The increase of antibiotic resistance in pathogenic bacteria, for example, meticillin-resistant Staphylococcus aureus (MRSA), and the lack of new antimicrobials in the developmental pipeline are huge challenges for human health. So, tests on an Anglo-Saxon recipe for eye infections suggesting that this old recipe could offer a remedy for modern-day resistant bacteria make interesting reading.
This medieval recipe originates from Bald’s Leechbook, an Old English leather-bound volume, housed in the British Library. Bald’s Leechbook, also known as Medicinale Anglicum, was probably compiled in the 9th century and is thought to be one of the earliest known medical textbooks. Divided into two volumes, one dealing with external remedies, the other with internal remedies, the leech book contains Anglo-Saxon medical advice and recipes for medicines, salves and other treatments.
The ancient eye infection recipe calls for the pounding together of two species of Allium (garlic and also onion or leek) in equal quantities with the addition of wine and ox gall. It describes a specific method of making the topical solution, including the use of a brass vessel to brew it in, straining to purify it and an instruction to let it stand in the brass vessel for nine days.
The idea to test this recipe came from scientists at Nottingham University. Sourcing the ingredients was a challenge according to an article in New Scientist. Although garlic and leeks are easily available, modern crop varieties are likely to be different from ancient ones so the researchers had to hope for the best. For the wine they used an organic vintage from a historic English vineyard and for the ox gall, cows’ bile salts available as supplements for people who have had their gall bladders removed. Because brass containers are hard to sterilise, the researchers used glass bottles lined with brass sheets.
The researchers made four separate batches of the remedy using fresh ingredients each time, as well as a control using the same quantity of distilled water and brass sheet to mimic the brewing container. Apparently after nine days the brew had killed all the soil bacteria introduced by the leeks and the garlic so they thought they were probably on to something. The remedy was then tested on cultures of MRSA in infected wounds in mice.
None of the individual ingredients alone had any measurable effect, but when combined according to the medieval recipe, only about one bacterial cell in a thousand survived in the infected wounds. The key to how the remedy might work lies in the team’s work to see what happened when they diluted the recipe. They found that when the recipe was too dilute to kill MRSA, it interfered with bacterial cell to cell communication. Bacteria have to communicate to switch on the genes that allow them to damage infected tissues and many microbiologists think that blocking this behavior could be an alternative way of treating infections.