"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.
Prof 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.
- AAP