Toronto (April 23, 1999) ­ An agent that causes respiratory tract infections  such as community-acquired pneumonia, called chlamydia pneumonia, may be a  factor in the development of multiple sclerosis (MS) in some patients,  according to a study released during the American Academy of Neurology 51st  Annual Meeting April 17-24 in Toronto.

These results suggest that infection of the central nervous system with  chlamydia pneumonia is an early event in MS, and may directly or indirectly  be responsible for the development of the disease," said study author and  neurologist Subramaniam Sriram, MD, of Vanderbilt Medical Center, in  Nashville, TN. "What is not clear is whether C. pneumonia is the cause of MS,
a fortuitous bystander, or whether it in some way triggers an autoimmune  response which causes the disease."

The cause of MS is not known. In MS, the insulating material of the nerves,  myelin, is destroyed. This leads to problems in vision, balance, gait, and  other neurologic functions. Current theories suggest that a poorly regulated  immune response against common infectious agents may be responsible for the  disease.

Chlamydial species are well-known pathogens involved in a number of human  diseases. Chlamydia pneumonia was discovered about 10 years ago and is now  thought to be responsible for many cases of community-acquired pneumonia. The  association between C. pneumonia and MS has not been previously noted.


In a study of 17 patients with newly diagnosed relapsing remitting MS and 13   patients without the disease, researchers found evidence of the chlamydia   pneumonia organism in the spinal fluid of all 17 MS patients. In 47 percent   of newly diagnosed MS patients, the organism was directly cultured from   cerebrospinal fluid. Using sophisticated genetic tests, researchers found the   DNA of chlamydia pneumonia in the cerebrospinal fluid of all the MS patients.   In contrast, the organism was not found in the cultures of any of the 13   control patients, and only two had evidence of C. pneumonia DNA.

"There is a possibility that these two patients may develop MS in the future   since their symptoms were suggestive of an initial attack," Sriram said.

Also, a majority of the MS patients had an antibody response to chlamydial  antigens in the cerebrospinal fluid, indicating evidence of a chronic immune  activation to chlamydia pneumonia.

In earlier studies, the researchers had established that a large number of  patients with chronic progressive MS had evidence of C. pneumonia infection  in the cerebrospinal fluid. However, it was unclear whether the infection was  a secondary event following long-standing inflammatory injury or was directly  involved in the immune process, Sriram said.

"It’s clear from this study that the association between MS and the presence   of C. pneumonia infection is extremely high—much higher than any other   organism people have looked at in the past," he said.

"Since a number of currently available antibodies prevent the replication of  C. pneumonia, a therapeutic trial is likely to answer the question of cause  and effect between C. pneumonia and multiple sclerosis," Sriram said.

Improving care for patients with neurological disorders through education and   research is the goal of the American Academy of Neurology, an association of   more than 15,000 neurologists and neuroscience professionals.

  This material is provided as general medical information and is not intended as advice for individual patients; please contact your physician for specific recommendations.