A new study reveals that two stressors may be better than one in preventing certain harmful bacteria from thriving in the human body. Researchers at the University of Illinois Urbana-Champaign report that physical fluid flow and the chemical presence of hydrogen peroxide can work together to halt the spread and growth of dangerous pathogens.
By treating cells with levels of flow and hydrogen peroxide (H2O2) that commonly co-occur in human host tissues, the Illinois researchers discovered that previous reports significantly overestimated the hydrogen peroxide levels required to block bacterial growth. They found that flow increases the effectiveness of hydrogen peroxide by 50-fold.
The findings, published in the journal Current Biology, stem from an interdisciplinary effort led by Joe Sanfilippo, an assistant professor of biochemistry at the University of Illinois Urbana-Champaign. His lab crafted tiny devices to mimic fluid movement through the body — like blood flowing through arteries or air passing through the lungs — and tested how these conditions interact with small amounts of hydrogen peroxide, a natural compound in human tissues.
“Traditionally, studying how bacteria handle physical flow in the body is hard because the standard lab tools — Petri dishes and test tubes — don’t recreate these conditions,” said Sanfilippo. “By building microfluidic devices, we can study the effect of realistic fluid flow at the cellular level. That gives us a whole new picture of how bacteria respond to stress.”
In their experiments, the researchers focused on Pseudomonas aeruginosa, a well-known pathogen that can cause serious infections. Under normal lab conditions, scientists believed the amount of hydrogen peroxide needed to suppress bacterial growth would be far beyond what the human body naturally produces. But this new study tells a different story.
Joe Sanfilippo, professor of biochemistry, and Anu Sharma, PhD student.
“When we added even a small flow — similar to what bacteria experience in the human body — the naturally occurring levels of hydrogen peroxide suddenly became powerful enough to block bacterial migration and growth,” said Anu Sharma, a PhD student, and the study’s lead author. “Without flow, we would need far higher doses of hydrogen peroxide to achieve the same effect. Under realistic conditions, it’s a 50-fold increase in effectiveness.”
The research also delves into how different types of stressors can work together. Rather than simply predictably stacking their effects, flow and hydrogen peroxide showed “positive synergy.” In other words, their combined impact in stopping bacterial spread was greater than the sum of their individual contributions.
“Stressors can add up in unexpected ways,” said Sanfilippo. “Sometimes two stressors combine to be weaker than expected: sometimes they’re stronger. Here, we saw a clear boost in their collective power. It’s like getting a 2+2=5 scenario.”
The team’s findings raise new questions: If flow and hydrogen peroxide can work together so effectively against bacteria, what about other pairs of stressors? The Sanfilippo lab plans to continue using microfluidic systems to explore how various challenging conditions — from chemical compounds to mechanical forces— combine to help or hinder harmful bacteria.
The National Institutes of Health supported the study, “Combining multiple stressors blocks bacterial migration and growth.”
That was awesome to read.