Posted on behalf of Nicola Jones
Imagine a world where ‘eat shit’ isn’t an insult, but way to save your life. Pathogen microbiologist Brett Finlay of the University of British Columbia has shown that, in mice, resistance to a deadly e. coli-like bacterium depends on their gut microbes – and that those microbes can be swapped around by effectively feeding the mice each others’ feces.
Finlay looked at a mouse model of e. coli 0157, a bug that often contaminates hamburger meat. In mice, the equivalent bug is called Citrobacter rodentium. One strain of mice (called NIH Swiss) is known to be resistant to this pathogen. Another (C3H/HeJ) is known to quickly fall victim to the bug – all will die within a couple of weeks of exposure. Finlay wiped out the normal gut bacteria of someC3H/HeJ mice with antibiotics, and then fed them a dose of treated NIH Swiss feces to repopulate their guts (through a technique called ‘oral lavage’, involving a feeding tube). This upped their survival rate from 0 to nearly 80%, he told the International Human Microbiome Congress in Vancouver, Canada, on Thursday. Feeding NIH Swiss mice with C3H/HeJ microbes similarly caused their downfall.
“When 100 people at a wedding eat the potato salad, only a few get sick,” says Finlay. He thinks these as-yet-unpublished results might help to explain why. “Resistance to many diseases could be from our microbiota,” he extrapolates. The results aren’t surprising, says Finlay, but nail down proof for an effect that most microbiologists assumed could happen.
Fecal transplants are already done for some people with serious colon infections; feces are taken from someone, usually a relative, and introduced rectally into the patient. But experiments like Smith’s and Finlay’s could help to point the way towards clinical applications (including preventative measures) for less serious conditions, with less invasive treatments – perhaps with a pill.
Francis Ouelette, a bioinformatician at the Ontario Institute for Cancer Research who is an external advisor for the US Human Microbiome Project, one of the big, over-arching bodies in this field, says that Finlay’s work is impressive, and that mouse models like these are the future of the field. “The kinds of thing that Brett does is definitely the way to go,” he says. Jeff Gordon’s lab at Washington University in Saint Louis, Missouri, is doing similar work, creating ‘humanized’ mice to study how microbes affect us (see Do gut bacteria worsen malnourishment?).
Image: Centres for Disease Control and Prevention