S202 Clinical Impact of Multiplex Polymerase Chain Reaction Pathogen Testing in Management of Outpatient Gastroenteritis

Abstract

Introduction: Multiplex gastrointestinal pathogen panels (GI PCR) for the detection of enteric infection offer advantages in turnaround time and sensitivity compared to conventional modalities of stool testing. Previous research on GI PCR has focused almost exclusively on hospitalized patients, however, most cases of gastroenteritis are managed in the outpatient setting. Our aim was to compare GI PCR to conventional stool testing in outpatients with gastroenteritis and evaluate the impact on clinical decision-making and management. Methods: We performed a retrospective study of outpatients presenting with acute gastrointestinal symptoms at an academic medical center from September 2015 to April 2019 who received stool testing with GI PCR, and from February 2009 to April 2012 who received stool culture and ova and parasite exam (“conventional testing”). Patients who received GI PCR were matched by age and sex to patients who received conventional testing. We recorded pathogens isolated, demographic data, presenting symptoms, risk factors, antibiotic therapy, and downstream associated healthcare utilization including abdominal imaging, endoscopy, emergency room visits, hospitalizations, and abdominal surgeries. Univariate and multivariate linear regression was used to estimate the effect of testing on empiric antibiotic therapy. Results: We identified 1,018 outpatients who received GI PCR or conventional stool testing. (n = 509 each). A pathogen was isolated in 208 (41%) patients with GI PCR and 49 (10%, P < 0.01, Table 1) with conventional culture. There were no significant differences in overall rates of antibiotic therapy or average duration of therapy, but GI PCR was associated with less empiric therapy (47% vs 70%, P < 0.01), and higher rates of narrowing (13 vs 4%) and discontinuation (3 vs 0%, P < 0.01) of empiric antibiotics after the initial visit, with a 1.6-fold lower likelihood (95% CI 1.04-2.57, P = 0.04) of initiating empiric antibiotics on multivariable analysis. There were no significant differences in other outcomes. Conclusion: GI PCR testing detected more pathogens compared to conventional stool testing, without a significant increase in antibiotics prescribed. PCR testing was associated with changes in prescribing patterns for antibiotics, with a shift towards less empiric therapy.Table 1.: Characteristics of 1,018 patients stratified by modality of stool testing