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H.
pylori is a common gastric pathogen that causes
gastritis, peptic ulcer disease, gastric adenocarcinoma, and low-grade
gastric lymphoma. Infection may be asymptomatic or result in varying
degrees of dyspepsia. Diagnosis is by urea breath test and testing
of endoscopic biopsy samples. Treatment is with a proton pump inhibitor
plus two antibiotics.
(See also the American College of Gastroenterology's guidelines for the management of
Helicobacter pylori infection.)
H.
pylori is a spiral-shaped, gram-negative organism that has adapted to thrive in acid. In developing countries, it commonly causes chronic infections and is usually acquired in childhood. In the US, infection is less common in children but increases with aging: by age 60 about 50% of people are infected. Infection is most common in blacks, Hispanics, and Asians.
The organism has been cultured from stool, saliva, and dental plaque, which suggests oral-oral or fecal-oral transmission. Infections tend to cluster in families and in residents of custodial institutions. Nurses and gastroenterologists seem to be at high risk because bacteria can be transmitted by improperly disinfected endoscopes.
Pathophysiology
Effects of H. pylori infection vary depending on the location within the stomach. Antral-predominant infection results in increased gastrin production, probably via local impairment of somatostatin release. Resultant hypersecretion of acid predisposes to prepyloric and duodenal ulcer. Body-predominant infection leads to gastric atrophy and decreased acid production, possibly via increased local production of IL‑1β. Patients with body-predominant infection are predisposed to gastric ulcer and adenocarcinoma. Some patients have mixed infection of both antrum and body with varying clinical effects. Many patients with H. pylori infection have no noticeable clinical effects.
Ammonia produced by H. pylori enables the organism to survive in the acidic environment of the stomach and may erode the mucus barrier. Cytotoxins and mucolytic enzymes (eg, bacterial protease, lipase) produced by H.
pylori may play a role in mucosal damage and subsequent ulcerogenesis.
Infected people are 3 to 6 times more likely to develop stomach cancer. H. pylori infection is associated with intestinal-type adenocarcinoma of the gastric body and antrum but not cancer of the gastric cardia. Other associated malignancies include gastric lymphoma and mucosa-associated lymphoid tissue (MALT) lymphoma, a monoclonally restricted B‑cell tumor.
Diagnosis
Screening of asymptomatic patients is not warranted. Tests are performed during evaluation for peptic ulcer and gastritis. Post-treatment testing is typically performed to confirm eradication of the organism. Different tests are preferred for initial diagnosis and post-treatment.
Noninvasive
tests:
Laboratory and office-based serologic assays for antibodies to H.
pylori have sensitivity and specificity of > 85% and are considered the noninvasive tests of choice for initial documentation of H. pylori infection. However, because qualitative assays remain positive for up to 3 yr after successful treatment and because quantitative antibody levels do not decline significantly for 6 to 12 mo after treatment, serologic assays are not usually used to assess cure.
Urea breath tests use an oral dose of 13C- or 14C‑labeled urea. In an infected patient, the organism metabolizes the urea and liberates labeled CO2, which is exhaled and can be quantified in breath samples taken 20 to 30 min after ingestion of the urea. Sensitivity and specificity are > 90%. Urea breath tests are well suited for confirming eradication of the organism after therapy. False-negative results are possible with recent antibiotic use or concomitant proton pump inhibitor therapy; therefore, follow-up testing should be delayed ≥ 4 wk after antibiotic therapy and 1 wk after proton pump inhibitor therapy. H2 blockers do not affect the test.
Stool antigen assays seem to have a sensitivity and specificity near that of urea breath tests, particularly for initial diagnosis; an office-based test is under development.
Invasive tests:
Endoscopy is used to obtain mucosal biopsy samples for a rapid urease test (RUT) or histologic staining. Bacterial culture is of limited use because of the fastidious nature of the organism. Endoscopy is not recommended solely for diagnosis of H. pylori; noninvasive tests are preferred unless endoscopy is indicated for other reasons.
The RUT, in which presence of bacterial urease in the biopsy sample causes a color change on a special medium, is the diagnostic method of choice on tissue samples. Histologic staining of biopsy samples should be done for patients with negative RUT results but suspicious clinical findings, recent antibiotic use, or treatment with proton pump inhibitors. RUT and histologic staining each have a sensitivity and specificity of > 90%.
Treatment
Patients with complications (eg, gastritis, ulcer, malignancy) should have the organism eradicated. Eradication of H. pylori can even cure some cases of MALT lymphoma (but not other infection-related malignancies). Treatment of asymptomatic infection has been controversial, but the recognition of the role of H.
pylori in cancer has led to a recommendation for treatment. Vaccines, both preventive and therapeutic (ie, as an adjunct to treatment of infected individuals), are under development.
H.
pylori eradication requires multi-drug therapy, typically antibiotics plus acid suppressants. Proton pump inhibitors suppress H. pylori, and the increased gastric pH accompanying their use can enhance tissue concentration and efficacy of antimicrobials, creating a hostile environment for H. pylori.
Triple therapy is recommended. Oral omeprazole 20 mg bid or lansoprazole 30 mg bid, plus clarithromycin 500 mg bid, plus amoxicillin 1 g bid (or, for penicillin-allergic patients, metronidazole 500 mg bid) for 14 days, cures infection in > 95% of cases. This regimen has excellent tolerability. Ranitidine bismuth citrate 400 mg po bid may be substituted for the proton pump inhibitor.
Quadruple therapy with a proton pump inhibitor bid, tetracycline 500 mg and bismuth subsalicylate or subcitrate 525 mg qid, and metronidazole 500 mg tid is also effective but more cumbersome.
Infected patients with duodenal or gastric ulcer require continuation of the acid suppression for at least 4 wk.
Treatment is repeated if H. pylori is not eradicated. If two courses are unsuccessful, some authorities recommend endoscopy to obtain cultures for sensitivity testing.
Last full review/revision January 2007 by Sidney Cohen, MD
Content last modified January 2007
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