The study was the work of Dr Nao Suzuki from Fukuoka Dental College in Fukuoka, Japan and colleagues and is published in the December issue of the Journal of Medical Microbiology.
Scientists recently discovered that infection by the bacterium Helicobacter pylori, which is carried by over 90 per cent of people in the developing world and 20 to 80 per cent of people in the developed world, was a possible cause of peptic ulcers and gastric cancers.
More recent research has also suggested that the human mouth, which is home to over 600 different species of bacteria (some of which cause disease), is a possible reservoir for H. pylori, particularly in the presence of periodontal or gum disease, a known cause of halitosis or bad breath.
Suzuki explained that bad breath or halitosis is common in humans and is mostly caused by gum disease, tongue debris, poor oral hygiene and badly fitted fillings (they trap bacteria).
"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," said Suzuki.
Suzuki and colleagues decided to investigate the prevalence of H. pylori in the mouths of people with bad breath.
"Recently, scientists discovered that H. pylori can live in the mouth," said Suzuki, adding that:
"We wanted to determine whether the bacteria can cause bad breath, so we tested patients complaining of halitosis for the presence of H. pylori."
For the study, the researchers did DNA scans of saliva taken from 326 Japanese people; 251 had actual bad breath or halitosis and 75 did not. None showed any signs of stomach illnesses.
They found H. pylori and other bacteria that occur with periodontal or gum disease, called periodontopathic bacteria, including Porphyromonas gingivalis, Treponema denticola and Prevotella intermedia.
More spefically the results showed that:
- 21 (6.4 per cent) of the participants had H. pylori in their mouths.
- These participants also had higher levels of other markers for periodontal disease, including higher levels of: methyl mercaptan (a bad breath gas); each of the periodontopathic bacteria; tooth mobility; periodontal pocket depth (PPD); and occult blood in the saliva.
- Of the 102 participants with periodontal disease, 16 (15.7 per cent) had H. pylori in their mouths.
"Progression of periodontal pocket and inflammation may favour colonization by this species and that H. pylori infection may be indirectly associated with oral pathological halitosis following periodontitis."
"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, who said the team will now be looking 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."
"Detection of Helicobacter pylori DNA in the saliva of patients complaining of halitosis."
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Source: Journal abstract, Society for General Microbiology press briefing.