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How a medieval medicine might become a treatment for modern day infections

One of the key challenges of modern day medicine is antibiotic resistance. There is now strong evidence that a medieval cure for eye infections will be able to greatly help meet this challenge.

Researchers at the University of Warwick have just released the paper “Anti-biofilm efficacy of a medieval treatment for bacterial infection requires the combination of multiple ingredients,” which was published today in the journal Scientific Reports. It describes a medieval remedy containing onion, garlic, wine, and bile salts, known as ‘Bald’s eyesalve’, and reveals it to have promising antibacterial activity.

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The research team of Dr Freya Harrison, Jessica Furner-Pardoe, and Dr Blessing Anonye are behind the discovery. Their work began in 2015 and are part of an interdisciplinary group of researchers including microbiologists, chemists, pharmacists, data analysts and medievalists at universities in Warwick, Nottingham and in the United States.

Antibiotic resistance is an increasing battle for scientists to overcome, as more antimicrobials are urgently needed to treat biofilm-associated infections. Bacteria can live in two ways, as individual planktonic cells or as a multicellular biofilm. Biofilm helps protect bacteria from antibiotics, making them much harder to treat. Therefore, researchers have been looking into medieval methods of using natural antimicrobials from every day ingredients.

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The Balds Eyesalve mixture in the lab. Photo courtesy University of Warwick

They found the Bald’s eyesalve remedy was effective against a range of Gram-negative and Gram-positive wound pathogens in planktonic culture. This activity is maintained against the following pathogens grown as biofilms:

1. Acinetobacter baumanii- commonly associated with infected wounds in combat troops returning from conflict zones.

2. Stenotrophomonas maltophilia- commonly associated with respiratory infections in humans

3. Staphylococcus aureus- a common cause of skin infections including abscesses, respiratory infections such as sinusitis, and food poisoning.

4. Staphylococcus epidermidis- a common cause of infections involving indwelling foreign devices such as a catheter, surgical wound infections, and bacteremia in immunocompromised patients.

5. Streptococcus pyogenes – causes numerous infections in humans including pharyngitis, tonsillitis, scarlet fever, cellulitis, rheumatic fever and post-streptococcal glomerulonephritis.

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All of these bacteria can be found in the biofilms that infect diabetic foot ulcers and which can be resistant to antibiotic treatment. These debilitating infections can lead to amputation to avoid the risk of the bacteria spreading to the blood to cause lethal bacteremia.

The Bald’s eyesalve mixtures use of garlic, which contains allicin, can explain activity against planktonic cultures, however garlic alone has no activity against biofilms, and therefore the anti-biofilm activity of Bald’s eyesalve cannot be attributed to a single ingredient and requires the combination of all ingredients to achieve full activity.

“We have shown that a medieval remedy made from onion, garlic, wine, and bile can kill a range of problematic bacteria grown both planktonically and as biofilms,” explains Dr Harrison. “Because the mixture did not cause much damage to human cells in the lab, or to mice, we could potentially develop a safe and effective antibacterial treatment from the remedy.

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“Most antibiotics that we use today are derived from natural compounds, but our work highlights the need to explore not only single compounds but mixtures of natural products for treating biofilm infections. We think that future discovery of antibiotics from natural products could be enhanced by studying combinations of ingredients, rather than single plants or compounds. In this first instance, we think this combination could suggest new treatments for infected wounds, such as diabetic foot and leg ulcers.”

“Our work demonstrates just how important it is to use realistic models in the lab when looking for new antibiotics from plants,” adds Jessica Furner-Pardoe. “Although a single component is enough to kill planktonic cultures, it fails against more realistic infection models, where the full remedy succeeds.”

In previous research Christina Lee, from the University of Nottingham, had examined Bald’s Leechbook, an Old English work dating back to the 9th or 10th century, to see if it really works as an antibacterial remedy. Bald’s Leechbook is widely thought of as one of the earliest known medical textbooks and contains Anglo-Saxon medical advice and recipes for medicines, salves and treatments.

The actual eyesalve remedy text. Image courtesy The British Library (Royal 12 D xvii)

“Bald’s eyesalve underlines the significance of medical treatment throughout the ages,” Lee notes. “It shows that people in Early Medieval England had at least some effective remedies. The collaboration which has informed this project shows the importance of the arts in interdisciplinary research.”

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The article, “Anti-biofilm efficacy of a medieval treatment for bacterial infection requires the combination of multiple ingredients,” by Jessica Furner-Pardoe, Blessing O. Anonye, Ricky Cain, John Moat, Catherine A. Ortori, Christina Lee, David A. Barrett, Christophe Corre and Freya Harrison is published in Scientific Reports. Click here to read it.

In 2015 the research by Christina Lee, Freya Harrison and others on Bald’s Leechbook made international headlines. Click here to read our report on it and our interview with Dr Harrison.

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