(82) Antibiotic Use for Diarrheal Illness in Patients with a Positive Molecular Gastrointestinal Pathogen Panel Result

Publication Number: 413

Background: Molecular gastrointestinal pathogen panels (GIPP) simultaneously test for many bacterial, viral, and parasitic pathogens with faster turnaround time and higher sensitivity than conventional stool tests. Data are needed on the heterogeneity of patients and their antibiotic treatment patterns before and after a positive GIPP result.

Objectives: To characterize antibiotic treatment of diarrheal illness before and after a positive GIPP result.

Methods: We analyzed electronic health records for patients evaluated for diarrhea in an inpatient, emergency, or outpatient setting in our academic-affiliated health system during 2018 and had a positive GIPP result for ≥1 pathogen. We excluded patients with HIV, on immunosuppression for transplant, biologics, or steroids. The dichotomous outcome of interest was change in antibiotic therapy after positive GIPP result –initiation, discontinuation, or switch. We constructed one directed acyclic graph for the outcome and covariates (symptoms at presentation, pre-GIPP treatment, GIPP-detected pathogen, age, comorbidity [inflammatory bowel disease, irritable bowel syndrome, diabetes, or cancer], gender, race/ethnicity, age, insurance type, and testing site). To avoid committing the Table 2 fallacy, we enumerated a specific adjustment set to estimate each covariate’s association with the outcome. We fit logistic regression models using g-computation to estimate risk differences (RD) for each covariate with bootstrapped 95% CIs.

Results: Among 193 included patients, the median age was 31 years (interquartile range, IQR 5-56); 35% were non-white, 45% were female, and 58% were privately insured. The median GIPP turnaround time was 31 hours; the most common pathogens detected were norovirus (21%), Salmonella species (21%), and Campylobacter jejuni/coli (18%). 29% of patients received empiric antibiotics before the GIPP result. After a positive GIPP result, 83 (43%) patients experienced a change in antibiotic treatment (primary outcome) – 48% of whom initiated antibiotics, 18% discontinued, and 11% switched. Post-GIPP antibiotic treatment change occurred in 12% of norovirus-positive patients, 53% for Salmonella, and 46% for Campylobacter. In standardized data, antibiotic treatment change was most strongly associated with having one or more comorbidities (RD 29%; 95% CI 2%, 53%), antibiotic use < 30 days before GIPP test (RD 20%; 95% CI 0%, 37%), and having public vs private insurance (RD 16%; 95% CI -0%, 32%).

Conclusions: One-third of patients with diarrhea experienced a change in antibiotic treatment after positive GIPP results, which varied substantially by pathogen and other individual-level clinical factors. Future work should address appropriateness and heterogeneity of treatment patterns before and after GIPP testing.