Common gut bacteria behave like vampires to target human blood

Scientists have discovered a shocking new trait in some of the world’s most common – and dangerous – bacteria. Turns out, bacteria like Salmonella and E. coli have a taste for human blood, and they’ll hunt it down like vampires.

Bacterial vampirism

Researchers at Washington State University have given this newly observed behavior the term “bacterial vampirism.” This term illuminates how certain bacteria have an unusual ability to migrate from the gut, where they cause illnesses like food poisoning, into the bloodstream where they pose a much more serious threat.

These bacteria demonstrate a remarkable capacity to detect serum, the liquid component of blood. Serum is a rich source of nutrients that bacteria thrive on. Even the smallest injury within the digestive system acts as an invitation for these bacteria to swarm towards it, allowing them to infiltrate the bloodstream.

Super senses of vampire bacteria

The research team, led by Professor Arden Baylink, found that these bacteria are like microscopic sharks. They can detect the tiniest trace of blood, even minuscule amounts.

“Bacteria infecting the bloodstream can be lethal,” explained Professor Baylink. “We learned some of the bacteria that most commonly cause bloodstream infections actually sense a chemical in human blood and swim toward it.”

Bacteria have ways to sense their environment. They have special proteins on their surfaces that act like tiny receptors. These receptors help bacteria detect various things, like chemicals in their surroundings that might signal sources of food or danger.

The bacteria analyzed in this study have a specific protein receptor that is designed to pick up on traces of blood (more specifically, serum, the liquid part of blood).

This receptor acts like a nose for the bacteria. It picks up the chemical signals from the blood and guides the bacteria toward the source. Think of it like a shark detecting a few drops of blood in the ocean and swimming towards it.

Imagine the chemicals in blood leaving a faint trail. The bacteria, using their specialized receptor, can follow that trail right to the injury where the blood is leaking into the gut.

Using vampire bacteria for new cures

By uncovering the mechanism behind how bacteria find their way into the bloodstream, scientists can now develop new strategies to prevent these infections.

“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 inflammatory bowel disease who are at high risk for bloodstream infections,” noted study co-author and PhD student Siena Glenn.

Significance of vampire bacteria

You might be wondering why it’s particularly important that bacteria like E. coli and Salmonella can target blood for nutrients especially given that these bacteria are commonly found in the human gut.

Normally, when these bacteria cause food poisoning, the body’s immune system is typically able to fight them off relatively efficiently. The symptoms, while unpleasant, are usually not life-threatening and tend to resolve with time.

However, the scenario changes drastically if these bacteria manage to enter the bloodstream. When E. coli and Salmonella transition from the gut to the bloodstream, they bypass many of the body’s natural defense mechanisms.

These defenses are primarily localized to the gastrointestinal tract. In the gut, the immune system is well-equipped to handle invaders through a combination of physical barriers, chemical secretions, and immune cells that target and eliminate pathogens.

Once bacteria enter the bloodstream, these localized defenses are no longer effective. This allows the bacteria to spread more freely and potentially cause more severe health issues.

In the bloodstream, these bacteria can spread throughout the body, potentially leading to systemic infections that are much more severe and difficult to treat.

This is particularly risky for individuals with chronic intestinal conditions like Crohn’s disease and ulcerative colitis. These conditions are characterized by inflammation and sometimes ulceration of the gut lining, which can compromise the integrity of the intestinal barrier.

Small lesions or microscopic tears in the gut — which might be inconsequential in a healthy individual — can act as portals for bacteria to escape from the gut and enter the bloodstream.

Life-threatening response

For someone with Crohn’s or ulcerative colitis, these microscopic breaches in the gut lining are far from benign. They provide potential entry points for opportunistic bacteria that otherwise remain confined to the gut.

Once in the bloodstream, these “bloodthirsty” bacteria can exploit the nutrient-rich environment to multiply and spread, leading to a dangerous condition known as sepsis.

Sepsis is a life-threatening response to infection that can lead to tissue damage, organ failure, and death if not promptly and effectively treated.

How to protect yourself

While you can’t stop these bacteria from living in your gut (and sometimes they’re even helpful), here are some important tips:

Cook food thoroughly

Bacteria like Salmonella and E. coli often cause food poisoning. Proper cooking destroys these harmful bacteria.

Use a food thermometer to ensure meats, poultry, and eggs reach their recommended internal temperatures before eating. This is especially important to avoid getting these bacteria into your system.

See your doctor

If you have a chronic gut condition like Crohn’s disease or ulcerative colitis, your gut lining may be more susceptible to small injuries or lesions. These create an opening for bacteria to enter your bloodstream, potentially leading to serious complications like sepsis.

Your doctor can help you understand your specific risks and provide guidance on managing your gut health to minimize potential complications.

While the idea of “vampire bacteria” might give you the creeps, this knowledge is power. Scientists are getting the upper hand, and that means new treatments and prevention strategies could be on the way.

The study is published in the journal eLife.

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