A Medieval Anglo-Saxon medical book in the British Library may hold the key to finding new ways to combat antibiotic-resistant bacteria. Scientists at the University of Warwick have found that a medical recipe from the ancient Bald's Leechbook is effective against five strains of bacteria that cause biofilm infections.
At a casual glance, Bald's Leechbook shouldn't be anything more than an interesting relic from the history of medicine. Also known as Medicinale Anglicum, it is estimated to have compiled around the time of Alfred the Great in the ninth century and is regarded as one of the oldest known medical textbooks. Today, only one leather-bound manuscript survives.
Although much of this Old English text would only be of interest to antiquarians, one of its recipes, called "Bald's eyesalve," may have modern applications. Currently, the medical world is fighting an ongoing battle against antibiotic-resistant bacteria which, if it isn't won, could see society return to a time when minor infections that are now easily treatable could become deadly once again.
One tactic of this effort is to look at natural or historical cures that might hold the key to a new weapon in the pharmacological arsenal. In particular, teams, such as Dr. Freya Harrison, Jessica Furner-Pardoe, and Dr. Blessing Anonye at Warwick, are looking for ways to counter biofilm infections.
Biofilms are a mechanism by which bacteria are able to defend themselves against attack. Free-swimming or planktonic bacteria are especially vulnerable to antibiotics, but when they collect together on a surface, they form biofilms that are much more resilient. Examples of these sorts of biofilms include tooth plaque and pond scum, but there are many more dangerous varieties that can infest implanted medical devices or infect diabetic skin ulcers. In the latter case, if the biofilm is antibiotic-resistant, the result could be amputation to avoid a lethal blood infection.
Bald's eyesalve is a simple mixture of onion, garlic, wine, and bile salts that the researchers have discovered is effective against various Gram-negative and Gram-positive bacteria in a culture, yet causes only a low level of damage to human cells.
Specifically, it works against Acinetobacter baumanii, Stenotrophomonas maltophilia, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes, which are associated with combat infections, respiratory infections, skin infections, medical device and surgical wound infections, and illnesses such as pharyngitis, tonsillitis, scarlet fever, cellulitis, rheumatic fever, and post-streptococcal glomerulonephritis.
According to the team, it isn't the individual ingredients that have this antibiotic effect, but their combined action. Garlic is already well-known for its antibacterial qualities, but it isn't effective against biofilms, so the other ingredients must play a part in the process.
"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 biofilm," says 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.
"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."
The research was published in Scientific Reports.
Source: University of Warwick