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Enteric Salmonella or Campylobacter infections and the risk of inflammatory bowel disease
  1. Tine Jess1,
  2. Jacob Simonsen2,
  3. Nete Munk Nielsen2,
  4. Kristian Tore Jørgensen2,
  5. Peter Bager2,
  6. Steen Ethelberg3,
  7. Morten Frisch2
  1. 1Institute of Preventive Medicine, Copenhagen University Hospital, Copenhagen, Denmark
  2. 2Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark
  3. 3Department of Bacteriology, Mycology and Parasitology, Statens Serum Institut, Copenhagen, Denmark
  1. Correspondence to Dr Morten Frisch, Department of Epidemiology Research, Statens Serum Institut, 5 Artillerivej, DK-2300 Copenhagen S, Denmark; mfr{at}


Objective Enteric pathogens have been implicated in the aetiology of inflammatory bowel disease (IBD), but increased rates of stool testing of patients with unclear gastrointestinal symptoms might cause detection bias. Hence, the objective of this study was to analyse incidence rates of Crohn's disease and ulcerative colitis among patients with Salmonella- or Campylobacter-positive and negative stool tests and to study the incidence of positive and negative stool tests among patients already diagnosed with IBD.

Methods The Danish population was followed for 94.3 million person-years during 1992–2008 using national registers to identify persons with positive and negative stool tests and patients with IBD. Using Poisson regression, incidence rate ratios (IRRs) for IBD after positive or negative stool tests and, conversely, IRRs for positive and negative stool tests following IBD, were calculated.

Results IRRs for IBD were significantly high in the first year after Salmonella- or Campylobacter-positive stool tests (IRRs 5.4–9.8), and they remained moderately increased 1–10 years later (IRRs 1.6–2.2), and less so >10 years later (IRRs 0.8–1.8). However, IRRs for IBD <1 year after a negative stool test were several-fold higher (IRRs 53.2–57.5), and a decreasing incidence pattern over time was parallel to that following positive test results. Among patients with IBD, IRRs for subsequent positive and—most notably—negative stool test results were also significantly high.

Conclusion Similarities in temporal risk patterns for IBD following positive or negative stool tests indicate that the increased occurrence of Salmonella- or Campylobacter-positive results around the time of first IBD hospitalisation results from detection bias.

  • Campylobacter
  • cohort studies
  • inflammatory bowel disease
  • Salmonella, crohn's disease
  • epidemiology
  • IBD

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  • Funding The study was supported by unrestricted research grants from the (Danish) Aase and Ejnar Danielsen's Foundation and the Gangsted Foundation.

  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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