Okay, it seemed like Dr. Wischmeier's presentation, he showed data for probiotics and seemed to suggest that we should all be taking them. Dr. Kreshe showed data and argued that probiotics should not routinely be used. It seemed like in Dr. Wischmeier's presentation, so I guess the thought process of the question is resolving some of these paradoxes that occasionally happen in microbiome research. And, you know, I would also add as the moderator that it's partly unique to microbiomes as well in terms of certain other interventions that in some, looking at it in some ways seem to show benefit, but looking at it in slightly different ways do not seem to show benefit. So I would ask any of the panelists who are on right now to sort of say that, you know, is there, how do they resolve this discrepancy about the role of probiotics in the critical ill? So, hey everyone, this is Paul Wischmeier. I didn't hear all of Gail's presentation, but I think the key point I was trying to make was, the key point I was trying to make was, I think in the non-critically ill patient for the average individual living freely in the world, I think now is quite robust data from large clinical trials, even the trial I presented from Nature that demonstrated really profound, potentially COVID and other illnesses. So I think in that setting, I think the data is quite compelling that the average individual taking a probiotic out in the world every day would probably greatly benefit, and we'd probably save billions of dollars in health care costs and millions of days of sick days if that was the case. It is not as clear, and my hunch is that's what probably what Gail was speaking to, and I think you're right, the data is not as clear, other than for C, I would say for C. diff prevention and for C. diff intervention, there the data I think is quite profound and quite clear that, you know, if you have a patient who's at high risk for C. diff, Cochrane analysis after analysis has actually shown growing improved signal of benefit in the patients at risk for C. diff or in patients that you're trying to prevent that in. I think beyond that, right, there's still a fair bit of research to do, and I think there's lots for us to learn, and so I think the dichotomy I would strike is in the healthy person and the person, the average person listening to this presentation I would strike is in the healthy person and the person, the average person listening to this presentation at home who's not a critically ill patient, I think all of us would benefit from taking your probiotic every day, as would our children, even starting from newborn age on, and my whole family takes one, including all my children, but I think in the critical care setting, I think here's what Gail will say and what her expert thoughts will be. Yeah, thank you. Okay, so this is Gail Cresci. So yeah, I think there's, you know, different worlds, you know, the microbiome when it gets in different environments is going to behave differently, so in a non-critically ill population, there has been data to support the use of probiotics for antibiotic-associated diarrhea and some other types of infections, including C. difficile infection. I think the critically ill, what I showed, and why it's been so confusing over the years is that there's been a number of studies that have been done, and then there's been a number of meta-analyses that have been done, and individual studies have, you know, there's those with very small number amongst the studies, and then when you try to compile these into a meta-analysis, your heterogeneity, of course, increases even more. So the meta-analysis that I presented was actually a recent one where they actually looked into the quality of the study, and that's what I think is really key, is trying to, you know, decipher, is this a good study or not? You know, these studies are hard to do, so any study I think that's accomplished is great, but to try to get more of a homogeneous population, and looking at that, the signal just isn't there, and the risk outweighs the benefit, just to just give everybody in the ICU a probiotic. And you know, these probiotics, you can't treat them all the same, so again, different ones have been strained to certain strains, but I don't think we have a clear-cut answer on that just yet. In looking at a healthy population, and we actually just did a study ourselves in healthy people, and it actually went against my hypothesis. I thought people who ate a diet that was high in processed foods, we rated, I thought they would have a better response. We actually gave a symbiotic to the symbiotic, but we didn't find that. We found that it was those that already had a relatively healthy diet responded to the symbiotic, meaning the response was that their diversity shifted, and certain taxa within the microbiome shifted. So I think the answer's not clear-cut, and I think there's too many other things going on in critical care, with a critical care patient, to just blanket give it to everybody. I think we need better-designed quality studies to determine that, studies to determine that. If I could speak up as well, I clearly, based on my talk with Gail on this, I think the data-supporting use, even for an indication like prevention of FAP, is really lacking in the ICU, and I totally agree. The higher the quality of the study, the weaker the signal, or the more absent clinical evidence, which is what we're discussing. There's also the microbiologic and ecologic rationale, and I think a fundamental difference between studies of healthy outpatients, which Dr. Wischmeier is referring to, and our typical ICU patients, is concurrent administration of big-gun, broad-spectrum antibiotics that penetrate into the gut, big-gun, broad-spectrum antibiotics that penetrate into the gut, and kill the very bacteria that we think are hoping to rescue these ecosystems. In that large JAMA VAP study that's been discussed by several of us, by our count, more than 80% of the patients were receiving ongoing antibiotics that had activity against the administered bacterial species. The analogy I made in my talk is, this is trying to repopulate a forest while there's an ongoing forest fire. I tend to think that it's going to be hopeless to try to repopulate the microbiome, so long as there's rampant, broad microbiome-depleting antibiotics being administered. I can't resist interjecting this, that, you know, having listened to these speakers beforehand, I've been influenced by all of them, and I must admit, Dr. Wischmeier has certainly influenced my decision to be religious about taking my probiotic. And also turning this there, Dr. Dixon, I remember we, you know, quantity and very broad spectrum of antibiotics. Perhaps, you know, one of the things that people can do, which I know is sort of a principle, but, you know, in managing ICU patients, really, really go sparingly on those anaerobics, because it looks like the ones that really damage the gut, because it looks like the ones that really damage the gut flora we want to preserve are the antibiotics with a big broad spectrum antimicrobial, but anaerobic activity, like the carbapenems and the zosins and everything like that. So, you know, I think very much limiting them, and by the way, one of the other questions I was sort of pondering in my mind, this may be why selective digestive decontamination actually seems to benefit, even though it's, in a sense, affecting the flora, it's because it's leaving the anaerobic bacteria alone, and just sort of concentrate on pathogenic rib. Yeah, I appreciate your making that point, Dr. Morrison, and I completely agree. We tend to reflexively just treat antibiotics as a single exposure, but, of course, they're not all created equal. They have very different activity, and, yeah, I avoid use of the term broad spectrum, even though it's tempting, because, for instance, cefepime is plenty broad spectrum, but it doesn't touch gut anaerobes, and as I showed, hopefully compelling data that both in our animal models and human studies, getting zosin or piperacil and tezobactam in the ED and cefepime have markedly different effects on the density of gut bacteria, the identity of gut bacteria, and how depleting of cefepime in the ED and cefepime have markedly different effects on the density of gut bacteria, the identity of gut bacteria, and how depleting of those protective anaerobes they are, and you're exactly right about selective decontamination of digestive tract. People lose sight of how selective it is. As intimidating as those antibiotics are, they don't suggestive tract. People lose sight of how selective it is. As intimidating as those antibiotics are, they don't touch the anaerobes, and they really are sparing, and that's been the motivation since it was started in the 80s, is don't just sterilize the lower gut, as if that were possible, selectively knock down the proteobacteria, the gram-negatives, so I appreciate your point. Your point, most, and this is obviously varied by what ICU you're working in, but in a medical ICU, most patients with sepsis do not need anti-anaerobic coverage. If it's a respiratory source, a urinary source, suspected bloodstream source, guidelines do not recommend empiric anti-anaerobic coverage for those patients. Of course, different if you're talking about intra-abduction, but I agree. To me, that's what's right in front of us, is we should be anaerobe-sparing when possible in these patients. Yeah. I'm trying to get that message across to my fellow surgeons, because as you know, we tend to love those, you know, those sort of antibiotics, and again, can be very effective, but I actually sort of hope maybe the recent stop-it, where we're at least saying we can at least limit the exposure, you know, and not give people weeks of it, but just stop it, particularly the anaerobic component after four days, might be helpful. So just getting to a couple questions, one, is there any data on how diets with high capsaicin-containing foods has on the GI microbiome? I certainly don't know. I don't know if any others do, but that's not something I've looked into, and obviously doesn't have immediate relevance in our ICU. I just don't know the answer to that. Yeah, you know, it's interesting, there's very little information on specific diets in the ICU. I mean, I presented, you know, global, like enteral feeding versus parenteral feeding, but in just ICU patients, just on the wide open, I think we really need to investigate that. And I think that's why we were so struck by the data we're submitting here on the prebiotic work we did at Mars Rescue, and I did, looking at prebiotic fibers, thinking hopefully they would show benefit in recovery of the microbiome when used, or at least preservation of the microbiome. And I think, Robert, your quote was a good one. You know, when you burn the whole forest down, all that's left is sort of the bad actors that can survive that fire. It looked as though in our data, right, that it looked like the pathogens were able to utilize the prebiotic FOS fiber to a significant degree and take advantage of it to grow, probably because then there, of course, was an absence of the commensal flora. And again, I use the same analogy as when I use the New Orleans analogy, when people leave, the looters come and they bring their looter friends, and if there's a bunch of food in the grocery store, the looters get that food. And that appears to be what FOS prebiotic administration does in the ICU in our microbiome data. It seems to lead to expansions of proteobacteria in certain pathogens, and perhaps even loss of diversity with the very intricate systematic interaction between the pathogens and other bacterial families in this setting. And so I think a symbiotic, if I was going to treat an ICU patient, would be the way to go, where the fiber would be given with a commensal species. And I think the other thing I would probably do is, I think, you know, given the Blue Journal paper that did show benefit in ventilator-associated pneumonia, the key difference in that study from all the other studies in the big trial that was done in JAMA was they gave a prebiotic, I'm sorry, to the oral mucosa. They smeared the lactobacillus GG into the mouth, and, you know, I think a lot of data is pinting that a lot of the, you know, I think a lot of data is pinting that a lot of the infectious etiology of pneumonia and ventilator-associated pneumonia is probably coming from deranged oral flora, not the gut flora. And so I think if we're ever going to have something work, we're going to have to be treating the oral flora and the gut flora. And I think that's why Lee Morrow from ventilator-associated pneumonia may have shown more benefit than other studies, because that was an NIH-funded, quite robust trial done, I think, under quite good study conditions, albeit single-center, but he gave a probiotic both to the mouth and to the gut. And I do think that may be important in the future as we think about what we're going to do. There's a couple other questions that I think can sort of be tied together. One mentions about some comments about the microbiome composition prior to critical illness, which, you know, it certainly varies for an individual. And I like the slide about how stable it is. I don't know if there's anything that prior to critical illness you can do anything to really significantly change that. And the other question is, basically, you know, how do you think this is going to reflect into clinical care? In other words, do you think that there's a point yet where it would be useful for people when they come in, analyzing the microbiome, and something implicit in the question is, you know, would that eventually maybe influence treatment? And something that wasn't in the question, but I would think maybe influence what we give them for enteral nutrition. I can start with that. I made that comment in my talk, is that if you think about, you know, people who come into the intensive care unit, they're from all walks of life. So a lot of our patients are likely not with a healthy microbiome. They have a lot of chronic diseases. And we know these different chronic diseases are, these people are not likely eating healthily. So here now, they come into the ICU. And as far as nutrition goes, we treat them like one size fits all. We do the same thing for everybody. We put them on these formulas, or maybe we're a proactive ICU and support the microbiome. So we're pushing fiber. Well, if their gut is not used to seeing fiber, because they don't normally eat fiber. And now in this setting of this critical illness, this could really cause a lot of potential issues within that person. I don't think that, you know, that person. I don't think that, you know, that technology is not here yet to be able to, you know, on the spot, analyze microbiome in a timely manner, and then do an intervention based on that. Hopefully that will be coming soon. But I, and I also think visual intelligence and, and future research, plugging in different algorithms, we might be able to predict some of these things, you know, based on what the patient's, you know, what their profile might be, chronic condition, et cetera, prior to entering the ICU, their diet, and they'd be able to, and they'd be able to come up, you know, meet them at where they are, and then try to feed them accordingly, you know, to that. But that, that would be my goal is like to try to do more of a personalized nutritional approach to these patients instead of the one size fits all, and try to make the assumption that everybody's going to make the assumption that everybody's going to be able to handle this. And who's to say, you know, we need to reboot their microbiome to what we see in a healthy population when they're not necessarily at that point, you know, to begin with. So that's my thought on that. I'll jump in. Does your microbiome before your critical illness inform your susceptibility, your trajectory once you get critically ill? If you just think practically, logistically, what it would take to study that, we are fortunate to have access to a lot of lower GI specimens from patients when they hit the ED or when they hit the ICU. But unfortunately, they hit the ED or when they hit the ICU, but unfortunately, we can't go back in time and figure out what their microbiome was a week, two weeks, three weeks before. We just, and if you study a general population, thankfully, ICU admission is so infrequent, you just couldn't do it prospectively. So it's just a real logistical challenge to answer that question. But there is a population that I think we can study, which is to answer that question. But there is a population that I think we can study, which is readmissions. So it's not uncommon, you know, just as a rough estimate, about a third of people who survive to leave the ICU will be back within a few months, often with a similar, but often a distinct infection or organ failure and infection or organ failure. And that, to me, seems like an exciting population to study, because we really know nothing about the long-term longitudinal recovery of the microbiome once you leave the ICU. And I mentioned the APS network in terms of what's coming in over the horizon. In the next few years, in this NIH-funded patients, longitudinally sampled, we'll get microbiome specimens from lower gut, oral, nasal communities, as well as blood. And we will know their microbiota at the time of discharge. And then we'll also know if they got readmitted, and if so, what the indication was. And for 500 of them, we'll actually have three months, six months, and 12 months of lower gut microbiome specimens, too. So we can start to answer the question of, does persistent dysbiosis contribute to subsequent critical illness? And to the second question of what would it take to actually characterize the microbiome in real time and act on it, I completely agree with what Gail said. The technology is not there to do it, but we're tantalizingly close. So I showed some slides showing that we're using nanopore sequencing. So the MinION is a palm-sized, literally you hold it in your hand, costs under $1,000. And we've used it to generate real-time microbiome data. So it's for with a conventional clinical micro lab. You need bioinformatic expertise and essentially all hands on deck for a lab personnel. So it's not anywhere near shovel-ready in terms of its use in the ICU. But I absolutely agree. The idea that there'll be a one-size-fits-all intervention for the microbiome is as naive as give monoclonal antibodies to all comers. We determine who has a deficiency or an excess of a given pathway. And it becomes a sort of chicken-and-egg problem of we can't really generate the clinical and scientific knowledge to know how to intervene until we generate this granular real-time data longitudinally. But right now there isn't so much of an incentive to generate that data because it's not like we really know what we do if we had it. So I think both the technology and the clinical science needs to advance arm-in-arm. So I think those are excellent points both of you guys just made. But I think there are some populations that Chet, you and I take care of more often because being surgical and cardiac people that do give us some opportunities. So a couple studies we're doing at Duke, one of which we're not far from publishing, I did a trial with my chair. He's a cognition expert after cardiac surgery. So for aortic repairs where they do circurest on cognition, delirium, dementia, and cognitive function over a year. And we added on a microbiome sampling panel to that where we got a sample between one and two weeks before surgery. And then we got between one and two weeks before surgery. And then we got samples longitudinally out to a year. And so in that population, we have found some interesting correlations. Now this study was not focused on clinical outcome, but it was focused on cognition and dementia, delirium, and cognitive function after surgery out to it. We had really explicit sorts of testing all the way to functional MRI. And we did find some relationships to some of the instruments to both some of the oral and gut microbiome changes that we saw in these patients. One could imagine right in that population, you could do some interesting things because you know, they're going to be admitted to the ICU. They're not, they're about to become critically ill. The other study we have going on at Duke that we're just starting to analyze data for us, we have what's called the thousand patient surgery program that Alan Kirk, our surgery chair funded himself actually, when he came to Duke, that's right when I came six, seven years ago, and I was able to take charge of the microbiome sampling for that, and we're getting samples again from months after major surgeries of 15 different subtypes, some of which are transplant and major cancer operations, people that end up in my ICU that I take care of ultimately. And so, you know, a surgical population, like a liver transplant population, a cardiac population, major surg-onc, people you know they're going to end up in the ICU, would be intriguing, right? And you could begin to get the sense of what a baseline microbiome will actually begin to get some of that data, and some of these populations would do to outcomes in that particular kind of critical illness. And I think it would be interesting to see then, you know, what if you layered on an intervention? What if you did, like, I think Gail's point is a good one, we don't know what normal is for everyone, but one can imagine layering on a probiotic intervention prior to a major operative intervention to try to optimize, if there is such a word, I don't know if there is actually, but optimize the microbiome. It would take a fair number of patients obviously, unless you could find a high enough risk surgical procedure, but I think that'd be a fascinating study and a fascinating baseline kind of information. I mean, we're starting to do metabolic CARTs and some of the other things preoperatively, and just because we're not even sure what happens to metabolism preoperatively and postoperatively, or pre-IC and post-IC much, those are some opportunities though to begin to get at some of those questions. And I think, like, for instance, this project at Duke is one that we're super excited about, because it also gets all the other omics, all the clinical outcomes, and all the inflammatory markers, both before and after surgery in these different patient populations. And so I think studies like this, I'm sure there's always going on in the populations, and so I think studies like this, I'm sure there's always going on in the US, will be interesting. But we definitely are seeing some associations to cognition and delirium of the microbiome in our cardiac surgery patients, who are obviously undergoing a pretty severe operation, and it looks as though perhaps their baseline and change in their microbiome over time does affect that. And so I think these affect that, and so I think these are populations that would be exciting for the future. I'm glad you mentioned that, because actually that leads to the next question, and the reason it does is because the question resolves from giving patients prebiotic fiber or not, just because, again, in certain patient populations, normally it isn't. And I can't help but wonder, then, when you're looking at these preoperative patients with sort of conditions, do you think maybe those are populations that prebiotic fiber might be helpful? I mean, that's a great question. I'd be curious what GeoHealth thinks, too, but, I mean, that's a great question. I'd be curious what GeoHealth thinks, too, but, I mean, that's a great question. I, you know, I went into the study that we did of prebiotic fiber in the trauma patients, right, and I didn't tell you a ton about that trial because of time, but that trial was targeted at patients who, they couldn't have any other chronic illnesses coming into the study. So they theoretically were the average, like they couldn't have diabetes, they couldn't have chronic disease, the average normal person undergoing trauma that also could not be GI trauma. They were largely neurotrauma and orthotrauma, with the idea being, if you take what should be a semi-normal, although anyone on a typical Western US diet isn't probably normal, but that population was what we were trying to study. We were trying to start the prebiotic fiber as quickly as possible beyond the ventilator, not beyond antibiotics in the US, but, which is interesting to think about. I don't know why that is, but nonetheless, in these trauma patients, right, the signals we saw, and we actually were worried we switched the samples at one point because we couldn't believe, sort of, even in this population, the significant sort of, what we sort of profound in what should have been otherwise a fairly normal-ish trauma population. These weren't chronically ill MICU patients with pneumonia who also had cancer and diabetes and four other diseases. These were largely sort of young to middle-aged, occasionally elderly trauma patients who didn't have other underlying disease and still immediately, who didn't have other underlying disease and still immediately had very severe dysbiosis, I think, like you said, Robert, from the antibiotics they got, and, you know, the fiber didn't help them. I would, I honestly would shy away from fiber until we can get more data in a critically ill population. I think there's many other populations of benefit, but I think you're better than I do even, and I'd be curious what she thinks. Yeah, no, I think it's an interesting question because you think that, you know, prebiotic, it's not, you know, viable microbes that can translocate across the barrier, and, but, you know, it depends. So the number of studies looking at prebiotics, and then you think of your critically ill patients being entrally fed. So we see a lot of, of course, GI symptoms, bloating, diarrhea. So if the prebiotic is a FODMAP, so there's been a number of studies looking at different types of pre-symptoms, bloating, diarrhea. So if the prebiotic is a FODMAP, so there's been a number of studies looking at different types of prebiotics, whether they're fructan-based or non-fructan, it's typically the non-fructan or better tolerated dose is shown to be more beneficial. But this is not an ICU population, this is a more healthy population. The other thing to consider, and we haven't really talked about this because we're talking about the microbes, but if you look at, if you do, you know, genomic sequencing of the microbes, and you look at, you know, what kind of genes are they expressing, and what types of genes for different metabolism, and what type of nutrients do these different microbes, what are they capable of metabolizing? And so I think getting down to that nitty-gritty is where you may be, that nitty-gritty is where you may be seeing some of these differential effects. So if in that population where you see that the pathogens are preferentially utilizing the prebiotic, number one, what was the prebiotic, the dosing, what were the pathogens, and then what were they metabolizing? This is why the more I study microbiome, the more I'm like, oh my gosh, we don't know much of anything. And why, you know, we need to back off and really just, and be more thoughtful in what we're doing. The way, I mean, in studies in healthy people, what's shown is that when fibers lacking in the diet is carbohydrate or polysaccharides as their fuel source, they're going to get it, and guess where they get it? They get it from our mucus layer. And so they start to degrade the mucus layer in the gut, and that, of course, then allows for the pathogens to take over and to penetrate into that, and then across the barrier. So it's kind of like, you know, what's the right answer for the critically ill? I think we just don't know it yet, and we need to be more, you know, mindful. I think, Paul, you've got that good data. If you have microbiome data that you can mine and actually look at what are some of the genes that these microbes are expressing, what are the genes that these microbes are expressing? What are they capable of metabolizing? And what's up-regular, down-regular with the different prebiotic? I think that would be very, I don't know if you've already done that, but that would be really good information to have, and try to help, you know, guide us in the future, so. Well, I'll mix on it, but we could. We did do, one of the other studies I didn't mention that we've done that the NIH funded was a trial looking for juvenile protective factors versus cognitively impaired people. So we took samples, microbiome and gut metabolomic samples from healthy children between the ages of 7 and 10 who weren't obese and didn't have other, ages of 7 and 10 who weren't obese and didn't have other illnesses. Cognitively impaired folks who came to our cognition clinic, and then their caregivers who are not cognitively impaired, so like their wives, husbands, whoever lives with them in the house. And we did both metabolomics and microbiome work on that, and we did see some interesting, and we did see some interesting signals that seem to indicate, you're right, the same bacteria can have a very different metabolic pattern, the same families of bacteria can metabolize things very differently. And we did see patterns of metabolism that changed pretty dramatically in the cognitively impaired folks, as well as changes in the microbiome itself. We're writing that paper right now. The microbiome makeup is one thing we need to know, and it's interesting, but like you said, the metabolomic profile, the ability of particular bacterial families with, even within the same looking microbiome, can be very different in what they're metabolizing. And I think that's equally as important. I think that will be really an interesting area to go on the first serve and ask you who's just this amazing person, like I said, we got from Hopkins, who has, over the last couple years, trained herself to be able to do all her own microbiome analysis like a computer scientist. She's one of the only critical care anesthesia trained folks that I know that is able to independently do all her own assays of metabolomics and microbiome 16s. So I'm excited, and microbiome 16s, so I'm excited to see where she can take this field. I'm sure she'll take it much further than I've ever been able to. Yeah, but also in addition, like metabolomics, but even which would be upstream of that, is just looking at the microbes and then looking at what their genome is, like what genes are they expressing, and then be able to, you know, these different metabolic pathways, and different, you know, different things that people are doing in their daily life. Like I study alcohol in my lab, and we just did shotgun metagenomic sequencing. These were mice, of course, but we found how ethanol pathways in these mice, and so you think about that, that, you know, we've got induction of oxidative stress in by the microbes, you know, these aren't even looking at the host cells. And then we had a seminar speaker that came a couple weeks ago, but her data was showing how just within, her data was showing how just within, you know, minutes, you know, we're talking like 30 minutes of some type of metabolic insult, how the microbiome is changing their gene expression to handle whatever that metabolic insult was, and that can then influence how they handle, you know, of course, nutrients and things like that. So it's really, it's really fascinating, but confusing at the same time. Yeah, okay, and you know what, Dr. Kresge, in terms of, like, your remarks on prebiotics, one of the course participants mentioned patients with liver failure and, you know, anything different you'd say about that. One of the things that I thought that actually just occurred to me with this question, I wonder how things would be in the post-transplant patient, in which we're actually giving them, you know, very powerful medications to modify their immune response and kind of, you know, influencing it that way. So for anybody else on the panel, their thoughts on patients with liver failure and transplanted patients. Yeah, absolutely. Actually, I have a data set. We're getting ready to publish this data here. We followed liver transplant patients within 24 hours of transplant, and then we followed them post-transplant, three, six, 12 months, post-transplant, three, six, 12 months, and we have stool samples for microbiome metabolomics. We had breath samples where we looked at volatile organic compounds in the breath, and then we also have urine samples where we looked at untargeted metabolomics of the urine, and then what we found is, what we found is, when we looked at, and this has been published too, like patients with liver failure post-transplant, well, pre-transplant, they all have gut dysbiosis, whatever the etiology is of the liver failure, but the dysbiosis is not the same amongst etiologies, and then post-transplant liver failure patients, they tend to, the microbiome tends to shift back to more of a normal, healthy control kind of profile, but what we did is we actually separated out our patients looking at their etiology. We found that those with alcohol, looking at their etiology, we found that those with alcohol-associated liver disease did not respond similarly, the same as the other etiologies did. They lagged behind the rebooting of their microbiome post-transplant, and then when we looked at urine metabolomics, oh my gosh, hundreds of metabolites related to amino acid metabolism, lipid metabolism, you name it. We're all still skewed post-transplant, and those with alcohol-associated liver failure, so I think that, again, it's, we can't necessarily treat, even though we do, it's all, that if we start to consider microbiome, there may be some tailoring we could do, and definitely these patients, there have been a number of studies, small studies, that have shown post-liver transplant, they've given symbiotics and probiotics, and showed to have some positive effect on antibiotics and probiotics, and showed to have some positive effect on infections and infectious complications post-transplant, but those things, I don't know why, they just haven't made it like into, you know, main therapy, so I think that's definitely an area of interest to investigate, of interest to investigate. I don't have much to add, I don't study liver dysfunction or do anything clinically related to liver transplant, but I do think it's a valuable and very familiar clinical scenario when people are surprised about a gut-brain axis, right, but that gut bacteria may make products that traffic to the brain and contribute to behavior, cognition. I point out that the very familiar clinical scenario of hepatic encephalopathy is managed most commonly with two microbiome interventions, lactulose and rifaximin, and that's, that's not specific therapies, and they work by way of altering gut microbiota, differential production of short-chain fatty acids, acidification of the stool, and it's always struck me as interesting, you might think, and I'm a broken record about this, that there would be differential efficacy based on what antibiotics, I'm a broken record about this, that there would be differential efficacy based on what antibiotics the patients are getting. It's extremely common for patients to come in with hepatic encephalopathy and get, for instance, zosyn, and I worry that that's actually counterproductive for related reasons like what we're talking about with diet and nutrition in the ICU. If you are antibiotics that get into the gut, are you also compromising your ability to manage their encephalopathy by way of a constructive microbiome modulation? So, I point out that the idea that the gut-brain axis is new is betrayed by decades of clinical experience. Can I add something to what Bob said? I think, considering what you guys are talking now, I mean, there's a lot of microbiome interventions that happen daily on these patients, and we're just scratching the surface. Even therapy that we think is very targeted, such as many antibiotics, that we claim that they are Narm or not, when you look at microbiome studies, such as what Bob presented with the anaerobes, it really gives you an idea that the spectrum of the impact on the microbiome is huge, and we just are now scratching the surface and starting to understand, and I think we need to understand that and go beyond taxonomy, go beyond what microbes are eliminated or not, but, you know, you don't need to eliminate microbes to change their function, and at the end, it's their function and what they are producing, the host. Before we go off, I would actually like to invite the panel, if anyone wants to say anything about maybe some areas of future microbiome research, and perhaps we could, I don't know, simulate a few ideas and interest among our course participants in future areas for this to go. I guess I'll start. I have a prepared answer because that was a focus of my talk. I think two things. One, I'll just repeat what Leo just said. As excited as I am about over-the-horizon thinking and one day doing point-of-care microbiome characterization and tailored super narrow therapy Don't get me wrong. I want that, too, but I think there's a lot of ground to be made looking critically at existing variation in practice, these things like are you giving sapopemers or zosyn, and asking what effects are we already having on the microbiome, and does that translate, does that mediate into clinical out-years? I think that's the low-hanging fruit, and then the other sort of big idea that I'd like the field to consider is it is awfully hard to engineer an ecosystem, and our existing therapies, antibiotics, fecal microbiota transplant, probiotics, prebiotics, are well-intentioned, but I worry that in the eye become the constant bombardment with our therapies, with their antibiotics. So what I'm more optimistic about, and granted a lot of work has to be done, is the preclinical data I showed with our pigs of rescuing them, not with an ecosystem, but with bacterial products. So it might be that in 15 years, if your patient needs zosyn, give them zosyn, but give them back what you took away. So you get an enema that has the butyrate, the propionate, and the acetate that restores the homeostatic function that would be awfully hard to recapitulate with existing therapies, with probiotics, and so forth. So that's what I'm enthusiastic about, and one thing we're really excited to pursue. All right, thank you. Anybody else want to weigh in? Sorry. Yeah, no, I think that's really, really great points. Coming from the nutrition aspect, I would like to, and kind of to what Rao was talking about, is kind of meet the patient where they're at, because I don't, I don't want to reboot their ecosystem in an ICU, but, you know, if a patient, it's clear that these patients have, you know, overabundance of proteobacteria, abundance of proteobacteria. Proteobacteria like to metabolize amino acids, and here we are giving, you know, high protein formulas to our patients. Are we, are we giving them the right amount of protein? Are we giving them the right amount of high protein formulas to our patients? Are we just supporting more proteobacteria? So, so where do we, you know, really come up with the ideal feeding, feeding regimen for our patients? And should it be, you know, give the protein through intravenous feeding and then try to support, you know, with more adequate polysaccharides and everything for the good microbes? I don't know what the answer is, and then the other thing is what we do for processed food, and we know ultra-processed food is not ideal for the microbiome, so do some of these real food formulas have a place in the ICU? I would like to see more investigation along those lines to, you know, to make sure they're safe and, and, you know, to make sure they're safe and, and by providing them, do the patients tolerate the feedings better? Do they have better outcomes, etc.? I can follow on that. I may throw a little bit of a wrench here, but in, I would say that a lot of the stuff that we're trying to do is very much niche-specific, you know, it's focused on the gut microbiome, on the upper airway microbiome, the channel microbiome, the airway microbiome, and, and these are not what, these are, the, the limits are, you know, fuzzy and they're, they're gray, so, so we probably need to start is, I think, on, on, on being able to characterize the different contributions, what might be a good niche in mucosa, might not be good in different mucosa, and that applies for microbes metabolites, and so forth. And the other concepts, and so forth, and the other concept that we're trying to tease out, which is, unfortunately, it's another wrench to the system, is that we tend to treat things as if they were stable. And stability is not something that I would consider that is a, is a premise for microbiome-host interaction. These things are competing for the same resources all the time. They're fighting to each other. They're killing each other. So, in, for some environments, this is, in, this is very prominent. Now, a lot of the studies that we've done, I saw, well, a long time ago on, on the, it's a very dynamic situation where, where microbes are constantly being eliminated on your repeated, you have repeated exposures. So, that doesn't mean that, even if it is transient, doesn't mean that it doesn't affect the host. But you need to be able to do studies that embrace that. But you need to be able to do studies that embrace that, and don't assume that the system is stable. And definitely, when complexity increases, such as in these critical mutations, and this, I would argue that the stability is even less, it's even more difficult to correct. Well, you know, I think that more or less brings us to the end of our presentation.

microbiome

patient populations

probiotics

clinical care

treatment plans

antibiotics

personalized nutrition

microbiome interventions