Researchers have discovered that proteins found in oyster blood have bacteria-killing properties and can boost the effectiveness of some common antibiotics whose use has been negatively affected by the global rise in drug resistance.
Oysters are divisive, culinarily speaking. People generally fall into two camps: those who enjoy the taste and ‘mouthfeel’ and those who view eating them as akin to swallowing a large glob of phlegm. Luckily, science doesn’t care how the mollusks taste; it’s more concerned with the health benefits they can convey.
A new study led by researchers from Southern Cross University in New South Wales, Australia, has discovered that proteins in the mollusk’s blood not only have bacteria-killing properties, raising the possibility of a new antibiotic, but also increase the effectiveness of some existing antibiotics.
“Most organisms have natural defense mechanisms to protect themselves against infection,” said study co-author Professor Kirsten Benkendorff from the University’s Faculty of Science and Engineering. “Oysters are constantly filtering bacteria from the water, so they are a good place to look for potential antibiotics.”
The present study built on the researchers’ previous work, in which they identified proteins in the hemolymph of the Sydney Rock Oyster that inhibited Streptococcus pneumoniae, bacteria that cause respiratory infections like pneumonia. In some invertebrates, including oysters, hemolymph is the equivalent of human blood.
Bacteria can be hard to kill. They can form biofilms, a community of microorganisms that merge into a sticky protective ‘case’ that enables the bacteria to attach to biological surfaces and protects them from antibiotics and the human immune system. Bacterial biofilms have contributed to a global rise in antibiotic resistance, which has created a serious healthcare risk by limiting treatment options.
The researchers found that the hemolymph proteins they tested demonstrated an antibacterial effect, especially on the Streptococcus species S. pneumoniae, mentioned above, and S. pyogenes, which causes throat infection and tonsillitis. The proteins also interfered with the bacteria’s biofilm-forming abilities.
“The oyster hemolymph proteins were found to prevent biofilm formation and disrupt biofilms, so the bacteria remain available to antibiotics exposure at lower doses,” Benkendorff said. “The hemolymph contains a mixture of proteins with known antimicrobial properties. These may act to directly kill the bacteria, as well as preventing them from attaching to the cell surface.”
Additionally, the researchers discovered that the hemolymph proteins improved the effectiveness of conventional antibiotics ampicillin, gentamicin, trimethoprim and ciprofloxacin by two- to 32-fold against clinically important bacteria. In addition to Streptococcus species, the proteins boosted antibiotic effectiveness against Pseudomonas aeruginosa and Klebsiella pneumoniae (both cause blood infections and pneumonia), Moraxella catarrhalis (causes upper respiratory tract infections), and Staphylococcus aureus (‘golden Staph,’ typically causes skin and soft tissue infections but can also cause serious blood, bone, and joint infections and pneumonia). Ampicillin, gentamicin, trimethoprim and ciprofloxacin are among the antibiotics to which bacteria have developed notable resistance worldwide.
Importantly, the hemolymph proteins were found to be safe and non-toxic to human lung cells. But, taking these study findings from here all the way down the drug development pipeline to where there’s a safe and effective new drug on the market is expected to take a long time and a not insubstantial amount of money. On the other hand, with the global marine-based drug market projected to be worth US$9.2 billion by 2034, it seems likely that financial backers may not be hard to find.
While you wait, the researchers recommend enjoying the health benefits of eating oysters. That’s if you’re predisposed to doing so.
“In the meantime, slurping oysters could help keep the respiratory bugs away,” Benkendorff said. “Oysters contain zinc, which boosts the immune system, and they have really good polyunsaturated fatty acids and vitamins that also help modulate immunity.”
The study was published in the journal PLOS One.
Source: Southern Cross University