STANFORD, Calif. (CBS Sacramento) – A potentially harmful bacteria could be hiding inside your nose, according to researchers at Stanford University.

Researchers tested 12 healthy people and found usually overlooked sites deep within the nose may be reservoirs for Staphylococcus aureus, a major cause of disease, reports WebMD.

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Doctors have known that this staph bacteria can live in other places farther down in the nose.

Usually when treated in those areas, the bacteria return within about a month.

This new finding could help explain why the infection returns so quickly after treatment.

“About one-third of all people are persistent S. aureus carriers, another third are occasional carriers and a remaining third don’t seem to carry S. aureus at all,” said study senior author Dr. David Relman, a professor of medicine and microbiology and immunology.

Not everyone who carries the bacteria gets sick.

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Relman says it’s a warning to hospitals to be aware that this difficult to reach bacteria is out there.

“But once a carrier enters a hospital with an underlying illness or a weakened immune system or a high likelihood of undergoing skin-penetrating procedures, S. aureus carriage is a major liability,” he said.

If S. aureus gets into the bloodstream through a wound, incision or catheter placement, it can cause potentially life-threatening problems such as sepsis, pneumonia or infection of heart valves.

The researchers also found a type of bacteria called Corynebacterium pseudodiphtheriticum that may compete with S. aureus at the sites deep within the nose.

They say that C. pseudodiphtheriticum, may prove useful in countering S. aureus infections.

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The study was published Dec. 11 in the journal Cell Host & Microbe.