It has been found that deadly bacteria from all over the world seek out and feast on human blood.
Researchers at Washington State University (WSU) discovered a new trait called ‘bacterial vampirism’ among bacteria like Salmonella and E. coli, which cause foodborne illness.
It has long been a mystery how and why these microorganisms can move so nimbly from the intestines into the blood, where they can be fatal.
The team discovered that these bacteria are attracted to the liquid part of blood, or serum, which contains nutrients that the bacteria can use as food.
The pathogens can easily find where the serum is located and enter the bloodstream through small cuts in the digestive system, sometimes causing death from sepsis in people with inflammatory bowel disease.
Even the smallest amount of blood is enough to attract vampiric bacteria, much like sharks with their famous ability to detect one drop of blood in 10 billion drops of water.
Researcher Arden Baylink of Washington State University holds a petri dish containing salmonella bacteria. Baylink and PhD student Siena Glenn have published research showing that some of the world’s deadliest bacteria seek out and eat serum, the liquid part of human blood. This serum contains nutrients that the bacteria can use as food.
Bacteria such as E. coli can enter the bloodstream through lesions in the intestines of people with inflammatory bowel disease, which can cause serious complications
Co-author Arden Baylink, a professor at WSU’s College of Veterinary Medicine, said in a statement: ‘Bacteria that infect the bloodstream can be fatal.
“We learned that some of the bacteria that usually cause bloodstream infections actually sense a chemical in human blood and swim toward it.”
According to the new studypublished in the journal eLife, enterobacteria such as E. coli and Salmonella can detect only a femtoliter of serum – a small amount equal to 0.0000000000001 milliliter.
Once they find the cut causing the blood to leak into the intestine, they crowd around it and enter it.
It’s a lot like the way sharks can detect prey through their blood, but bacteria don’t have noses, so they rely on other senses.
The team used a powerful microscope system to simulate intestinal bleeding by injecting microscopic amounts of human serum and watching how the bacteria navigated to the source.
They watched as the microbes searched for the serum and found that it took less than a minute.
In this case it is a strategy called ‘chemotaxis’, in which bacteria move towards higher concentrations of specific substances.
The team also found that Salmonella has a special protein receptor called Tsr that allows bacteria to sense and swim to the serum.
In discovering Tsr, researchers used high-resolution microscopy to see the protein’s atoms that interact with serine.
Washington State University PhD student Siena Glenn uses a powerful microscope to study deadly bacteria like E. coli and salmonella
The scientists believe that serine is one of the chemicals from the blood that the bacteria sense and consume.
This new understanding of how bacteria can take up residence in the bloodstream paves the way for new drugs that will prevent sepsis before it even occurs, rather than treating it once someone is sick, according to the scientists behind the new study.
‘By learning how these bacteria can detect blood sources, we can in the future develop new drugs that block this ability. These drugs can improve the lives and health of people with inflammatory bowel disease who are at high risk for bloodstream infections, according to Ph.D. student Siena Glenn, co-author of the study.
Usually, intestinal infections are resolved by the immune system without any serious problems – perhaps a little diarrhea.
But people with inflammatory bowel disease, including Crohn’s disease and ulcerative colitis, are at much greater risk of developing bleeding in their intestines, which can allow bacteria to enter the bloodstream, causing a more serious bacterial infection.
This puts them at particularly high risk of developing a condition called sepsis, which is essentially a chain reaction of the immune system attacking the body in response to an infection.
By understanding exactly why gut bacteria are so adept at entering the bloodstream through tiny tears or cuts in the intestine, scientists can prevent serious illness in people with these chronic conditions.
Under normal circumstances, there are populations of bacteria in our intestines that are often considered harmful, such as E. coli and salmonella.
When we are healthy, they are kept in check by other bacteria and our immune system.
But if they enter our bloodstream, they can lead to sepsis.