Stanley Falkow: The Man Who Gave Bacteria Their Bad Reputation

It’s hard to believe, but before the 1960s, bacteria were mostly seen as a nuisance rather than dangerous. Then along came Stanley “Stan” Falkow, a scientist who changed everything. Falkow had an idea: What if bacteria had ways of adapting, learning, and spreading that made them more dangerous than we ever imagined? Falkow’s research and discoveries on the topic would turn the world of medical science upside down and give bacteria the “bad” reputation they carry today.

Bacteria as Strategic Invaders

The story begins in the 1960s. Stanley Falkow wasn’t your average scientist. Born in Albany New York, he had a mind full of questions and an intense curiosity about the tiny, invisible world of microbes. After earning his PhD from Brown University, in Rhode Island, Falkow quickly made a name for himself. He began teaching as a faculty member at Georgetown University, then the University of Washington, and later joined the Stanford University School of Medicine as a professor of microbiology. But no matter where he went, he remained fascinated by one question Why do bacteria make us sick?

Most scientists in the 1960s thought that bacteria caused disease because they happened to be in the wrong place at the wrong time. Falkow didn’t believe it was that simple. In his early research endeavors, he noticed that bacteria carried special instructions within their cells, like tiny blueprints, for infection. He believed that these blueprints were hidden in DNA sequences called plasmids, small, circular bits of DNA, separate from the bacterial chromosome, that encodes unique information for bacterial survival. 

The Discovery: Bacteria Share Their Secrets

Falkow set out to study plasmids in detail and noticed that bacteria weren’t just holding onto these plasmids—they were sharing them with each other. This ability to transfer genetic information between bacteria is known as horizontal gene transfer, and it blew open the doors to a new understanding of how bacteria operate. Falkow discovered that bacteria could spread their “blueprint” for infection from one bacteria to another creating stronger, more dangerous bacterial strains that can evade the immune system and the potential for antibiotic resistance. His work showed that bacteria were constantly evolving and adapting and that fighting bacterial infections wouldn’t just be about killing germs, it would require outsmarting them.

Molecular Pathogenesis: Understanding How Bacteria Cause Disease

Stanley Falkow's discovery of plasmids and horizontal gene transfer paved the way for a new field called molecular pathogenesis, which focuses on how bacteria cause disease at the molecular level. Falkow realized that by understanding the mechanisms bacteria use to invade the body and evade the immune system, scientists could develop better ways to combat infections.

One of Falkow’s most significant contributions was the concept of “Molecular Koch’s Postulates.” Named after Robert Koch, the scientist who developed the original Koch’s Postulates (which explained how bacteria cause disease), Falkow’s version targeted the specific genes involved in making bacteria pathogenic.

Through diligent research, Falkow and his team used Molecular Koch’s Postulates to identify which bacterial genes were responsible for infection. They demonstrated how these genes allowed bacteria to thrive within a host. Falkow’s postulates became the gold standard for identifying bacterial virulence factors—the parts of bacteria that make them harmful to humans.

Awards and Achievements: A Lifetime of Discovery

Stanley Falkow was renowned worldwide for his contributions to the study of infectious diseases. In 2008, he received the Lasker-Koshland Award for his groundbreaking work, and in 2015, he was honored with the National Medal of Science, one of the highest scientific accolades in the United States. Despite these prestigious awards, Falkow remained humble, always curious, and constantly searching for the next big discovery.

As a professor at Stanford University School of Medicine and other institutions, he mentored countless young scientists, encouraging them to lead with curiosity and passion. Falkow’s remarkable ability to inspire others set him apart from many other scientists.

The Microbe Hunters: Falkow’s Lasting Influence

Stanley Falkow’s fascination with bacteria wasn’t just a passing interest—it was a lifelong passion. Inspired by Paul de Kruif’s famous book, “Microbe Hunters,” which told the stories of scientists who first discovered bacteria and viruses. Falkow himself became part of the next generation of microbe hunters.

Stanley Falkow’s work reminds us that curiosity—the drive to understand the world around us—is the key to solving those mysteries. Falkow’s research on bacterial virulence, plasmids, and host-cell interactions has forever changed how we think about disease and infection. His Molecular Koch’s Postulates gave scientists a new framework for studying bacteria at the genetic level, and his discoveries about antibiotic resistance continue to influence research today. But perhaps the greatest lesson we can learn from Falkow is this: never underestimate the power of small things. Whether it’s a tiny bacterium or a single idea, small things can have a huge impact. Stanley Falkow gave bacteria their bad reputation, but in doing so, he gave us something even more important: a deeper understanding of the microscopic world that surrounds us. 

Check out these resources to learn more about Stanley Falkow:

Conger, Krista. "Renowned Microbe Hunter Stanley Falkow Dies at 84." Stanford Medicine News Center, 1 May 2018, https://med.stanford.edu/news/all-news/2018/05/renowned-microbe-hunter-stanley-falkow-dies-at-84.html. Accessed 28 Oct. 2024.

"Microbial Genomics: Standing on the Shoulders of Giants: Professor Stanley Falkow, Part I." Microbiology Research, www.microbiologyresearch.org/sotsog/stanley-falkow. Accessed 28 Oct. 2024.

"Microbial Genomics: Standing on the Shoulders of Giants: Professor Stanley Falkow, Part II." Microbiology Research, www.microbiologyresearch.org/sotsog/stanley-falkow. Accessed 28 Oct. 2024.

"Microbial Genomics: Standing on the Shoulders of Giants: Professor Stanley Falkow, Part III." Microbiology Research, www.microbiologyresearch.org/sotsog/stanley-falkow. Accessed 28 Oct. 2024.