Lecture 6- Antimicrobials and resistance - selection

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En provenance du cours de Technical University of Denmark (DTU)

Antimicrobial resistance - theory and methods

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Technical University of Denmark (DTU)

Antimicrobial resistance - theory and methods

570 notes

The course will cover the topics related to antimicrobial resistance with basic definitions and overview on antimicrobials their use and the emergence and spread of resistance. The course will guide you through the concepts and the importance of resistance spread and dissemination and how that happens. It will show you how bacteria become resistant and which mechanisms they might use for this. And as part of the course you will also receive some training in methods for antimicrobial susceptibility testing (AST) and detection of specific resistance in the microbiological laboratories with the basic methods available and with focus on the obtention of good quality results which can be interpreted and used for different purposes. Additionally, it will show you how to use genomic analysis tools to analyze whole genome sequencing data to detect resistance genes (and or other genes of interest) in a simple and easy way using online tools freely available. In the new new version an additional module including detection of specific resistance mechanisms was added. After this course you should be able to: 1. Describe the most important families of antimicrobials and mode of action 2. Understand the basic concepts of antimicrobial resistance from several perspectives (clinical, research and microbiological) 3. Enumerate and describe how bacteria can become resistant and the mechanisms that may be involved in that process 4. Describe how antimicrobial resistance emerges and spreads around the world including concepts of antimicrobial resistance transfer, selection and dissemination 5. Enumerate the methods used for antimicrobial susceptibility testing (AST) 6. Compare dilution and diffusion methods and know the basic techniques of agar disk diffusion, broth dilution and agar dilution methods 7. Have detailed theoretical knowledge on how to perform the main methods in a laboratory 8. Know the basic concepts about analysis and interpretation of results of AST, including different breakpoints, cut-off setting and their applications. 9. Understand the importance and related concepts related to quality management and quality assurance method standardization, applied to AST 10. Relate the information obtained in this course with real cases of resistant bacteria spreading in patients, the community, animals or the environment 11. Relate the phenotypical results with results from genotyping using molecular techniques for detection of resistance mechanisms 12. Understand the concept and be able to apply genomic analysis tools used to detect resistance genes and other relevant genes from Whole Genome Sequencing (WGS) data (with demonstration of selected online tools) Disclaimer: Please note that the guidelines and methods referred or links included in these materials are updated when the videos lectures are produced and before the course is released, however these might become outdated with time.

À partir de la leçon

Module B - Antimicrobials and resistance

This module containd information about antimicrobials and the development of resistance in bacteria including causes for resistance and their mechanisms, as well as an insight in how resistance disseminates and how it can be selected.

Lecture 3- Antimicrobials and resistance18:27

Lecture 4- Antimicrobials and resistance- causes and mechanisms14:21

Lecture 5- Antimicrobial resistance- emergence and dissemination12:28

Lecture 6- Antimicrobials and resistance - selection8:16

Rencontrer les enseignants

Lina Cavaco
Ext Associate Professor
Copenhagen University- ICMM /Statens Serum Institut - Department for Bacteria, Parasites and Fungi
Pimlapas Leekitcharoenphon
PostDoc
Research Group for Genomic Epidemiology, DTU Food
Rene S. Hendriksen
Professor, PhD
Technical University of Denmark, National Food Institute, Research Group of Genomic Epidemiology
Valeria Bortolaia

[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]

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