Deadly bacteria, such as E Coli, have been observed to "sniff out" and swim towards human blood in order to feed on it, a phenomenon that has been dubbed "bacterial vampirism" by scientists.
The serum — the liquid portion of blood that provides nutrients the bacteria may consume — is what attracts the bacteria, according to research led by Washington State University.
The study, which was written in the journal eLife, gives researchers a better understanding of blood infection mechanisms and may also lead to more effective treatment strategies.
"Bacteria infecting the bloodstream can be lethal," stated Professor Arden Baylink of the university's College of Veterinary Medicine.
It was discovered that certain bacteria that typically cause bloodstream infections are able to detect a chemical in human blood and will actively seek out the chemical, according to Metro UK.
In addition to E Coli, which can induce fever, cramping in the stomach, and diarrhoea, other bacteria that have been reported to exhibit "bacterial vampirism" include Salmonella enterica and Citrobacter koseri, which can cause meningitis and brain abscesses.
For those suffering from inflammatory bowel disease (IBD), these bacteria are the main cause of death.
Patients frequently have bleeding in the intestines, which can serve as a gateway for germs to enter the bloodstream and cause more widespread and potentially fatal infections.
The scientists used a powerful microscope setup to observe the germs and inject tiny amounts of human serum to mimic this intestinal bleeding.