Small intestine & ampulla
Infectious disorders

Topic Completed: 1 August 2012

Minor changes: 12 March 2019

Copyright: 2003-2019,, Inc.

PubMed Search: Yersinia[TI] small bowel

Hanni Gulwani, M.B.B.S.
Page views in 2019: 529
Page views in 2020 to date: 281
Cite this page: Gulwani H. Yersinia. website. Accessed August 11th, 2020.
Definition / general
  • Common cause of bacterial enteritis in U.S., Canada, Australia, Western Europe, Northern Europe (eMedicine: Yersinia enterocolitica [Accessed 15 February 2018])
  • Infection due to Y. enterocolitica, Y. pseudotuberculosis, gram negative invasive rods
  • Bacteria present in infected milk, pork, water supplies, domestic pets and farm animals
  • Causes enterocolitis, acute appendicitis, mesenteric lymphadenitis in children and adolescents
  • Pathogenic strains invade small intestinal mucosa via M cells overlying Peyer patches, multiply there and within regional nodes, then spreads hematogenously and via lymphatics
  • Patients homozygous for thalassemia major are at risk of Y. enterocolitica because they have iron overload and the bacteria require iron for growth
  • Ileum, right colon, appendix
  • Culture
Case reports
Microscopic (histologic) description
  • Elongated ulcerations overlying lymphoid hyperplasia
  • Also small aphthoid ulcers overlying colonies of gram negative rods and with neutrophils at ulcer base
  • Also necrotizing granulomas (particularly with Y. pseudotuberculosis)
  • Mesenteric nodes show follicular hyperplasia with variable scattered microabscesses and epithelioid granlomas
Microscopic (histologic) images

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