Today, I am thankful for how one amazing discovery can open the door to more discoveries.
Dr. Heinrich Robert Koch was a German microbiologist and physician who helped change microbiology forever. He is eminently regarded as the ‘Father of Modern Microbiology’ for his pivotal discovery of the causative agents responsible for many bacterial diseases. He did so using a revolutionary method to selectively culture bacteria on a solid medium.
And, all of this might not have happened without some serendipity. Let me take a moment to explain.
Several years after graduation from medical school, Koch served as a surgeon in the Franco-Prussian War, where he witnessed the horrors of infection. After the war, this harrowing experience compelled Koch to conduct research on microorganisms in his laboratory, which was adjacent to where he saw patients.Now, it’s important to realize that, up until that point, bacteria had been grown in liquid broth, so it was technically not feasible to isolate bacteria.
One day, as the legend is told, he inadvertently left his unfinished lunch in his laboratory. After a long weekend, he returned to discover that part of his uneaten potato was covered by different colored growths. Those growths turned out to be colonies of microorganisms. This serendipitous discovery gave Dr. Koch the idea to plate bacteria on a solid medium, as opposed to a liquid broth. He confided his finding to one of his colleagues (Julius Petri) who helped invent in a shallow jar that could be used to hold the medium; together, Koch and Petri would invent the “Petri dish” as a novel vehicle to isolate, analyze, and identify bacteria.
Although his work in ‘pure culture’ microbiology was truly the transformative advance, it was actually Koch’s subsequent discoveries that won him a Nobel Prize. Knowing he now had a critical tool to identify bacteria, Koch outlined 4 principles that have historically served as the foundation of microbiology discovery (The Koch Postulates). The 4 tenets are as follows:
1. An organism must always be present, in every case of disease.
2. That organism must be isolated from a host with the disease and then grown in pure culture.
3. Once grown in a pure culture, that organism must elicit the same disease upon inoculation into a healthy animal in the lab.
4. The organism must then be isolated from the inoculated animal and identified as the same original organism.
How simple. How logical. How brilliant.
So, Koch put his postulates to work to identify the cause of tuberculosis, or TB for short. At that time, many scientists had theorized that TB was an inherited disease, but Koch was convinced TB was caused by a bacterium.Through elaborate experiments in guinea pigs, he uncovered that TB satisfied all four of his postulates. On this day (Mar 24) in 1882, he publicly announced his findings identifying the causative agent of TB as a the slow-growing bacterium, Mycobacterium tuberculosis.
Using the same 4 postulates, Koch proved it again and again for other diseases, such as anthrax and cholera. But, his discovery of the etiology of TB would result in his receipt of the Nobel Prize in Physiology or Medicine in 1905.
Today, we celebrate World TB Day in honor of Koch’s stellar discovery. Today, we also celebrate how we can use these same tenets to tackle infectious pathogens of any etiology, including pesky, respiratory viruses.
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