Microbes as a medicine Inspire article

The diverse bacteria in and around us can influence our health in a multitude of ways

Whether it’s on our skin, in our guts, in our homes or the oceans, there’s a lot of hype about the microbiome but it can also be a fascinating subject with many implications for human health. At the EuroScience Open Forum (ESOF) in Manchester this week this has been increasingly evident. The human microbiome might even be an untapped source of new antibiotics.

A microbiome is an ecosystem of microbes: bacteria, viruses and other creatures invisible to the naked eye. In our bodies, we have around the same number of bacterial cells as human cells and they add around 1.5kg to our bodyweight. Many of these are in the gut, but other ecological niches exist for specialised bacteria, and one of those is the nose.

Bacteriologists at the University of Tübingen in Germany started looking up patients’ noses to investigate the prevalence of S. aureus, a common cause of post surgical wound infections in hospitals. As part of their study, they discovered a new antibiotic compound. ‘We never thought we’d come up with a new antibiotic,’ says Andreas Peschal, one of the researchers.

It was, adds Andreas, an example of how basic research can lead to unexpected discoveries. 

Although you might not think it when you’re suffering from a cold, the nose is not a rich environment for bacteria. But some bacteria, including S. aureus, are well adapted to the salty wet environment of our nostrils. But only 30% of us have S. aureus in our noses. Andreas and his colleagues set out to find out why the other 70% don’t.

By taking swabs from different noses the Tübingen group found that patients without S. aureus had a different bacteria in their nose, S. lugdunensis. Could this new bacteria have a way of keeping S. aureus out? 

The answer was yes, by isolating and purifying the compounds made by S. lugdunensis the group found one compound that inhibited S. aureus. They named it Lugdunin, a circular peptide. 

Now this compound isn’t going to be prescribed for patients any time soon, if ever. There are a lot of refinement and further study that will be needed. The researchers don’t even know exactly how the antibiotic works, but it does suggest that antibitoics could be found by systematically looking at how different microbial ecosystems work.

But if the microbiome could be a future source of antibiotics, the microbes in our bodies and in our environments are already influencing our health.

You might have heard of the hygiene hypothesis, that dust and microbes in our environment protect against allergies and asthma in children. You might hope that that is a reason not to be too house proud but sadly Sabina Illi of Ludwig-Maximilian University in Munich, Germany, says that neither personal nor home cleanliness was associated with a risk for asthma and allergies. Instead, what makes a difference, she says, are the bacteria in that dust. Your home’s microbiome.

In countries across Europe, says Sabina, accession to the EU correlates with an increase in asthma as accession often happens at the same time as people become less rural and spend less time in farms. Sabina has taken swabs of various environments to look at the microbiome of different environments. She showed us that children who visit stables early in life have few instances of asthma because they are exposed to more diverse microbiota. How to get this in the city? The answer seems to be pets. Houses with dogs have a different microbiome to houses without, and that seems to be protective.

There is, however, a lot of hype about the microbiome, and what it can and can’t do said Peer Bork of the European Molecular Biology Laboratory (EMBL) in the same session. The clinical success story for the microbiome is the use of faecal transplants to treat C. difficile infections. Giving poo from a healthy person to someone with the severe and potentially fatal diarrhoea.

Peer’s group has shown that there are three main “enterotypes” – or gut microbial communites  – in developed countries and showed that each human appears to carry individual strains of different bacterial species. Not only that but the environment in the human gut also impacts the efficacy of orally administered drugs.

It seems we are only just beginning to understand how the microbial communities in, on and around us affect our health, and how they might be used to improve it.