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Helicobacter pylori Infection
Helicobacter pylori is a gram-negative, spiral, flagellated bacterium that inhabits the mucous layer of the stomach. Warren and Marshall first described H. pylori as a pathogen in humans and clearly documented and correlated the organism's association with gastritis and peptic ulceration.
The prevalence of H. pylori varies greatly. Approximately 40% of persons in developed countries are affected, and as many as 85% are affected in underdeveloped countries. In all areas, prevalence is associated with low socioeconomic status and advanced age. Most people remain infected for life unless they are treated. Marriage does not appear to be a strong risk factor for acquiring the infection.
Data on how the organism is acquired are controversial, although crowded living conditions and poor hygiene are associated with higher infection rates. Transmission does appear to be based on person-to-person spread ( Fig. 32.1 ). However, the exact mode of transmission remains unclear. Helicobacter heilmanii colonizes both animals and humans. Although it may be pathogenic, H. heilmanii has not been shown to be as prevalent a pathogen as H. pylori.
Etiology and Pathogenesis of Helicobacter pylori Infection.
Clinical Picture
It is now clear that H. pylori is a major risk factor for gastritis, peptic ulcer, gastric adenocarcinoma, and gastric lymphoma. Consequently, patients may have epigastric pain and ulceration, bleeding from gastritis or ulceration, or pain, nausea, vomiting, and weight loss from malignancy. It is not clear why H. pylori rarely causes diarrhea. Anemia from chronic blood loss may be the only symptom in those who feel little pain. The picture of chronic dyspepsia may unfold over the years.
H. pylori has been known to cause acute gastritis. In these patients, it may actually cause severe acute achlorhydria, which appears to be self-limiting. Not only can prolonged disease cause ulceration, but it also has been known to cause gastric atrophy and, in association with any metaplasia, appears to result in a high risk for adenocarcinoma.
Diagnosis
The diagnosis of H. pylori infection can be made using histologic, serologic, breath, or stool testing.
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