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Hello. My name is Sebastien Gagneux and I am
a group leader at the MRC National Institute for Medical Research in London.
I'm going to talk about the role of Darwinian fitness and
compensation in the evolution of drug resistance in bacteria.
I would like to start this presentation by introducing
the concept of Darwinian fitness in the context of antibiotic resistance.
I will then outline why we should care about the role of
Darwinian fitness in drug resistance and present several ways fitness can be measured.
I will discuss how the fitness of drug-resistant bacteria
can vary depending on the particular drug resistance mutation,
the environment, or strain genetic background.
And we'll review various aspects of compensatory evolution and
end with a few suggestions for future research.
Darwinian fitness can broadly be defined as
the ability of an organism to survive and reproduce in a given environment.
In addition to measuring the total or absolute number of viable offsprings,
Darwinian fitness is often expressed as a relative measure.
For example, as the relative fitness of
a drug-resistant organism compared to the corresponding drug-susceptible form.
There are at least four main reasons why we should
care about the effects of drug resistance in bacterial fitness.
First, we would like to be able to make predictions about
the future trajectory of the global epidemic of drug resistance,
and I will show you an example of that.
Second, we need to be able to evaluate
interventions aimed at reducing the spread of drug-resistant organisms.
For example, will the withdrawal of
a particular antibiotic result in the reduction of resistance?
Third, a better knowledge of the fitness impact of
drug resistance could help us design better antimicrobials.
For example, by focusing on compounds to which developing resistance to,
will be particularly costly to the pathogen.
And four, studying fitness in the context of drug resistance
allows us to address fundamental evolutionary questions.