Association between infection with Helicobacter pylori and Chlamydia pneumoniae and risk of ischemic stroke subtypes: Results from a population-based case-control study.

Abstract

Helicobacter pylori and Chlamydia pneumoniae have been associated epidemiologically and pathogenetically with coronary atherosclerosis. However, population-based data on chronic infection and stroke are lacking. Therefore, we investigated the association of both bacterial pathogens and ischemic stroke subtypes in a population-based case-control study. Patients with first ischemic stroke in the population-based Erlangen Stroke Project were collected as cases. Neighborhood controls were drawn from the study population, matched for age, sex, and place of residence. IgG antibodies to H pylori were measured by enzyme immunoassay, and IgG antibodies to C pneumoniae were measured by microimmunofluorescence technique. Conditional logistic regression was used. Analyses were stratified for etiologic stroke subtypes according to Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria. A total of 145 case and 260 control subjects were included. Chronic H pylori infection was associated with a higher risk of stroke caused by small-artery occlusion (adjusted odds ratio, 3.31; 95% CI, 1.15 to 9.56) and a lower risk of cardioembolic stroke (adjusted odds ratio, 0.21; 95% CI, 0.06 to 0.71). Overall, elevated H pylori as well as elevated C pneumoniae antibodies were not associated with ischemic stroke. Our population-based study does not provide evidence of any strong association between the immune response to C pneumoniae as a marker of prior infection and ischemic stroke. Further studies are required to reveal the role of chronic H pylori infection as an independent risk factor for the subgroup small-artery occlusion.