Professor David McAdams is an economist trained in game theory, the science of strategic situations. He has spent the last three years developing strategies to combat and even reverse the troubling rise of antibiotic resistance, whereby bacteria are becoming resistant to the antibiotics we use to treat them. His ideas are outlined in his recent book "Game-Changer."
McAdams elaborates on how we can overcome antibiotic resistance in this Fuqua Q&A.
Q: Explain the antibiotic resistance problem you're trying to tackle here.
We all take it for granted that drugs will be available to treat us when we get sick. The fact is, however, that drugs are failing and right now people are sick with bacterial diseases that cannot be treated by any drug known to man. The logic behind this rise of antibiotic resistance is that since antibiotics kill the bacteria that are susceptible to them, only the resistant bacteria survive. So, it would seem, every time we prescribe antibiotics we create a selective pressure that favors antibiotic-resistant bacteria, allowing them to grow in number and eventually take over the bacterial population. Consequently, when people get sick with the diseases that these bacteria cause, antibiotics no longer work. For this reason, many in the medical community view it as just a matter of time until antibiotics don't work anymore. Even the director general of the World Health Organization routinely speaks of a "post-antibiotic future" in which, she says, "strep throat or a child's scratched knee could once again kill." I'm not willing to accept that. We need to change this game.
Q: You're not an expert in the health care field. How did you approach this subject?
This is an extremely complex problem, and I've spent the past three years studying the scientific literature and engaging with and learning from leading experts in the field, including Dr. Mario Raviglione, director of the Global TB Programme at the World Health Organization; Dr. Arjun Srinivasan, associate director of Healthcare Associated Infection Prevention at the Centers for Disease Control and Prevention; Professor Gerald Wright, a bacterial genome expert at McMaster University; members of the antibiotics discovery team at GlaxoSmithKline. These experts were extraordinarily generous with their time and in their willingness to review my ideas, correct my misunderstandings and share their own thoughts on how to improve my analysis and recommendations.
Q: How does game theory apply here?
We tend to think of ourselves as playing a game—a battle—with the bacteria that have invaded our bodies. From a game-theory point of view, however, the life-and-death struggle that matters most is between competing strains of the same disease, each battling for supremacy among the total population of bacteria that cause the disease. The winner will be the one that can infect us, transmit itself, and survive medical treatment most effectively. Susceptible bacteria, the ones we can kill with our drugs, are actually our allies. If we can find a way to give susceptible bacteria an advantage—rather than putting them at a disadvantage like we currently do with antibiotic treatment—we can let them do the dirty work to beat the resistant strains back, and even drive resistant bacteria to extinction.
Q: How can susceptible strains be given an advantage in this game?
There's an important movement already under way to use antibiotics more sparingly. Also, some farms are producing antibiotic-free meat. But such efforts can only slow down the rise of antibiotic resistance, not reverse it. What I propose is a more fundamental way to change the game, taking advantage of recent advances in the science and technology of disease diagnostics. It's now possible, when a patient comes to the doctor, to run a test that shows not only what sort of disease the patient has, but also which drugs will be most effective against it. In the past, this sort of susceptibility diagnosis took weeks and had to be performed by a skilled laboratory technician. Because of recent advances in molecular diagnostics, however, it is now possible to "read the genes" of bacteria that have infected us and detect whether they are resistant to antibiotic treatment, all within about an hour, at a cost that can be as low as $10 per test. One such test, the GeneXpert, is now in use worldwide against drug-resistant tuberculosis, and in the United States against drug-resistant staph infections. With such a test, we can identify patients who are infected with resistant bacteria before treatment is prescribed, and hence target treatments at resistant bacteria in ways we could not before. If these targeted treatments are even more effective at stopping the spread of resistant bacteria than the standard treatment is at stopping susceptible bacteria, then resistant bacteria will be at an overall disadvantage. In this way, we can treat every patient with the best care, while also giving susceptible bacteria an advantage in their battle against resistant bacteria. Because of this recent technological advance, we really are at a watershed moment in the fight against antibiotic resistance. If we move quickly enough, we can stop the rise of antibiotic resistance and even reverse it. In so doing, we can preserve the effectiveness of antibiotics, forever.