Armbruster Studies Biofilms in Diverse Environments

An interest in opportunistic infections led Catherine Armbruster to her life’s work studying biofilms.

Armbruster, who joined Carnegie Mellon University in January 2024 an assistant professor in the Department of Biological Sciences, was working at the U.S. Centers for Disease Control and Prevention in Atlanta from 2008 to 2011, while she worked toward her master’s degree in public health at Emory University. Part of her team’s job at the CDC was to investigate the causes of infectious outbreaks in hospitals. She said most could be traced back to biofilms.

“As a public health scientist at the CDC I became obsessed with biofilms,” she said, referring to communities of bacteria or other microbes where the cells are encased in a protective, slimy glue. “I wanted to dig deeper into molecular mechanisms of biofilm formation and how they allow bacteria to persist in stressful environments, whether that’s in the host or the natural or built environment.”

Armbruster went to the University of Washington for her Ph.D. in microbiology, joining two labs focused on biofilms. Matthew Parsek’s lab studies molecular genetics and biofilm signaling. Lucas Hoffman, a pediatric pulmonologist and microbiologist, leads a lab focused on cystic fibrosis (CF). She went on to study how bacteria evolve in CF biofilm infections during her postdoctoral training in the laboratory of Jennifer Bomberger at the University of Pittsburgh and Dartmouth College.

A genetic disease where people develop respiratory infections caused by biofilms, Armbruster said CF is an ideal subject for study. People with CF have chronic, polymicrobial infections in their airways, allowing scientists to study how the host-biofilm relationship evolves over years. Advances made in the treatment of CF in recent decades — particularly a new type of drug first approved by the FDA in 2012 — have meant that the life expectancy for people with CF has almost reached that of the general population just during the time that Armbruster has been studying it.

Connecting with the researchers, clinicians and CF families every year at the CF Foundation’s conference personally invests her in the community’s work. The CF Foundation’s slogan is “until it’s done.”

“We’re going to keep studying CF until there are treatment strategies for everybody, not just people with the most common mutations that cause CF, who are the people currently benefiting from the drugs,” she said. “That’s the spirit — we keep studying the disease until everybody benefits.”

Armbruster has been recognized by the National Institutes of Health and the CF Foundation. She earned a K22 career transition award from the NIH, and she earned a Postdoc-to-Faculty Transition Award from the CF Foundation. Most recently the CF Foundation gave her an additional $50,000 a K-boost grant to support her work.

Armbruster’s new lab investigates the ecology and evolution of opportunistic pathogens in biofilms, especially Pseudomonas aeruginosa, on both sides of the environment to host transition. In one study, she is partnering with two physicians at Dartmouth College, Drs. Laura Paulin and Alix Ashare, whose CF patients have shared swabs of their homes. Armbruster is investigating if locations in the homes may house a reservoir of bacteria that go on to cause infections. The patients have long-term respiratory infections, which can persist even in patients taking drugs that correct the protein folding and protein abundance problems caused by CF.

One of the things that drew her to Carnegie Mellon was the opportunity to collaborate with experts in other disciplines, including engineering, automation and computational biology. Her lab will provide a range of training opportunities in both wet bench experimentation and dry lab bioinformatic analyses, she said. Undergraduate and graduate students working in the lab can build skillsets at the intersection of bacterial genetics, microbial pathogenesis, and ecology and evolutionary biology.

“Science is more fun when you have people with diverse backgrounds and experiences,” she said. “Somebody with a different skill set can approach the same problem as me from a completely different angle, and it can be really exciting. I think that intersection is where some of the most innovative work happens — when you bring together people with those distinct backgrounds and expertise.”