Researchers have discovered that certain bacteria normally found in the mouth play a key role in allowing other bacteria, such as E. coli, to infect the body through the blood. It was discovered that F. nucleatum bacteria contain a substance named FadA that promotes cellular breakdown on blood vessel surfaces. This allows F. nucleatum along with other bacteria in the area to gain access to the blood. Once inside the blood, the microbes can travel almost anywhere throughout the body.
FadA acts as a bonding agent that initiates a cascade of signals that leads to the breaking of bonds between vessel cells. According to researcher Yiping Han, "This cascade knocks out the guard on duty and allows the bacteria to enter the blood and travel like a bus loaded with riders throughout the system. Whenever the F. nucleatum wants to get off the bus at the liver, brain, spleen, or another place, it does." Once the microbes leave the blood, they colonize in the area where they settle. This can lead to serious infections that result in tissue death and even fetal death in pregnant women.
Even healthy pregnant women can be at risk for pregnancy problems caused by oral bacteria. Researchers from Case Western Reserve University began to understand which bacteria from the 700 species living in the mouth are responsible for the growing health problem of preterm and stillbirths.
Yiping Han from the department of periodontics in the CWRU School of Dental Medicine led the study, which found several new bacteria originating in the mouth travel through the blood to cause an inflammatory reaction in the placenta and eventually cause a range of health issues from miscarriages to stillbirths.
The findings were reported this month in Infection and Immunity.
Pregnant women with or without mild oral health problems have baffled researchers as to why oral bacteria have shown up in the placenta or amniotic fluids of premature or stillbirths.
The researchers found that after injecting the tails of pregnant mice with saliva from healthy people and dental plaque from those with periodontal disease, oral bacteria continued to grow in the placentas after it had left the blood 24 hours later.
Prior to Han's work in connecting oral bacteria to the problems in pregnancy, it was thought that infections were transmitted through the vaginal tract.
Information from Han's previous studies over the past decade shows that oral bacteria can be transported through the blood when there is a cut in the mouth's lining or an oral health problem like gingivitis or periodontitis which breaks down the defenses in the mouth's lining that protect bacteria from entering the bloodstream.
According to Han, this suggests that even healthy pregnant women should be concerned that normally occurring bacteria in the mouth can enter the blood stream and make their way into the placenta's immune-free environment to ignite an inflammatory reaction that can lead to premature or stillbirths.
