Episode 40: Mycoplasma hyopneumoniae and investigating its antimicrobial susceptibility.

In the podcast, Swine Extension Educator Sarah Schieck Boelke speaks with associate professor Maria Pieters about her research investigating the antimicrobial susceptibility of Mycoplasma hyopneumoniae. Mycoplasma hyopneumoniae is a bacterial pathogen of the respiratory tract of pigs. 

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Sarah Schieck Boelke:
Hello and welcome to Minnesota Swine and U Podcast series, a University of Minnesota Extension Swine Program. Today's Podcast is a research update on mycoplasma hyopneumoniae and investigating its antimicrobial susceptibility.

My name is Sarah Schieck Boelke, your host, and I'm a Swine Extension Educator with the University of Minnesota. Joining me today is Maria Pieters, who is an Associate Professor in the Department of Veterinary Population Medicine. Welcome Maria.

Maria Pieters:
Thank you for the opportunity, Sarah, to be here today and to share results of our research with your audience.

Sarah Schieck Boelke:
Yeah, I'm excited to hear about your research. Before we get really into the discussion here. Would you further introduce yourself if you would like to talk kind of about your lab or kind of your research that you like to focus on.

Maria Pieters:
Sure. You know I can tell you. I am a veterinarian by training right? I am originally from Venezuela, but I have been in Minnesota for about 20 years. Now I came here originally for graduate school, and then I went to the University of Illinois for a postdoctoral training and came back to Minnesota over a decade ago. And all this time I have been working on mycoplasma research specifically for swine. What I did in Minnesota referred to mycoplasma hyopneumoniae. And when I went to Illinois as well, I was able to keep working with the same you know, bacterian model.

However, we were looking at things, you know, from a different perspective. We can look at maybe models that would help us understand immunity and immune responses in hosts and things like that. So then I came back to Minnesota and I have been working on specifically, diagnostics, control and eradication of mycoplasma.

So I do. As part of my job. I have responsibilities in research, teaching and outreach and service as well. So I work for the diagnostic laboratory. You know part of my appointment, and that implies that I work on development of assays and test or interpretation of results. You know all those things to try to say, well, are we really seeing an issue with this agent or not? You know all those diagnostics. The other part of my job that I enjoy a lot is doing disease eradication.

We have done so much, you know, with mycoplasma. And when I say we, I'm including, you know, like that it is the practitioners, and it is the producers who are in the field doing the work. But we have been generating information to tell them about. You know, ways in which they can do eradication. So what we are going to be talking about today is something related to one of those projects.

And that ties very well with another one of my responsibilities. That is, you know. Being the director of the Swine Disease Eradication Center, which is a center of, you know, here in the University of Minnesota. But it's a center of partners or members from the industry, and in production companies. clinical veterinary clinics and all these as a group, you know, thinking of ideas that will can help us move forward on disease eradication. So all that ties into what I do on a daily basis.

Sarah Schieck Boelke:
Very good. Thank you. I didn't realize all the different things that you're involved in. So it's great to hear that before we get too far into our discussion. I know that all research cannot happen unless we have a funding source, and I think it's important that we recognize those funding sources. When we talk about the research. So are you able to share with the audience here? Who funded, or what were the funding sources for the research that you're gonna talk about today?

Maria Pieters:
Yeah, maybe you know, I will try to focus on one topic right? But maybe I'll talk to the about different things. But the main study that we will be discussing today was funded by the Minnesota Agricultural Experiment Station. And they have this program that is called the Rapid Response Funds. And those were the ones that we applied with this project. Right? So this is. This was mainly the funding agency for this project.

Sarah Schieck Boelke:
So now let's get into talking about the research topic that you're gonna focus on today. Can you give us a brief introduction of that research study, explaining why it was a valuable project to do.

Maria Pieters:
And one thing is Sarah, that I mean like when we talk about Mycoplasma hyopneumoniae, it is a bacterium right? And then you think well, bacterium do grow in the laboratory, and then you can do all the testing. And you know what to treat it with, and all that right? Well, mycoplasmas are bacteria. Yes, but they are different types of very unique type of bacteria.

And they don't grow very easily. At least, you know, mycoplasma hyopneumoniae is the one that causes enzootic pneumonia and pigs. And you know it's part of the respiratory disease complex. It is a very important issue in the industry, right, you know, for pigs, but it doesn't grow very well in the laboratory, and that, you know, affects the way in which we can go about it for control.

So when we think about any other bacterium, then it can grown. You can test it for antimicrobial resistance on, you know to know which antibiotics you could use for treatment but for hyopneumoniae because it's so hard to grow it in the lab. It takes weeks and sometimes even months, and you know, like, even if you try to isolate it, you may not be able to, even if the bacterium is there in the sample. So it's like, really, it's a finicky bug and it's really you know, it's expensive and time consuming labor intensive. So all that to say that there are not many isolates for this agent. Right?

And this is not only in Minnesota, I would say, you know around the world. Not a lot of people do isolation, culture, and isolation of this agent. So just for you to have an idea, there are, you know, institutions, research and academic institutions in which they have large collections. We will say, you know, in quotation large collections of Mycoplasmas. And then we're talking about. I don't know. 40 strains, you know, like something really, really small.

So for that reason, antimicrobial testing, or, you know, antimicrobial susceptibility testing for mycoplasma hyopneumoniae doesn't happen very often, and if we go to the literature you'll see that at least in the United States we have reports. The most recent reports were from the 9, I think 1978 was the one of the most recent one. So just for you to have an idea, nobody's really doing that and it's very old information, right? And data.

So what that means is that whenever animals are treated in the field, when they are infected, they are treated with antibiotics that we think I mean, like that. We know that the mechanism would add, you know, be effective on Mycoplasma, and we think that it will work. But in reality we do not test for it.

So the question that we had was. Do it? I mean, like, for all the eradication programs that are taking place in the field, sometimes we see failures. Are those failures related to the fact that maybe an antibiotic to which the bacterium was resistant was used, and we wouldn't know that right?

So we wanted to identify a way in which we could say, okay, this Mycoplasma strain or variant that you have at this farm, maybe resistant or susceptible to this antimicrobial, without having to do the culture of the bacteria. So I know it was, you know, like very ambitious. This is what we had in mind.

But the idea was to tie those results from the diagnostics that we're getting to see where those were affecting the lack of success. In some specific instances, I would say for the eradication, because the eradication programs are very successful in general. But in some cases we're having, you know, these issues. So it's this part of what is happening. And that's basically why we designed this tie.

Sarah Schieck Boelke:
Very interesting. I did not know, I guess, that mycoplasma hyopneumoniae was so difficult to like grow in the lab. So that's interesting.
So now, can you share? How did you complete this? This project?

Maria Pieters:
Well, we started by you know, in investigating the antimicrobial persistence or susceptibility in some strains that we have collected over the years. Right? So we have worked with practitioners, producers, companies, and we have been able to do cultural and isolation of Mycoplasma. Not, you know that many strains, but we have a little bit over, you know, 10 of them, and we are actually growing our collection. And now we have close to 20.

But by the time we did this study it was a little bit over 10 strains that we were comparing. And we compared those 2 reference strains, strains that have been known for a very long time, and that we have very good results for. But like if we know their behavior sort of in the laboratory and then in, you know, that was all in vitro. We did the comparison of those strains to certain antibiotics that had, like a different mechanism.

All of them different mechanisms, and that they are usually or or frequently used in the field to treat these antimicrobial or infections, for example, and then that was we used a method that is called micro dilution growth, micro dilution, because this is a pathogen that doesn't grow very well in on plates like other you know, bacteria do so. We use this broth microdilution to see whether we could observe that antimicrobial susceptibility or persistent certain agents. Oh, certain compounds. Excuse me.

So. That was the first step. And then what we wanted to do was, okay. We have those variants or those strings. Then can we? Compare them at a different molecular level right to see whether we can identify certain genes that can be responsible for this. And I have to say I was a little bit naive, you know, like proposing all these, because in reality I mean antimicrobial resistance is such a complex issue, right? And it's not like we're going to go and, you know, identify a single gene that is involved in these.

So we're still trying to, you know, like working in that analysis and in comparing it to other databases. And this is ongoing. But the other thing that we wanted to do was to develop a Pcr based test to be able to look at that antimicrobial sensitivity or susceptibility or resistance. And to me that was the most important outcome that we were going to have from this study. Because if we had that Pcr, you know working, then we wouldn't have had to isolate the agent, which is the most difficult thing to do.

So we did work on a Pcr based on 5 different genes that have been identified to be related to persistent to certain types of antimicrobials. And we were able to make that work. I mean, at least in the research laboratory. We run that test, and that's something that we could do for you know, certain producers or veterinarians if they needed to. However, this is not something that is in the hands of the diagnostic laboratory. So it's not routine service for the diagnostic laboratory so far. To date. Everything is you know, in the research area. And we're still trying to figure out what will be the best way to have this, as you know, like a high throughput test or something like that. But there is a lot of interpretation that goes into it.
The other aspect that is important to mention is that we're looking at only these genes, right? Like with, we know those ones are related to those results. And then we can see. Okay, there is susceptibility or not to certain antimicrobial compounds. However, that doesn't you know, take into account other genes that could play an important role. So this I would say, you know, like one way to explain, it would be like, Okay, partially, we can say what is happening, but not totally so many things could be escaping. What we can know about the behavior of the bacterial strain against the different antimicrobial compound. Does that make sense.

Sarah Schieck Boelke:
I think so. So. Kind of, from what I gathered is a lot of this project was kind of like in lab, like, once you got your different strains, then you were doing different lab work and stuff like that and ultimately trying to get a Pcr test. That was gonna work.

Maria Pieters:
Definitely. And you know, the thing is that this was funded by the Rapid Response Funds, right? Like this is something that you want a good answer, because it's something that is timely. And the issue is that there are many programs for eradication of mycoplasma that are taking place as we speak. Okay. And you know, like, if the trend is growing right and there is more and more eradication. And then we wanted to be able to support those efforts further, you know, with these tests.

And maybe in some specific cases we can do that like I said, this is research at this point. But the beauty for this project was that we had this collection of mycoplasmas that we could go off of, and those were all collected in the United States, you know, from commercial farms. So we were not, you know, like getting or purchasing strains from different countries and seeing you know how they behave. No, these are strains that would have been isolated from the United States in the last 10 years. Less than that, actually.

But you know, during that time. So those are what we'll call the contemporary strains, even though, you know, like they, they may be a little bit old, but it is more recent than what is reported in the literature. So I mean, this is all to say. There is very little information out there. In this aspect of the treatment of these pathogen and definitely, we need better tools for diagnostics that can help us support those efforts in the field. So this is a very good, you know case of the connectivity of you know what the vdl that the veterinary diagnostic laboratory does, and how that can help. You know those projects to increase the health in swine herds increase. You know, productivity for pork.

Sarah Schieck Boelke:
Week. So to kind of help put it in perspective. You know what your project is attempting to do.

Currently, if a farm sends in a sample, and it's going to be tested for mycoplasma hyopneumoniae. Can you briefly explain, like, what are the protocols that the vdl would use to test that?

Maria Pieters:
That's a very good question. And I would say, Sarah, that it all depends on. You know what the diagnostic objective is right like, what is it that you're looking for? What type of answer? And if you're only trying to detect if the agent is, you know, causing disease, if the pigs are still infected with it. Right then. We don't do bacterial isolation because of all the limitations that I mentioned earlier.

But Pcr, for example, Pcr, testing would be really sensitive, really accurate. To tell if the agent is there in the end? Right? And then you may have talked, you know, or you may have known about the viability Pcr, that we already have, and that that's a different project, right? But that's another Pcr test that we have to try to tell. Well, now that do they take that mic plus my honey? There? Was it an infectious Mycoplasma? So you know. Sort of a live Mycoplasma, or or a dead one? And can it cause disease?

That's a different question. But with Pcr, we can do those things. Sometimes we also receive like blood samples, for example, to separate serum, and in the serum we look for antibodies. That can help us know about the exposure of the host or the pig to one specific agent. So if we look for those antibiotics, we can tell. Okay, yeah. They have seen the agent, or they have been vaccinated, you know, like, we can try to tell about exposure to the agent itself. But here, what we're trying to say is, okay.

If I select one specific drug to treat these animals, am I going to be able to be successful in that treatment? Or are the pigs going to, you know not they are not going to see a difference, because, basically it is an antibiotic that the bacteria, the bacterium is resistant to.

So that's what we were going after. And the thing is that basically, that's not performed anywhere in the world. It's like, it's not really a thing that people do. You will have to do like a special request, if you really want you know the culture and in setting up the antimicrobial resistibility testing is not that easy, either. So I mean, like that will be.

That's the route that I would like to, you know, be able to streamline with this Pcr test. But we see that. Still, there is a lot of you know that we need to cover a lot that we need to cover, because it's not going to be that easy. But at least this is the first step, and the idea would be to be able to say, Yes, this is an antibiotic that you can use to treat these signs.

Sarah Schieck Boelke:
Very interesting. I have lots of other questions, but probably should stay on task or so, so that we can learn what your results were. So can you share of this specific project that you're choosing to talk about today, what were the results from your study?

Maria Pieters:
Well, first of all, I mean, I have to admit this is a very complex issue. The question is not easy to answer. It's not just one single project that is going to help us get there right.

But at least knowing, you know, like from the strains that we looked into and the variance that we compared. We did not identify any very high, you know, antimicrobial resistance. So that was great news, you know. For us, it's like, Okay, most of the antimicrobial compounds that are being used in the field may be effective. To the agents that we are dealing with. But once again you have to, you know keep in mind that we only tested a very limited number of strains, or you know of mycoplasma hyopneumoniae, and then we may be missing the ones that can be resistant.

Yes, that could happen. But in general, you know, from this information we gather that then the other part that was very important to me was, you know, like being able just to know that with the Pcr testing, even though it's partial information that we'll get, we can get you know, we can have an idea of the once again, the efficacy that certain antibiotics could have against in in agents.

And this is something that you wouldn't be using, you know, like, if you use that. Pcr. it's not going to be like, okay, let's do it for all the cases, you know. Like, if you are doing an elimination program and things didn't go as planned.

Can we look into the very end that you have at the farm, and and and try to see whether this could be the issue. But many different things could be playing a role there and and you know a failure in the elimination that's not equal, you know antimicrobial resistance always right? So I want to be very clear in the sense that there are many factors that could, you know, play a role there and then that could lead into a failure. But investigating, you know other aspects and then trying to see whether we can, you know. Find the smoking gun, you know, like that would be ideal.

But then, this test, this Pcr test will be another you know, tool that we will be able to use in those cases, trying to figure out what went in a different way, that, as we planned.

Sarah Schieck Boelke:
So based off of what you just shared, what conclusions can be made from this research. Or maybe it's further questions.

Maria Pieters:
I mean, like definitely, there are further questions right? And then I would like to see more research taking place. And you know, like development of maybe better techniques and better media that we could to grow the agent and make that process easier and doable and and being able to do on a regular basis. You know the monitoring of that antimicrobial susceptibility that would be ideal. We are. We are not there, and then, because of that, we'll have to, you know. Keep working with the molecular tools that we have this time and maybe I mean, like, make the best interpretations that we can with those results.

But being, you know, careful enough, knowing that the information is only limited, this is partial, and we are not going to get all the results.
Sarah Schieck Boelke:
So of what you shared, how are those important takeaways from this project?

Maria Pieters:
To me it's very clear that still, I mean, like we need to do some work on diagnostics and being able to provide information that is useful to the field and to the, you know, in initiatives that are taking place in the field is super important. Even though this sounded like a study that was very, you know, like a lab based and just in vitro and all that. This is very applicable, because we can use it directly with samples from the field.

So just keep in mind. This will not give us all the answers, and we're still developing and working with these tests to to make it even. you know more useful. But these are the, you know, the first steps, I would say, for a more applied way to look into antimicrobial resistance for mycoplasma hyopneumoniae.

Sarah Schieck Boelke:
Thanks for sharing that. I think you have an important point in in all of that. In that for a lot of your research. It's not necessarily kind of a quick answer that a lot of times you need to do different projects that often, maybe have other questions that come up, and then that leads you to doing another project. And then all of those projects together. Kind of combine into your kind of final result. If you want to say, or kind of the outcome, I shouldn't say result. But the outcome that you want to get to.

Maria Pieters:
Definitely Sarah. And I mean, like, that's, that's a way, research is right. And we do one study, and we have more questions and start a new one. But we learned along the way, and I would say as well that you know we working with mycoplasma for over 2 decades. Now.

I have learned that we need to be patient, and Mycoplasma is a very slow pathogen in any way that you think about it. It's like it grows slowly in the lab, and it takes a while to, you know, show clinical science when pigs are infected, and it takes a very long time, as well, you know, for the pigs to clear it out of their system. So you learn that you need to, you know. Take, you know, understand that pace.

And that's one thing. But that has not stopped us from, you know, being really creative and coming up with initiatives. So you know, for control and doing different things. And maybe, you know, like in the past, we didn't think about it. But yeah, you know what for mycoplasma. We don't have this type of product. We'll have to, you know, do things this different way, and it has helped so much, and it is so rewarding to see. You know the farms that you know, 15 years ago you were working with them, or 10 years ago, 5 years ago, and now you cannot collaborate with them because they are free of the disease. That's great.

I mean, it's an issue. Because now I like, I am running out of, you know, farms to work with or systems to work with. But it is great. We are achieving the goal of, you know, this is elimination, and that's what you know makes your work so worth it. You know it's super super interesting.

And the other thing that I wanted to mention is, you know, like this support from everybody who is, you know, like they have ideas, or they say, I can collaborate this way. And you know, like, from your perspective, Sarah, the support that we have had from Extension on the University of Minnesota as well. So everything is very much appreciated, because it is not only one person or only one group doing things. It's like you have to work together with other people, to be able to really move forward.

Sarah Schieck Boelke:
So to wrap up our discussion here. Is there any other closing remarks that you would like to make before we end?

Maria Pieters:
I would say, you know, like yes, there are obstacles in the way for mycoplasma hyopneumoniae eradication. But I have been so impressed with how, you know, like the people out there in the field, they jumped over those or they, you know, they dodged them. And they have been so creative on going around those things and being able to do eradication, that it is exciting to be in this field and to work with this progressive industry.

Sarah Schieck Boelke:
Yeah. And I'm sure the producers enjoy the work that you do. They wouldn't be where they are today if it wasn't for you and your lab doing the work that you're doing.

Maria Pieters:
It's just great to be part of this group.

Sarah Schieck Boelke:
Well, thank you, Maria, for sharing your research on mycoplasma hyopneumoniae, and investigating its antimicrobial susceptibility with us today.

Maria Pieters:
Well, thank you for the invite to share this information, Sarah.

Sarah Schieck Boelke:
And thank you to all of the listeners.

Once again, this is the University of Minnesota, Swine, and U Podcast and this has been Sarah Schieck Boelke, Swine Extension Educator along with Maria Pieters, associate professor in the Department of Veterinary Population Medicine.

To further connect with UMN Extension, please visit the swine specific pages on our University and Minnesota Extensions website at www.extension.umn.edu/swine. And on those pages you'll find connections to our blog as well as our Facebook page, and also previous podcast recordings.

To learn about research being done by our swine faculty in veterinary medicine, you can visit their blog, which is Swine in Minnesota at www.umnswinenews.com.