How should Helicobacter pylori infection be diagnosed?

The ideal approach for the initial diagnosis of Helicobacter pylori infection is to perform an endoscopy to obtain biopsy specimens for histology and culture. Histology allows classification of any gastritis lesions present and may have prognostic value, and culture enables susceptibility testing of antimicrobial agents to direct proper treatment. Biopsy specimens must also be taken from the corpus if the patient was pretreated with proton pump inhibitors. The cost of these tests and the delay in receiving results limits their use in clinical practice. Therefore, the urease test, a quick and inexpensive test, is used to detect the presence of H. pylori and constitutes the basic invasive test for H. pylori. A new urease test based on a strip instead of an agar disk may be the test of choice in the future, because of its increased sensitivity and 2-hour delay (instead of 24 hours) in obtaining the result. In some countries, because of the cost, endoscopy will be used in selected patients only, either because of alarm symptoms or age > 45 years, which is considered a threshold for gastric cancer risk. In other patients, the noninvasive tests will be used. The cost of serology makes it more attractive compared with the urea breath test. Currently, there are accurate enzyme-linked immunosorbent assay tests that can be performed in any laboratory and that provide precise and quick diagnoses. In the event of a doubtful result, an immunoblot can be performed, as is the case for other infections. Patient follow-up after treatment provides a different situation because bacterial load is usually lower. A noninvasive test should be performed, and only the urea breath test can be used within the timing originally proposed to test eradication efficacy (i.e., 4-6 weeks after treatment). If the result is positive, susceptibility testing is required before administering a second course of treatment. The increasing use of antimicrobial agents to treat H. pylori is likely to result in antimicrobial resistance, requiring that bacteriologic surveillance programs be implemented. There are numerous research projects ongoing in this area, and one can expect that improved methods, such as colorimetric polymerase chain reaction (PCR) and improved antibody tests, will also be used in the future.