Study of the Esophageal String Test (EST) for the Diagnosis of Helicobacter Pylori

Study Description: Adults with active Helicobacter pylori infection will undergo an esophageal string test (EST). The gastric portion of the string will be used for detection of H. pylori by polymerase chain reaction (PCR), as well as assessment of resistance genes to clarithromycin, levofloxacin, and metronidazole. Participants will be treated per current American Gastroenterological Association (AGA) guidelines. A stool antigen test for H. pylori will be performed 4 weeks after completion of therapy to assess cure. Participants who have failed \>=2 courses of therapy will undergo endoscopy with resistance testing per AGA recommendations. Patients will be offered antibiotic therapy based on the EST results and will have a repeat H. pylori stool antigen test 4 weeks after completion of therapy. Primary Objective: To assess the sensitivity of the gastric portion of the EST in detecting H. pylori infection. Secondary Objectives: To assess the ability of the gastric portion of the EST in detecting antimicrobial resistance to clarithromycin, levofloxacin, and metronidazole. Primary Endpoint: Proportion of the study population identified positive for H. pylori in EST eluates by PCR. Secondary Endpoint: Detection of H. pylori antibiotic resistance genes in EST eluates.