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Superbugs resistant to existing antibiotics are a growing health problem around the world.
According to , globally, almost five million people die every year due to infections resistant to antimicrobials.
It is predicted that the annual number of antimicrobial-resistant infections increase by 70%it is estimated that, by 2050, around 40 million people will die.
To solve this problem, researchers need to discover new agents that improve the effectiveness of existing antibiotics.
Hope can come from a surprising source: the oysters!
In new research in PLOS ONE, it is possible to see that antimicrobial proteins isolated from oyster hemolymph (the equivalent of blood) can kill certain bacteria responsible for a number of infections.
Proteins may also improve the effectiveness of conventional antibiotics against problematic bacterial species.
A pneumonia is an acute infection of the lungs, usually caused by Streptococcus pneumoniae. It is the leading cause of death among children under five years of age and a common cause of hospitalization and death in older people.
As upper respiratory tract infectionssuch as tonsillitis, are also common. In fact, they are the most common reason children are prescribed antibiotics.
Persistent skin and throat infections caused by Streptococcus pyogenes can lead to the development of acute rheumatic fever and of rheumatic heart disease.
The high prevalence of these bacterial infections and the excessive use of antibiotics have contributed to the evolution of drug-resistant bacteria. This fact makes these infections difficult to treat.
Biofilms are populations of millions of bacterial cells embedded in a self-secreted substance that adhere to surfaces. Protect bacteria from the host’s immune system — and antibiotics. Almost all bacterial infections involve biofilms.
For this reason, new antibiotic treatments that can inhibit, disrupt or penetrate biofilms are very valuable.
As oysters as a source of new antimicrobial agents. More than 90% of the antibiotics we currently use are derived from nature. The same applies to more than 65% of the antibiotics that are being developed recently.
In the search for new antimicrobial drugs, researchers typically begin by analyzing the organisms that produce antimicrobial chemicals to self-defense.
Oysters are exposed to high concentrations of various microorganisms in their natural marine environment. For this reason, have developed strong immune defenses.
For example, they rely heavily on antimicrobial proteins and chains of molecules known as peptides in their hemolymph to protect themselves from infections.
Research carried out in recent decades has revealed that oyster hemolymph contains antiviral and antibacterial proteins and peptides. These are active against a range of human and marine pathogens.
Oysters, along with other shellfish, plants and animals, have a long history of use as traditional medicines to treat infectious diseases.
In traditional Chinese medicine, various oyster preparations are recommended to treat symptoms of respiratory infections and inflammatory conditions.
For millennia, oysters have also played an important role in the health of Australia’s indigenous people. This fact provides useful clues for drug discovery.
The latest research confirms that antimicrobial proteins present in the hemolymph of Sydney rock oysters (Saccostrea glomerata) are particularly effective at killing bacteria Streptococcus spp.
The proteins were also effective in inhibiting the formation of biofilms in Streptococcus spp. and were able to penetrate already formed biofilms.
To improve the effectiveness of currently available medicines, they are increasingly combined with antimicrobial peptides and proteins.
These peptides and proteins can disrupt bacterial cell membraneshelping conventional antibiotics reach their targets more easily. Many of these proteins and peptides can also stimulate the host’s immune system, making the treatment even more effective.
We tested the activity of Sydney oyster hemolymph proteins against a series of conventional pathogens reaching their targets more easily.
Many of these proteins and peptides can also stimulate the host’s immune system, making the treatment even more effective.
We tested the activity of Sydney oyster hemolymph proteins against a range of bacterial pathogens in combination with different commercially available antibiotics.
At very low concentrations, the proteins improved the effectiveness of antibiotics by between two and 32 times.
The results were particularly promising for Streptococcus spp., Staphylococcus aureus (also known as “staphylococcus dourado“, a leading cause of drug-resistant skin and bloodstream infections) and Pseudomonas aeruginosa (a major problem for immunocompromised patients with cystic fibrosis). There were also no toxic effects on healthy human cells.
Overall, oyster hemolymph proteins are promising for future development as antimicrobial therapy.
They can kill pathogens embedded in biofilms, work in synergy with conventional antibiotics and are non-toxic.
However, it is more work neededincluding animal testing and human clinical trials.
Sustainable sourcing of the proteins for research and medical use is an important consideration, but is helped by the fact that Sydney rock oysters are commercially available.
The results of this work represent an opportunity for the pharmaceutical and aquaculture industries to collaborate with researchers to develop new, more effective antibiotics.
Teresa Oliveira Campos, ZAP //
