'Good' bacteria seen as potential cavity fighters

July 1, 2002

Last Updated: 2002-06-28 14:00:47 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Arming a type of friendly bacteria to do

battle with cavity-promoting bacteria could offer a new way to prevent

tooth decay, early research suggests.

In experiments with cells and rats, scientists found that a type of

" good " bacteria called lactobacillus could be genetically modified to

produce an antibody that kills off a particular cavity-causing bacterium

and helps prevent dental woes.

The researchers, led by Lennart Hammarstrom of the Karolinska Institute

in Huddinge, Sweden, report the findings in the July issue of Nature

Biotechnology.

Lactobacillus bacteria have long been used in food fermentation and are

commonly found in items such as yogurt. Some forms of the bacterium

dwell normally in the human intestines. Lactobacillus-laden foods and

supplements--commonly referred to as " probiotics " --have grown

increasingly popular because they are believed to promote good

gastrointestinal health.

In addition, lactobacilli have been proposed as " carriers " for oral

vaccines, according to Hammarstrom's team.

In their study, rats were given lactobacilli armed to produce antibodies

against Streptococcus mutans, a bacterium that lives in the human mouth

and causes cavities by converting sugar into enamel-eroding lactic acid.

The rats were given the good bacteria over 2 weeks, and the researchers

found that the friendly bugs were still in the animals' mouths 1 week

after the final treatment.

Moreover, the treated rats showed a sharp reduction in S. mutans in the

mouth and developed far fewer cavities compared with untreated animals,

according to the report.

The researchers conclude that the effectiveness of the transformed

lactobacilli, coupled with their persistence in the rats' oral cavity,

suggest a " viable approach " to preventing or treating tooth decay in

humans.

SOURCE: Nature Biotechnology 2002;20:702-706.

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