1571. Novel T2 Magnetic Resonance Assay Compared to Standard Blood Cultures for Detection of Candidemia.
Session: Poster Abstract Session: Mycology: Diagnostic
Friday, October 28, 2016
Room: Poster Hall
Posters
  • poster draft - T2MR Poster for MIDS (modified for ID week) - final3.pdf (748.9 kB)
  • Novel T2 Magnetic Resonance Assay Compared to Standard Blood Cultures for Detection of Candidemia.

    Shamik Dwivedi D.O., Eloy Ordaya M.D., Brie Kezlarian M.D., Rachel

    Kenny PharmD, Robert Tibbetts PhD, Linoj Samuel PhD, George Alangaden M.D.

    Background: Outcomes of candidemia are improved with rapid diagnosis and therapy. Blood culture (BC) has a turn-around-time (TAT) of 2-5 days. T2 magnetic resonance (T2) assay, a nano-diagnostic blood test, detects: C.albicans/C.tropicalis (Ca/Ct), C.krusei/C.glabrata (Ck/Cg), and C.parapsilosis (Cp). Clinical trials of T2 showed good sensitivity and specificity, NPV 99% and TAT of 3-5 hours. We evaluated use and performance characteristics of T2 assay at our institution.

    Methods: Observational, retrospective, cross-sectional evaluation of patients with suspected candidemia who had T2 performed from 10/2015 - 4/2016 at Henry Ford Health System, a large healthcare system in Detroit, MI. Candida Score of ≥3 was defined as high risk for candidemia (Crit Care Med 2009;37:1624). Discordant results of T2 and BC were assessed. PPV and NPV were calculated for all specimens vs. specimens drawn simultaneously.

    Results:

    Of 120 pts, 33 (28%) had positive T2 and/or BC:

    ·   10/33 (30%) had T2 and BC positive and 23/33 (70%) were discordant. Possible reasons for discordance: different dates of blood collection (30%); antifungal therapy before collection (35%); Candida sp. not detected by T2 (4%).

    ·   11/33 (33%) had only positive BC: 5 Cg, 3 Ca, 2 Cp, 1 C. lusitaniae. Av. Candida score 2.1 (0-4), other characteristics in Table 1.

    ·   12/33 (37%) had only positive T2: 7 Ca/Ct, 3 Cp, 2 Cg/Ck. Av. Candida Score 2.1 (0-5).

    ·   Av. TAT for T2 was 13 hrs (5-41) and 34 hrs (21-109) to initial positive BC and 4 days (3-13) to final positive BC.

    ·   Overall PPV and NPV for T2 was 45% and 89% vs. 60% and 95% for simultaneous specimens.

    Conclusion: Performance characteristics of T2 in routine clinical practice differ from those reported in clinical trials. Targeted use of T2 in only high-risk pts and uniformity in sample collection will be important for accurate interpretation of this test. The rapid TAT and good NPV of T2 should help support antimicrobial stewardship efforts.

    Table 1. Characteristics of BC positive, T2 negative results (n=11)

    Description

    No.

    T2 sample drawn ≥1 day after BC

    5

    T2 sample peripheral blood, BC from central-line

    3

    Antifungals initiated before T2 sample obtained

    2

    C. lusitaniae in blood culture

    1

    Shamik Dwivedi, DO1, Eloy Ordaya, MD1, Brie Kezlarian, M.D.2, Rachel Kenny, PharmD3, Robert Tibbetts, Ph.D. D(ABMM), F(CCM)4, Linoj Samuel, PhD., D(ABMM)5 and George Alangaden, MD, FIDSA1, (1)Infectious Diseases, Henry Ford Hospital, Detroit, MI, (2)Pathology, Henry Ford Hospital, Detroit, MI, (3)Pharmacy, Henry Ford Hospital, Detroit, MI, (4)Pathology and Microbiology, Henry Ford Hospital, Detroit, MI, (5)Microbiology, Henry Ford Hospital, Detroit, MI

    Disclosures:

    S. Dwivedi, None

    E. Ordaya, None

    B. Kezlarian, None

    R. Kenny, None

    R. Tibbetts, None

    L. Samuel, None

    G. Alangaden, None

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