Low Prevalence of Helicobacter pylori But High Prevalence
Background and Aims: The role of Helicobacter pylori infection in gastroduodenal lesions might be different between the general population and AIDS patients. The aim of the present study was to compare the prevalence of H. pylori and cytomegalovirus (CMV) infection in AIDS patients and HIV-negative controls. The impact of CD4 lymphocyte counts on H. pylori and CMV infection in the same subjects was also assessed.
Methods: One hundred and fifty-six patients (52 HIV-positive, 104 HIV-negative) with gastrointestinal symptoms were evaluated with upper gastrointestinal endoscopy and biopsy. Comparison of the prevalence of H. pylori and CMV infection was made by dividing AIDS patients into two groups: those with CD4 counts >100/mm and those with CD4 counts <100/mm, and ulcer and non-ulcer patients.
Results: In comparison with HIV-negative controls, AIDS patients had a lower prevalence of H. pylori infection (P < 0.0001) but a higher prevalence of CMV infection (P < 0.0001). Cytomegalovirus infection was frequently found in AIDS patients with CD4 count <100/mm, in comparison with those with a CD4 count >100/mm. In AIDS patients, CMV was more frequently detected in subjects with peptic ulcers (P = 0.0125). Conversely, the prevalence of H. pylori infection in AIDS patients was not different between those with and without peptic ulcers.
Conclusions: The low prevalence of H. pylori infection and peptic ulcer in AIDS patients suggests a different role of H. pylori infection in peptic ulcer or even a different mechanism of peptic ulcerogenesis in HIV-positive subjects. Cytomegalovirus, rather than H. pylori, may be the main causative pathogen of peptic ulcers in AIDS patients.

After its discovery in 1982, Helicobacter pylori has been linked to many gastroduodenal diseases, including gastritis, peptic ulcer and gastric malignancies. The reported prevalence of H. pylori infection in unselected HIV-negative populations ranges from 32 to 56%. In contrast, the prevalence of H. pylori in patients with HIV infection is remarkably low. The cause of low rates of H. pylori infection in HIV-positive patients remains unclear. Although HIV-positive patients, particularly those with acquired immunodeficiency syndrome (AIDS), frequently present with upper gastrointestinal (GI) tract diseases, the etiologies are usually opportunistic infections, such as cytomegalovirus (CMV) infection. There have been few studies that simultaneously investigated the role of H. pylori and other opportunistic pathogens in the development of gastroduodenal diseases of HIV-positive patients.

The aims of the present study were to assess the prevalence and role of H. pylori infection and opportunistic infections, especially CMV infection, in HIV-positive patients and age-matched controls without HIV infection. Some studies indicated that the ratio of CD4 and CD8 in gastric mucosa was different in subjects with and without H. pylori infection. Accordingly, the CD4 lymphocyte, which is depleted in AIDS patients, may be closely associated with sustained infection by H. pylori. The impact of CD4+ count and use of antibiotics on the prevalence of H. pylori and CMV infection was also assessed.