Was an ancient medicine a remedy for MRSA?

May 24, 2015

The recipe is for a topical solution. It is quite specific, both in terms of ingredients and preparation. It calls for two species of allium (garlic and onion or leek), wine, and oxgall (bile from a cow's stomach). It explains how to make the mixture, including brewing it in a brass vessel, straining to purify it, and letting it sit for nine days before use.

What is this? Believe it or not, it is a remedy for eye infections found in a 1,000-year-old Anglo-Saxon book, and it has been found to be effective in killing methicillin-resistant Staphylococcus aureus (MRSA). It comes from a time when the forerunners of physicians were called “leeches,” and when germ theory was unknown—but the Dark Ages may be casting some light on modern science.

We don't read about research collaborations between university Departments of English and Molecular Biology very often, but such was the nature of one recent partnership, and it might provide a solid lead in efforts to develop therapies for antibiotic-resistant pathogens. Christina Lee, PhD, Associate Professor in Viking Studies and member of the University of Nottingham's Institute for Medieval Research, teamed with microbiologist Freya Harrison, PhD, from the University's Centre for Biomolecular Sciences, and laboratory colleagues.

Lee, an expert in Anglo-Saxon literature, worked with Harrison's team to recreate the tenth-century medicine for eye infections from a recipe in Bald's Leechbook, an Old English volume in the British Library, to see if it really works as an antibacterial remedy. The Leechbook, a sort of medical textbook, includes recipes for medicines, salves, and other treatments.

According to a press release from the University, Lee translated the recipe from a transcript of the original Old English manuscript in the British Library. Early results on the “potion,” tested in vitro at Nottingham and backed up by mouse model tests at Texas Tech University, show that the solution has had remarkable effects on MRSA.

Researchers have replicated data showing that the Bald's eye salve kills up to 90% of MRSA bacteria in in vivo wound biopsies from mouse models. They believe the bactericidal effect is not due to a single ingredient but rather to the combination used, and to the methods of preparation and the container material. Further research is planned to investigate how this works.

The scientists at Nottingham made four separate batches of the remedy using fresh ingredients each time, as well as a control treatment using the same quantity of distilled water and brass sheet to mimic the brewing container but without the vegetable compounds. The remedy was tested on cultures of S. aureus, in both synthetic wounds and infected wounds in mice. None of the individual ingredients alone had any measurable effect, but when they were combined according to the recipe, the Staphylococcus populations were almost totally obliterated: about one bacterial cell in a thousand survived.

The team then endeavored to see what would happen if they diluted the eye salve. They found that when the medicine was too diluted to kill S. aureus, it interfered with bacterial cell-cell communication (quorum sensing). This is a key finding, because bacteria have to talk to each other to switch on the genes that allow them to damage infected tissues. Many microbiologists think that blocking this behavior could be an alternative way of treating infection.

Says Lee: “Medieval leech books and herbaria contain many remedies designed to treat what are clearly bacterial infections. How systematic was the development of these remedies? And how effective were they against the likely causative species of bacteria? Answering these questions will greatly improve our understanding of medieval scholarship and medical empiricism, and may reveal new ways of treating serious bacterial infections that continue to cause illness and death.”