For immediate release: September 8, 2003
For more information, contact Susan Griffith at 216-368-1004 or susan.griffith@case.edu

CLEVELAND—A team of researchers, led by microbiologist Yiping Han from the Case Western Reserve University School of Dentistry, has discovered that a bacterium (Fusobacterium nucleatum) found in orally related periodontal disease enters the blood, targets placentas and amniotic fluid of pregnant mice and triggers preterm or term stillbirths and infant deaths.

Yiping Han

The researchers injected mice with Fusobacterium nucleatum isolated from the placenta and amniotic fluids of women who had given birth to premature infants. Within 24 hours of injection, the placentas of some mice already were affected by the bacteria and within 48-72 hours most mice gave birth to stillborn pups.

The researchers found that the animal model mimicked the human situation in three ways:
* The infection spread only to the uterus and did not affect other organs.
* Live bacteria could be isolated from the placenta
* The infection spread to the amniotic fluid and fetal membranes mimicking an infection in humans known as chorioamnionitis which is associated with preterm birth.

These similar results in humans and mice strengthen the link between the oral bacteria and preterm births and suggest that transmission to the placenta occurs through the bloodstream.

Studies of the placentas and amniotic fluids of women who have undergone premature labor have indicated the presence of F. nucleatum in as many as 30 percent of the women. Han said she wanted to find out how the bacteria reach the sterile environment of the womb because F. nucleatum's presence is uncommon in the vaginal tract but frequent in the mouth.

"The number of bacteria can increase 10,000-fold when periodontal disease is present. This bacterium may take the opportunity to enter the blood stream when bleeding occurs with the gum disease," said Han. She added that the immune system during pregnancy may be "turned down" to protect the baby and hence may have a harder time warding off and keeping in check the numbers of the bacteria normally present in the mouth.

"Periodontal disease is treatable and preventable," Hans said. She advises women, who are thinking about getting pregnant or are expecting a baby, to visit the dentist for a check-up and maintain healthy oral hygiene practices of brushing and flossing daily.

One of the reasons for pursuing these studies, according to Han, is because despite improvements in medicine, the number of premature births has remained constant over the past 40 years. Han wants to find the reason why women give birth early and then try to prevent it.

The poster, "Fusobacterium nucleatum induces premature and term stillbirth in pregnant mice: implication of oral bacteria in preterm birth," that Han presented to the Infectious Disease Society of Obstetrics and Gynecology won the best poster award during the group's 30th annual meeting in Cape Cod, Mass.

Other researchers on the project were Raymond Redline and Thomas McCormick from the Case School of Medicine, Mei Li and Lihong Yin from Case School of Dentistry and Gale Hill from the Duke University Medical Center.

–Case–

 

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