‘Vampire’ bacteria with thirst for human blood discovered

By Stephen Beech via SWNS

Potentially deadly "vampire" bacteria with a thirst for human blood have been discovered by scientists.

They say infectious organisms make a beeline for blood - just like sharks.

Bacteria, including E coli, seek out and feed on human blood, in a newly discovered phenomenon researchers are calling “bacterial vampirism.”

They say their findings could improve the lives and health of people with inflammatory bowel diseases.

The American team, led by Washington State University (WSU) scientists, discovered that the bacteria are attracted to the liquid part of blood, or serum, which contains nutrients they can use as food.

One of the chemicals the bacteria seemed particularly drawn to was serine, an amino acid found in human blood that is also a common ingredient in protein drinks.

The findings, published in the journal eLife , provide new insights into how bloodstream infections occur and could potentially be treated.

Study corresponding author Professor Arden Baylink, of WSU’s College of Veterinary Medicine , said: “Bacteria infecting the bloodstream can be lethal.

“We learned some of the bacteria that most commonly cause bloodstream infections actually sense a chemical in human blood and swim toward it.”

Baylink and study lead author Siena Glenn found at least three types of bacteria - Salmonella enterica, Escherichia coli, or E coli, and Citrobacter koseri - are attracted to human serum.

They said these bacteria are a leading cause of death for people who have inflammatory bowel diseases (IBD), about one percent of the population.

IBD patients often have intestinal bleeding that can be an entry point for the bacteria into the bloodstream.

Using a high-powered microscope system designed by Baylink called the Chemosensory Injection Rig Assay, the team simulated intestinal bleeding by injecting microscopic amounts of human serum and watching as the bacteria navigated toward the source.

The response was rapid, taking less than a minute for the disease-causing bacteria to find the serum.

As part of the study, the research team determined Salmonella has a special protein receptor called Tsr that enables bacteria to sense and swim toward serum.

Using a technique called protein crystallography, they were able to view the atoms of the protein interacting with serine.

The researchers believe serine is one of the chemicals from the blood that the bacteria sense and consume.

Glenn, a WSU doctoral student, said: “By learning how these bacteria are able to detect sources of blood, in the future we could develop new drugs that block this ability."

She added: "These medicines could improve the lives and health of people with IBD who are at high risk for bloodstream infections."

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