'Poo pills' and the war on superbugs

Scientists fighting the ever-growing threat posed by antibiotic-resistant 'superbugs' are increasingly confident that they might have found a solution – in pills of poo. And, if preliminary trials are successful, these poo pills could even play a role in recovery from cancer and depression, too.

What are 'poo pills' and how do they work?

Poo pills contain carefully screened, freeze-dried faeces samples, taken from healthy donors, that are packed with "good bacteria". Once taken by a patient whose guts have been colonised with antibiotic-resistant bacteria, the pills dissolve and the "good bacteria" flush out the "bad bacteria", stopping them from lurking in the patient's bowel and potentially escaping elsewhere in the body to cause extremely hard to treat infections.

A recent, small-scale trial, published in the Journal of Infection, showed "really promising signals" that the poo pills could get rid of the superbugs altogether or "reduce them down to a level that doesn't cause problems", said study lead Dr Blair Merrick, of Guy's and St Thomas's Hospital, London.

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The idea of a poo pill "isn't as far-fetched as it might seem", said the BBC. Faecal transplants (sometimes called "trans-poo-tion") are already approved in the UK for treatment of adults who have had repeated episodes of infection by Clostridium difficile – a bacteria that can cause severe diarrhoea and is notoriously resistant to most antibiotics. These transplants are often delivered via enema, colonoscopy or naso-gastric tube but pills are sometimes used instead.

How big a problem are superbugs?

'Superbug' is a term used for different strains of bacteria that have developed resistance to most known antibiotics – mainly because we have misused and overused these antibiotics over the years.

The main superbugs include MRSA (methicillin-resistant Staphylococcus aureus), VRE (vancomycin-resistant Enterococcus), Clostridium difficile, and the bacteria that cause multi-drug-resistant tuberculosis.

Resistance to antibiotics has led to at least 1 million deaths globally since 1990, according to a study by the Global Research on Antimicrobial Resistance Project published last year in The Lancet. Increasing rates of drug-resistant infections are expected to claim more than 39 million lives between now and 2050.

"It's very scary," England's former chief medical officer Sally Davies told The Guardian last year. Now the UK's special envy for antimicrobial resistance, she said "some people talk about it being a pandemic – it is. It's pretty awful." Certainly, according to a National Audit Office report earlier this year, the UK "remains a long way" from its goal of containing, controlling and mitigating it.

Could poo pills fight other diseases?

There are several studies being carried out on other uses for faecal transplants, including for treating cancer and mental health issues.

Researchers have begun "wondering if altering these microbial populations" could make cancer tumours "more receptive to existing treatment options", said Popular Science. In Canada, a two-year poo pill trial has just started on a small group of pancreatic cancer patients.

Also in Canada, researchers at the University of Calgary, intrigued by studies suggesting that altering the gut microbiome can improve signalling between the gut and the brain, have began a trial to see if poo pills can reduce the effects of depression and obsessive-compulsive disorder.

But some new research is suggesting faecal transplants can alter the intestinal environment in less helpful ways, said The Independent. Studies on mice, published in Cell, showed shifts in liver metabolism and the genes involved in immune function. The study author recognise the advances faecal transplants promise but advise caution in developing future treatments.