30. Patient Characteristics and Clinical Data Predictive of Overdiagnosis of Clostridium difficile Infection with PCR Assay
Session: Posters in the Park: Posters in the Park
Wednesday, October 3, 2018: 5:30 PM
Room: N Hall D Opening Reception and Posters in the Park Area
  • ID week c diff poster pdf.pdf (857.4 kB)
  • Background: There is increasing appreciation for the overdiagnosis of Clostridium difficile (C. difficile) infection with nucleic acid-based tests compared to toxin-based assays. Several studies have shown patients who test positive by PCR and negative by toxin-based assays have outcomes similar to uninfected patients.

    Methods: Our study sought to examine differences in patient demographics and clinical variables classically associated with C. difficile risk between PCR-positive/toxin-positive and PCR-positive/toxin-negative patients. We examined a retrospective cohort of fifty-two hospitalized patients with diarrhea in 2016-2017. Fischer exact test was used on discrete data and Wilcoxon Rank Sum test was used on continuous data.

    Results: Over half of the patients in our sample were PCR-positive/toxin-negative (27/52 = 52%). The only significant difference between PCR-positive/toxin-positive and PCR-positive/toxin-negative patients was median white blood cell count 14.3 vs 7.4 (p-value <0.001). Variables which trended towards significance included median temperature (p=0.072) and median albumin (p=0.09). There was no significant difference between the two groups in terms of patient gender, age, history of C. difficile infection, long term care facility residence, prior hospitalization, co-morbid conditions, presence of acute kidney injury, clinician diagnosis of sepsis, treatment in intensive care unit, length of stay, receipt of laxatives, receipt of proton pump inhibitor, number of antibiotics received during hospitalization or number of bowel movements on day of diagnosis.

    Conclusion: The results of our study are consistent with prior studies which have shown that many of the traditional risk factors for C. difficile infection are not useful for predicting whether PCR-positive patients will have positive results on toxin-based assays. In our population, white blood cell count was higher in patients with positive toxin assays and all cases had white blood cell counts greater than 10.6. These results also suggest that even facilities with preagreed upon criteria for submission of stool may consider a multi-step algorithm for accurate diagnosis of C. difficile infection. Facilities may consider using white blood cell count as part of their C. difficile testing criteria.

    Kaitlyn Hardin, MD/MPH&TM, UCLA David Geffen School of Medicine, Los Angeles, CA, Arthur Jeng, MD, Infectious Diseases, Olive View-UCLA Medical Center, Sylmar, CA and Brian Kim, PharmD, Pharmacy, Olive View-UCLA Medical Center, Sylmar, CA


    K. Hardin, None

    A. Jeng, None

    B. Kim, None

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