|Clostridium difficile establishes infections following|
antibiotic treatment and causes diarrheal disease.
Before we dive into the paper, it is important that we understand the basics of C. difficile infections. As I mentioned above, C. difficile infections are often brought on by heavy exposure to antibiotics or chemotherapeutics, which can both disrupt your commensal gut bacterial communities. The idea is that the destruction of your commensal gut bacteria opens up an ecological niche which can be filled by the opportunistic C. difficile. This occupation is what leads to infection, which can result in a nasty diarrheal disease that is a bit of a nightmare to deal with. One therapy that has been showing promise is the fecal microbiome transplant therapy.
The fecal microbiome transplant is a procedure that does just what it says. This is a procedure in which a healthy fecal donor sample is prepared and transplanted to the gut of the C. difficile infected patient. This is a promising approach and is gaining momentum in C. difficile treatment. While the commensal gut bacterial community provides increased resistance to C. difficile infection, the specific bacteria that mediate the resistance phenotype remain unknown. Understanding the specific bacteria that promote resistance, and how they promote resistance, could allow for more targeted and fine tuned approaches to treating C. difficile infection.
|Electron microscopy image of C. difficile. <Source>|
To get at functionality and causality, the group administered a cocktail of four bacteria that were correlated with increased infection resistance, and also administered C. scindens alone. This was done after the mice were treated with antibiotics, and before they were infected with C. difficile. Surprisingly, the cocktail and C. scindens alone both promoted resistance against C. difficile infection, and the individual cocktail bacteria alone did not improve resistance. This is a really cool result, and to make things better, they followed up on this by evaluating what specific C. scindens functionality was promoting infection resistance.
|Fecal transplants are currently being investigated as|
treatments for C. difficile infections. <Source>
Overall this paper was a really cool read and I would suggest you check it out. And what can we say about the paper? We can say that, despite a loss in bacterial diversity previously being associated with C. difficile infection, it appears specific bacteria are primarily involved in mediating infection resistance. C. scindens was the best candidate for mediating C. difficile infection resistance, and its resistance potential was functionally supported. C. scindens mediated protection is potentially mediated through bile acid synthesis.
Finally, what does this mean in the clinic? Does this mean you should try to get a pill of C. scindens next time you take antibiotics so that you can prevent a C. difficile infection? As of now, I think that would be a bit premature. These are certainly interesting findings, and will be worth watching in the future, but more research will be needed before we can use these bacteria to treat patients in the clinic.
Buffie CG, Bucci V, Stein RR, McKenney PT, Ling L, Gobourne A, No D, Liu H, Kinnebrew M, Viale A, Littmann E, van den Brink MR, Jenq RR, Taur Y, Sander C, Cross J, Toussaint NC, Xavier JB, & Pamer EG (2014). Precision microbiome reconstitution restores bile acid mediated resistance to Clostridium difficile. Nature PMID: 25337874