[MUSIC] So hello, welcome. I'm here for this antimicrobial resistance lecture, this time on selection. My name is Lina Cavaco and I have a very interesting presentation about this selection issue. In the previous lectures you have heard about how resistance happens and how it can spread around. And here, selection would be how can it really be a bigger problem, how this problem can grow. So we'll look into that more in detail. I'll have some introduction about what this selection and selection of resistance as such, and how a bacteria can be even multidrug resistant. So and then come in the news as a big, big threat and issue. And how a little bit of about the history of emergence and now we have been talking about single bacterias. I'll also bring it just a touch up on that bacteria sometimes are not alone and they are together in a society. So to start with, well, many of you have heard about Charles Darwin and that he figured out how we evolve and how we are selected naturally so that the best ones survive and go ahead. In bacteria it is quite similar. So if they are adapted to the environment and if they can survive better, they will be fittest and they will survive. So also in antimicrobial resistance, that's what happens. The best ones, the most resistant ones are the ones that can survive to the environment. So we can think of selection theoretically as something that happens well. We have these bacteria, they are normal, they are growing around in the environment. Or maybe in an animal or in a human, it doesn't matter. They are dividing, and suddenly one of these bacteria became resistant. Let's say it became resistant by a mutation. It could be by a resistant gene. It doesn't matter in this case, but it became more resistant than the others. Here in this environment they are living happily and they don't have any antimicrobials. But, let's say that some point they are transferred into this environment that has antibiotics. Suddenly only the green ones survive. So the blue ones are dead, they are not there anymore, and the green ones take all the space. So suddenly, it's a big advantage to be green. And that's what selection is about. And when we talk about reduction of use of antimicrobials when it's not necessary. For example if you have a flu that you should not take antibiotics it's to avoid this. To avoid that bacteria become or select to be resistant even when it's not necessary. So if we take, for example, now we have two populations of bacteria, the blue ones and the green ones. The green ones have some resistance genes, but they are living in the place where it's not really necessary. But because they are in the same population they might have some contact with each other. And because they have some contact with each other way, one of the round ones become green because it's acquired this resistance determinant. But it doesn't really need it. But once there is some selective pressure, and this is a definition that we also need to give, that is, for example, an environment where antimicrobials are present. And give some pressure towards the resistance, so that the pressure makes that the resistance is an advantage. Suddenly being green is an advantage. So also the blue ones become green more often. Because the blue ones might be dying under that pressure. So the key word in this is selection. If we have a resistance level that is low and there is some antimicrobial in the environment or in the animal or in the human, there is some treatments going on, the tendencies get higher and higher. So that's why in countries we measure resistance and we look at, is it getting higher, is it getting worse? Do we get still people treated with these antimicrobials? And we start to worry once it gets worse. So and here we have one thing that if it can get worse, it will. It's the law of Murphy in a way. So if we have resistance going on and there's more and more use, you get the same bacteria maybe getting even more resistant genes, and more resistant genes, and it will get worse and worse. So there's kind of a snowball effect. And if we keep on using a lot of antibiotics, it might be that at some point we don't have possibilities for treatment because it gets worse and worse in the bacteria. And, we don't want it to get here, but, unfortunately, I must tell you that some bacteria are really so difficult to treat that there is almost no antimicrobial to treat them. If we go really back, we had only plants to do some treatments. If you go a little bit then there were some that making potions out of these plants. Then in 1941, that's where penicillin came into the market. It was discovered a few years before. Then they say well potions are quite poisonous. We have antibiotics that are better and then don't cause so much problem to the person that takes them. Let's take penicillin. Then other scientist found maybe some bacteria are getting resistance. Other drugs are being found. Let's take other drugs. And then, it happens that some are resistant now to this one too, let's take a new one. And it went on with new one and new ones. Now for a few years, we don't really have many new ones. They haven't been discovered many. So we hope we don't get there. If we many oops later need to eat the plant again, I hope not. But sometimes in the hospitals it's already there that doctors don't really have many choices anymore or almost no choices anymore. So this is to give you an idea about bacteria as one. But we haven't talked about societies. Sometimes bacteria are together in a, living together on a surface or living together in a society where they are quite structured. They're not only living for themselves. And here they are not only acting for themselves and having their own resistance. They also have some resistance as a group. So actually in this situation they might have some modifications. And they might have some stress responses and cells that are becoming more persistent and more adapted. And actually the tendency is if they are in these biofilms and in the societies they're actually more resistance to the action of drugs. So it's more difficult to get rid of a bacteria that are in this situation. So that's why sometimes we have hospital infections due to bacteria in a certain surface or in catheters for example. So this is also something that the doctors worry quite a lot about, about the biofilms and the bacteria as a society. Thank you very much. That was it for selection. Another good thing about selection is, if we don't use it as much, if we turn down the use, we can still have antibiotics for a little longer time at least. So that's why we also worry about that. Thank you very much, and see you for the next lecture. [MUSIC]