Otherwise innocuous bacteria can cause deadly infections when people have surgery or fall ill. To prevent trouble, patients sometimes have their bodies scrubbed clean of Staphylococcus aureus.
But it doesn't always work.
That may because the germs thrive in upper recesses of the nose, far from the spots typically tested for staph bacteria, or where antibiotics are applied.
Researchers at Stanford University School of Medicine voyaged up the nose to meet the natives — the bacteria that live in these warm, dark places. They found that staph germs just love the middle and upper nose cavity, much more so than the relatively arid nostrils.
The nostrils are "a bit more like coastal grasslands than a nice, wet rain forest," says Dr. David Relman, a professor of microbiology and immunology at Stanford and senior author of the study. Those upper regions, he says, "are kind of a little out-of-the-way cul-de-sac."
And indeed, though these cavities are invitingly tropical they're not easily reached. The Stanford crew needed a tiny swab and an endoscope to take samples from the middle meatus, a wet mucus-producing area halfway up the nose, and the sphenoethmoidal recess, way up in the roof of the nose.
About one-third of people have staph bacteria growing on their bodies, most often in the nose, armpits and groin. Another third carry staph from time to time.
Those bugs can live on us for years without doing any harm. But when a person suffers a skin injury or undergoes surgery, the formerly harmless staph can migrate inside the body and cause sepsis, pneumonia or heart valve infections. Some strains of staph have become resistant to antibiotics, making it particularly hard to combat infections picked up in the hospital.
The fact that staph germs are hanging out in remote precincts of the nose may explain why efforts to kill off the germs on carriers before elective surgery can fail, Relman thinks.
The voyage up the nose also revealed that staph thrived only when another bacterial species, C. pseudodiptheriticum, was in short supply. It could be that this second microbe produces substances that keep staph at bay.
"It's like natural warfare going on deeper in the nose," Relman told Shots. "We think there are lots of natural antibiotics that haven't been discovered at all."
That may someday prove useful in treating staph infections, Relman speculates, as well as making better tests to identify people at risk of dangerous staph infections.
This study was published online in the journal Cell Host & Microbe. In this case, we're the host.