How the garden snail could help solve the antibiotics crisis

A Brighton scientist has made a breakthrough in the search for new antibiotics – courtesy of the common garden snail.

Dr Sarah Pitt, taken by Simon Dack

Researchers have suspected that snail mucus contains antibacterial properties but the University of Brighton’s Dr Sarah Pitt has conclusively identified proteins that could directly lead to the development of an antibiotic cream to treat deep burn wounds, and an aerosol for lung infections suffered regularly by patients with cystic fibrosis (CF).

The overuse of existing antibiotics has led to drug-resistant superbugs and while researchers around the world are racing to find new medicines Dr Pitt’s discovery came about by accident – triggered by professional rivalry with her animal biologist husband.

The friendly disagreement led microbiologist Dr Pitt, Principal Lecturer in the University’s School of Pharmacy and Biomolecular Sciences (PABS), to unexpectedly finding small proteins in the snail’s mucus which work against bacteria.

Her research, published today in the peer-reviewed British Journal of Biomedical Science, concludes: “The study has identified novel proteins with antimicrobial properties which could be used to develop treatments for use in human medicine.”

It was Dr Pitt’s husband Dr Alan Gunn, Subject Lead for Biosciences in the School of Natural Sciences and Psychology at Liverpool John Moores University, who started the research.

Dr Pitt said: “He was idly wondering about snails moving over the soil etc in a garden which is full of bacteria and how/why they appear to stay healthy. Was there something in the mucus which fought against infections?

“He started testing the frothy mucus snails secrete as a defence against bacteria for an undergraduate student project. He thought something interesting might be happening but when I discussed his lab methods it was clear he was doing it all wrong.

“So I did what wives tend to do and said ‘you are doing that all wrong – give it to me and I’ll sort it out’ – which I did.

“So it was chance really – I don’t think either of us really expected anything much to come of it. However, once I had tried it here with some of my undergraduates and it looked as though there might possibly be some effect, I worked on the assay one summer until I had developed a method which gave me reproducible results.”

Dr Pitt began collecting the frothy mucus from the brown garden snail and tested it for antibacterial activity against a panel of bacteria.

She said: “In previous work, we found that the mucus consistently and convincingly inhibited the growth of one species of bacterium Pseudomonas aeruginosa, a tough bacterium that can cause disease, but it did not seem to work against other bacteria.

“So in this study we tried all the control strains of Pseudomonas aeruginosa we had available in the lab here at the University as well as five strains taken from patients with CF who had lung infections with this bacterium.

“Pseudomonas aeruginosa is a very important cause of lung infections in patients with CF and strains which are resistant to the most commonly used antibiotic treatments are becoming increasingly common. Therefore a new antibiotic would be useful.”

Working with colleagues at Kings College London Dr Pitt separated sterile solutions of proteins known as protein fractions in a novel way so that smaller portions could be sent back to Brighton for antibacterial testing.

With help from University technician and Master of Research student Joe Hawthorne, they spent a day collecting the fractions and rushing them back to Brighton to ensure they remained active.

Then came the breakthrough: “We found that fractions containing some smaller proteins also worked against the bacteria – something we were not expecting at all, based on our previous results.”

Using specialist technology at Liverpool University they then sequenced the proteins’ RNA, the code that makes proteins: Dr Pitt worked with Dr Gunn and his colleague at Liverpool John Moores University, Dr Rachael Symonds, to identify the sequences of their proteins.

Dr Pitt said: “Matching them with the international data base of proteins, we found that no one had reported them before, so they are newly identified – by us.”

More research is needed: “If we can make the proteins artificially in the lab, we can try and work out what they are doing to the bacterium. We think that it might be possible to incorporate the purified protein into a cream to treat deep burn wounds and possibly an aerosol to treat lung infections.”

Dr Pitt has led on the lab work from the beginning and the bulk of the research was conducted at the University of Brighton, with help from Master of Research students and support from a University of Brighton Rising Star grant and the PABS output enhancement fund.

Dr Pitt said: “I did that initial work in the summer of 2014 and we have persevered with it because it is interesting.”

There is more research needed before the antibiotic can be refined and manufactured for humans but Dr Pitt believes her research is a major step forward: “It has taken a long time to get this far – now we just want to know what is going on between the protein and the bacterium.” For more on Dr Pitt go to: https://research.brighton.ac.uk/en/persons/sarah-pitt

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