Fighting Faeces with Faeces

Beware, this may be NSFW. Or for a few hours if you just ate.

An article published in PLOS Pathogens(1) caught my eye recently (truthfully it was on the nature news feed). A research group from the Sanger Institute near Cambridge (UK, not MA) have been studying how to deal with a very difficult hospital infection, Clostridium difficile (C. difficile). This probably doesn’t sound very interesting until you realise that one of the methods they used to combat the infection is faecal transplantation.

Yes that means taking one persons poop and putting it inside another (ill) person. The only difference here is that the experiment was done on mice. A lot of people might have just gone WTF right about there.

Ok lets start with the infection. C. difficile is a bacteria which usually becomes infectious in hospital after a course of antibiotics. It is a gut (more specifically, colon) infection which can give symptoms such as colitis and diarrhoea (hence the title). In extreme cases it can kill.

Why does it become infectious after a course of antibiotics? Competition. Your normal gut bacteria not only helps you to digest food, it also helps you to fight off infection through competition (for infectious bacteria it is like trying to get into a 2×2 room packed with 20 other people). However C. difficile is resistant to the antibiotics prescribed by the doctors which instead kills your normal gut bacteria (leaving that room more or less empty). Therefore C. difficile can enter and spread, causing infection.

You can imagine that this may cause a few problems with the treatment, especially as antibiotics are generally the first port-of-call for bacterial infections. Still, doctors were not put off. In medicines never ending attempts to see what is the most gross thing that doctor’s can see/do, they came up with the homogenised stool transplant (basically get some donated poo, make it liquidy, and put it in someone with diarrhoea). Seriously, there is a reason why doctors are respected worldwide.

The logic behind the procedure is that by giving the ill person healthy poo, you reintroduce the good bacteria. Competition is re-established and C. difficile can’t survive. Amazingly enough, it works! This study alone reported 92% effectiveness in the worst effected mice. Thankfully the research group took one step further to make doctor’s lives that bit easier, and patients lives that much nicer.

Reasoning that it is the bacteria in the stool that is important, the research lab extracted just the bacteria from the stools and then transplanted this into the ill mice. This process was a bit trial and error, but eventually a mix of six specific bacteria were found that worked.

Many of the combinations failed (see below) but we ultimately identified a mixture of six bacteria that effectively and reproducibly (20/20 mice) suppressed the C. difficile 027/BI supershedder state

Hurrah! No nasty treatments for people with horrible infections! Or is it?

In standard pharmacological terms it takes about 10-20 years for a treatment to get from initial animal research to a marketed drug. Forgetting that, faecal transplantation is already an accepted treatment for C. difficile infections. So it looks like we’re stuck with the dirty for a bit longer…



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  1. Cavemen Are Better at Art Than Modern Artists? « Science Defined

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