Can H. pylori Cause Colon Ulcers?
No, Helicobacter pylori does not cause colon ulcers. H. pylori is a bacterium that specifically colonizes the stomach and duodenum, where it causes gastric and duodenal ulcers, but it does not infect or cause ulceration in the colon 1.
Where H. pylori Actually Causes Disease
H. pylori is a gram-negative, microaerophilic bacterium that normally resides exclusively in the stomach 2. The infection affects the gastroduodenal mucosa through acid-peptic damage, resulting in mucosal erosion 1. Specifically:
- Gastric ulcers: H. pylori infection with cagA-positive strains increases the risk of gastric ulcers by 2.9-fold 3
- Duodenal ulcers: The association is even stronger for duodenal ulcers, with an 18.4-fold increased risk among those infected with cagA-positive H. pylori strains 3
- Not colonic ulcers: The bacterium does not colonize the colon and is not implicated in colonic ulceration 1
Why This Distinction Matters Clinically
The location of peptic ulcer disease determines both diagnostic approach and management. H. pylori testing is mandatory for all patients with gastric or duodenal ulcers, as eradication dramatically reduces recurrence and complication rates 1, 4. However:
- Colon ulcers have different etiologies: Colonoscopic perforations, inflammatory bowel disease (particularly Crohn's disease), ischemia, and other causes are responsible for colonic ulceration 1, 5
- Testing for H. pylori in colon disease is not indicated: The test-and-treat strategy applies only to gastroduodenal disease 6
Common Clinical Pitfall
Do not attribute colonic pathology to H. pylori infection. While H. pylori may affect up to 50% of the world's population and is the most common infectious disease worldwide, its pathologic effects are confined to the stomach and duodenum 2. If a patient presents with colonic ulceration, investigate alternative diagnoses such as inflammatory bowel disease, ischemic colitis, NSAID-related injury, or infectious colitis rather than pursuing H. pylori eradication 1, 5.
When H. pylori Testing IS Appropriate
H. pylori testing should be performed in patients with:
- Confirmed gastric or duodenal ulcers on endoscopy 1
- Dyspepsia in patients under 60 years without alarm symptoms (test-and-treat strategy) 6
- Bleeding peptic ulcer disease, where eradication reduces rebleeding rates from 26% to near zero 4
The preferred non-invasive tests are urea breath test (sensitivity 88-95%, specificity 95-100%) or stool antigen test (sensitivity 94%, specificity 92%) 1, 7.