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Disorders of the Stomach and Duodenum Helicobacter pylori Infection cannot distinguish between active and previous infection. Although the negative predictive value of serologic testing is Indications for Testing reasonably high, a positive serologic result in a population Indications for H. pylori testing include active PUD, history of with low prevalence of H. pylori infection, such as in the PUD without documented cure of H. pylori infection, gastric United States, may require confirmation with the ’C-urea mucosa-associated lymphoid tissue lymphoma, or history of breath test, stool antigen test, or gastric biopsy. Serologic test- endoscopic resection of early gastric cancer. Other conditions ing is most useful as an adjunct test in patients with bleeding in which H. pylori testing should be considered include dys- PUD because of the decreased sensitivity of biopsy in acute pepsia, before long-term low-dose aspirin or NSAID use, bleeding. Conditions that lower H. pylori density, such as PPI unexplained iron deficiency anemia, and idiopathic thrombo- use, recent antibiotic use, atrophic gastritis, intestinal meta- cytopenic purpura in adults. Routine testing for H. pylori is plasia, or mucosa-associated lymphoid tissue lymphoma, can not indicated in patients with typical gastroesophageal reflux result in false-negative results on the noninvasive studies. disease symptoms, lymphocytic gastritis, hyperplastic gastric Upper endoscopy that is done to evaluate dyspepsia should polyps, or hyperemesis gravidarum or in asymptomatic indi- include gastric biopsy for H. pylori testing. viduals with a family history of gastric cancer.

Helicobacter pylori Infection cannot distinguish between active and previous infection. Although the negative predictive value of serologic testing is Indications for Testing reasonably high, a positive serologic result in a population Indications for H. pylori testing include active PUD, history of with low prevalence of H. pylori infection, such as in the PUD without documented cure of H. pylori infection, gastric United States, may require confirmation with the ’C-urea mucosa-associated lymphoid tissue lymphoma, or history of breath test, stool antigen test, or gastric biopsy. Serologic test- endoscopic resection of early gastric cancer. Other conditions ing is most useful as an adjunct test in patients with bleeding in which H. pylori testing should be considered include dys- PUD because of the decreased sensitivity of biopsy in acute pepsia, before long-term low-dose aspirin or NSAID use, bleeding. Conditions that lower H. pylori density, such as PPI unexplained iron deficiency anemia, and idiopathic thrombo- use, recent antibiotic use, atrophic gastritis, intestinal meta- cytopenic purpura in adults. Routine testing for H. pylori is plasia, or mucosa-associated lymphoid tissue lymphoma, can not indicated in patients with typical gastroesophageal reflux result in false-negative results on the noninvasive studies. disease symptoms, lymphocytic gastritis, hyperplastic gastric Upper endoscopy that is done to evaluate dyspepsia should polyps, or hyperemesis gravidarum or in asymptomatic indi- include gastric biopsy for H. pylori testing. viduals with a family history of gastric cancer. Treatment Diagnosis Any patient with a test result positive for active infection H. pyloriinfection can be diagnosed with gastric biopsies dur- requires treatment with the goal of H. pylori eradication. The ing upper endoscopy or noninvasively by “C-urea breath, stool first course of treatment offers the best chance of eradication antigen, or serologic testing. The “C-urea breath test and the and should be carefully chosen. Several first-line treatments monoclonal stool antigen test are preferred noninvasive tests are available, with the choice based on resistance patterns of because sensitivity and specificity both exceed 95% for active H. pylori, previous antibiotic use by the patient, and antibiotic infection. Serologic testing for IgG antibodies against H. pylori allergies (Table 9). In most cases, duration of therapy is 14 days. is the cheapest and most convenient method; however, it When treatment fails, second-line therapy should last a

Treatment Diagnosis Any patient with a test result positive for active infection H. pyloriinfection can be diagnosed with gastric biopsies dur- requires treatment with the goal of H. pylori eradication. The ing upper endoscopy or noninvasively by “C-urea breath, stool first course of treatment offers the best chance of eradication antigen, or serologic testing. The “C-urea breath test and the and should be carefully chosen. Several first-line treatments monoclonal stool antigen test are preferred noninvasive tests are available, with the choice based on resistance patterns of because sensitivity and specificity both exceed 95% for active H. pylori, previous antibiotic use by the patient, and antibiotic infection. Serologic testing for IgG antibodies against H. pylori allergies (Table 9). In most cases, duration of therapy is 14 days. is the cheapest and most convenient method; however, it When treatment fails, second-line therapy should last a TABLE 9. First-Line Treatment Options for Helicobacter pylori Infection | Treatment Regimen Duration of Therapy Clinical Indicators PPI, standard? or double dose twice daily 14 days H. pylori clarithromycin resistance is known to be <15% (esomeprazole, once daily only) No history of macrolide exposure for any reason Clarithromycin, 500 mg twice daily Amoxicillin, 1 g twice daily PPI, standard or double dose twice daily 14 days H. pylori clarithromycin resistance is known to be <15% | Clarithromycin, 500 mg twice daily No history of macrolide exposure for any reason Metronidazole, 500 mg three times daily Penicillin allergy PPI, standard dose twice daily 10-14 days Previous macrolide exposure

| Clarithromycin, 500 mg twice daily No history of macrolide exposure for any reason Metronidazole, 500 mg three times daily Penicillin allergy PPI, standard dose twice daily 10-14 days Previous macrolide exposure Bismuth subcitrate, 120-300 mg or Penicillin allergy subsalicylate, 300 mg four times daily Tetracycline, 500 mg four times daily Metronidazole, 250 mg four times daily or 500 mg three times daily PPI, standard dose twice daily 10-14 days May be an alternative to standard clarithromycin triple therapy Clarithromycin, 500 mg twice daily Not validated in North America | Amoxicillin, 1 g twice daily Metronidazole or tinidazole, 500 mg twice daily PPI, standard dose twice daily 10-14 days May be an alternative to standard clarithromycin triple therapy Levofloxacin, 500 mg once daily Not validated in North America Amoxicillin, 1 g twice daily PPI = proton pump inhibitor. *Standard-dose PPls: esomeprazole, 40 mg; lansoprazole, 30 mg; omeprazole, 20 mg; pantoprazole, 40 mg; rabeprazole, 20 mg. Adapted with permission from Chey WD, Leontiadis GI, Howden CW, Moss SF. ACG clinical guideline: treatment of Helicobacter pylori infection. Am J Gastroenterol. 2017;112:212-239. [PMID: 28071659] doi:10.1038/ajg.2016.563. 13