ORLANDO, FLORIDA--For 3 years, researchers at Vanderbilt University in Nashville, Tennessee, have advanced the theory that multiple sclerosis (MS) may be caused by a common bug called Chlamydia pneumoniae. But others have failed to replicate the results, and the work is hotly debated. Now, a new team has failed to find any link. The findings were presented here on 23 May at the General Meeting of the American Society for Microbiology.
C. pneumoniae is suspected to do more than just cause respiratory infections: It has been fingered as an accomplice in atherosclerosis (Science, 3 July 1998, p. 35 ) and since 1998, the Vanderbilt team has published three papers showing that the bug occurs in the cerebrospinal fluid of patents with MS, a lethal disease that slowly cripples by destroying the myelin sheath surrounding nerves.
The Vanderbilt team argues that the bacterium somehow causes the disease, which would fit with epidemiological studies that have suggested an infectious cause. If true, it would mean that MS might be treated with antibiotics; indeed, some neurologists have proposed starting treatment trials, says Charlotte Gaydos of Johns Hopkins University in Baltimore. But at least four teams--including Gaydos's--have been unable to replicate the Vanderbilt findings.
Taking a slightly different tack, Ellena Peterson of the University of California, Irvine, and her colleagues decided to look for signs of infection elsewhere in the body of MS patients. Using a polymerase chain reaction test, the team hunted for the bacterium in a type of white blood cells that Chlamydia is known to infect. The team didn't find the bug in 63 patients; another 63 healthy people--mostly spouses or friends of the patients--also tested negative. Nor did the patients have higher levels of antibodies against Chlamydia, Peterson reported at the meeting.
Vanderbilt's Song-Yi Yao says Peterson's study doesn't disprove his team's findings, because they never tested for the bacterium in blood cells. But to Gaydos, the study is just another nail in the coffin of the Chlamydia-MS link. "It just isn't there," she says--and it's about time to end the debate, she adds.