Deadly ‘vampire’ bacteria seek out and feast on human blood
Deadly bacteria including E coli ‘sniff out’ and swim towards human blood in order to feast on it, a newly-discovered phenomenon scientists are calling ‘bacterial vampirism’.
Researchers led by Washington State University have found the bacteria are attracted to the liquid part of blood, known as the serum, which contains nutrients they can eat.
The research, published in the journal eLife, helps scientists better understand how infections in the blood occur – and potentially how they could be better treated.
Professor Arden Baylink, from the university’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.’
Alongside E coli, which can cause diarrhoea, stomach cramps and a fever, the bacteria Salmonella enterica and Citrobacter koseri – which can lead to meningitis and brain abscesses – were also found to show ‘bacterial vampirism’.
These bacteria are the leading cause of death in people with inflammatory bowel disease (IBD). Patients often suffer from intestinal bleeding, which can be entry points for the bacteria into the bloodstream, leading to wider and potentially lethal infections.
Using a high-powered microscope system, the team simulated this intestinal bleeding by injecting microscopic volumes of human serum and observing the bacteria.
They found the response was rapid, with the bacteria taking less than a minute to hunt down the blood using a process called chemotaxis – in which they move towards areas where a particular chemical is concentrated.
The bacteria seemed particularly drawn to a chemical in the blood known as serine, an amino acid often found in protein drinks.
The team also discovered that salmonella has a special protein receptor that helps it sense the presence of blood.
‘By learning how these bacteria are able to detect sources of blood, in the future we could develop new drugs that block this ability,’ said co-author Siena Glenn.
‘These medicines could improve the lives and health of people with IBD who are at high risk for bloodstream infections.’
E coli, salmonella and Citrobacter koseri infections can all lead to gastrointestinal illnesses, such as vomiting and diarrhoea, but can cause the much more serious sepsis if infecting the bloodstream. Sepsis is a life-threatening condition in which the immune system overreacts to an infection and turns on the body, damaging tissues and organs.