Faecal bacteria cocktail treats superbug infection
Some bugs are good for us (Image: Eye of Science/Science Photo Library)
Feeding faeces to people with chronic infection can cure them, but who wants to eat poo? A synthetic alternative could provide a more palatable option.
Hospital superbug Clostridium difficile can wreak havoc in the guts of vulnerable people, especially those who have lost some of their protective gut flora as a result of antibiotic use. Once it takes hold, the bacteria can cause nasty diarrhoea and in some cases is fatal. The usual treatment for the infection, which affects over half a million people in the US each year, involves a strong course of antibiotics. But the infection returns in about 20 per cent of cases, and some people become chronically infected.
One treatment appears to be remarkably successful. It involves ingesting the faeces of healthy individuals – either via a tube to the stomach or colon – to help repopulate their guts with so-called good bacteria. This boosts defences against reinfection and unpleasant as it may sound, works in around 90 per cent of cases.
"The faecal transplant is fairly disgusting but it works really well," says Emma Allen-Vercoe at the University of Guelph in Ontario, Canada. The therapy is still a little too disgusting for some infected individuals and doctors, though, she adds.
To get around these issues, Allen-Vercoe, together with Elaine Petrof at Queens University in Kingston, Ontario, and their colleagues attempted to create an alternative version of the faecal transplant – a concoction that contains only the good gut bacteria found in faeces.
The first step – getting hold of the faeces of a healthy person – was the hardest, says Allen-Vercoe. "We wanted someone with no chronic disease and a good body mass index who doesn't drink, smoke, take drugs and had never been exposed to antibiotics," she says.
The team's closest match was a woman who was born and raised in rural India. The group then set about identifying the bacteria within her faeces, isolating the individual species and attempting to cultivate them.
Culturing bacteria is a tricky process as the bugs do not survive well in lab conditions. So far, Allen-Vercoe's team have been able to culture 10 per cent of the bacteria they isolated. This should be enough for therapy, says Allen-Vercoe. "There's an awful lot of redundancy and you don't need everything to get a functional ecosystem."
To find out if the cultures could be used therapeutically, the team gave a suspension of their cultured bacteria to two people with recurrent C. difficile infection. The bacteria cocktail was effectively "drizzled" along the inside of each person's large intestine using a colonic tube. Both people avoided C. difficile infections for the six months they were monitored.
While the synthetic stool therapy will need to be trialled in more people, the early results are promising, says Allen-Vercoe. And it offers another important advantage.
"Faecal transplants have been heralded as a wonderful thing… but we don't know what the long-term consequences are," she says. There's always a chance that there'll be a pathogen lurking in faeces, for example. The benefit of using a synthetic stool therapy is that you know exactly what is in it, and can ensure that no dangerous bacteria or antibiotic-resistant strains are present, she says.
Vincent Young, a microbiologist at the University of Michigan, Ann Arbor, agrees. "It's a move in the right direction," he says.
Young cautions that more research is needed before therapies that target gut bacteria become more common. For recurrent C. difficile infections, you cannot argue with the success of the treatment, he says. "But at the same time, gut bacteria has been linked to diabetes, obesity, allergies… the list goes on." Gut bacteria that make one person healthy might cause health problems in another, he says.
Journal reference: Microbiome, DOI: 10.1186/2049-2618-1-3
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