2345. Reduction in Testing and Change in Testing Algorithm Associated with Decrease in Number of Nosocomial Clostridium difficile Infections

BACKGROUND: Previous data at our facility indicated 37% of patients with Clostridium difficile infection (CDI) were receiving at least one laxative at the time of testing, suggesting the possibility of false-positive results. Nucleic acid amplification testing (NAAT) does not distinguish between colonization and infection with C. difficile. We implemented two interventions to address these issues and evaluated our rates of nosocomial CDI before and after these changes. METHODS: This was a retrospective study of all positive test results for adult patients with nosocomial C. difficile from October 1, 2017 through March 31, 2019 at Vidant Medical Center, a 911-bed hospital. In June, 2018, we implemented a best practice advisory (BPA) in our electronic health record to recommend against testing for CDI in patients receiving laxatives. We reviewed the number of C. difficile tests ordered before and after initiating the BPA. In December, 2018, we removed NAAT and replaced it with a cell cytotoxicity assay (CCA) for specimens that were enzyme immunoassay (EIA) negative and glutamate dehydrogenase (GDH) positive. Antimicrobial use was measured in days of therapy (DOT) per 10,000 patient-days (PD). Mann–Whitney U test was used for continuous variables. Linear regression was used to monitor antimicrobial use. RESULTS: The number of C. difficile tests ordered per month decreased 19.5% after implementing the BPA (P < 0.0001). There was a 44% reduction in the number of EIA+/GDH+ specimens per month after the BPA intervention (P = 0.003). Following substitution of CCA for NAAT for EIA-/GDH+ specimens, there was a 61% reduction in the rate of nosocomial CDI (8.6 cases/10,000 PD to 3.3 cases/10,000 PD; P = 0.005). Total antimicrobial use was unchanged over the course of the study (673 to 677 DOT/10,000 PD). Carbapenem use decreased 56% (P = 0.009); cefepime use increased 85%(p = 0.002); quinolone and clindamycin use were unchanged. CONCLUSION: Laxative use in hospitalized patients is common and likely contributes to a false elevation in the CDI rate by identifying carriers in addition to those who have true infection. Implementing a BPA to reduce inappropriate testing and changing our testing algorithm for Clostridium difficile by substituting CCA for NAAT has resulted in a lower rate of nosocomial CDI. [Image: see text] [Image: see text] [Image: see text] [Image: see text] DISCLOSURES: All authors: No reported disclosures.