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(3) and those with CD4 counts 100 /mm(3). 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. (C) 2004 Blackwell Publishing Asia Pty Ltd. ; 附設醫院內科部 ; 醫學院附設醫院 ; 期刊論文