An MRI study of Chlamydia pneumoniae infection in Italian multiple sclerosis patients.

We amplified sequences of the Chlamydia pneumoniae (CP) major-outer membrane protein in the cerebrospinal fluid (CSF) from 23 of 107 (21.5%) relapsing-remitting or secondary progressive multiple sclerosis (MS) patients and two of 77 (2.6%) patients with other neurological diseases (OND) (P = 0.00022). CP+ patients showed magnetic resonance imaging (MRI) evidence of more active disease (P = 0.02) compared to CP- MS patients and tended to have an anticipation of age at disease onset (32.3 +/- 12 versus 28.5 +/- 10 years; P = ns) causing a longer disease duration (7.5 +/- 5 versus 4.4 +/- 4 years; P = 0.016) at the time of clinical evaluation. These findings, although indirectly, suggest that CP infection of the central nervous system (CNS) might affect disease course in a subgroup of MS patients.