Dena was awarded her PhD in 1995, investigating the genetic and molecular determinants of three phenotypes associated with the TraB region of plasmid RP. Her postdoctoral research focused on the pathogenesis of bacteria and in 2010 she established her independent research laboratory at Monash University. Dena was awarded an ARC Future Fellowship in 2012 and was promoted to Associate Professor, to investigate molecular aspects of hypervirulence and the infectious cycle in Clostridium difficile. Professor Lyras leads the Functional  Biology of Bacterial Pathogens Laboratory in the Biomedicine Discovery Institute.

Dena is the Deputy Director of the Biomedicine Discovery Institute and the Deputy Head of the Department of Microbiology, both at Monash University, and the President for the Australian Society for Microbiology.

 In 2020, Dena joined the Centre to Impact AMR as a founding member.

A superbug of our own creation

The rapid evolution of bacteria and the excessive use of antibiotics have turned our hospitals from institutions of healing to incubators of new breeds of superbugs. The challenge for researchers such as Dr Dena Lyras is to uncover the secrets and weaknesses of bacteria that are changing before their eyes.

Dena has spent her research career developing world-leading knowledge of the bacterium Clostridium difficile, a gut bacterium that causes disease in the intestines. The bacterium usually attacks hospital patients that are being treated with antibiotics for other, unrelated, infections.

Over the past decade the bug has undergone a radical evolution that has allowed it to thrive in hospital environments and develop into the leading cause of death from hospital-acquired antibiotic associated intestinal infection.

Clostridium difficile has become so successful at exploiting our modern hospital practices that it is now found in every hospital in the world that uses antibiotics. And not only is the bactrium surviving medical science's best attempts to kill it, it is actually becoming more deadly.

"I'm interested in this bacterium because it has adapted so well to our modern hospital environments. It is really a product of our times," Dena says.

"It was not known to cause problems before antibiotics, but the introduction of antibiotics changed things and it found a new niche to occupy. As a consequence it has become a significant problem in hospitals worldwide.

"It has also changed genetically and now causes more severe disease. Where people would normally be treated and recover, now we have people who are far sicker, and more people are dying because they cannot recover from these infections.

"The reason for this is that the bacteria quickly adapt to the environment they are in - in this case hospitals - resulting in newer versions of the bacteria that are far better at causing disease. In other words, superbugs. I am interested in how that process happens."

Researchers in Dena's lab, the Clostridial Genetics Laboratory, are trying to understand how Clostridium difficile causes disease, and in particular why these new versions of the bacterium have become more potent.

Part of the bug's success lies in the use of antibiotics in hospitals. Not only have the bacteria developed increasing resistance to antibiotic treatments, but the devastating effect some drugs have on the good bacteria that protect our bodies is creating a space that harmful bacteria can exploit.

Dena's team have enjoyed some success in better understanding the bug through genetic manipulation. She was the lead author of a study published in the prestigious journal Nature, which shed new light on the essential role specific toxins play in causing disease, a discovery that disproved prevailing opinion.

More recently, Dena's team have discovered new genetic factors responsible for creating the increased virulence of the bacteria in research that has recently been accepted for publication in another prestigious journal.

Dena is now using this knowledge to develop new therapeutic strategies capable of tackling the ever-changing super bug. She heads an ARC Linkage project in collaboration with industry partners who are developing strategies for handling these infections.

But there are no promises of an easy fix.

"We think of these bacteria as lacking complexity, but when we see what they can do we see that they are incredibly complex and can change at a frighteningly fast rate," Dena says.

The Lyras laboratory is focussed on enteric pathogens, particularly those involved in antibiotic-associated diarrhoea such as C. difficile, and they examine how these pathogens interact with the host and cause disease through the use of animal infection models. Her laboratory uses genetic approaches to understand how these micro-organisms harness regulatory and virulence factors to cause disease, and they are developing immunotherapeutics and small molecules to prevent and treat these infections in collaboration with industry partners. Antibiotic resistance and DNA mobility are also studied in her laboratory, in the context of gut pathogens and antibiotic-associated diarrhoeal disease.