world’s most deadly bacteria are now known to have a habit of feeding on human blood, a behavior that scientists have named ‘bacterial vampirism.’ These bacteria are specifically attracted to the liquid part of blood, called serum, which contains essential nutrients for the bacteria to thrive. One of the key substances that the bacteria are especially attracted to is serine, an amino acid present in human blood and also commonly found in protein drinks. The research, which was published in the journal eLife, offers new insights into the mechanisms of bloodstream infections and potential treatments.Researchers at Washington State University have discovered a new behavior in deadly bacteria that they have named “bacterial vampirism.” The bacteria are drawn to the liquid part of human blood known as serum, which contains nutrients that they can use as food. In particular, the bacteria are attracted to serine, an amino acid found in human blood and commonly used in protein drinks. This discovery, published in the journal eLife, sheds light on how bloodstream infections occur.
“Bacteria that infect the bloodstream can be deadly,” stated Arden Baylink, a professor at WSU’s College of Veterinary Medicine and the main author of the study. “We discovered that some of the bacteria that commonly cause bloodstream infections can actually detect a chemical in human blood and move towards it.”
Baylink and Siena Glenn, a WSU Ph.D. student and the lead author of the study, identified three bacteria types, including Salmonella enterica, Escherichia coli, and Citrobacter koseri, that are attracted to human serum. These bacteria are a leading cause of death for individuals with inflammatory bowel disease.The study focused on patients suffering from inflammatory bowel disease (IBD), which affects around 1% of the population. These patients often experience intestinal bleeding, which creates opportunities for bacteria to enter the bloodstream.
The researchers used a high-powered microscope system known as the Chemosensory Injection Rig Assay, developed by Baylink, to mimic intestinal bleeding. They injected small amounts of human serum and observed as the bacteria moved toward the source. The bacteria’s response was rapid, taking less than a minute to reach the serum.
As part of the study, the researchers discovered that Salmonella has a specific protein receptor called Tsr, which allows the bacteria to effectively locate and navigate toward the source.The researchers used protein crystallography to observe the protein’s interaction with serine, a blood chemical that the bacteria can detect and consume. The team hopes that by understanding how the bacteria sense blood sources, they can develop drugs to block this ability and improve the health of people with IBD who are at high risk for bloodstream infections. The scientists involved in the study include Zealon Gentry-Lear, Michael Shavlik, Michael Harms of the University of Oregon, and Tom Asaki, a mat.Mathematician at WSU, Siena J. Glenn, contributed to the research. The study was funded by WSU and the National Institute of Allergy and Infectious Diseases.
