Solving how harmless bacteria become an unwelcome guest

BUFFALO, N.Y. – Researchers at the University at Buffalo have received a $239,000 grant from the National Institute of Dental and Craniofacial Research to study what happens when seemingly harmless bacteria overstay their welcome.

The research, led by Jason Kay, PhD, assistant professor of oral biology in the UB School of Dental Medicine, will examine Streptococcus gordonii, a bacterium found in all healthy mouths.

Although they are nonpathogenic inside the mouth, when the bacteria reach the bloodstream – often through bleeding gums – they can cause infective endocarditis, a rare but fatal inflammation of the heart valves.

“Our white blood cells have a number of ways of destroying invading microbes, but somehow these bacteria manage to escape, sometimes surviving inside the cells meant to kill it. How this occurs is not understood,” says Kay.

“Once we understand how this survival occurs, the knowledge will allow us to develop treatments that prevent normally good bacteria from going bad.”

Kay’s lab specializes in studying phagocytes, the white blood cells responsible for eating bacteria, dead cells and other harmful particles.

The researchers have a hunch that Streptococcus gordonii survive inside the phagocytes by resisting the cell’s kill mechanisms. The answer, they believe, partly lies within the genes of the bacteria, says Kay.

The study aims to identify genes that may increase the bacteria’s survival inside the white blood cells by turning off specific genes within the microbes and monitoring the interactions.

The researchers will also examine if the phagocytes are modified or damaged during the killing process, and how the maturation process of white blood cells affect their ability to destroy the bacteria.

Understanding these interactions will help clinicians better prevent one of the causes of infective endocarditis, a disease that is of higher risk to people who have undergone a heart valve replacement.

Additional researchers from the School of Dental Medicine include M. Margaret Vickerman, DMD, PhD, co-investigator and professor of periodontics and endodontics, and Stefan Ruhl, DDS, PhD, professor of oral biology.