1364. Inappropriate Clostridium difficile infection (CDI) testing increased CDI rates without identifying carriers of C. difficile at risk for transmission or recurrence
Session: Poster Abstract Session: Clostridium difficile
Saturday, October 5, 2013
Room: The Moscone Center: Poster Hall C
  • ID Week 2013 poster 2.png (426.4 kB)
  • Background: Diagnosis of CDI requires both positive lab test and presence of diarrhea or other clinical symptoms of CDI.  We examined frequency of inappropriate testing for CDI in our facility and compared characteristics of patients with inappropriate versus appropriate testing. We hypothesized that patients with positive but inappropriate CDI tests are asymptomatic carriers who present a significant risk for transmission but are unlikely to develop subsequent symptomatic CDI. 

    Methods: We conducted a 1-year prospective study of inpatients with positive polymerase chain reaction (PCR) assays for toxin B genes from unformed stool specimens submitted for clinical testing.  Medical record review and patient interviews were conducted to assess symptoms of and risk factors for CDI.  CDI testing was deemed inappropriate if patient did not have diarrhea (>3 unformed stools within 24 hours) or if diarrhea was present but with an alternative cause (e.g., laxatives) in the absence of prior antibiotic exposure. For inpatients, skin and environmental surfaces were cultured to assess shedding of spores.

    Results: Of 122 patients with positive CDI testing,  19 (16%) deemed to have inappropriate testing, including 6 of 66 ( 9%) hospital-associated cases, 3 of 17 (18%) long-term care facility onset cases, 8 of 22 (36%) community-associated cases, and 3 of 17 (18%) outside healthcare facility associated cases. In comparison to 103 CDI patients, 19 patients with positive CDI tests that were deemed inappropriate were less likely to have recent antibiotic exposure and none met criteria for severe CDI, developed subsequent recurrence, or had skin and/or environmental shedding (Table).


    Conclusion: In our facility, 16% of positive CDI tests occurred in patients who were tested inappropriately. These patients were unlikely to have received prior antibiotics or to develop subsequent recurrence of CDI and did not represent a significant risk for transmission. 

    Table: Characteristics and outcomes for CDI patients versus patients with positive CDI test results associated with inappropriate testing



    Patients with positive CDI tests but inappropriate testing

    N = 19

    CDI Patients

    N = 103

    P value

    Antibiotics in < 90 days



    < 0.0001

    Severe CDI




    Skin/environmental shedding




    Recurrent CDI




    Sirisha Kundrapu, M.D.1,2, Venkata C.K. Sunkesula, M.D., M.S3, Abhishek Deshpande, M.D., Ph.D.1 and Curtis J. Donskey, MD3, (1)Infectious Diseases, Case Western Reserve University, Cleveland, OH, (2)Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH, (3)Case Western Reserve University, Cleveland, OH


    S. Kundrapu, None

    V. C. K. Sunkesula, None

    A. Deshpande, None

    C. J. Donskey, None

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