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Postdoc named to Forbes’ 30 Under 30 list for health care

Studies of C. difficile infection led to interest in gut microbiome

by Julia Evangelou StraitJanuary 19, 2017

Robert Boston

Clostridium difficile is a type of bacteria that can cause deadly intestinal infections, especially in hospitalized patients undergoing multiple rounds of antibiotics, which deplete their normal gut flora. According to the Centers for Disease Control and Prevention (CDC), there are more than 450,000 C. difficile infections annually and just over 29,000 associated deaths.

Carrie A. Cowardin, PhD, now a postdoctoral researcher at Washington University School of Medicine in St. Louis, studied C. difficile while a doctoral student at the University of Virginia. Her work has opened doors to exploring new ways to thwart C. difficile infections and led to her being named to Forbes magazine’s list of “30 Under 30″ in health care. The honor highlights young people who have made major contributions to improving healthcare through innovations in health policy, entrepreneurship or biomedical research.

Cowardin’s C. difficile findings, published in Nature Microbiology, showed that highly virulent strains of C. difficile don’t just take advantage of a disrupted community of gut microbes — they also produce a toxin that actively kills the body’s protective immune cells.

Cowardin discussed how she came to study C. difficile and where her research is headed.

What drew you to studying biology?

As an undergraduate at the University of Virginia, I took an immunology course just for fun and ended up loving it. After that, I decided if I cared so much about a subject, that was the way to go. After becoming a biology major, I did independent research in the lab of William Petri, MD, PhD, who studies infectious disease with a focus on the gut. He later became my doctoral adviser. Having the opportunity to do independent research as an undergraduate was really important for me in deciding to pursue biology as a career.

How did you end up doing research on C. difficile?

Clostridium difficile is a huge problem in hospitals. My mom is a clinical microbiologist, and she would talk to me about the bacterial infections she analyzed in the clinical lab where she works. Knowing the severity of the problem motivated me to want to understand more about that infection and the immune system of the gut in general. A lot of my interest in biology comes from my mom. She took me into the lab when I was younger and showed me different bacterial cultures and assays. She also had a homemade microscope. We would go out into the backyard and find things to look at under the microscope. So having her as a role model was really important for me.

What surprised you about your C. difficile research?

The biggest surprise from the Nature Microbiology paper was what we learned about immune cells called eosinophils. We know they play a role in causing allergies and asthma and that they’re also important in protecting against parasitic infections. But we really did not expect to see a major role for them in protecting against a C. difficile bacterial infection. The more eosinophils the mice had, the better they did against this bacterial infection. In the highly virulent strain of C. difficile we were studying, we discovered that the bacteria produce a toxin that kills eosinophils.

What drew you to Washington University?

I was really interested in joining the lab of Jeffrey Gordon, MD. His focus on the gut microbiome and especially his work on the gut mucosal immune system are big attractions for me. He has an amazing group set up to examine gut microbes and their impact on human biology.

What are you working on now?

Working with C. difficile gave me an appreciation for the importance of the interaction between the gut’s immune system and gut microbes. The composition of the microbiota — the community of microbes living in the gut — is really important in C. difficile infection. You usually have to have some disruption of a healthy microbiota in order to get infected with C. difficile. In my current research, I’ve switched gears a little bit from disease-causing bacteria to studying the development of a healthy microbiota in general. The Gordon lab is focused on the gut microbiota’s role in childhood malnutrition. I’m studying how the maturation of the gut microbiota can influence immune development and bone growth, especially in a state of malnutrition. One of the things that’s really interesting about studying the developing microbiota is this relatively new understanding of the communication between the gut and other systems in the body, like the skeletal system.

What do you hope comes out of your research?

Malnutrition is a huge global problem, and I hope my research can help us understand its impacts and find possible means to alleviate it. I think the goal of anyone in biomedical research is to pursue work that will somehow positively impact human health.

Washington University School of Medicine‘s 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children’s hospitals. The School of Medicine is one of the leading medical research, teaching and patient-care institutions in the nation, currently ranked sixth in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children’s hospitals, the School of Medicine is linked to BJC HealthCare.

Julia covers medical news in genomics, cancer, cardiology, developmental biology, otolaryngology, biochemistry & molecular biophysics, and gut microbiome research. In 2022, she won a gold award for excellence in the Robert G. Fenley Writing Awards competition. Given by the Association of American Medical Colleges, the award recognized her coverage of long COVID-19. Before joining Washington University in 2010, she was a freelance writer covering science and medicine. She has a research background with stints in labs focused on bioceramics, human motor control and tissue-engineered heart valves. She is a past Missouri Health Journalism Fellow and a current member of the National Association of Science Writers. She holds a bachelor's degree in engineering science from Iowa State University and a master's degree in biomedical engineering from the University of Minnesota.