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Our Understanding of Bad Breath Bacteria Has Come a Long, Long Way

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Bad breath studies and bacteriology have gone hand in hand for a long time. That's why today's specialty breath fresheners offer such targeted treatments -- they are the result of decades, sometimes even centuries, of research into what causes halitosis. From early microscopes to modern genetic sequencing and halimeters, scientists will use whatever technology it takes to explore the microbe-filled habitat that is your mouth.

We've looked into quite a few bacteriological topics this past month, from the discovery of bacteria in plaque to the revelation that each of us harbors thousands of species of microorganisms in our bodies and mouths. Here are some of the most popular:

Leeuwenhoek discovers oral bacteria (and the futility of alcohol-based mouthwash). Dutch scientist Antonie van Leeuwenhoek was a very motivated guy. Working in the late 1600s and early 1700s, he was exceedingly interested in what things looked like up close -- wood, water, coffee beans, and even dental plaque. Of course, he needed microscopes, a new instrument at the time, to investigate what really small things looked like, but most such instruments of the day were underpowered and not very useful.

So, he made his own. Using a lens-crafting technique that he kept a secret from everyone, even his scientist friends at the British Royal Society (whom he wrote to constantly), he created some of the world's most powerful microscopes. And what he saw was quite a shock: Little beings, which he termed "animalcules," lived nearly everywhere! In water, in oils, and even in our mouths.

Ever the intrepid scientist, Leeuwenhoek devised one of the first mouthwash experiments. He knew from tests that vinegar and brandy appeared to kill animalcules (which we call bacteria) taken from dental plaque. So, according to a 1997 review published in the Journal of the American Dental Association, Leeuwenhoek tried gargling with them, to see if they'd work right at the site of oral bacterial colonies. They didn't. Thus, Leeuwenhoek was not only the discoverer of single-celled organisms, but also probably the first person to find out that alcohol-based mouthwashes don't work.

Scientists find thousands of bacterial strains in human body. Leeuwenhoek more or less founded microbiology. In fact, he was so ahead of his time that the Royal Society -- which, in his day, included members like Isaac Newton and Robert Hooke -- thought he was lying. It wasn't until a group of Englishmen took a trip to visit Leeuwenhoek in Delft that they were convinced: The mouth does indeed contain tiny living beings!

Today, we know that the body is home to more than a few species of microbes. In fact, a huge new investigation called the Human Microbiome Project determined that humans harbor thousands of different species of bacteria in their mouths, guts, blood and skin.

Researchers from 80 different institutions collaborated on the project. Using sophisticated DNA sequencing technology, they collected about 3.5 billion unique genetic base pairs from the microorganisms in human tissue.

So how many species did they find? About 10,000. In total individual microbes, that adds up to about 100 trillion. That's... a lot. Dr. Eric Green, director of the NIH's National Human Genome Research Institute, says if you take every single bacterium from your body and put them all on a scale together, they'd weight as much as five or six pounds.

Your mouth is an especially bacteria-rich region of your body, which is why it is so prone to halitosis. A study in the Journal of Clinical Microbiology estimated that the oral environment is home to 600 different microbial species, many of which pump out oral odor almost constantly. No wonder oral health probiotics are a must.

Your office is crawling with microbes. Your body isn't the only place that might as well be a Petri dish. According to a piece published by Medical News Today, a team of microbiologists recently tested samples taken from hundreds of places in different office settings. Researchers found that the areas most likely to be a-swarm with microbes were those that get touched a lot -- the microwave door handle, the water cooler button, the refrigerator door, kitchen tap handles and keyboards. Of course, one danger with all these bacteria around is that a few may transfer from hand to mouth, adding to your risk of halitosis.

Bacteria may contribute to "old people smell." This one was all over the news, and regardless of how it may sound, it was a legitimate study. Researchers from Philadelphia had volunteers smell armpit pads that were used by people of all ages. Not only could participants guess a person's age by their smell, but they also tended to find the smell of older people the least offensive!

Of course, aging Americans often experience another odor that's all their own: elderly bad breath. This can come from xerostomia, a dryness of the mouth that becomes more severe with age. Likewise, unclean dentures can aggravate oral odor, which is why it is so important to use alcohol-free specialty mouthwashes and to sip on water throughout the day.

For more by Dr. Harold Katz, click here.

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