Veterinary Vertex

Veterinary antibiograms as one-health tools

September 12, 2023 AVMA Journals
Veterinary Vertex
Veterinary antibiograms as one-health tools
Show Notes Transcript

Drs. Catherine Lorenz and Heather Fritz authors of "Antibiograms as one-health tools for antimicrobial stewardship: California’s experience with livestock antibiogram development in: Journal of the American Veterinary Medical Association Volume 261 Issue 9 (2023) (avma.org)" discuss antibiogram creation, use, and development by US veterinary diagnostic laboratories. Hosted by Associate Editor Dr. Sarah Wright and Editor-in-Chief Dr. Lisa Fortier.

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Sarah Wright:

You're listening to Veterinary Vertex, a podcast to the AVMA journals. In this episode, we chat about antibiograms as one health tools for antimicrobial stewardship with our guests Heather Fritz and Catherine Lorenz.

Lisa Fortier:

Welcome to Veterinary Vertex, I'm Editor-in-Chief Lisa Fortier, and I'm joined by Associate Editor Sarah Wright. Today we have Heather and Catherine joining us, Heather and Catherine, thank you so much for taking time out of your busy day in your work in your profession and your personal lives to be with us here today.

Heather Fritz:

Great to be here. Thank you. Thank you for having us.

Sarah Wright:

Your Currents in One Health manuscripts in JAVMA discusses antibiograms as one health tools for antimicrobial stewardship. Can you explain to our listeners what antibiograms are?

Heather Fritz:

Sure. an antibiogram represents a cumulative summary of results of antimicrobial susceptibility tests. Those are over a defined period of time and that is usually a year. They are specific to a bacterial organism, a host species and also a disease condition and or body sight. As an example, we have generated clinical antibiograms for bovine respiratory disease organisms, and antibiograms for Mannheimia haemolytica that would show the percentage of mannheimia haemolytica isolates tested over a one year timeframe that were susceptible to each of the drugs tested in the panel. Those isolates would have come from respiratory sites from cattle with respiratory disease optimally, and the antibiogram would have at least 30 different isolates over that one year timeframe and it would be comprised of isolates that were recovered from a defined population. And that may be a hospital practice, it could be a specific region. And when we're thinking of livestock species that might be a production type, like dairy or beef cattle in a particular region. Antibiograms are widely used in human hospital settings, both to guide empiric treatment decisions, but also to monitor trends and susceptibility or resistance in that population. So antibiograms can be useful as a tool for antimicrobial stewardship programs. But we always emphasize that it should not replace a routine culture and testing on individual animals for susceptibility.

Sarah Wright:

Thank you for that nice disclaimer, it's good for our clinicians listening to know. What are some of the important findings from this study?

Heather Fritz:

Well, we started this study really wanting to for ourselves to establish a framework and procedure for generating veterinary antibiograms. And we wrote this manuscript to share our approach with the veterinary community to promote antibograms as a One Health tool for stewardship programs. To do that, we utilized antimicrobial susceptibility tests data from clinical samples that we received here at my lab at the California animal health and food safety lab in Davis and we follow the guidelines that were established by the Clinical and Laboratory Standards Institute, to the best of our ability to produce these clinical entity diagrams. We also consulted with a panel of experts, those included veterinary clinicians, microbiologists, and research faculty, to determine what the format in the content of antibiograms would look like to be most useful for them. And this actually led to the development of three different types of antibiograms. So ultimately, we paired one that we refer to as the simple antibiogram. That reports only the percentage of isolates that were susceptible to each drug. And we made a second one that people thought would be handy as kind of a quick reference tool that is a graphical bar chart illustration, again, just showing percent susceptibility. But then we also developed a third that many thought would be useful, because it provided additional information that we refer to as our detailed antibiogram. And that has also the distribution of MIC values for each isolate we tested along with the breakpoints for classifying an organism as susceptible, intermediate or resistant. And then we also portrayed the percent susceptible, intermediate and resistant for all of those isolates. So in the process, we encountered several challenges and limitations, I would say to developing these livestock antibiograms, and one of the most significant is that there just aren't very many breakpoints available for veterinary species, in particular livestock animals, as most breakpoints are established using a combination of microbiological characteristics, pharmacokinetic, and pharmacodynamic data for PK PD data, and clinical outcome studies. So many of the interpretations used for livestock species because the studies are lacking, or actually extrapolated either from other animals, like dogs where we have more data or from human breakpoints. So I would say that one of the most important findings was that there remains a really significant need for additional studies and data to develop breakpoints specific to veterinary species. And that will help us to ensure that the ASD data that we use is optimally applied to the animals, and informing the process of developing the antibody grams. We're looking to the clinical history data provided, because optimally, we would select samples that were submitted before and microbial use, and more from animals that had disease, and not necessarily for surveillance purposes. And we discovered that many of our submission forms are really lacking in that level of data. So most importantly, the most important finding of this study was that veterinarians in California, were eager to access the antiboigrams. I wanted to learn more about how to interpret antibiograms, and how to utilize antimicrobial susceptibility data, and antibiograms in particular, to practice judicious use of antimicrobials. And so we will continue to update our antibiograms and make them available to licensed veterinarians in California as a part of our stewardship program.

Lisa Fortier:

Thank you, Heather. Either one of you can answer this question. One of the criticisms about antibograms, and you could even say perhaps, wellness approaches, because each region each area has a different pressure on, you know, is equine shortages or emergency critical care, that sort of thing. What do you say to the critics that say, well, you pointed out Heather, some take home messages, we need more information, we need better histories. But what can I in Ithaca, New York learn from your UC Davis regional California antibiogram? And you could say what you said earlier? Well, you need one for a region, it could be a private practice. And we commonly get from reviewers that it doesn't have any practical application, because it's too regional. What would either one of you say to those critics?

Heather Fritz:

I think one of the really valuable aspects to publishing regional antibiograms and making those available even though they may not apply to patients or animals outside of that region. So it's also very useful information to compare patterns in susceptibility or resistance across regions. And that may inform treatment decisions or management decisions. Even antimicrobial usage patterns.

Lisa Fortier:

Yeah, cultural sensitivity, like on the broad scale to write what's going on in our whole profession. So thank you for addressing that. As editors at JAVMA and AJVR, when we get those sorts of comments, we're like, well, isn't that true about everything, whether it's a bladder stone or hoff abscesses, or whatever it is, all these things have breed specificity us regional. So thank you for adding that into the antibiogram. Catherine, what sparked your interest your research interest in antibody diagrams?

Catherine Lorenz:

And this is a great question and I'll give a little bit of background first. So the Antimicrobial Use and Stewardship Program, which is part of the California Department of Food and Agriculture serves to monitor antimicrobial resistance in livestock species and provide stewardship guidance for veterinarians and producers. And the ultimate goal is to preserve drug efficacy and protect animal and public health. So while we were looking for ways to support veterinary antimicrobial stewardship, we found that antibiograms are regularly used in the human medical field, but they're much less common in veterinary medicine. And so taking a One Health approach, we wanted to explore how antibiogram is might be implemented in a veterinary setting. And there's a lot of attention and regulations surrounding antimicrobial use, especially in livestock. And so having a statewide antibiogram is one way to look at overall resistance trends and possibly highlight areas that should be addressed by stewardship programs. And then additionally, antibiograms can be really useful to veterinarians, if they are waiting for culture and susceptibility results to come back for a patient because they can inform empiric therapy decisions. And so after diving into the literature on antibiograms, I remember thinking, I wish I had had access to an antibiogram when I was in practice. And here I was with a group of people with the expertise and the data to really create these antibiograms for livestock species. And so it was really just a matter of convening the right group of experts and working through some of the obstacles to create and distribute antibiograms to practicing veterinarians and then also to provide guidance to those vets on how to optimally use the antibiograms.

Lisa Fortier:

There's so much helpful, useful information in there, especially the guidance part that Heather was alluding to earlier, like every state, every diagnostic lab can really jump on. And as Sarah said, in the opening, we have other antibiogram manuscripts as well. So kudos to all of you for bringing this to the forefront in veterinary medicine. Catherine, what inspired you? You said like, I wish I had this available. And that's, that's fine. But it's everybody needs to get to the next level. Like what inspired you to really dig in and get this data and write this manuscript?

Catherine Lorenz:

So we realized that it was not common to have an organization create and disseminate veterinary antibiograms for clinical use, and especially for livestock species. So we had a few motivations to create this manuscript. One was to raise awareness of antibiograms as tools for veterinarians to improve their antimicrobial stewardship practices. Another was to highlight some of the things that veterinarians should understand and pay attention to when using an antibiogram. And then the third was to spread the word that we had already done some troubleshooting already and we wanted to share our process, and also some of the limitations that we encountered with other organizations that might be interested in creating similar antibiograms.

Lisa Fortier:

Yeah, well, certainly you and your co authors, congratulations, you achieved all of those goals. And thank you so much for sharing it with us at JAVMA. What is really important for our readers? What when you're looking at your manuscript, maybe not what is the most clinically important part raising awareness, but what was the most surprising thing to you when you were writing your manuscript?

Heather Fritz:

Okay, I'll jump in. As we were writing the manuscript, as you know, this manuscript is written together with the publication in AJVR. And so we had a lot of interactions with experts in the field across the United States. And I was surprised and also relieved, I would say, to be faced with all the different perspectives on how this data should be used can be used what we can do to advance usage of antibiogram development, but also antimicrobial susceptibility testing going forward for livestock species. So I discovered that this is remains a challenging area for diagnosticians to provide, and very applicable and high quality antimicrobial susceptibility testing, but also with clinical predictions. So I was very surprised and excited to see what a growing field this is, and how exciting it can be to hear all the different experiences and perspectives from people who are tackling this subject currently.

Sarah Wright:

It's great to hear that there's more room for growth, because there's always need for more research. That's always one of the take home messages from these podcast episodes. If you want to a PhD, we have space for you. So you're both very accomplished. And we're just so happy to have you with us today. Catherine, how did your advanced training prepare you to write this manuscript?

Catherine Lorenz:

I've held a variety of different jobs within the veterinary field, but I think that they have all served to strengthen my science communication skills, which I think was the biggest help when it came to writing this manuscript. And in particular, in my position with the Antimicrobial Use and Stewardship Program. I create educational materials about stewardship topics for veterinarians, and I think that experience really helps to ensure that this paper was relevant and easily digestible by an audience of veterinarians.

Sarah Wright:

Heather, how did your background and training prepare you to write this manuscript?

Heather Fritz:

My experience in clinical practice, also in research and now in diagnostic microbiology, I think it has given me a good understanding of the materials presented in the manuscript. I've never felt that writing a manuscript was done. The thing that came particularly naturally to me as a member of an academic institution, I'm compelled to write manuscripts. And I first learned how to prepare manuscripts during my PhD. But I also realized just how dependent I am on scientific publications to keep current on knowledge and new discoveries. And so honestly, the best preparation, I would say, comes from reading other high quality manuscripts.

Sarah Wright:

The give and take, right, it's like we love learning from them. But like you said, you have to contribute as well. So sadly, a two sided relationship. Then Catherine, what is one piece of information the veterinarian should know before discussing this topic with the client?

Catherine Lorenz:

I actually have a few pieces of information that I want people to take away from this paper. Antibiograms can be an excellent tool to improve antimicrobial stewardship, but they are only one part of a comprehensive stewardship plan. And they should also always be used in conjunction with the veterinarian's clinical judgment to ensure that therapeutic decisions, adhere to legal requirements and really make sense for the patient that's being treated. And then additionally, the user should always understand certain characteristics of the data. So that includes the source population, the body site, the samples were taken from, if possible, the number of isolates included in the antibiogram, and the animal species and bacterial organisms for which each breakpoint was developed. And I think the major take home message from this paper is that antibiograms are most useful when they are developed using data from a population that is as similar as possible to the animal that's being treated. And they should not replace individual culture and susceptibility testing, as the cumulative data that's represented in the antibiogram may not reflect the exact bacterial infection and organism recovered from an individual animal.

Sarah Wright:

Thank you, it's really important information to know. And then we're going to flip things around a bit. So on the other side of the equation, what is one piece of information that the client should know about this topic? So if you had to present some information to a client that was easily digestible, which they know about antibiograms?

Heather Fritz:

I think it's important to inform the client that while this information can help their veterinarian to make treatment decisions in advance of having culture and susceptibility results, as Catherine already said, it really shouldn't replace aerobic culture and susceptibility, but also in performing those tests on individual animals, that also helps us to build the data set. And so as well as hopefully, establishing a treatment plan in advance of having additional results, which may shorten the period of illness for an animal, that data the clients are also contributing to this body of data by and their individual animals susceptibility testing going forward.

Lisa Fortier:

Yeah, as you both have said it is a give and take and contributing to the veterinary literature takes just that little bit even more effort than already overworked, veterinarians and MPHs. So it takes it a whole level of resilience and determination. Catherine, we'll start with you. Where do you think your resilience determination inspiration came from?

Catherine Lorenz:

I'm really lucky to have been surrounded by very hardworking family, friends and co-workers that have all inspired me and encouraged me to accomplish big goals. And my parents especially always told me to pursue a career I was passionate about. So I started out certain that I would work with wildlife. But that morphed into a passion for population level medicine and a love of infectious disease epidemiology. And so although my career has not quite had that straight line trajectory that I originally envisioned when I was in vet school, I've really sought opportunities to broaden both my impact and my perspective. And then now more recently, it's my almost two year old son who inspires me to keep setting and achieving goals because I want to show him that his mom can do hard things, and I'm hoping that that's going to inspire him someday.

Lisa Fortier:

That's fantastic. I went to undergraduate because I wanted to be a radio sports broadcaster. And then I found that my passion was really biology and chemistry and then I ended up in veterinary medicine. And so I love that follow your passion. Yeah, I often think that the people with the most interesting stories are always somewhere other than where they expected to be. For sure. Heather, how about you? Where does your resilience and inspiration come from?

Heather Fritz:

Oh,quite similar to what Catherine shared, but I would say also from a very early age, I was encouraged by my parents and teachers and other mentors to invest in my education that was really impressed upon me and also to follow my passion. And like many of us who ended up in the veterinary field, there was a love for animals at an early age. And that led to my pursuit of an education in veterinary medicine. But that evolved into a very strong interest in infectious diseases and one health. And part of that came from my experiences traveling prior to vet school. As a student, I studied ecology in Costa Rica. And then as soon as I graduated from college, I backpacked around Southern Africa, before returning to work in the Pediatric AIDS clinic. And I think seeing how other people live and the impact of infectious diseases in other parts of the world in particular, that it really inspired me to both really invest in that field, but also helped me to recognize all the opportunities I'd had. And it motivated me to work hard to positively impact both animal and human health. Like Catherine said, my career path also has not been linear. And I've had some experiences that people may perceive as setbacks in my career trajectory. But along the way, it's providing me with insights and experiences I wouldn't have had otherwise. And also, perspective that has definitely made me more resilient. And I'm extremely grateful for where I am now. And the path that brought me here.

Lisa Fortier:

Very beautifully said by both of you. While we're winding down, we love and our listeners love this, the answer to this question, because they're all very unique. Catherine, we'll start with you. Now, what is the oldest or the most interesting item on your desk or in your desk drawer?

Catherine Lorenz:

This is probably the oldest and the most interesting thing that I have in my desk. It's a pen that my dad made for me. So he let me pick out the piece of wood and then he turns the wood on his lathe and made it into a pen. And it was probably made when I was in middle school. And I just remember feeling so fancy and special when I used it. And so it's stayed with me on my desk ever since.

Lisa Fortier:

That's wonderful. Does it still work?

Catherine Lorenz:

It does still work. Yeah, I think because I use it so rarely, because it's it's like a special occasion pen.

Lisa Fortier:

That's fabulous. We haven't gotten that answer before. Heather, how about you?

Heather Fritz:

Mine is actually a very small brass kaleidoscope that was given to me as a gift when I graduated from college from undergraduate. And it has been on my desk from vet school, grad school, various jobs. And it's really beautiful. My daughter and I, it's one of our favorite things to pull out of my desk drawer and play with them like crew.

Sarah Wright:

That's excellent. Thank you so much for sharing. It really allows our listeners to to get to know you both a bit more on a personal note. So thank you, and we appreciate your contribution to our journals and for being here today.

Heather Fritz:

Thank you so much for having us.

Sarah Wright:

To our listeners, you can read Heather and Catherine's manuscript on our journals website. I'm Sarah Wright with Lisa Fortier and we want to thank each of you for joining us on this episode of the Veterinary Vertex podcast. We love sharing cutting edge veterinary research with you and we want to hear from you. Be sure to leave us a rating and review on Apple Podcasts or whatever platform you listen to