Evidence for Chlamydia pneumoniae infection in cerebrospinal fluid of patients with multiple sclerosis

To assess the relevance of Chlamydiae pneumoniae (CP) infection in multiple sclerosis (MS), we evaluated the presence of CP-free DNA and antibodies in serum and in cerebrospinal fluid (CSF) from 116 Italian patients (106 relapsing-remitting, 8 secondary progressive, and 2 primary progressive; 78 F, 38 M, mean age 35.2, SD±11) affected by definite MS according to Poser criteria and in 86 control subjects (40 F, 46 M, mean age 53.1, SD±17.4) affected by other neurological diseases (OND), including periferal neuropathies, cerebrovascular disorders, movement disorders, dementia, vasculitis, viral infections, psychiatric diseases, and toxic or metabolic diseases. We excluded myelitis and optic neuritis of unknown inflammatory origin from both groups. CSF analysis for CP determination and for the ubiquitous β-actin gene was done by polymerase chain reaction (PCR); serum and CSF IgG, IgA, and IgM levels were determined by microimmunofluorescence. A total of 23/116 MS patients (19.8%) showed evidence of CP DNA in their CSF compared to 2/86 OND (P = 0.00019). No differences between the two groups were found for IgG, IgM, and IgA determinations either in serum or CSF. No correlation was found between CP detection in CSF and the presence of oligoclonal bands or evidence of intrathecal IgG synthesis. We conclude that CP can be detected in the CSF of a consistent quota of Italian MS patients. Our positivity rate (≃ 20%) lies halfway between the previously reported data; genetic and environmental heterogeneity may account for this apparent inconsistency. Our data fit with the view (Ann Neurol 2000; 47:707-717) that an "infectious" MS subgroup is likely to emerge as a different entitiy from the general "MS syndrome.".