Vegemite ingredient key to superbug fight:

But consuming jars of the popular yeast extract before your next hospital visit isn't the answer to warding off potentially deadly staph infections.

Researchers said their results were achieved by administering megadoses of nicotinamide, more commonly known as niacin or vitamin B3, far beyond what any normal diet would provide.

The research, published in the Journal of Clinical Investigation, found high doses of the vitamin increased by 1000 times the ability of immune cells to kill staph bacteria.

"Antibiotics are wonder drugs, but they face increasing problems with resistance by various types of bacteria," said Associate Professor Adrian Gombart from Oregon State University's Linus Pauling Institute.

"This could give us a new way to treat staph infections that can be deadly, and might be used in combination with current antibiotics," he said.

Gombart warned people against taking high doses of the vitamin because there was no evidence normal diets or vitamin B3 supplements could prevent or treat bacterial infection.

Australian Professor Lyn Gilbert, the director of the Centre for Infectious Diseases and Microbiology, said the study was plausible, but it would be a difficult and expensive task to test the findings in human trials.

However, she said it was good science that explained the mechanisms at work to eliminate the infectious organisms from the blood.

The researchers used laboratory animals and human blood to show that megadoses of vitamin B3 increased the numbers and effectiveness of neutrophils, a particular type of white blood cells that can kill harmful bacteria.

One of the most serious staph infections, methicillin-resistant Staphylococcus aureus, or MRSA, was part of the study.

Researchers said the widespread use of antibiotics had boosted the emergence and spread of MRSA.

When used in human blood, clinical doses of vitamin B3 wiped out the staph infection in just a few hours.

"This vitamin is surprisingly effective in fighting off and protecting against one of today's most concerning public health threats," said senior co-author Dr George Liu, an infectious disease expert at Cedars-Sinai Medical Centre.