Impact of Biologics and Proton Pump Inhibitors on Gastrointestinal Infection Risk in Inflammatory Bowel Disease Patients: A Retrospective Analysis of Pathogen-Specific Outcomes and Treatment Interactions.

: Inflammatory bowel disease (IBD) patients face elevated gastrointestinal (GI) infection risks due to immune dysregulation and gut dysbiosis. While steroids and immunosuppressants are known to increase infection risk, data on biologics and proton pump inhibitors (PPIs) remain limited, particularly for non-Clostridioides difficile (C.diff) infections. : This retrospective cohort study analyzed 9849 hospitalized IBD patients (2013-2023) from the Northwell Inpatient Database. Patients were categorized into four groups: biologics-only, PPIs-only, both, or neither. GI infections were identified via C.diff PCR, GI PCR, and chart review. Multivariate logistic regression adjusted for demographics, BMI, and IBD type. : GI infections occurred in 1.75% of patients, with significantly higher odds in those on biologics alone (OR 21.5, 95% CI 11.7-39.4) or with PPIs (OR 16.6, 95% CI 10.2-26.8) versus untreated patients. Non-C.diff infections were strongly associated with biologics (OR 20.7, 95% CI 10.2-41.9). PPIs alone increased slightly the risk of GI infections (OR 1.6, 95% CI 1.1-2.4). Vedolizumab and adalimumab had the highest infection risks among biologics (26.8% and 22.7%, respectively). Bacterial pathogens, such as and , predominated, with no significant difference in causative agents across treatment groups. : Biologic therapy greatly increases GI infection risk in IBD patients independent of PPI use. Clinicians should weigh infection risks when prescribing biologics, particularly in high-risk populations. Further studies are needed to assess risks by biologic subtype and the interplay with PPIs.