Friday, January 07, 2005

Down in the mouth? Blame bacteria for that rotten breath

Down in the mouth? Blame bacteria for that rotten breath

What causes bad breath, and how can I get rid of it?

Bad breath (halitosis) is often caused by bacteria in the mouth or upper airway that produce sulfur-containing compounds. Usually, it can be banished by flossing and brushing teeth twice a day and brushing and scraping the tongue. If bacteria are also lurking in deep "pockets" in the gums, a dental professional must scrape them out.

But even with excellent oral hygiene, some people need more drastic approaches.

About 90 percent of bad breath is caused by bacteria in the mouth itself, and a only small percentage is caused by bacteria in the tonsils, said Dr. Richard Price, a retired dentist and a spokesman for the American Dental Association.

But an Israeli scientist, Dr. Yehuda Finkelstein, director of palate surgery in the department of otolaryngology, head and neck surgery at Meir Medical Center, is testing out a high-tech solution for bacteria lodged in tonsils: lasers that burn away small "crypts" or hollow spaces in apparently normal tonsils that harbor bacteria.

In a study of 53 people, one 15-minute laser session got rid of halitosis in 50 percent of people, while the rest needed two or three treatments, Finkelstein said in a telephone interview. A seemingly simpler solution, antibiotics, does not work well against the bacteria found in tonsils, he said.

In Boston, Bruce Paster, a microbiologist at the Forsyth Institute, also turned to sophisticated technology to study bad breath. He and his team used DNA sequencing to study bacteria from tongue scrapings in people with and without halitosis.

The people with halitosis often had "bad" bacteria on their tongues, while the sweet-breathed people had an abundance of "good" bacteria, he said. The solution in the Forsyth study was an initial scraping of bacteria from the tongue and anti-microbial mouthwashes for a week, followed by tongue-brushing with a zinc chloride gel for a year.

Result? The "bad" bacteria disappeared, he said, and were replaced by "good" bacteria.

I go out with wet hair, even in the winter. Does this raise the risk of getting a cold?

Probably not. "People think there is a connection between being cold and getting a cold, because colds get spread in the wintertime when people are in close quarters," said Timothy Springer, an immunologist on sabbatical from CBR Biomedical Research Institute. "But the only way to get a cold is by getting the virus."

Catching colds actually "has nothing to do with lowered immunity," said Dr. Jack Gwaltney, a leading cold researcher and professor emeritus at the University of Virginia School of Medicine.

Colds result from cold viruses directly entering the nose. When cold viruses are experimentally introduced into the noses of volunteers, nearly all of them get infected, even those who are happy, healthy and, presumably, immunologically strong.

But only three-quarters actually get sick, and those who do get runny noses and begin sneezing may have an excessive immune response, not a weak one.

"So it may be backwards from what people think," said Gwaltney. People who get sick pump out high levels of kinins, specific immune system chemicals, while people who get infected but not sick pump out low levels.

Both groups get better at roughly the same rate, suggesting that the exaggerated kinin response, while causing lots of symptoms, doesn't do much good.

The only way to be sure never to catch a cold, Gwaltney added, "is to stay away from humans, especially human children." Failing that, wash your hands after you've been in contact with people with colds or objects they've touched.

I am definitely going to affix my mask more carefully!

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