The Nobel Prizes should remind us that every day there are eye-opening advancements being made in every field of science. One that we tend to overlook is the study of microbiology and, in my opinion, it shouldn’t be. These marvelous single-celled organisms display amazingly diverse chemical and physical properties. They also sport more shapes and colors than all the fruits in our supermarkets.
These organisms are small but hardy and can be found almost anywhere in the world, from the deep sea volcanos off the coast of Hawaii and the boiling hot springs of Yellowstone to the Utah's Great Salt Lake and in winding caverns deep beneath the Earth.
Bacteria also divide at a rate that would boggle our minds. A new generation of Escherichia coli, for example, can grow every 15-20 minutes under optimum conditions.
Some species, however, are pathogenic and dangerous to humans, especially to patients that have recently undergone intensive surgery. In the past, treatment with antibiotics would be recommended to a patient with a bacterial infection. Due to the emergence of antibiotic resistance among certain bacteria strains, however, it is becoming more and more common nowadays for patients to die from bacterial infections.
One particularly nasty example is MRSA (Methicillin-resistant Staphylococcus aureus). After years of doctors unnecessarily prescribing this antibiotic to patients with symptoms unrelated to Staph infections, this bug has become resistant to many of the antibiotics that were once effective treatments for it.
The concept of antibiotic resistance is difficult to grasp because the methods we have to observe it are limited. Motivated to see the development of antibiotic resistance in action, scientists at Harvard Medical School built MEGA, a giant 2-by-4-foot petri dish filled with black agar infused with a gradient of antibacterial drugs.
At the far left- and right-hand side of the plate, E. coli were allowed to grow in regions containing no antibiotics. Being white, the bacteria could easily be seen growing on top of the black agar.
Over the course of 11 days, the E. coli were imaged every 10 minutes as the colonies inched closer and closer towards the center of the plate, where antibiotic concentration was highest. They noticed that the bacteria would pause at a boundary where the dose of antibiotics was higher. Mutants, however, would occasionally occur that could survive at increasingly higher concentrations of antibiotics. By challenging the bacteria with different concentrations of antibiotics, they mimicked a real-life scenario. They showed that bacteria like E. coli, which has been the cause of several food-related deaths, evolve antibiotic resistance more quickly if they introduced to smaller doses of antibiotics.
Where could this happen in real life? Say, for instance, you were prescribed antibiotics by your doctor. If you did not take the full regime (as it is common for patients to do), then the survivors left in your system could develop into a mutant strain Doctors also sometimes prescribe antibiotics to patients for unrelated illnesses. Under this selective pressure, potential pathogens in your body could evolve and become resistant to those treatments. As the video below shows, this type of evolution occurs at a blindingly fast rate. It makes it difficult to develop new, effective drugs because, once resistance develops, they become virtually useless against infection.
This giant petri dish makes this process easier to visualize and should hopefully raise some awareness about this issue. As a public service announcement, please obey your prescriptions and take the full course of your antibiotics, even if you think you might be cured of an infection. Also, do not flush your medications down the toilet. There is a higher risk of antibiotic resistance developing in aquatic microbe populations if the drugs enter the water system, especially at diluted levels.
Try following this link if you’re interested in the details of the experiment:
