Just like in the gut, is it normal to have have bacteria living in our brains?

Question

When I say bacteria in the brain, I mean non-pathogenic type bacteria such that is seen in the intestines and colon - probiotic.

I am asking because I want to  understand our symbiotic nature with bacteria and how far this can go because we are starting to see these bacteria play a role in biology and immune system more than we thought.

The NIH has invested in a "Human Microbionome project" researching and mapping various regions where bacteria live on humans such as the stomach, lunges, skin, etc.

Now with this out of the way, my question is this: Are there regions directly in the CNS with a more direct access to the brain than through the ENS? That is bacteria be found perhaps on the brain or in places more "near" the nervous system?

Thanks

Ted K · Accepted Answer

No, it is not normal at all--both for brain AND for the gut.  You've probably heard the old expression, "a place for everything and everything in its place."  That's never more true than in talking about bacteria and our body--as long as they're OUTSIDE, everything is ok.  But if they get in, look out.

Strictly speaking, the bacteria in our gut are not really "in" our body at all--they are in the lumen of the gut, which topologically, is OUTSIDE the body, and the epithelial barrier and mucosal immune system operate to keep them "outside"--if they get inside, you have real trouble--infections, sepsis, inflammatory bowel disease...

That's not to say that bugs in the gut lumen don't affect central neural function--they undoubtedly do, but not directly--they do it indirectly by triggering hormonal and neural signals which then can affect the brain.  Direct effects of bacteria ANYWHERE that's really inside the body are uniformly associated with pathology and [often, life-threatening] disease, NOT normal function..

bevley b · Answer

symbiotic processes are ok for certain things.  algae on trees.
but even if a bacteria is a nonpathogen, it can be under the right
conditions a pathogen.   you never want any bacti in the blood system.  in your gut that is fine, as that is the process. I have seen people die
from a simple infection that got out of its normal environment, and got
into the blood.

Smeghead · Answer

Definitely not.  Bacteria in the nervous system - ANY bacteria - is very very very bad news, and is considered one of the very few infectious medical emergencies.  As in, you'll die quickly unless major medical help is offered.  You may have heard of meningitis.  That's what that is.

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Just like in the gut, is it normal to have have bacteria living in our brains?

3 Answers