Evolution of drug resistance

Published on November 30, 2023   36 min

Other Talks in the Series: Introduction to Evolutionary Biology

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Hi everyone. My name is Pleuni Pennings, and I'm an Associate Professor at San Francisco State University. I use population genetic theory and analysis of patient data to study the evolution and spread of drug resistance in human pathogens to find better ways to prevent drug resistant infections. Today, I will talk about the evolution of drug resistance in HIV, Mycobacterium tuberculosis, and Staphylococcus aureus. The lecture will include information also on selective sweeps and clonal interference.
According to Wikipedia drug resistance is the reduction in effectiveness of a medication, such as an antimicrobial, in treating a disease or condition. In other words, we speak of resistance when a medication such as an antibiotic which normally works on a pathogen like bacteria in the sense that it kills it or it makes that it cannot replicate, doesn't work anymore. The pathogen, bacteria, viruses or other pathogens are now resistant to the medication. This picture illustrates drug resistance. In the upper panel, we first see how bacteria multiply, but then when the patient takes antibiotics, the bacteria die. In the lower panel however, the bacteria are resistant. They don't die when the antibiotics are used. That means that the antibiotics cannot cure the patient. What you see in this picture as well is that the genetic material of the bacterium, a circular genome, now has an added red piece in the lower panels. This additional piece of the genome can be a gene or a set of genes that cause drug resistance. Drug resistance can also be caused by smaller changes to the genome. Sometimes a simple mutation that leads to a single letter change is enough to make a pathogen resistant to a drug. We'll see that in HIV and Mycobacterium tuberculosis.