It takes less than a minute to feed on human blood.
A blood infection is when a microorganism (such as bacteria) passes from part of the body into the blood. These infections are extremely serious, the microorganism can spread throughout the body and cause death. A team of scientists has discovered why certain bacteria enter the bloodstream of people with inflammatory bowel diseases (such as Crohn’s disease or ulcerative colitis) and cause deadly infections. They called this phenomenon “bacterial vampirism.”
These Washington State University scientists designed a special device to simulate bleeding in the intestine to observe the behavior of bacteria from the Enterobacteria family (those associated with gastrointestinal bleeding), Their results published in the journal “elife” reveal that they are quickly attracted to the part of the blood called “serum.” This contains nutrients that they can use as food for their growth. The researchers named this behavior “bacterial vampirism” because the bacteria move to the serum, colonize the bleeding areas and consume the serum’s nutrients. It took them less than a minute to find the serum. “They detect a chemical in human blood and swim towards it” explains Professor Arden Baylink, one of the authors of the study. This chemical is L-serine, an amino acid found in large quantities in serum. In the Enterobacteria family, three bacteria are sensitive to L-serine and can therefore cause blood infections:
►The Salmonella enterica : their transmission is mainly through the consumption of contaminated food according to theHandles
►TheEscherichia coli (also called “E.coli”): the main route of transmission is indirect through the consumption of contaminated food. It manifests itself by gastrointestinal symptoms with hemorrhagic colitis which can progress to serious forms.
►The Citrobacter koseri : transmission occurs through direct contact with hospital staff, contaminated equipment or from mother to child.
These bacteria are one of the main causes of death in people with inflammatory bowel disease (or IBD), or 1% of the population. This type of disease is characterized by inflammation of the wall of part of the digestive tract, due to dysregulation of the immune system. Some patients experience intestinal bleeding that can provide entry points for bacteria into the bloodstream, experts say.
This discovery could boost research into treatments for people with blood infections and IBD. “By learning how these bacteria are able to detect blood sources, we could in the future develop new drugs that block this ability. These drugs could improve the lives and health of people with IBD who are at high risk of ‘blood infection’said Sienna Glenn, one of the study’s researchers.