BACKGROUND: It is uncertain whether Helicobacter pylori is associated with 
ischemic syndromes and whether this association is mediated by the induction of 
atherosclerosis. In this study, we tested the hypothesis that atherosclerotic 
stroke shows a selective association with virulent H pylori strains.
METHODS AND RESULTS: The seroprevalence of infection by H pylori and by strains 
bearing the cytotoxin-associated gene-A (CagA), a strong virulence factor, was 
assessed by ELISA in 138 patients with large-vessel stroke (group A), in 61 
patients with cardioembolic stroke (group B), and in 151 healthy control 
subjects. The 3 groups had a similar socioeconomic status. Serum levels of 
C-reactive protein were also measured by ELISA. The prevalence of infection was 
71% in group A, 63.9% in group B, and 70.2% in the control group (P=NS), whereas 
the prevalence of CagA-positive strains was higher in group A than in group B 
(42.8% versus 19.7%, respectively; odds ratio 3.04, 95% CI 1.43 to 6.49; 
P<0.001) and higher in group A than in the control group (42.8% versus 17.9%, 
respectively; odds ratio 4.3, 95% CI 2.12 to 8.64; P<0.001), after adjusting for 
main cardiovascular risk factors and social class. A trend toward a difference 
in C-reactive protein was observed between CagA-positive (2.00+/-3.43 
[mean+/-SD] mg/dL) and CagA-negative (1.31+/-1.72 [mean+/-SD] mg/dL) patients 
(P=0.072, Mann-Whitney U test).
CONCLUSIONS: The association between H pylori and acute cerebrovascular disease 
seems to be due to a higher prevalence of more virulent H pylori strains in 
patients with atherosclerotic stroke.