Helicobacter pylori is a gram negative bacterium. It was first discovered by Barry Marshall and Robin Warren, who identified the bacteria present in the stomachs of patients suffering from gastritis and ulcers. Although initially greeted with extreme scepticism from the medical and scientific community, Marshall and Warren proved that Helicobacter pylori could survive in the stomach and that infection with the bacteria led to symptoms of gastritis and over time to gastric ulcers. The discovery took place in the early 1980s and Marshall and Warren were jointly awarded the Nobel Prize in Physiology or Medicine in 2005 “for their discovery of the bacterium Helicobacter pylori and its role in gastritis and peptic ulcer disease”
The number people infected with Helicobacter pylori infection varies by region, socioeconomic class and healthcare standards. It is believed that at least half of the world’s population is infected with Helicobacter pylori and in some regions nearly 90% of people may be infected. The prevalence is over 80% in South America and Africa, whereas in the United States between 30% and 70% of people are infected. In Europe prevalence ranges from 30% in Northern Europe, 50% in Mediterranean countries and 70% in Eastern Europe. Australia is thought to have a low prevalence of 20%. Infection with the bacteria is transmitted by swallowing the bacteria.
The most common problem caused by infection with Helicobacter pylori is gastric ulcers. Between 1 and 10% of patients with Helicobacter pylori infection develop gastric or duodenal ulcers. Prior to the discovery of Helicobacter pylori, gastric ulcers were thought to be as a result of spicy food and stress. After the discovery of Helicobacter pylori and the efficacy of combining antibiotics and drugs to reduce acid production in the stomach, the treatment of stomach ulcers was revolutionised.
By administering treatment to eradicate the infection, a prolonged cure of stomach ulcers not associated with NSAID use is achieved in more than 80% of patients. The standard treatment involves triple or quadruple therapy for between 7 and 14 days. Triple therapy involves the administration of two antibiotics combined with a proton pump inhibitor. Quadruple therapy may include a bismuth preparation. The most commonly used antibiotic in the eradication of Helicobacter pylori infection is clarithromycin. The emergence of antibiotic-resistant Helicobacter pyloriis is of increasing concern and is reducing the effectiveness of standard therapy. Moreover, patients may not take their medication as prescribed because the burden of remembering to take three or four different drugs every day for up to two weeks leads to non-compliance and non-adherence.
A clear link has been established between infection with Helicobacter pylori and the later development of gastric cancer. Between 0.1% and 3% of infected patients develop gastric cancer in later life. According to the World Cancer Research fund, stomach cancer was the fourth most common cancer in the world in 2008 representing 7.8% of all cancers. The World Health Organisation International Agency for Research on Cancer classified infection with Helicobacter pylori as a class 1 (definite) carcinogen. Helicobacter pylori infection is also associated with a number of other diseases including unexplained iron deficiency anemia, or chronic idiopathic thrombocytopenic purpura.
There is strong demand for an effective vaccine against Helicobacter pylori. A vaccination strategy was recommended by the European Helicobacter Study Group, http://www.helicobacter.org/, in their Maastricht IV/ Florence Consensus Report as best option for eliminating Helicobacter pylori infection in the population and they have recommended that a significant effort be invested in developing a new vaccine against Helicobacter pylori.
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