What is a key reason to test for Helicobacter pylori in patients with dyspepsia or peptic ulcers, and which two diagnostic methods are commonly used?

• A. It is causally linked to peptic ulcer disease and gastric cancer; urea breath test and stool antigen test
• B. It is present as a harmless gut commensal; colon biopsy and stool culture
• C. It only causes gastric cancer; serology and imaging
• D. It is a respiratory pathogen; chest X-ray and sputum culture

Answer: (A)

Testing for Helicobacter pylori in people with dyspepsia or peptic ulcers is important because the infection is causally linked to peptic ulcer disease and is a risk factor for gastric cancer; eradicating the bacterium can promote ulcer healing and reduce cancer risk. The two commonly used noninvasive diagnostic methods are the urea breath test and the stool antigen test. In the urea breath test, the patient ingests labeled urea; if H. pylori is present, urease breaks it down and labeled CO2 is detected in the breath. The stool antigen test detects H. pylori–specific antigens in the stool, indicating current infection. Other tests exist (such as serology or invasive endoscopy with biopsy), but serology can’t reliably distinguish current from past infection, and endoscopy is reserved for specific clinical scenarios.