Medieval antibiotic

Drs. Norbert Herzog & David Niesel

Drs. Norbert Herzog & David Niesel

Medical Discovery News

Almost every week there is another report about the catastrophe of drug-resistant bacteria, and very few new antibiotics have been developed to treat people who have been infected. But a possible solution to this modern-day problem has been discovered in a 1,000-year-old source: an eye salve, as recorded in a ninth-century text, has effectively killed methicillin-resistant Staphylococcus aureus, or MRSA.

One of the oldest known medical texts, “Bald’s Leechbook” contains instructions for various medicines and treatments. One is a remedy for sty, an infection of the eyelash follicles that is usually caused by the bacterium Staphylococcus aureus. Christina Lee, an expert in the Anglo-Saxon language at the University of Nottingham, translated the instructions for making the eye salve and collaborated with the university’s Centre for Biomolecular Sciences to test its effects on MRSA. The recipe is simple: equal parts of minced garlic and onion or leek are crushed in a mortar for two minutes, then mixed into 25 milliliters of wine from a historic English vineyard. To that, cow bile salts dissolved in distilled water were added, and then the mixture was aged in a brass vessel for nine days at refrigerator temperature. Finally, it was filtered through a cloth to clear it and put into a horn. The instructions said to apply the salve to the eye with a feather.

Each of the ingredients in this medieval eye salve has well-known antibacterial activity. Copper, bile salts, and members of the garlic family all have proved antibacterial properties. The scientists made several batches of the salve and applied them to artificial wounds or wounds on mice. It effectively killed 999 out of 1,000 MRSA bacteria. This suggests that experimentation was done centuries before the discovery of bacteria, and “Bald’s Leechbook” contains several remedies for infections.

Cloth merchant Anton van Leeuwenhoek ground his own glass magnifying lenses, achieving magnifications of 500 times life size in the 1660s, was the first to see bacteria when he observed pond water through his lenses. He sent detailed drawings of his observations to the Royal Society of London in 1670. It took another 200 years for the link between bacteria and disease to be discovered.

Ignaz Semmelweis, a physician in Vienna in the 1840s, made the rather unpopular suggestion that physicians wash their hands between patients and wear different clothing in the autopsy suite than when treating patients. This resulted in a large drop in mortality. Despite this success, Semmelweis was fired from this job and the next for making these changes, eventually dying in a mental institution in 1865. Bacteria’s link to disease was proved in the following decade by two other men. Louis Pasteur disproved the theory of spontaneous generation by boiling liquids to kill microorganisms, a process called pasteurization we still use today. Robert Koch created the basic criteria to prove an infectious agent causes a specific disease, which are also still used.

While the germ theory of disease is common knowledge, don’t be quick to dismiss medieval remedies, since Bald’s eye salve has successfully killed one of the most worrisome antibiotic-resistant bacteria in the modern world.

Professors Norbert Herzog and David Niesel are biomedical scientists at the University of Texas Medical Branch. Learn more at

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