# Gastrointestinal bacterial infections precede disease activation and treatment intensification in patients with inflammatory bowel disease

## TL;DR

Gut infections like Campylobacter and Salmonella can trigger flare-ups in inflammatory bowel disease patients, often requiring stronger treatment.

## Contribution

This study shows that GI bacterial infections are linked to IBD flares and treatment intensification, independent of known risk factors.

## Key findings

- 37% of infected IBD patients had a flare within 6 months, compared to 11% of controls.
- UC patients were hospitalized more often than CD patients after infection.
- IBD duration under 2 years doubled the risk of GI infection.

## Abstract

Patients with inflammatory bowel disease (IBD) are at heightened risk of infection for several reasons.

To evaluate the factors predisposing IBD patients to gastrointestinal (GI) infections, the elements influencing the severity of these infections and the likelihood of hospitalization, and the impact of GI bacterial infections on the progression of IBD.

Retrospective, single-center, case-control study of IBD patients with GI infection and matched controls.

Patients with ulcerative colitis (UC) or Crohn’s disease who tested positive for Campylobacter spp., Yersinia spp., Salmonella spp., or enterohemorrhagic Escherichia coli were enrolled. Clostridioides difficile was excluded due to its distinct epidemiology. For each patient with a GI bacterial infection, a control patient with IBD but without the infection was matched by sex and proximity in calendar age. Data were collected from electronic patient records spanning from January 2008 to June 2023. Various risk factors for medical consultations and hospitalizations due to GI bacterial infections were evaluated. Fisher’s exact test and logistic regression were used to assess the associations between GI infections and clinical outcomes.

Of the 5194 IBD patients in the IBD registry, 123 patients had a confirmed GI infection, the majority having UC (n = 79, 64%). Patients who experienced GI infection had a higher likelihood of experiencing an IBD flare within 1–6 months post-infection, often requiring intensification of medication, than the control group. However, such factors as age, IBD phenotype, disease activity, comorbidities, IBD pharmacological treatment, and prior travel to countries with lower hygiene standards did not increase the risk of severe bacterial infection or the likelihood of requiring hospitalization.

Our study indicates that IBD patients diagnosed with GI infections may be at elevated risk of experiencing an IBD flare within 1–6 months post-infection, often necessitating the intensification of their pharmacological treatment.

Bacterial gut infections can trigger IBD flare-ups

Gastrointestinal (GI) infections such as Campylobacter, Salmonella, Yersinia, and EHEC are common causes of diarrhea. Patients with inflammatory bowel disease (IBD), Crohn’s disease (CD) and ulcerative colitis (UC), are at higher risk of these infections, which may worsen their disease. We studied 123 IBD patients with proven GI infections (2008–2023) and compared them with age- and sex-matched IBD patients without infection.

Main findings:

• 37% of infected patients had a flare within 6 months vs 11% of controls.

• UC patients were hospitalized more often than CD patients.

• Biologics and thiopurines did not raise hospitalization risk.

• Having IBD for less than 2 years doubled infection risk.

Conclusion: GI infections can trigger IBD flares. Testing for infection during flares is important, and patients should be monitored for 6 months afterward. Immunosuppressive therapy appears safe.