Noninvasive diagnostic methods for Helicobacter pylori infection.

Helicobacter pylori is one of the most frequently occurring and persistent bacterial infections worldwide. H. pylori bacteria are associated with peptic ulcer disease, mucosaassociated lymphoid tissue lymphoma, and gastric cancer. Various diagnostic methods are used to detect H. pylori infection. However, only highly accurate tests with 90% sensitivity and 90% specificity should be used in clinical practice. Commonly, the invasive diagnostic methods include endoscopy with histology, rapid urease test, bacterial culture, and molecular method (such as polymerase chain reaction); the noninvasive methods include serology, urea breath test, and stool antigen test (SAT). The use of a saliva antigen or antibody test for H. pylori detection remains premature. Herein, we briefly review these noninvasive diagnostic methods. The 13 C-urea breath test (13C-UBT) is one of the most reliable tests for diagnosing H. pylori infection. It is a simple, noninvasive, and safe test that provides excellent accuracy both for the initial diagnosis of H. pylori infection and for the confirmation of its eradication. Posttreatment UBT is usually performed 4e6 weeks after the eradication therapy. With the most widely used protocol (75 mg of urea with citric acid), excellent accuracy is obtained when breath samples are collected as early as 15 minutes after urea ingestion. The 13CUBT in adults has a high sensitivity (88e95%) and specificity (95e100%). However, the test has shown heterogeneous accuracy in the pediatric population, especially in young children. The SAT is a noninvasive method used to detect H. pylori, usually recommended when UBT is not available. This method is especially relevant for children's access to a safe diagnosis. There are two types of SATs used for H. pylori detection: the enzyme immunoassay and an assay based on immunochromatography. A meta-analysis revealed that the global sensitivity and specificity of SATs are 94% and 97%, respectively. H. pylori SAT (easy One-Step Test, Firstep Bioresearch Inc., Tainan, Taiwan) was added to the fecal occult blood test used for colorectal cancer screening in a program in Taiwan in order to detect upper gastrointestinal (GI) lesions, mostly due to H. pylori. The prevalence of upper GI lesions was higher in those patients with a positiveH. pylori SAT than in those with a positive guaiac-based test (34.6% vs. 24.7%). Detecting anti-H. pylori antibodies [immunoglobulin G (IgG)] with enzyme-linked immunosorbent assay through routine serology is recommended for initial screening,