For Dr. Jeffrey Smith, professor of microbiology and immunology, the renewal grant will permit him to continue his research on the organism Bacteroides fragilis. The organism, among many other species of bacteria, is commonly found in the intestinal tract of humans and other mammals where it contributes to digestion but can cause infection
under certain conditions.
Smith has been funded to characterize B. fragilis since 1989. An anaerobic bacterium, it thrives in the gut in the absence of oxygen but normally cannot survive when exposed to the atmosphere — with one important exception. When the organism spills into the oxygen-rich peritoneal cavity as the result of trauma or disease process, it undergoes an “oxygen stress response” that allows it to adapt to and survive this threat to its existence. It encapsulates itself in an abscess — in effect, a microenvironment — that excludes oxygen and helps the bacteria withstand attacks by the body’s immune system.
In earlier work, Smith has shown that certain genes in the bacteria are activated in response to environmental stress from oxygen. These genes produce proteins that modify the organism’s microenvironment. He hopes to identify all the genes involved in this response and assess their relative importance.
Armed with these new insights about how the bacteria become pathogenic, scientists may be able to design therapies that disable the process, said Smith, who is also interim chair of the medical school’s Department of Microbiology and Immunology.
These developments would be of particular interest in the health care setting, where a daily battle is waged with B. fragilis and a variety of similar bacteria, some of which are resistant to antibiotics. Smith said what he is learning should be applicable to other pathogenic bacteria.
“Bacteroides fragilis is typical of the most abundant group of bacteria in the intestinal tract,” said Smith. “Everything we learn will translate well to the other indigenous gut flora.”
Smith is one of several researchers in the department studying bacterial virulence and pathogenesis. Drs. Marty Roop and Everett Pesci are the other investigators with NIH-funded projects to study bacterial pathogenesis.
Last year Smith received ECU’s lifetime achievement award for excellence in research and creative activity, the university’s highest research honor.