A new study offers the first evidence that fungal infections can be detected in MS brains. According to researchers, fungal DNA and the direct visualization of fungal structures, can be detected. In addition, bacteria can be identified in neural tissue from MS patients. The researchers claim the findings point to the novel idea that MS could be caused by polymicrobial infections.

The possibility that microbial infections, such as viruses or bacteria, can trigger an autoimmune reaction in CNS tissue has been previously put forward. However, the recent discovery that bacteria are present in central nervous system tissue points to a direct involvement of microbial infections in the etiology of MS. A new study by researchers at the Universidad Autónoma de Madrid, in Spain, provides the first evidence of fungal infection in CNS tissue of MS patients, showing fungal DNA from different species can be detected in the CNS. 

The study’s authors identified the fungal species in the nervous tissue of 10 patients with MS. Strikingly, Trichosporon mucoides was found in the majority of MS patients, and particularly high levels of this fungus were found in two patients. Importantly, T. mucoides was not detected in the CNS of control subjects. 

They were also able to visualize fungal structures in CNS tissue sections using specific antifungal antibodies, which also showed the accumulation of a number of microbial cells in microfoci. Again, microbial structures were not observed in CNS sections from controls. In addition to fungi, neural tissue from MS patients was also positive for bacteria. 

Thus, mycosis of the CNS may be accompanied by opportunistic bacterial infection, promoting neuroinflammation and directly causing focal lesions, followed by demyelination and axonal injury.

The findings were published in the journal Neurobiology of Disease.