Chlamydia pneumoniae infection as a risk factor for subarachnoid hemorrhage

Cerebrovasc Dis. 2005;19(4):209-13. doi: 10.1159/000083884. Epub 2005 Feb 8.


Many risk factors for subarachnoid hemorrhage (SAH), such as hypertension and recent infection, have already been established. Chlamydia pneumoniae is a common respiratory pathogen that has been implicated as a potential risk factor for hypertension and atherosclerotic diseases. The purpose of the case-control study presented here was to examine the causative relationship between C. pneumoniae infection and SAH. Serum C. pneumoniae IgG and IgA antibodies were measured using an enzyme-linked immunosorbent assay in 52 patients with SAH and in 104 healthy age-matched control subjects. Multivariate analysis revealed a significant association between SAH and both a strong seropositivity for IgG and/or IgA antibodies against C. pneumoniae (odds ratio, OR, 3.62; 95% confidence intervals, CI, 1.06-12.39; p = 0.040), which indicates the presence of acute C. pneumoniae infection, and hypertension (OR, 2.91; 95% CI, 1.42-5.96; p = 0.0035). These results provide evidence that infection with C. pneumoniae may be a risk factor for SAH from a ruptured intracranial aneurysm.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antibodies, Bacterial / blood
  • Chlamydia Infections / epidemiology*
  • Chlamydia Infections / immunology
  • Chlamydophila pneumoniae*
  • Female
  • Humans
  • Immunoglobulin A / blood
  • Immunoglobulin G / blood
  • Male
  • Middle Aged
  • Risk Factors
  • Subarachnoid Hemorrhage / epidemiology*


  • Antibodies, Bacterial
  • Immunoglobulin A
  • Immunoglobulin G