Scientists have discovered a soil-based bacteria in humans for the first time, and they believe it may be a trigger of multiple sclerosis. This is according to a study published in the journal PLOS ONE. Researchers from Weill Cornell Medical College and Rockefeller University discovered the bacterium Clostridium C. perfringens type B in a 21-year-old patient suffering from multiple sclerosis (MS). The researchers say although their study is small, their findings are so “intriguing” that it has caused them to start work on new treatments for the debilitating disorder. The researchers explain that Clostrodium perfringens – found in soil – is one of the most common bacteria worldwide. The bacterium is divided into five types, A to E. Type A is a common form found in the human gastrointestinal tract that is thought to be harmless. However, the researchers say that type B and D carry a gene (epsilon toxin) that emits a protoxin, which develops into a potent epsilon toxin in the intestines of grazing animals. The epsilon toxin then goes through the blood stream to the brain, causing damage to brain blood vessels and myelin – insulation protecting neurons – resulting in symptoms similar to that of MS in humans. The researchers say that only two humans have been found with type D bacterium, while type B had never been found. But they wanted to determine whether both types B and D did exist in humans, and whether these bacterium are linked to MS.

C. perfringen type B in humans ‘truly significant’ After blood and spinal fluid samples were taken from patients with MS, these were tested for antibody reactivity to epsilon toxin and compared with samples from patients without MS. Stool samples were also taken from both MS patients enrolled in the Harboring the Initial Trigger for MS (HITMS) trial, and those without the disease. Results showed that patients with MS had levels of epsilon toxin antibodies ten times higher than those without MS. Furthermore, the stool samples showed that only 23% of MS patients carried the type A bacterium, compared with 52% of healthy patients. “This is important because it is believed that the type A bacterium competes with the other subtypes for resources, so that makes it potentially protective against being colonized by epsilon toxin secreting subtypes and developing MS,” the researchers note. But most importantly, the researchers discovered the type B bacterium in one patient who they say was experiencing a “flare-up” of MS. The researchers explain that this discovery is of vital importance: “This bacterium produces a toxin that we normally think humans never encounter. That we identified this bacterium in a human is important enough, but the fact that it is present in MS patients is truly significant because the toxin targets the exact tissues damaged during the acute MS disease process.”

Bacterium ‘may send toxin to the brain’ The researchers hypothesize that after a human is infected with C. perfringens B or D, the bacterium can reside in the gut as an endospore, defined as a “seed-like structure” allowing certain bacteria to stay dormant for long periods. “The human gastrointestinal tract is host to approximately 1,000 different bacterial species, but is not a hospitable environment for C. perfringens type B or D, so it does not grow well there,” explains Dr. Timothy Vartanian, professor of neurology and neuroscience at Weill Cornell Medical College and senior study author. “It hibernates in a protective spore. When it does grow, we anticipate it generates a small quantity of epsilon toxin, which travels through the blood into the brain.” He adds that they believe the bacterium’s growth is always present, but “rears its ugly head from time to time.”