The PCR based assay for Clostridium difficile (C diff) toxin B gene is highly sensitive. Like any diagnostic test, interpretation requires assessment of the clinical context and pre-test probability. IDSA guidelines state that “test of cure” for C diff may be misleading and should not be performed. Positive tests in asymptomatic individuals do not connote clinical disease. In this study, we analyzed hospitalized patients who tested positive for C diff after laxative use and found a low frequency of C diff Infection (CDI).
A retrospective chart review of 45 patients hospitalized between November 1, 2013 and May 1, 2014 was performed. Each patient tested positive for toxin B of C diff using the BD GeneOhm C diff assay coincident with laxative administration. Every chart was reviewed by at least two infectious disease physicians. Each case was classified as likely CDI, unlikely CDI, or indeterminate. Consensus was achieved on all cases. Criteria utilized included clinical course, response to therapy, patient symptoms, laboratory findings and imaging studies if available. Pearson Chi Square tests of clinical variables for each classification were calculated.
We found a plurality of patients did not have CDI. Out of 45 cases, only 11 (24%) were deemed likely to have CDI. 19 cases (42%) were determined unlikely to have CDI, and 15 (33%) were indeterminate. Antimicrobial use was less common in the unlikely group (Χ2 =43.40; p=.000). Unlikely to have CDI patients failed to respond after C diff treatment more frequently than the other groups (Χ2=12.7; p=.002)
|Did not improve||Improved||Improvement not clear||Had transient diarrhea|
|% of people that used antimicrobials|
Patients with laxative induced diarrhea are unlikely to have CDI in the absence of other signs and symptoms of inflammatory colitis. Testing these patients leads to over-diagnosis, exposes them to unnecessary treatment, inappropriate isolation and cohorting, unnecessarily increased costs and impairs our ability to appreciate C diff epidemiology. C. diff testing should be avoided in patients with laxative use.
J. Fried, None
K. Brady, None
A. Baghban, None
R. Schwartz, None
B. Edwards, None
B. Hirsch, None
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