754. Clinical Impact of Switching from Conventional Enzyme Immunoassay (EIA) to Nucleic Acid Amplification Test (NAAT) for Suspected Clostridium difficile-associated Diarrhea
Session: Oral Abstract Session: Clostridium difficile: Detection, Transmission, and Treatment
Friday, October 21, 2011: 2:30 PM
Room: 151AB
Background: Rapid Enzyme Immunoassay (EIA) for C. difficile toxin has become the standard method for testing for C. difficile despite the poor sensitivity and specificity. Unreliable result reporting may lead to excessive retesting, inappropriate and prolonged empiric antibiotic treatment and unnecessary isolation of patients. We assessed the impact of changing C. difficile testing from EIA to nucleic acid amplification (NAAT) on clinical management of patients with suspected C. difficile.

Methods: An educational campaign aimed at appropriate testing and treatment of C. difficile infection (CDI) was initiated just prior to the stool assay conversion. Data was collected retrospectively for C. difficile EIA stool assays in February 2010, and prospectively for C. difficile NAAT in February 2011. Empiric days of therapy (DOT) was defined as antibiotic treatment without a positive stool assay.

Results: One-hundred thirty-five patients undergoing C. difficile NAAT testing in February 2011 were reviewed and compared with patients from one year prior (2010) when testing was done by EIA. There was no difference in the mean number of requests (1.37 vs. 1.68, p=0.34) and the mean number of performed stool assays (1.1 vs. 1.48, p=0.22) per patient. The percentage of tested patients receiving empiric treatment was no different at 11% (NAAT) vs. 14% (EIA), p=0.59. However, NAAT reduced empiric DOT by 4.2 days (95% CI 3.67-4.77) per patient (mean 2.4 [NAAT] vs. 6.6 [EIA]) for a cumulative 87.8 days over the study period compared to the EIA study period (total DOT 38 [NAAT] vs. 125.8 [EIA], p<0.01); an associated cost savings of $19,662 (average wholesale price) was demonstrated.

Conclusion: Directed housestaff education and transition to NAAT demonstrated decreased antibiotic expenditure by significantly reducing the duration of empiric therapy in patients with suspected C. difficile.

Subject Category: D. Diagnostic microbiology

Steven W. Johnson, Pharm.D.1, Meganne Kanatani, Pharm.D.1, Romney Humphries, Ph.D.2 and Daniel Z. Uslan, M.D.3, (1)Department of Pharmaceutical Services, University of California, Los Angeles, Los Angeles, CA, (2)Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA, (3)Infectious Diseases, David Geffen School of Medicine/University of California, Los Angeles, Los Angeles, CA


S. W. Johnson, None

M. Kanatani, None

R. Humphries, None

D. Z. Uslan, None

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.