Typhoid fever: Peyer patch ulcers and typhoid nodules
- Lesion
A Salmonella that only infects humans enters through the small bowel, spreads through the body, and ulcerates the lymphoid patches of the ileum.
What it is
Typhoid (enteric) fever is caused by Salmonella enterica serovars Typhi and Paratyphi. Unlike food-poisoning Salmonella, these organisms enter M cells of the ileum, are carried by macrophages to lymph nodes, spleen, liver and marrow, and produce a systemic illness with reactive hyperplasia of phagocytes and lymphoid tissue. Humans are the only reservoir, and the gallbladder can harbour a chronic carrier state.
Structure
- Peyer patches: plateau-like swellings, then longitudinal oval ulcers.
- Lamina propria: macrophages containing bacteria, red cells and nuclear debris, with lymphocytes and plasma cells; neutrophils superficially.
- Liver: typhoid nodules (macrophage aggregates replacing necrotic hepatocytes).
Step by step
- Acid-resistant S. Typhi is swallowed in contaminated food or water.
- It crosses the ileal epithelium through M cells over Peyer patches.
- Macrophages carry it to mesenteric nodes, then the bloodstream.
- It multiplies in liver, spleen, marrow and gallbladder: fever and bacteraemia.
- Re-entry into the gut from bile inflames Peyer patches: ulcers and possible perforation.
Clinical notes
- Complications: intestinal bleeding and perforation, encephalopathy, myocarditis, cholecystitis, Salmonella osteomyelitis in sickle cell disease.
- Vaccines and antibiotics exist, but drug resistance is spreading.
Test yourself
Think of the answer, then tap the question to see it.
How are typhoid ulcers of the ileum oriented?
Oval and along the long axis of the bowel, over Peyer patches.
What is a typhoid nodule?
A small focus of hepatocyte necrosis replaced by an aggregate of macrophages, seen in liver, marrow and nodes.
Where does the chronic carrier of S. Typhi usually harbour the organism?
In the gallbladder, often in association with gallstones.
Elsewhere in DurgiPedia
Connections
Microorganisms1
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Typhoid (World Health Organization, 2023).
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Representative model, for educational purposes only.