was defined as an MIC >1.0 µg/mL. Chi-square test, Fisher’s Exact test and t-test were used to determine statistical significance.

    Results:

    In the case cohort, the source of BSI was endovascular in 11(32%) patients, central-line associated in 3(9%), secondary BSI in 13(38%), and unknown in 7(21%). Table 1 is a summary of the results.

    Table 1. Clinical characteristics and outcomes of cases and controls

    Cases

    N=34(%)

    Controls

    N=34(%)

    p-value

    Mean age (SD)

    63.5 (12.0)

    61.9 (11.2)

    0.572

    Male

    18 (52.9)

    21 (61.8)

    0.462

    Mean bacteremia duration in days (SD)

    4.4 (3.2)

    5.9 (4.9)

    0.195

    Mean LOS in days (SD)

    19.5 (13.6)

    18.4 (14.6)

    0.751

    Mean van MIC (SD)

    2.04 (1.19)

    1.39 (0.36)

    0.003

    Mean dap MIC (SD)

    2.69 (1.32)

    0.57 (0.24)

    <0.0001

    Epidemiologic acquisition

    Community-acquired

    Healthcare-associated

    Hospital-acquired

    0 (0)

    21 (63.6)

    12 (36.4)

    9 (26.5)

    22 (64.7)

    3 (8.8)

    0.002

    0.927

    0.007

    90-day prior dap exposure

    23 (82.1)

    3 (9.7)

    <0.0001

    Mean dap exposure in days

    23.6 (21.0)

    2.68 (10.6)

    <0.0001

    90-day prior van exposure

    25 (89.3)

    9 (29)

    <0.0001

    Mean van exposure in days

    13.0 (14.7)

    4.19 (12.7)

    0.020

    30-day mortality*

    10 (32.3)

    6 (18.8)

    0.218

    Mean Charlson Comorbidity Index (SD)

    5.7 (3.07)

    4.4 (2.9)

    0.077

    90-day MRSA BSI recurrence*

    8 (44.4)

    2 (9.5)

    0.025

    * From date of index BSI

    Conclusion:

    Prior exposure to dap and van, and higher van MIC in MRSA isolates are risk factors for DNS MRSA BSI. DNS is associated with significantly higher risk of 90-day MRSA BSI recurrence.

    Hind Hadid, MD1, Hira Rizvi, MD1, Helina Misikir, MPH2, Nathalie Baratz, MD3, Ana Cecilia Bardossy, MD4, Ayesha Sundaram, BS5, Lillian Haddad, BS5, Mary Beth Perri, MT6, Marcus Zervos, MD4 and Erica Herc, MD1, (1)Infectious Disease, Henry Ford Health System, Detroit, MI, (2)Henry Ford Hospital, Detroit, MI, (3)Infectious Disease, Henry Ford Health System, Detriot, MI, (4)Henry Ford Health System, Detroit, MI, (5)Wayne State University, Detroit, MI, (6)Infectious Diseases, Henry Ford Health System, Detroit, MI

    Disclosures:

    H. Hadid, None

    H. Rizvi, None

    H. Misikir, None

    N. Baratz, None

    A. C. Bardossy, None

    A. Sundaram, None

    L. Haddad, None

    M. B. Perri, None

    M. Zervos, None

    E. Herc, None

    Findings in the abstracts are embargoed until 12:01 a.m. PDT, Wednesday Oct. 3rd with the exception of research findings presented at the IDWeek press conferences.