Periodontics professor’s research paper on mobile bacteria tops reading for dentists

Yiping HanThe idea that bacteria in your mouth could prove problematic for the rest of your body proved nearly irresistible for readers of the Journal of Dental Research.

The concept, from Yiping Han, professor of periodontics, earned the American Association of Dental Research’s distinction as a research break-through and of being one of most-read and most-cited dental research papers in the past year. It ranks in the top five most read articles for the JDR from May 2013 through April 2014.

Her paper “Mobile Microbiome: Oral Bacteria in Extra-oral Infections and Inflammation,” theorizes that bacteria living in the mouth are mobile microbes that can travel to other parts of the body and cause major health difficulties.

Han calls the oral bacteria as mobile microbiome that has created a shift in dental thinking from oral diseases to oral bacteria in systematic infections.

She has made her own discoveries regarding the connection between elements present in the mouth to negative outcomes elsewhere in the body—including adverse pregnancy outcomes and colon cancer.

Using DNA technologies, Han linked a bacterium in a mother’s mouth and the bacteria found in her amniotic fluid.  In another instance, and again using DNA testing, she discovered a link between a fetal death and the mother’s oral bacteria.  She has also linked the oral bacteria of pregnant mothers who infected their babies through the cord blood and infected amniotic fluid, which caused sepsis in the first days of life. And most recently linked oral bacteria to inciting the growth of colon cancer.

With these examples in mind, Han wondered if other researchers had found ties of their own. She searched more than 100 studies and found several that linked oral bacteria to various health problems: heart, arthritis, inflammatory bowel disease, respiratory tract infections, appendicitis and other diseases.

Han likens oral bacteria to passengers that hop on the train at the first subway stop (the mouth) and continue along the track (gastrointestinal tract or the blood circulation) with bacteria leaving at other stops for destinations in other parts of the body. And some stay on the train until they reach at the end of the line.

One particular bacteria, Fusobacterium nucleatum, she explains, can get into the blood and travel through the body, calling it one of the most harmful bacteria in the mouth. But this bacterial villain isn’t alone. Many of these diseases had one or more bacteria present.

With the arrival of new technologies, such as DNA testing, more bacteria from the mouth have been found at the infected body sites, she said. What prevented their discoveries sooner was that many of these bacteria can’t be grown in the petri dishes.

Han believes new technologies can refocus the idea of focal infections to what she now calls mobile microbiome (the 700 species of bacteria that live in the mouth) and their impact on diseases.

The research was supported by a grant from the National Institute of Dental and Craniofacial Research (ROI DE14924).