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Bacterium and fungus act in tandem to cause early childhood caries, Penn researchers say

March 14, 2014

The relationship between a bacterium and a fungus may be responsible for early childhood caries, report University of Pennsylvania School of Dental Medicine investigators online Feb. 24 in the journal Infection and Immunity.

"Our data will certainly open the way to test agents to prevent this disease, and even more intriguing, the possibility of preventing children from acquiring this infection," said Dr. Hyun Koo, lead investigator.

The bacterium Streptococcus mutans and the fungus Candida albicans act together, the researchers say, with S. mutans enabling C. albicans to produce a glue-like polymer in the presence of sugar. The polymer allows the fungus to stick to teeth and to bind S. mutans. This relationship with S. mutans aids the fungus in contributing to the bulk of plaque, they say.

The assumption prevails that S. mutans is the sole organism contributing to tooth decay, but the Penn researchers say that their study showed infection by the bacterium along with C. albicans doubled the number of cavities and increased the disease's severity in rats.

Dr. Koo and his collaborators—as well as other investigators—noticed that C. albicans is very often present in early childhood caries biofilm. The Penn investigators studied the relationship in vitro and in vivo.

"The combination of the two organisms led to a greatly enhanced production of the glue-like polymer, drastically boosting the ability of the bacterium and the fungus to colonize the teeth, increasing the bulk of the biofilms and the density of the infection," said Dr. Koo, a dentist who holds a Ph.D. in oral biology.

The online article "Symbiotic Relationship Between Streptococcus mutans and Candida albicans Synergizes the Virulence of Plaque-Biofilms In Vivo" is available here. The final version of the article is scheduled for print publication in the May edition of Infection and Immunity.