Multiple sclerosis (MS) is an inflammatory, demyelinating disease which affects the central nervous system (CNS). The etiology of MS is unknown, although the immune system appears to play a role. Many different infectious agents have been proposed as potential causes for MS, including Epstein-Barr virus, human herpesvirus 6, and coronaviruses. Recently Dr. Sriram at Vanderbilt University has found evidence for active Chlamydia pneumonia infection in the CNS of MS patients. These findings have been replicated in part by other laboratories.

The purpose of the current study is to test whether antibiotic treatment aimed at eradicating Chlamydia infection will reduce the disease activity in MS.

The primary outcome measure will be reduction in new enhancing MS lesions on brain MRI. Forty patients will be entered into the trial. To be eligible, patients must have evidence of chlamydia infection in their spinal fluid and enhancing lesions on their pre-randomization MRI scans. Patients who meet these criteria will be randomized to either placebo or antibiotic therapy, and followed for 6 months on treatment.