487. Severity and clinical outcomes of Clostridium difficile infection based on Toxin B Assay Results
Session: Poster Abstract Session: Healthcare Epidemiology: Updates in C. difficile
Thursday, October 4, 2018
Room: S Poster Hall
  • IDSA-2018-Poster-Final.pdf (739.9 kB)
  • Background:

    Clostridium difficile infection (CDI) remains a major health problem in the US. The IDSA guidelines recommend using stool toxin assay as part of a multistep algorithm rather than nucleic acid amplification test (NAAT) alone. However, the clinical significance of toxin negative tests remains a subject of debate. We performed a prospective study in our institution to describe clinical outcomes of CDI based on the results of the stool toxin assay.


    Our lab utilizes a 2 step algorithm, using glutamate dehydrogenase plus detection of toxin B by enzyme immunoassay (EIA) arbitrated by NAAT for testing stool samples submitted for Clostridium difficile testing. The study was conducted between Jan-Dec 2017. Patients diagnosed with CDI based on lab results were divided into 2 groups based on toxin B assay results. Shotgun metagenomics was performed directly on stool specimens using Illumina NextSeq in a subset of patients. Chart reviews were performed to assess clinical outcomes. Our primary outcome was incidence of severe CDI and 30-day mortality.


    2823 samples were submitted to the lab for testing for suspected CDI. 338 samples in 290 discrete patients were considered positive using the 2 step algorithm. Whole genome sequencing was performed on samples from 57 patients (Fig 1). Clinical outcome data was available for 53 patients. 34 % were on active chemotherapy. 34 patients were toxin B positive (group 1), 19 were toxin B negative (group 2) by EIA. Hospital onset disease was seen in 10 (27%) of patients in group 1 vs 7 (37%) in group 2 (p=0.57). 30-day mortality was 3% in toxin positive vs 5% in toxin negative groups (p=0.67). Severe CDI was seen in 14 (41%) in group 1 vs 8 (42%) in group 2 (p=0.94). NAP 1 strain was detected in 10.5% of patients in group 2. Percentage of Clostridium difficile reads on sequencing in fecal samples in group 1 (0.17%) was not significantly different from group 2 (0.24%) (p=0.70, Fig 2).


    In our cohort, detection of Clostridium difficile toxin in stool samples was not associated with increased severity of disease. Our cohort has a higher prevalence of patients on active chemotherapy than previously studied cohorts.

    Bioburden of Clostridium difficile was not significantly different in toxin positive and negative disease.

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    Jorge Jo Kamimoto, MD1, Sandra Susanibar, MD1, Meera Mohan, MD2, Piroon Jenjaroenpun, PHD3, Krishnan Gayathri, MD4, Juan Carlos Rico, MD5, Mary J Burgess, MD5, Ruslana Tytarenko, MS1, Nicole Emery, BS M(ASCP)6, Eric Rosenbaum, MD, MPH6, Brian Walker, PHD1, Intawat Nookaew, PHD3 and Atul Kothari, MD5, (1)Myeloma Institute, University of Arkansas for Medical Sciences, Little Rock, AR, (2)Division of Hematology Oncology, University of Arkansas for Medical Sciences, Little Rock, AR, (3)Department of Biomedical Informatics, University of Arkansas for Medical Sciences, Little Rock, AR, (4)Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, (5)Division of Infectious Diseases, UAMS, Little Rock, AR, (6)Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, AR


    J. Jo Kamimoto, None

    S. Susanibar, None

    M. Mohan, None

    P. Jenjaroenpun, None

    K. Gayathri, None

    J. C. Rico, None

    M. J. Burgess, None

    R. Tytarenko, None

    N. Emery, None

    E. Rosenbaum, None

    B. Walker, None

    I. Nookaew, None

    A. Kothari, 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.