and Purpose-Several lines of evidence point toward a relationship between infection and atherosclerotic vascular disease. Thus, infection and inflammation often precede ischemic neurological events. Transient alterations in coagulation and direct arterial invasion by certain microorganisms have been reported. Helicobacter pylori infection is the major cause of peptic ulcer disease and appears to be a risk factor for ischemic cerebrovascular disease. However, in contrast to other chronic

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... us agents, H pylori has not been consistently isolated from atherosclerotic lesions. Methods-We investigated the presence of H pylori in 38 atherosclerotic plaques obtained at carotid endarterectomy by using morphological and immunohistochemical techniques and a highly sensitive polymerase chain reaction method. We performed immunohistochemical detection of intercellular adhesion molecule-1, a marker related to inflammatory cell response. We also examined 7 carotid arteries obtained at autopsy from subjects without carotid atherosclerosis. Results-H pylori DNA was found in 20 of 38 atherosclerotic plaques. Ten of the H pylori DNA-positive plaques also showed morphological and immunohistochemical evidence of H pylori infection. None of 7 normal carotid arteries was positive for H pylori. Intercellular adhesion molecule-1 was expressed in 75% of H pylori-positive plaques and in 22% of H pylori-negative plaques. The presence of the microorganism was associated with male sex but was independent of age, vascular risk factor profile, and prior neurological symptoms. Conclusions-H pylori is present in a substantial number of carotid atherosclerotic lesions and is associated with features of inflammatory cell response. This study provides additional evidence of the relationship between H pylori infection and atherosclerotic disease. (Stroke. 2001;32:385-391.