One of the most pressing concerns in medical innovation is how to address the problem of bacteria becoming resistant to antibiotics. There are regular news updates about diseases that are becoming resistant to traditional drugs, such as MRSA and even Super Gonnoreah.
Harvard Medical School just released the video above to showcase a recent experiment to map out how bacteria adapt and evolve to overcome antibiotics. And apparently, the experiment was inspired by Hollywood.
It shows an enlarged petri dish (2ft by 4 ft), divided into nine zones with varying concentrations of antibiotics designed to kill the E-coli bacteria introduced into the least concentrated areas. The experiment was designed to see if (and how), bacteria could spread in the zone they were comfortable in, but then had to adapt when they met the boundary which would ordinarily kill each individual cell.
As you can see in the video, the bacteria quickly colonised the first section (rectangle) without any antibiotics, but stopped once they met a slight dosage of antibiotics. After some time though, random mutations as the bacteria reproduced allowed a few cells to resist the antibiotics, enabling them to outcompete their other neighbouring cells and colonise the new area. This is a perfect example of evolution by natural selection, as these new mutant cells could take advantage of their new trait. This process repeated itself several more times until there were several different mutant variants all competing for the resources in the most concentrated centre section.
Co-investigator Tami Lieberman says the images spark the curiosity of lay and professional viewers alike.
“This is a stunning demonstration of how quickly microbes evolve. When shown the video, evolutionary biologists immediately recognize concepts they’ve thought about in the abstract, while nonspecialists immediately begin to ask really good questions.”
First author of the study Michael Baym also noted:
“What we saw suggests that evolution is not always led by the most resistant mutants. Sometimes it favors the first to get there. The strongest mutants are, in fact, often moving behind more vulnerable strains. Who gets there first may be predicated on proximity rather than mutation strength.”
Interestingly, the initial idea for the experiment was inspired by Hollywood. Senior study investigator Roy Kishony, of HMS and Technion, had seen a digital billboard advertising the 2011 film “Contagion,” a grim narrative about a deadly viral pandemic. The marketing tool was built using a giant lab dish to show hordes of painted, glowing microbes creeping slowly across a dark backdrop to spell out the title of the movie. The original promo video is below:
Work like that of the Harvard team is vital in understanding how bacterial infections spread and evolve. Thankfully, there are hundreds of scientists around the world trying to find new and innovative ways of attacking dangerous bacteria without requiring higher concentrations of existing antibiotics.
By looking around us in nature for examples of where other organisms are already using their own chemical cocktails to fight infection, we are finding a wide array of new compounds which could be used to fight the same battles inside our own bodies. And with a larger selection of ways to attack bacteria, it becomes significantly more difficult for the bacteria to evolve resistance to each one, and almost impossible to evolve resistance to combinations of compounds.
Several different teams are already making progress and finding promising new antibiotic compounds in:
- Leafcutter ant colonies
- The Atacama desert
- Soil
- Marine Sponges
- Golf course
- Our own noses
- Men’s beards
- A medieval remedy cookbook, whose onion & garlick eye salve appears to kill MRSA!
A fantastic example of how looking outside of your normal boxes can lead to you finding novel solutions to difficult problems.
Nick Skillicorn
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This may not actually show what it is purported to. There are no replicates and the antibiotic needs to remain stable in the agar at 37C for 11 days – highly unlikely. I suspect what this actually shows is the antibiotic breaking down to a level some mutants of the bacterium can tolerate. The apparent pause and then proliferation could be due to higher starting levels of antibiotic taking longer to degrade to a tolerable level.