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Scientists have finally discovered why specific bacterial strains are so deadly: they’re vampires! No, really! They literally have a thirst for human blood. Washington State University researchers discovered that the world’s deadly bacteria consume nutrients in the blood as food, including common infections like salmonella and E. coli.

Scientists have discovered that certain bacteria are drawn to the serum in human blood, a behavior they have coined “bacterial vampirism.” These bacteria are attracted to the amino acid called serine, which is present in human blood and is an ingredient in protein drinks. This discovery provides valuable insight into how bloodstream infections can quickly become life-threatening. Medical professionals can now better understand the mechanism behind the rapid spread of these infections.

“Bacteria infecting the bloodstream can be lethal,” says Arden Baylink, a professor at WSU’s College of Veterinary Medicine and the study’s corresponding author, in a university release. “We learned some bacteria that most commonly cause bloodstream infections actually sense a chemical in human blood and swim toward it.”

A recent study published in eLife found that three types of bacteria are naturally attracted to human serum. These bacteria are Salmonella enterica, Escherichia coli (E. coli), and Citrobacter koseri. Salmonella and E. coli are common infections people often get from consuming contaminated food. Citrobacter koseri, on the other hand, can cause urinary tract infections and is present in wounds and cases of sepsis.

These bacterial strains are a major cause of death in people with  Inflammatory bowel disease (IBD). Intestinal bleeding provides a gateway for bacteria exit the GI and enter the bloodstream… And now we know why they do that!

Arden Baylink, a professor at Washington State University, invented a microscope system called the Chemosensory Injection Rig Assay. The system was designed to study how bacteria move towards human blood in the event of intestinal bleeding. The experiment found that bacteria could find and consume the serum in less than a minute.

The team also discovered that salmonella has a unique protein called Tsr. This protein gives the bacteria the ability to detect and move towards serum. The team used a protein crystallography technique to observe this protein’s atoms, which also target serine.

“By learning how these bacteria are able to detect sources of blood, in the future we could develop new drugs that block this ability. These medicines could improve the lives and health of people with IBD who are at high risk for bloodstream infections,” concludes WSU Ph.D. student Siena Glenn, the study’s lead author.

Likewise, Salmonella is responsible for over 1.3 million infections every year in the United States, according to the CDC. These infections lead to the hospitalization of over 26,000 people and cause more than 400 deaths annually.

This understanding has so much potential to save life and minimize suffering. We can’t wait to see the novel treatments that are developed. Step by step, we’re moving closer to a future with less disease, less suffering, and much longer lives!