US – Researchers at Washington State University (WSU) have discovered a new trait called “bacterial vampires” among bacteria, such as Salmonella and E. coli, that cause foodborne illnesses.
The subtle movement of these microorganisms from the intestines to the blood, where they can be deadly, has been a mystery for a long time. Now, researchers have found that these bacteria are attracted to the liquid part of the blood, or serum, which contains nutrients that the bacteria can use as food.
Pathogens can easily find where serum is located and enter the bloodstream through small wounds in the digestive tract, sometimes causing death from sepsis in people with inflammatory bowel disease.
Even the smallest amount of blood is enough to attract vampire bacteria, just like sharks that have the ability to detect one drop of blood in 10 billion drops of water.
“Bacteria that infect the bloodstream can be fatal,” study co-author Arden Bailink, a professor at Washington State University College of Veterinary Medicine, said in a statement. “We’ve learned that some of the bacteria that most commonly cause bloodstream infections actually sense a chemical in human blood and swim toward it.”
According to the new study published by eLife magazine, intestinal bacteria, such as salmonella and E. coli, can detect as little as a femtoliter of serum, which is a small amount equal to 0.0000000000001 milliliters.
Once they find a wound that is leaking blood into the intestines, they collect around it and seep into it.
The team used a high-energy microscopic system to simulate intestinal bleeding by injecting microscopic amounts of human blood serum and observing the bacteria moving toward the source.
They watched the microbes search for the serum, and found that it took less than a minute. In this case, it’s a strategy called “chemotaxis,” where bacteria move toward higher concentrations of certain substances.
The team also suggested that salmonella has a special protein receptor called Tsr that enables the bacteria to sense and swim toward the serum.
In discovering Tsr, the researchers used a high-resolution microscopic model to view protein atoms interacting with serine. Scientists believe that serine is one of the chemicals in the blood that bacteria sense and consume.
The researchers said this new understanding of how bacteria get into the bloodstream paves the way for new drugs that prevent sepsis before it occurs, rather than treating it once someone is sick.
By learning how these bacteria are able to detect blood sources, we could in the future develop new drugs that block this ability.
Doctoral student Sienna Glenn, who participated in the study, explained that these medications can improve the lives and health of those who suffer from inflammatory bowel disease and who are at high risk of developing bloodstream infections.
Usually, intestinal infections are treated by the immune system without serious problems, perhaps by diarrhea. But those with inflammatory bowel disease, including Crohn’s disease and ulcerative colitis, are at greater risk of bleeding within the intestine, which can allow bacteria to enter the bloodstream, causing a more serious bacterial infection. This puts them particularly at risk of developing a condition called sepsis, which is a chain reaction of the immune system attacking the body in response to infection.
A precise understanding of why gut bacteria are so adept at entering the bloodstream through small tears or wounds in the intestine can help prevent serious illness in those with these chronic conditions.
Source: Daily Mail
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2024-04-22 18:31:34