S0698 More Pathogens, Less Insight: Comparing Extended Stool PCR Panels to Basic Stool PCR Panels

Abstract

INTRODUCTION: Stool Polymerase Chain Reaction (PCR) panels can be used to rapidly detect specific pathogens responsible for gastrointestinal (GI) infections. This is particularly important in patients with inflammatory bowel diseases (IBD) as the symptoms of IBD flare often overlaps with those of GI infections. While the increased risk of Clostridioides difficile (C. difficile) among IBD patients is well established, the risk of other gastrointestinal pathogens is less well studied. Our study compares the utility of two stool PCR panels that tests for 22 pathogens in IBD patients hospitalized for gastrointestinal symptoms. METHODS: We retrospectively reviewed the electronic medical records of adult patients with IBD hospitalized at a southeastern New England hospital between January 1, 2017 and April 1, 2019. Patients were included if they had a stool PCR panel test and symptoms consistent with an IBD flare or infectious gastroenteritis. Patients with positive C. difficile stool PCR or culture were excluded. Statistical analysis with generalized linear mixed modeling was used to compare the utility of the basic verses extended stool PCR panels. RESULTS: A total of 770 IBD patients (82.5% Caucasian, 56.6% female; mean age 49.51 years, SD = 19.42) with 1,189 hospitalizations were included in the study. The basic stool PCR panel yielded positive results (13/1651, 0.79%) slightly more often than the extended stool PCR panel (14/2354, 0.59%) (Table 1). In general, the most common pathogens detected were Enteropathogenic Escherichia Coli (2.38%), Norovirus (2.38%), and Sapovirus (2.38%) (Table 1). On linear mixed modeling (Table 2), none of the factors were associated with a significantly increased utility of performing an extended stool PCR panel over a basic panel except when comparing patients on IBD medication (P = 0.0433) or those who presented with nausea (P = 0.0477). Participants who identified as Asian were more likely to have a positive test result compared to participants who identified as white for both tests (basic, P = 0.0147; extended, P = 0.0969). CONCLUSION: Our study identified no advantage when ordering the extended stool PCR panel over the basic stool PCR panel in hospitalized IBD patients. While the extended stool PCR stool panel identified some unique bacteria/viruses, these cases were extremely rare and without clinical predictors. Clinicians should be judicious when ordering extended stool PCR panels for IBD patients as they have low positive rates and may not change medical management.Table 1.: Detection rate of non-C. difficile pathogens using the basic stool PCR panel verses the extended stool PCR panel among hospitalized IBD patientsTable 2.: Model Results Estimating Probability of a Positive Test