Bacteria Like E. coli Swim Upstream in Our Bodies To Infect the Urinary Tract and Gut
When bacteria like Escherichia coli (E. coli) enter our bodies, they swim toward targets like the intestines and the urinary tract. These intruders will stop at nothing to colonize and infect spaces. In fact, bacteria can swim upstream, going against the flow to launch their invasion.
In a new study published in the journal Newton, researchers tracked the movement of E. coli to see how bacteria move throughout the body. They found that bacteria are experts at navigating the channels within our bodies, and can even dash through strong fluid currents. Beyond showing how bacterial infections spread, this knowledge may also provide a blueprint for microrobots that deliver drugs in the body.
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E. coli are Remarkably Fast Swimmers
Bacteria are able to swim effortlessly, all thanks to their flagellum; this appendage that extends from bacteria rotates to propel them in liquid environments. It contains a motor that can switch between clockwise and counterclockwise motions, allowing bacteria to change direction as they move, according to a study in Trends in Microbiology.
“Bacteria are remarkably fast, adaptive swimmers, capable of moving hundreds of body lengths per second while being subjected to strong fluid flows,” said study author Arnold Mathijssen, a biophysicist at the University of Pennsylvania, in a statement.
But rather than go with the flow, bacteria swim upstream and eventually reach areas like the respiratory, gastrointestinal, and urinary tracts. They also move the same way in medical equipment, like catheters. Against all odds, bacteria have no trouble contaminating and infecting spaces that would normally seem difficult to reach.
Going Against the Flow
The researchers involved with the new study wanted to figure out why bacteria are able to swim so well, even when fluid currents are pushing against them. To solve this mystery, they created nanoscale, multichannel tubes that mimic those found inside the body, and then had E. coli swim through them.
The researchers tracked thousands of cells, combining these observations with simulations and mathematical analysis to predict bacterial flux — the total number of cells moving upstream over time — across different microtube shapes and configurations.
E. coli easily swam through the tubes that resemble those in the human body, with smooth and rounded corners. Sharp corners, on the other hand, disrupted the bacteria’s motion and stalled their spread. If medical devices were to implement these sharper corners in their designs, it may help prevent contamination by bacteria.
In terms of fluid flow, the researchers were surprised to see that stronger flow helped bacteria swim faster rather than slowing them down or washing them away. The bacteria used stronger currents like guide rails, aligning with the flow and ultimately reaching upstream locations faster than they would in less abrasive conditions.
“Within minutes, we see the first cells arrive all the way upstream,” said coauthor Suya Que, an undergraduate researcher at the University of Pennsylvania. “Once they’re there, those early pioneering cells seed new colonies and create a ‘two-way’ invasion that advances from both ends.”
Robots Inspired by Bacteria
Once bacteria reach their destination, they form streamer-like bioaggregates that drift back downstream to colonize the whole channel.
The researchers say that this has important implications for infections like UTIs; the presence of bacteria in a lower part of the urinary tract, for example, may be a precursor to a larger problem higher up in the kidneys.
Knowing how bacteria swim could help with infection prevention, and it may also inspire the design of microrobots that can deliver drugs to targets within the body.
“The mechanisms that they use to reorient against the flow direction and to swim upstream are very similar to that of a microrobot,” said Mathijssen. “I think this is a very exciting area in biomimicry — learning from biology — that could help us create better biomedical tools and potentially new therapeutics.”
This article is not offering medical advice and should be used for informational purposes only.
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