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Common oral bacteria breaks into blood stream to infect organs, researcher says

February 20, 2012

By Jean Williams, ADA News staff

Yiping Han, Ph.D.

Cleveland—Fusobacterium nucleatum, a common oral bacteria, acts like a common thief picking locks to let in itself and other bacteria.

Yiping Han, Ph.D., professor of periodontics at Case Western Reserve School of Dental Medicine in Cleveland, discovered that the bacteria, one of hundreds in the mouth, can open a door in human blood vessels allowing itself and other bacteria to infiltrate the body and cause disease.

Dr. Han, a microbiologist, has studied F. nucleatum for more than a decade. She discovered F. nucleatum binds to endothelial receptors that trigger breakdown of intercellular junctures interlocking endothelial cells on the surface of blood vessels. The bond-breaking process is described in a December 2011 article in Molecular Microbiology: “Fusobacterium Nucleatum Adhesin FadA Binds Vascular Endothelial Cadherin and Alters Endothelial Integrity.”

The gram-negative anaerobe’s presence has been uncovered in brain abscesses and in infections in the lungs, liver, spleen and joints. Dr. Han also found direct evidence linking the bacterium to preterm labor and fetal death, as F. nucleatum can cross the blood-brain and placental barriers that usually block disease-causing agents.

When F. nucleatum invades the body through breaks in the mucous membranes in the mouth, due to injuries or periodontal disease, it may trigger an increase in endothelial permeability allowing it and other bacteria to colonize at different sites throughout the body. The colony of bacteria induces an inflammatory reaction that can lead to tissue necrosis and fetal death.