Helicobacter pylori, the same bacteria that causes stomach ulcers and is a cause of some gastric cancers, was present in 21 out of 326 Japanese people with halitosis and 16 out of 102 people with gum disease who took part in a research study in Fukuoka, Japan.
"Recently, scientists discovered that H. pylori can live in the mouth," said Dr. Nao Suzuki of Fukuoka Dental College. "We wanted to determine whether the bacteria can cause bad breath, so we tested patients complaining of halitosis for the presence of H. pylori."
"Halitosis is a common problem in humans, and bad breath is largely caused by periodonitis, tongue debris, poor oral hygiene and badly fitted fillings," said Suzuki. "Bacteria produce volatile compounds that smell unpleasant, including hydrogen sulphide, methyl mercaptan and dimethyl sulphide. Doctors often measure the levels of these compounds to diagnose the problem. Gastrointestinal diseases are also generally believed to cause halitosis."
An estimated 20 to 80 percent of people in the developed world and over 90 percent of people in the developing carry the bacterium.
"Although the presence of H. pylori in the mouth does not directly cause bad breath, it is associated with periodontal disease, which does cause bad breath," said Suzuki. "We now need to look into the relationship between H. pylori in the mouth and in the stomach. We hope to discover the role of the mouth in transmitting H. pylori stomach infections in the near future."
The patients in the study carrying H. pylori also were carrying Prevotella intermedia, another type of bacteria and had more blood in their saliva.
There are more than 600 different species of bacteria that can live in the mouth. Scientists have named only about half of them.