A Recipe for Antibiotic Success May be Found in Medieval Texts

Medieval medicines, like those detailed in 'Bald's Leechbook', are being re-evaluated for antibiotic resistant infections (Image: British Library)
Medieval medicines, like those detailed in 'Bald's Leechbook', are being re-evaluated for antibiotic resistant infections (Image: British Library)

For a long time, medieval medicine has been dismissed as irrelevant. This time period is popularly referred to as the “Dark Ages,” which erroneously suggests that it was unenlightened by science or reason. However, some medievalists and scientists are now looking back to history for clues to inform the search for new antibiotics. The Conversation

The evolution of antibiotic-resistant microbes means that it is always necessary to find new drugs to battle microbes that are no longer treatable with current antibiotics. But progress in finding new antibiotics is slow. The drug discovery pipeline is currently stalled. An estimated 700,000 people around the world die annually from drug-resistant infections. If the situation does not change, it is estimated that such infections will kill 10 million people per year by 2050.

I am part of the Ancientbiotics team, a group of medievalists, microbiologists, medicinal chemists, parasitologists, pharmacists and data scientists from multiple universities and countries. We believe that answers to the antibiotic crisis could be found in medical history. With the aid of modern technologies, we hope to unravel how premodern physicians treated infection and whether their cures really worked.

To that end, we are compiling a database of medieval medical recipes. By revealing patterns in medieval medical practice, our database could inform future laboratory research into the materials used to treat infection in the past. To our knowledge, this is the first attempt to create a medieval medicines database in this manner and for this purpose.

Bald's eyesalve

In 2015, our team published a pilot study on a 1,000-year old recipe called Bald's eyesalve from “Bald's Leechbook,” an Old English medical text. The eyesalve was to be used against a “wen,” which may be translated as a sty, or an infection of the eyelash follicle.


Human white blood cells (in blue) take on Staphylococcus aureus bacteria.

A common cause of modern styes is the bacterium Staphylococcus aureus. Methicillin-resistant Staphylococcus aureus (or MRSA) is resistant to many current antibiotics. Staph and MRSA infections are responsible for a variety of severe and chronic infections, including wound infections, sepsis and pneumonia.

Bald's eyesalve contains wine, garlic, an Allium species (such as leek or onion) and oxgall. The recipe states that, after the ingredients have been mixed together, they must stand in a brass vessel for nine nights before use.

In our study, this recipe turned out to be a potent antistaphylococcal agent, which repeatedly killed established S. aureus biofilms – a sticky matrix of bacteria adhered to a surface – in an in vitro infection model. It also killed MRSA in mouse chronic wound models.