A new study has discovered that some of the deadliest bacteria in the world have a taste preference for human blood.

Deadly Bacteria

Citrobacter koseri, E. coli, and Salmonella are all leading causes of death among individuals who struggle with inflammatory bowel diseases, a condition phased by millions of individuals worldwide. Such bacteria are known to enter a person's bloodstream via intestinal bleeding, where they could lead to life-threatening sepsis (bacterial food poisoning) and blood infections.

The US Centers for Disease Control and Prevention notes that almost 270,000 Americans die each year due to sepsis. Hence, knowing how the bacteria goes into the bloodstream is crucial for public health.

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Bacterial Vampirism

The new study suggests that the bacteria's blood-bound trajectories do not happen accidentally. Rather, they are active in seeking out and feeding on human blood. Such findings were noted in the "Bacterial vampirism mediated through taxis to serum" study.

Researchers have dubbed this phenomenon bacterial vampirism. It provides novel insights regarding bloodstream infection mechanics and how they could be treated.

Arden Baylink, a corresponding study author and a professor at the College of Veterinary Medicine at Washington State University, explains that they learned that some of the bacteria that typically lead to infections in the bloodstream can actually sense human blood chemicals and gear toward them.

As part of the study, the researchers used high-powered microscopes to examine how the various bacteria react to human blood presence. The response appeared rapid, as each bacterial species sought the blood source in under one minute.

As they looked closer, the researchers discovered that the Salmonella bacteria had a particular receptor, known as Tsr, over the surface, allowing the bacteria to pick up certain chemicals in the human blood serum. It is also likely that such receptors are present on the surface of other vampire bacteria, such as E. coli.

With this, the researchers hypothesize that bacteria likely feed off the human blood serum's nutrients. This offers an evolutionary advantage for such a behavior.

Siena Glenn, a PhD student and the study's lead author explains that by knowing how the bacteria can detect blood sources, drug development that blocks such an ability could be done in the future. Such medicine enhances the health and lives of individuals with inflammatory bowel disease who have a high risk of getting bloodstream infections.

In most cases, the immune system resolves intestinal infections without any serious issues. However, individuals with inflammatory bowel diseases, such as ulcerative colitis and Crohn's disease, have a higher risk of having bowel bleeds. This could allow bacteria to enter their bloodstream and trigger more serious bacterial infections.

Knowing why gut bacteria are adept at entering the bloodstream via tiny cuts or tears within the bowel could aid scientists in preventing illness among individuals with these chronic conditions.

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