Scientists have identified a hormone critical for preventing pneumonia bacteria from spreading throughout the body, which may help fight off a severe form of the deadly disease.

Stimulating hepcidin production in patients who do not produce it well, such as people with iron overload or liver disease, may help their bodies effectively starve the bacteria to death, said researchers, including those from University of Virginia in the US.

Researchers found that mice that had been genetically modified to lack hepcidin were particularly susceptible to bacterial pneumonia.

Nearly all of the mice had the pneumonia bacteria spread from the lungs into their bloodstream, ultimately killing them.

"It is the exact same thing that happens in people," Borna Mehrad of University of Virginia.

"The mice that lacked the hormone weren't able to hide iron away from the bacteria, and we think that's why the bacteria did so well in the blood," Mehrad said.

The hormone, hepcidin is produced in the liver and limits the spread of the bacteria by hiding the iron in the blood that the bacteria need to survive and grow, said researchers.

"The rate at which these organisms become resistant to antibiotics is far faster than the rate at which we come up with new antibiotics," Mehrad said.

"Increasingly, the choice of antibiotics to treat these infections is more and more limited, and there are occasions where there just isn't an antibiotic to treat with, which is a very scary and dangerous situation," he added.