Phil Stewart discusses career during Provost’s Distinguished Lecturer Series

As medical technology advances, Phil Stewart is addressing problems it may cause through his research as part of the Center for Biofilm Engineering. Stewart spoke March 8 as a part of the Provost’s Distinguished Lecturer Series about his research on biofilms and the infections they can cause around medical implant devices.

Stewart received his bachelor’s degree in chemical engineering from Rice University in Texas. He went on to get his master’s degree and doctorate from Stanford. “When I was starting out there [were] few courses at the intersection of biology and engineering,” Stewart stated during his lecture. In fact, the only biology education he has came from a plant physiology class and a birdwatching class, both of which he took as an undergraduate. After receiving his bachelor’s degree, Stewart went to Switzerland for a year to work in research and development labs at Lonza. Here he worked on scaling up the synthesis of a pharmaceutical product using organic chemistry.

Upon returning to the U.S., Stewart studied at Stanford under the lone chemical engineering professor, Channing Robertson, who at the time was doing research on exploring ways to use microorganisms to make high value products in a single step under benign conditions. After this time, Stewart received a National Science Foundation Scholarship to go and work in a NATO country. He chose France and consequently spent time working in Paris as a  postdoctoral fellow. Stewart joined the staff at MSU in 1991.

Stewart explained that biofilms can be defined as microorganisms that group together in dense aggregates which makes them hard to kill. Examples of biofilms include the slime that is found forming on the surface of a river rock, dental plaque and certain infections that form around implanted medical devices like artificial joints, pacemaker leads and urinary catheters. In catheters, biofilm infections can cause encrustation which can impede the catheter from doing its work and it may even lead to urinary tract infections.

Biofilm infections are slow moving, localized, very persistent infections that form on foreign bodies or dead or damaged tissue, which common everyday antiseptics like hydrogen peroxide cannot kill. In fact, hydrogen peroxide cannot even penetrate the microorganisms in the biofilm. In addition, biofilm infections can cause collateral damage to neighboring healthy tissue. “We are finding more and more infections fitting this paradigm” Stewart said.

In Stewart’s current research, the “Zone of Compromise” models the area around the implanted medical device that is more susceptible to infections. When a bacteria lands in this zone, white blood cells, also referred to as neutrophils, get confused. “We don’t know why, but they don’t get the job done,” Stewart explained during his lecture. The job of a neutrophil is to swarm in and destroy the bacteria as it is found in the body. Stewart proposed that a solution needs to be found to jumpstart the individual body’s own defense mechanisms.

As of now, Stewart is watching the interactions between neutrophils and infections, especially when they are inoculated at the same time. He claimed that none of his success would be possible if it were not for the creative teamwork he has encountered from the Center for Biofilm Engineering or the support he has found in his own collegial home department of chemical and biological engineering.