2354. Report at Your Own Risk! Diagnostic Stewardship of Clostridioides difficile PCR Results from Syndromic Diarrhea Panel and Implications for Patient Outcomes

Abstract

BackgroundWe implemented a syndromic gastrointestinal pathogen panel (GIP) in May 2018, for rapid diagnosis of infectious diarrhea. GIP Clostridioides difficile polymerase chain reaction (PCR) results were suppressed due to concerns about oversensitivity. All positive (+) GIP and standard of care (SOC) C. difficile results were reviewed to understand C. difficile epidemiology and clinical outcomes.MethodsBetween May and December 2018, an audit of all adult patients with C. difficile (+) GIP results was conducted. Stewardship team obtained daily GIP results, reviewed patient charts, recommended a confirmatory SOC test, isolation, and treatment as indicated. Patients were classified as true C. difficile infection (CDI) with diarrhea and toxin or PCR positivity (Figure 1). We also reviewed GIP (+)/SOC negative (−) tests, and GIP (−)/SOC (−) tests (control group). GIP (+) patients with no confirmatory SOC test were excluded from the analysis. A multivariable logistic regression model was used to compare CDI at 3 months among groups.ResultsWe reviewed 274 patients with a GIP C. difficile (+) result (Table 1). Seventy-one (26%) had no SOC sent. Of positive SOCs, 45 patients (37%) were positive by toxin A/B enzyme immunoassay (EIA), and 77 (63%) by PCR only (Figure 2A). There were 2153 total SOC tests sent, of these 332 (15%) were positive; 130 (39%) by toxin, and 202 (61%) by PCR only (Figure 2B). Mortality and 30-day re-admission were not significantly different between groups (Table 2). CDI rates within 3 months were not significantly different between GIP (+) only and control group (P = 0.11). In contrast, those with SOC (+) tests had more true CDI within 3 months, compared with controls (P < 0.001) (Table 2).ConclusionForty percent of patients analyzed with GIP (+) C. difficile result were (−) by SOC test, suggesting that true CDI was not present in these patients. The percentage of toxin vs. PCR only (+) results from all the GIP positive patients mirrors that of all SOC (+) tests, indicating that the majority of CDI patients at our institution are PCR (+) only. Our results suggest that an additional PCR-based test may potentially over-report colonization as true infection. We strongly support diagnostic stewardship of C. difficile results within syndromic gastrointestinal panels. Disclosures All authors: No reported disclosures.