Acute infection is manifested by epigastric pain, nausea , vomiting , hematemesis, and guaiac-positive stools.Symptoms usually resolve within a few days despite persistence of infection for years or life. Helicobacter pylori causes chronic-active gastritis and duodenal ulcer and is associated less frequently with gastric ulcer; chronic infection has a high attributable risk of gastric cancer.
Helicobacter pylori infection is not associated with autommune or chemical gastritis.


 Helicobacter pylori is a gram-nagative and spiral, curved , or U-shaped microaerophilic bacillus that has 2 to 6 polar sheathed flagella at one end.


 Helicobacter pylori have been isolated only from humans and other primates. An animal reservoir for human transmission has not been demonstrated .The routes by which organisms are transmitted from infected humans are unknown, but fecal-oral transmission may occur. Infection rates are low in children, but prevalence rises until age 60 years. Most carriage is asymptomatic, but almost all infected persons have chronic gastritis. Infection is a acquired at a younger age in developing countries, in persons in lower socioeconomic groups, and among Latino, African , Asian , and Native Americans.

The incubation period is unknown.


 Helicobacter pylori infection can be diagnosed by culture of gastric biopsy tissue on nonselective media (eg,chocolate agar) or selective media (eg,Skirrow)at 37C (98F) under microaerobic conditions for 2 to 5 days.

Organisms usually can be visualized on histologic sections with Warthin-Starry silver, Steiner, Giemsa, or Genta staining. Infection with H pylori can be diagnosed but not excluded on the basis of hematoxylin-eosin stains. Because of production of ureaseby the organisms , urease  testing of a gastric specimen can give a rapid and specific microbiologic diagnosis. Each of these tests requires endoscopy and biopsy.
Noninvasive, commercially available tests include the breath test, which detects labeled carbon dioxide   in expired air after oral administration of isotopically labeled urea, and serology for the presence of immunoglobulin G to H pylori. Each of the diagnostic tests has a sensitivity and specificity of  95% or more. 


  Treatment is recommended only for infected patients who have peptic ulcer disease,gastric mucosa-associated lumphoid tissue type lymphoma, or early gastric cancer. Helicobacter pylori is susceptible to a variety of antimicrobial agents, including amoxicillin, tetracycline, metronidazole, clarithromycin, and bismuth salts, but none have proven therapeutic effectiveness as single agents. Therapy for H pylori infection consists of 2 weeks of 1 or 2 effective antimicrobial agents plus ranitidine, bismuth citrate , bismuth subsalicylate, or a proton pump inhibitor ( lansoprazole or omeprazole). These regimens are effective for eliminating the organism, healing the ulcer, and avoiding recurrence. The tolerance and efficacy of regimens other than a proton pump inhibitor plus an antibiotic in children are unknown. Such therapies result in eradication rates ranging from 61% to 94%  in adults depending on the regimen used . Triple-drug therapy regimens are more effective for eradication than are 2-drug therapy regimens.


 Standard precautions are recommended.
 


Disinfection of gastroscopes  prevents transmission of the organism between patients.

Red Book 2000