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Diagnosis of Helicobacter pylori infection: a look into molecular aspects of urea breath test

Helicobacter pylori ( H. pylori ) is a bacterium that selectively colonizes gastric epithelium in more than 50% people over the world. The infection is usually acquired in early childhood and rarely resolved spontaneously; transmission is mostly person to person, and occurs by fecal-oral or oral-oral modality. Diagnosis and antibiotic treatment may lead to eradication of H. pylori , improving the prevention and the outcome of gastric and extragastric diseases. Many tests are currently available for the diagnosis of H. pylori infection and the choice depends on several clinical aspects including symptoms, age, indications for testing, concomitant medications and comorbidities. Invasive tests (i.e. endoscopy with histologic assessment) are considered the gold standard, but they are expensive and should be performed only in an appropriate context. The most common non-invasive tests are urea breath test (UBT), stool antigens test and serology. UBT is non-invasive, quick, safe, accurate and cheap. This test is performed mainly with 13 C and is based on the presence of H. pylori urease, an enzyme that converts urea (labelled with an isotope) into CO 2 . Labelled CO 2 is then exhaled and measured by dedicated spectrophotometers. This review analyses with special emphasis UBT, focusing on its molecular aspects.