Staphylococcus aureus -- the notorious bacteria known to be a major cause of food poisoning, which can also cause dangerous sepsis or pneumonia if it gets in the bloodstream -- can lurk in deeper parts of the nose than previously expected.
Researchers from the Stanford University School of Medicine examined three different parts inside the nose to determine the presence of S. aureus: The anterior naris, which is the most commonly studied and is located near the nostril; the middle meatus, which is a mucus-producing fold that is wet and is about halfway up the nasal cavity; and the sphenoethmoidal recess, which is also wet and mucosal and is in the cavity near the roof of the nose (this is the deepest of the three parts).
An association was found between the presence of S. aureus in one of these three areas of the nose, and its presence in the other two areas of the nose. In other words, if the bacteria exists in the anterior naris, it's likely also present in the middle meatus and the sphenoethmoidal recess.
It's not new that S. aureus is present in the nose; the nose is a long-known reservoir for the bacteria, as is the skin of the groin and armpits. Most of the time, it doesn't harm health at all, but if the bacteria gets into the bloodstream, it can lead to infection or sepsis. Some strains are also resistant to methicillin (methicillin-resistant Staphyloccocus aureus, or MRSA) and can cause life-threatening infections.
Sometimes, people have S. aureus in their noses or on their skin eliminated, but these procedures don't work permanently -- the bacteria comes back weeks or months later. Experts said this study could explain why the bacteria seem to come back even after being eliminated.
"Not everyone who carries S. aureus gets sick," study researcher Dr. David Relman, M.D., a professor of medicine, microbiology and immunology at the university, said in a statement. "When they're out walking the streets and otherwise healthy, attempts to rid them of their S. aureus are not necessary, and even sometimes futile. 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."
Relman, whose findings are published in the journal Cell Host & Microbe, conducted his study on 12 healthy people who had their noses swabbed at a Stanfrod ear, nose and throat clinic.
Researchers also found an inverse relationship between S. aureus and the bacterial species C. pseudodiphtheriticum, meaning when a person had high S. aureas levels, he or she had low or absent C. pseudodiphtheriticum levels, and vice versa. Further study revealed that C. pseudodiphtheriticum seemed to block growth of S. aureus.