1982. A Diagnostic Stewardship Intervention for Clostridioides difficile: Impact of Stool Toxin Testing on Treatment of Adult Inpatients

Background Testing for Clostridioides difficile infection has been the subject of recent debate. Guidelines from the Infectious Diseases Society of America now support the addition of a stool toxin test to a positive nucleic acid amplification test (NAAT) as part of a multi-step testing algorithm. In November 2017, the University of Kentucky HealthCare system added stool toxin testing to any specimen positive for C. difficile by NAAT. This change was accompanied by face to face education with provider groups and clinical decision support in the form of interpretive verbiage added to the results that are reported into the electronic record. The objective of this study was to assess whether this diagnostic stewardship intervention made an impact on C. difficile treatment Methods We performed a retrospective review of adult patients admitted to UK HealthCare from November 1, 2017 through October 31, 2018 who tested positive by NAAT but negative by stool toxin test to determine whether or not they were treated. We also assessed treatment by service line to see whether there were treatment differences among these groups. A cost analysis was also performed. Results A total of 300 adult inpatients were positive for C. difficile by NAAT during the study period with 71% (213 patients) having a negative stool toxin test. Of those, 58% (123) were never started on C. difficile therapy and an additional 14% (30) had their therapy stopped after 48 hours. Only 28% (60) of these patients received a full course of therapy. Hospital medicine had the highest rate of non-treatment at 82%. Conversely, our solid-organ and bone marrow transplant services had the lowest rate of non-treatment at 31%. Overall, this approach was associated with an estimated 1470 oral vancomycin days avoided (5,880 doses) and a cost savings of $6,278. Conclusion The addition of stool toxin testing to NAAT combined with education and clinical decision support lead to a dramatic reduction of treatment for NAAT positive but toxin-negative patients. This form of diagnostic stewardship had a significant impact on therapy decisions and can be a powerful antimicrobial stewardship approach to decrease unnecessary treatment of C. difficile colonization. Disclosures All authors: No reported disclosures.

839. Effect of Clostridioides difficile (C. difficile) Toxin Test Reporting on Clinical Treatment and Outcomes of Toxin-Negative PCR-Positive Patients at Five California Hospitals

Background Guidelines support the use of toxin tests after C. difficile antigen detection or nucleic acid amplification tests (e.g., PCR) to help clinicians distinguish colonization from infection and reduce overdiagnosis but the safety of toxin-based diagnostic approaches remains controversial. Methods Five California hospitals monitored hospitalized adults with C. difficile testing before and after operational changes to reduce test-related overdiagnosis (2016–2018). Four added a toxin test to an existing GDH antigen/PCR-based approach and/or changed reporting to encourage the use of toxin results for clinical decision-making (i.e.,“toxin-dominant reporting”). One used the same test (toxin only) and reporting strategy throughout. All used a standardized tool to document clinical outcomes and treatment four days after testing (i.e., Day 5). Results In total, 1,034 patients had a Day 5 assessment with PCR-dominant reporting (pre-operational changes); 2,511 patients had a Day 5 assessment with toxin-dominant reporting (post-operational changes and single facility with no test change). Fewer Toxin-negative/PCR-positive (Toxin−/PCR+) patients received treatment with toxin-dominant reporting (median change: −52.1% [interquartile range (IQR): −35.1%, −69.1%]; aggregate P < 0.001). Day 5 outcomes were similar or better with toxin-dominant reporting despite less treatment. Patient discharge rates and in hospital diarrheal recovery was greater in the subset of Toxin−/PCR+ patients during the toxin-dominant reporting period: median discharge rate change = 8.8% [IQR: 1.5%, 11.9%] (aggregate P = 0.04); median diarrheal recovery rate change = 11.8% [IQR: 8.8%, 18.2%] (aggregate P = 0.018). Conclusion In a 5-center study, toxin-dominant test result reporting decreased anti-C. difficile treatment and improved discharge rates and diarrheal recovery in Toxin−/PCR+ patients. More work is needed to determine the rate of C. difficile-related adverse events in Toxin−/PCR+ patients. Disclosures All Authors: No reported Disclosures.

Immunochromatography Method Was Useful in Prompt Diagnosis of Potentially Fatal Norovirus Gastroenteritis After Hematopoietic Stem Cell Transplantation

Abstract 4542 Background: Norovirus-gastroenteritis (NV-GE) is considered as a highly transmittable disease that can lead to fatal outcomes in vulnerable populations. Therefore, prompt detection of norovirus in stool specimens is important for patients who undergo hematopoietic stem cell transplantation (HSCT). The commercially available immunochromatography kit (Denka Seiken, Tokyo, Japan) is a diagnostic tool that can easily and rapidly detect norovirus antigens with high specificity and relatively less sensitivity compared with reverse transcription polymerase chain reaction (RT-PCR). Although previous studies used RT-PCR to detect norovirus in stool, this method is not necessarily a standardized technique for the clinical use, and only limited information is available about clinical significance of norovirus infection among the HSCT recipients. Here, we report an analysis of patients with NV-GE in our HSCT unit using the immunochromatography method. Patients and Methods: We prospectively examined stool specimens to detect norovirus antigens in patients who developed diarrhea in our HSCT unit between December 2008 and June 2011. We also retrospectively examined stool specimens which had been collected for Clostridium difficile (CD) toxin test and frozen at –40°C between January 2007 and November 2008. During the study period, a total of 468 patients underwent HSCT (autologous 83, allogeneic 385) at our center and we tested stool specimens from 355 patients who developed diarrhea. Results: Norovirus was detected by the immunochromatography method in 11 patients among the HSCT recipients, and in 1 patient who died before HSCT because of disease progression. Among the 12 patients with NV-GE, 3 were retrospectively diagnosed using the frozen specimens. The CD toxin test was also positive in 1 of the 12 patients with NV-GE. The median age of the 12 patients was 56 years (range, 29–66). The median duration of symptoms was 30 days (2–134). Among the 11 patients who developed NV-GE after HSCT, primary disease included lymphoma (6 patients), acute leukemia (4 patients), and multiple myeloma (1 patient), and 9 of them were not in remission at HSCT. One patient developed NV-GE after autologous HSCT, and 10 patients after allogeneic HSCT. Among the 10 allo-HSCT recipients, 6 received grafts from unrelated bone marrow donor and 4 received grafts from related donor. Five patients received myeloablative conditioning and 5 received reduced-intensity conditioning before allo-HSCT. The median time from HSCT to the onset of symptoms was 36 days (4–93). The median time from HSCT to diagnosis of NV-GE was 37 days (11–101). At diagnosis of NV-GE, all allo-HSCT recipients were given immunosuppressive agents, and 2 of them received corticosteroids for intestinal graft-versus host disease (GVHD). The volume of diarrhea was more than 500 ml per day in 4 patients. Among 4 patients who underwent endoscopy of the lower gastrointestinal tract, intestinal GVHD was diagnosed in 2 patients by histopathology findings, whereas the other 2 patients had no evidence of intestinal GVHD, which resulted in no need for an intensification of immunosuppression. Of the 12 patients with NV-GE, 6 were alive with a median follow-up of 826 days (17–1168) after the diagnosis of NV-GE. No patients died of NV-GE, and 6 died of other causes (disease progression, 4; GVHD, 1; multiple organ failure, 1). There was no outbreak of NV-GE as we promptly implemented isolation of infected patients and enhanced hygiene strategy within an hour of collection of stool specimens in patients with diarrhea. Conclusions: In this study, we detected 11 patients who developed NV-GE after HSCT using the immunochromatography method. Our results suggested that this method is helpful in the differential diagnosis of patients with diarrhea after HSCT and enable us to take an appropriate and prompt preventive measure. In the future study, validation with RT-PCR and immunochromatography method is warranted among the immune-compromised populations. Disclosures: No relevant conflicts of interest to declare.