A team of scientists from Washington State University in the United States has discovered that bacteria are attracted to the liquid part of blood, called blood serum, which contains nutrients that serve as food.
One of the chemicals that bacteria are particularly attracted to is serine, an amino acid found in human blood that is also a common ingredient in protein drinks.
The discovery is particularly interesting in that it could provide new information about the development of bloodstream infections and possible treatments, points out EurekAlert.
"Bacteria that infect the bloodstream can be lethal. With this research, we learned that some of them detect a chemical substance in human blood and swim towards it," explained researcher Arden Baylink, author of the scientific article published in eLife.
The scientists from the American university discovered that at least three bacteria - Salmonella enterica, Escherichia coli and Citrobacter koseri - are attracted to blood serum, and these bacteria are one of the main causes of death in people with inflammatory bowel diseases, which comprise around 1% of the world's population.
Typically, these patients experience intestinal bleeding, which can be the entry point for bacteria into the bloodstream. So, using a high-powered microscope system, the scientists simulated this type of bleeding by injecting microscopic amounts of blood serum.
The experiment concluded that the disease-causing bacteria take less than a minute to find human serum.
In addition, the scientists determined that Salmonella has a special protein receptor, called Tsr, which allows the bacteria to detect and travel to the serum. Using protein crystallography, they were able to visualize the protein atoms interacting with serine.
The observation allowed scientists to conclude that serine may actually be one of the blood chemicals that bacteria detect and consume.
