The human body contains 10 times more bacteria, fungi and other micro-organisms than human cells (explore some of them here). Collectively, these 100 trillion microbes are known as the microbiome, and some have gone so far as to say that we are our microbiome.
Recently, scientists working through the Human Microbiome Project, examined 242 healthy people and tracked them, or rather their microbiome, over two years.
The scientists sequenced the genetic material of bacteria and recovered more than five million genes. The massive amount of data is visualized below.
Most of these species are harmless and even beneficial (e.g., in the gut, microbes synthesize vitamins and break down tough plant compounds into digestible components) – although they can still cause illness if they wind up in the wrong place (e.g., Staphylococcus aureus can cause serious infections if it makes its way into the body). The vital role of the microbiome is still largely being uncovered, however in the case of the gut microflora it is already quite evident. (Click here to listen to the Radiolab episode on Guts).
Antibiotics not only kill off harmful bacteria (yay!), but broad-spectrum forms can kill off many desirable species (boo!). It is not uncommon for a person’s gut microflora to be severely compromised after a course of antibiotics. The absence of a “nice” consortium of gut bacteria, makes the gut susceptible to invasion by other, less desirable species, such as Clostridium difficile. The New York Times reported that from 2000 to 2009, the number of hospitalized patients in the United States found to have C. difficile more than doubled, to 336,600 from 139,000. Most commonly, C. difficile infection causes diarrhea, which can lead to serious complications, including dehydration and colitis, and in rare cases, death.
Few treatments exist for people with recurring C. difficile infections, however a growing number of doctors are treating C. difficile with fecal transplants (pictured left) Stool from a healthy donor is delivered like a suppository to an infected patient. The idea is that the good bacteria in the stool establish themselves in the gut and begin to compete with C. difficile. This technique, while effective, has certain concerns beyond just the ick factor, including the risk of introducing unknown pathogens into a patient. The technique is also limited by its current lack of widespread acceptance among patients and health-care facilities and a lack of standardization, which is key for any new therapy. These specific drawbacks lead researchers at the University of Guelph to develop a synthetic poop known as RePOOPulate.
PePOOPulate is a super-probiotic taken from purified intestinal bacterial cultures (derived from a single healthy donor) grown in “Robo-gut” equipment in a Guelph laboratory that mimics the environment of the large intestine. The first clinical results of RePOOPulate were recently reported in the inaugural issue of Microbiome. The test was very limited, having been administered to only two patients, both of whom were women in their seventies who had failed at least three courses of metronidazole or vancomycin. But the early results are very promising; described by Ed Yong, “One women had spent 18 months in hospital with C.difficile. Ten days after receiving [artificial] stool substitute, her bowel movements were back to normal and C.difficile had been eradicated. The second woman was fighting her third bout with C.difficile, and she too resumed normal bowel movements within 3 days of treatment“. Both patients have been free of C. difficile for 6 months.
Being such a small test, it is difficult to make any big conclusions yet, but this proof-of-concept paper opens the doors for future testing. As the science behind stool transplants and gut microbiome continues to develop, scientists will be better able to control the bacterial mixture in RePOOPulate, tweaking it to meet the needs of different patients. These experiments once again demonstrate that everything comes down to poo.
- Fake Feces To Treat Deadly Disease: Scientists Find They Can Just Make Sh*t Up (blogs.scientificamerican.com)
- Synthetic Poop Could Fight Hospital-Acquired Stomach Infections (geekosystem.com)
- Faux faeces helps combat Clostridium difficile bacteria (wired.co.uk)
- Say hello to your 100 trillion invisible friends (aka friendly bacteria) (mnn.com)
- American Gut – what’s in your gut? (journeythroughthecortex.blogspot.com)