Helicobacter pylori (H. pylori) is a helical shaped Gram-negative bacterium that infects various areas of the stomach and duodenum. Many cases of peptic ulcers, gastritis, duodenitis, and perhaps some cancers are caused by the H. pylori infection. However, many who are infected do not show any symptoms of the disease.
Symptoms may be worse before or after meals. One third of the people who are infected never have any symptoms. By middle age, 50% of adults have been infected with H. pylori bacteria.
Diagnosis of infection is usually made by checking for dyspeptic symptoms and then doing one of the following tests which can suggest H. pylori infection:
In peptic ulcer patients where infection is detected, the normal procedure is the eradication of H. pylori to allow the ulcer to heal. The standard first-line therapy is a one-week triple therapy. Today, the standard triple therapy is amoxicillin, clarithromycin and a proton pump inhibitor such as omeprazole.
A meta-analysis of randomized controlled trials suggests that supplementation with probiotics can improve eradication rates and reduce adverse events.
Unfortunately, an increasing number of infected individuals are found to harbor antibiotic-resistant bacteria. This results in initial treatment failure and requires additional rounds of antibiotic therapy or alternative strategies such as a quadruple therapy. Bismuth compounds are also effective in combination with the above-mentioned drugs. For the treatment of clarithromycin-resistant strains of H. pylori the use of levofloxacin as part of the therapy has be suggested.
While the incidence of H. pylori infection in humans is decreasing in developing countries, presumably because of improving sanitation and increasing use of antibiotics, in the United States the incidence of gastric cancer has decreased by 80% from 1900 to 2000. This apparent correlation is consistent with an epidemiological link between H. pylori and cancer. Specifically, both gastric cancer and gastric MALT lymphoma (lymphoma of the mucosa-associated lymphoid tissue) have been associated with H. pylori. Nonetheless, among bacteria suspected to cause cancer, H. pylori is the leading contender.