Accurate diagnosis of Helicobacter pylori (H. pylori) infection is a crucial part in the effective management of many gastroduodenal diseases. Several invasive and non-invasive diagnostic tests are available for the detection of H. pylori and each test has its usefulness and limitations in different clinical situations. Although none can be considered as a single gold standard in clinical practice, several techniques have been developed to give the more reliable results. Invasive tests are performed via endoscopic biopsy specimens and these tests include histology, culture, rapid urease test as well as molecular methods. Developments of endoscopic equipment also contribute to the real-time diagnosis of H. pylori during endoscopy. Urea breathing test and stool antigen test are most widely used non-invasive tests, whereas serology is useful in screening and epidemiological studies. Molecular methods have been used in variable specimens other than gastric mucosa. More than detection of H. pylori infection, several tests are introduced into the evaluation of virulence factors and antibiotic sensitivity of H. pylori, as well as screening precancerous lesions and gastric cancer. The aim of this article is to review the current options and novel developments of diagnostic tests and their applications in different clinical conditions or for specific purposes.

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Fecal microbiota transplantation (FMT) is a method to directly change the recipient's gut microbiota to normalize the composition and gain a therapeutic benefit. The history of FMT has been traced back to the 4th century and has been highly regarded since 2013, when the United States Food and Drug Administration approved FMT for treating recurrent and refractory Clostridium difficile infection. Since then, the range of FMT applications extended rapidly and broadly not only in gastrointestinal disorders, but also in extra-gastrointestinal diseases. Donor selection with questionnaire, interview, blood tests, and stool examinations should be strictly performed before FMT to reduce and prevent occurrence of any adverse events. Step-by-step cautious fecal and recipient preparation along with adequately choosing delivery methods based on individual clinical situations are key points of the FMT process. Although current evidence deems FMT as a generally safe therapeutic method with few adverse effects, the long-term outcomes of FMT have not been completely elucidated. Therefore, establishing periodicity and length of regular follow-up after FMT to monitor the clinical efficacy and long-term adverse events are other essential issues. In the future, we will look forward to personalized FMT for different patients and conditions according to varied hosts and diseases.