Matters Microbial #71: Disinfecting the Built Environment

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I appreciate every listener and viewer as well as every email and comment. Many thanks by the way to Marvin Curry for the encouraging and kind email. It meant a great deal to me. A student in my microbiology course here at the University of Puget Sound sent me this meme suggesting that I replace a swear jar with a "talk too much about microbes jar." Student is not wrong. I remain an unrepentant microbial centrist. I mentioned last week that my micronauts in bio 350 screened a functional metagenomic phosmolibory made from a soil sample taken from a cloud forest in Puerto Rico, far away from any human interactions. As you can see, they found canamycin resistance genes easily. Also, carbanacillin resistance genes. The colony sizes you see here make me wonder if there are different resistance genes involved. And here is a phosmode with beta-galacticides activity visualized with X-Gal. I hope to get DNA from these phosmode sequenced and begin to learn what organisms these genes originated. Again, students found these colonies and that makes all the difference to them. I cannot emphasize that enough. The micronauts in my class also had a last chance to do a little bit more lux art, painting with the living light of luminous bacteria. Here's a nice drawing of a person with long hair. Here's a slightly disturbing portrait of me with a choked jar in my lab. And finally, a nice reminder of what I try to remind students of. They are all micronauts now. Yesterday was the last lecture from my microbiology course at the University of Puget Sound. It's especially bittersweet as I plot along uncertainty toward retirement. I encourage my students and all of my classes to be creative for extra credit. It actually does help them learn and it's always amazing to see their creation. I had a micronaut fascinated by Camp LeBacter. So here is a handful of nit Camp LeBatterer microbes to appreciate. Also, here are some clay figurines of a macrophage, two types of bacteria and a trichome from a cyanobacterium. More to come. I'm going to miss students like this. It's been a privilege. As I've said before on this podcast, the concept of antimicrobial resistance is so very important and should be an integral part of introductory biology courses, not just microbiology. Also, the way that microbes interact between ourselves and the environment in which we live is an essential topic. I often ask students where they keep their toothbrushes when they flush the toilet. I'm not sorry. I don't do this to be flippant or rude but accurate. We swim in a veritable sea of microbes every moment of every day. As with my angel microbes, devil microbes, and meh microbes concept, most microbes don't interact with us. But some do. And we would be wise to learn so much more about this topic. For this reason, I am genuinely pleased to have Dr. Erica Hartman of Northwestern University on the podcast to discuss the research that she and her collaborators do on antimicrobial resistance and the built environment. Welcome to the quality quorum for today, Erica. Thanks so much for having me. It is really a pleasure and I'm so delighted we share a sense of humor, but they don't know that immediately, do they? I guess they'll find out. And they will. I think the first thing that if you wouldn't mind, I'd like to ask, I'm going to get later to your path to microbial science, but I would like to have for the listeners and viewers your idea of what the built environment is because as I read it, I instantly think of conduits in the ceiling. And that is not wrong. So the built environment is this really like expansive term. It can refer to basically any engineered system. So your home is a built environment within your home conduits in the ceiling, within your home, also though maybe the back of your fridge is also a built environment. But also outside of your home, the cities that we live in, all of these different engineered structures that we inhabit, all of it together is this big built environment system. It's essentially our habitat. I think that's a good way to look at it. And I wanted to notice I looked over the slides that you've you kindly sent. And there were so many images that I hope will be able to talk to things ranging from dust grains to toothbrushes once again to other items. And this is something that I've been interested in for some time because one of the things that I do with my students is I teach them microbiology is the kinds of organism that live in their reusable water bottles. I call them water bottle buddies, but you know, you have to know that's me. So why should we care about the microbes that cohabitate our habitat with us? Yeah, because I would say it's really important to acknowledge that these are the microbes that are around us for a couple of reasons. One is that, you know, we spend we Americans, people in the developed world, probably most of the people watching this. We spend upwards of 90% of our lives within the built environment. You know, you think about you spend a lot of time in your home or in your office or at school, maybe in a car. And so a lot of your life, you're in these types of systems. And so a lot of the microbial exposures that you're getting are mediated by these types of systems. Either you're being exposed to the microbes themselves, so the microbes that are in your water bottle, for example, or even the types of exposures you're getting are being sort of orchestrated by the way the built environment moves us around. Who you come into contact with and for how long and what the ventilation system is like in that particular context. And so the built environment is really important from the point of view of microbial exposures. And then it's also important or rather just interesting from the point of view of us shedding because a lot of the microbes that are in the built environment actually come from us to begin with. And so that's interesting just from a point of view of sort of, you know, how we shed our microbial aura everywhere we go. And then from the point of view of understanding who survives, who could survive both on your skin and in the built environment or things like that. You know, it's funny. You bring this up because years ago I had a student in my microbiology class who's now a fabulous dentist. But I talk a lot and you could see that she was kind of zoning out a little bit. And same thing happens to all my family members, so I'm really not offended. And then what happened is I wanted to grab her attention. So I said that right now I'm omitting all of these Doc Martin microbes. And you yourself are omitting microbes. And the question becomes what happens when they contact one another. And her eyes got really large because I guess that was a disturbing image. And then she sent me an illustration of the character pig pen from Charlie Brown. But rather than dust, it was microbes. And that's really how we live. It's absolutely how we live. And I think there are obvious concerns about that from the point of view of communicable diseases and that kind of thing. But it turns out it's also really important that, you know, we wouldn't do so well in sterile environments. And we wouldn't do so well without our microbes. And there's, you know, the idea of the hygiene hypothesis is that by over sanitizing our environments and by not getting sufficient microbial exposures, we're actually worse off for it. So again, like thinking about the built environment as where you're spending most of your time, and also thinking about the key thing about the built environment is that it is engineered. So I'm not going to go out and change the microbiome of a rainforest because that's that's not how anything works. But I can definitely think about how I would change the materials that I would use in a building or the way that I operate the air conditioning system or the types of water treatment that we use as levers of adjusting the types of microbes that we either retain or exclude. And so that's a way of both potentially preventing infectious disease and making sure that we are getting hopefully the good microbial exposures. You know, it's funny you say this because one of the things that I talk about with students and I call these as a joke, swab stories as opposed to sob stories where someone swabs an environment and gosh willikers there are microbes there, which is hardly a surprise to anyone who's ever taken a microbiology course. And but the fact of the matter is there's a negativity that happens with the with the just actual concept of microbes when the fact is most microbes could care less about us we're not even a surface to most of them. And we get all of our attention because we're narcissists on the ones that cause disease or the ones that have perceived positive benefits. So this idea of looking at the built environment as a whole microbial ecosystem is one that's interesting. I know that when I took microbiology a million years ago, we would routinely isolate microbes from our skin because there it was easy to do because they tolerated quite a bit of salt. I always ask students why that is and they they I tell them not to sweat it as kind of as a hint and then they get that fact and it really does remind everybody that we're a series of ecosystems walking around our environment as a series of ecosystems and microbes have co evolved with all of that. So how long have we had a built environment so as long as we started doing things like agriculture and having kind of place to sleep indoors. So it's not yeah. So that's one reason to care about it and I just wanted to make that comment I did because sometimes I fear there's a little bit too much negativity about microbes in general. But one of the things that your laboratory group studies is the issue of antimicrobial resistance. And I think a good introduction to that is would be good to for people to know and then how that factors in. And I think things I think is really interesting about the build environment because we have this type of relationship with it is the sort of attention that we pay to trying to clean it. And a lot of that trying to clean is thinking about oh, how do I get rid of the microbes? How do I prevent myself from getting sick. And I would say that's kind of an anachronistic way of thinking we now like I said we know better that a lot of these microbial exposures are in fact important. But that doesn't stop us from wanting to have our room our rooms and our things and a lot of systems as sort of sterile and sanitized as possible. And so that leads to us using a lot of antimicrobials in our buildings and one of the sort of things that I think it's a way that people are increasingly starting to think about antimicrobial resistance is as just a stress response. So antimicrobial resistance is a really big problem from the medical standpoint because it's resistance to the drugs that we use to treat infections and that is really, really bad. But more broadly antimicrobial resistance is a trait that microbes have had forever because it's how they communicate or how they fight or how they you know just deal with different stressors. So if we go then back to this idea of the built environment where we're using a bunch of antimicrobials obviously you're not cleaning your kitchen counter with penicillin. But if you are cleaning it with an added chemical antimicrobial that stress can be very similar to the stress of being exposed to an antibiotic drug or the microbes might react to it in a sort of non logical non linear sort of way that makes it both more resistant to the antimicrobial that you used and to the antibiotic drug. And so one of the reasons I think antimicrobial resistance in the built environment is so important is because there's a chance and we have some evidence now to sort of back this up that the way that we're cleaning and the way that we're maintaining and the way that we're building our built environments might actually favor antimicrobial resistance. And again, thinking that this is where we're getting the majority of our microbial exposures from. It means that you're potentially exposing yourself to more antimicrobial resistance, which in and of itself isn't necessarily a bad thing until you have an infection that we now can't treat with our existing arsenal of antibiotic drugs. So that was sort of a long winded answer if if. But hopefully you got something from that. No, I think that's that's exactly right and and I'm holding myself back from the next question because there's a reason I'm going to ask it and you know what I'm going to throw caution to the wind. Do you want to talk about triklisan. Triklisan is speaking of caution it's sort of a cautionary tale so triklisan if I'm getting my history right was basically created in like the 1960s and was used in a lot of different. And it's a lot of different scenarios over the following decades, but it seems really, really exploded in the 1990s and it was for a long time the main ingredient in antibacterial hand soap. This is where I always stop and say if you only learn one thing from this entire podcast if you only take one one thing from this entire discussion, it is that you do not need an antibacterial hand soap that soap is actually just fine and the FDA recommends that you do not need antibacterial hand soap use regular soap and water. The CDC recommends you do not need antibacterial hand soap use soap and water so and there are some links I think we can hopefully share to the FDA and the CDC's guidance on that. But anyway, so triklisan was used as this added antibacterial to hand soap one of the reasons it's not necessarily that useful in hand soap is because you need a contact time of something like a minute and a half. And most people wash their hands for like 20 seconds or less, no, I think 20 seconds is the recommended and it's like seven seconds or less. So anyway, point is triklisan was used all over the place for all kinds of reasons. And a lot of the insinuation of including triklisan in various personal care products, but even like building materials so you could find it in like flooring, you could find it in textiles and like carpets, you could find it in all kinds of different products. The insinuation is that it would keep you healthy and no one's ever demonstrated that there was a lawsuit against play school, I think at one point. But basically play school was saying like, oh, buy these plastic blocks or whatever for your kids and it'll keep them healthy because it has this antimicrobial in it and that's not how that works at all and no one had ever showed that. Because of the lawsuit, you can no longer claim that adding an antimicrobial to a product makes you healthier. But we still include it and I think a lot of people sort of. Again, because of that negativity associated with microbes, a lot of people infer that, oh, if this is antimicrobial, it'll keep me from getting sick, it'll keep me healthier. It's not the case. And specifically with trichlessan, it's not only is it not necessarily keeping you healthier, but all of this evidence started to come out that it's an endocrine disruptor that it was an environmental pollutant that it had all of these potential side effects, including potentially enriching for antimicrobial resistance. So, in 2016, the FDA finally banned trichlessan in a bunch of other antimicrobials specifically from consumer hand washes. And there's been sort of a like ripple effect of it being removed from a lot of other products as well. So yeah, so that's the story of trichlessan in a nutshell. And what's interesting because, and I'm old enough to remember this boom in the 1990s that you mentioned, and I would see it in the paper that you put down on shelving. And it's like antimicrobial and that's because microbes have a negative connotation to the public. That's one of the reasons that I'm a microbial evangelist because it's just not true. And if you come back, I mean, I give a whole talk on the genesis of the word germ that everyone thinks is a negative term. But when Louis past year made a popular, he was using it to defeat the people who believed in spontaneous generation. He just meant a piece of life. So I'll often wave around a bottle of wheat germ and see how people respond to that. Right. What I used to do in my micro classes originally is I would offer extra credit to people that would find trichlessan in various consumer products. And that's when I discovered it was in some toothpaste. Absolutely as I mentioned before in some of the linings to cabinets, building materials. I even saw them put it in electronics, which I I thought was unusual. - Yeah, and I think so, this is, I could soapbox around about this forever and ever, but I think one of the big issues is at least in the US. So in toothpaste and hand washes at least, those are regulated as their personal care products. They're regulated by the FDA, so they have to have an ingredients label, and if they contain something like triglysan, as the active ingredient, they specify that it is added as an antimicrobial. In contrast, if you're thinking about that liner on your shelf or a textile or anything like that, the way those products are regulated, you don't have to demonstrate efficacy to actually include it. You just, if it is marketed as antimicrobial, it must contain an approved antimicrobial at a certain percentage by weight, and it does not have to be labeled as such, so they don't actually have to tell you what's in it, and just because it doesn't say antimicrobial, doesn't mean that it doesn't have an antimicrobial in it. Sorry, that was a lot of negatives. But it makes it really difficult. Once you are aware of this problem, it can make it extremely challenging to then think about, well, what products do I want in the built environment, and what things do I really want to use? So I think I also shared some links with you guys on the Perkins and Wilb precautionary list and the red list, and there are a few resources specifically out there for interior designers. So professionals working in this sphere, the people who are specifying things like surface coatings and treatments and things like that. So there are increasingly some resources out there for professionals, but I think there's a real lack of consumer advocacy and consumer education around, like let's say I just, Joe Schmo, go to the store and I'm looking at a rug for my living room or whatever, other than finding out that it's wool versus poly, it doesn't really tell me if there are any added antimicrobials or anything like that, flame retardants or another big one. All of these chemicals that we might be concerned about, both from a point of view of our individual health, because again, some of these chemicals can be endocrine disruptors, they can cause cancer, they can cause reproductive harm. And from the microbial perspective of they can change the types of microbes that we're exposed to, they can change the, whether or not they're antimicrobial resistant or the types of things that they're doing. And so yeah, I think it's so important for us to think about these kinds of things. - I'm a little bit embarrassed that I don't know off the top of my head, the nature of how trikeless and inhibits bacterial growth, is it involving fatty acid synthesis? - Yes, so I always hesitate to say, - Okay. - Anything like as a blanket statement, because there are like whatever trillions and trillions of microbes out there, and I'm sure it has one effect for some microbes and another effect for others. The general thought is that it inhibits fatty acid synthesis. And so there are a few different ways that microbes can become resistant. One is by modifying the target, which is basically part of the fatty acid synthesis pathway. And if you have one variant of that gene, you're basically immune to trikeless and. But there are other ways of things like efflux pumps, which are concerning because a lot of those can be things like multi-drug efflux pumps, where I'm spitting out trikeless and but I'm also spitting out beta lactams, I'm also spitting out whatever, just whatever. And then there are other things that are like sort of lifestyle changes. So you can make changes to the membrane structure, you can make changes to whether you're in a biofilm, if you're a spore former, you can form spores. And those things don't necessarily make it more difficult to prevent say an infection or sorry, not to prevent, to treat an infection, but it can make it much more difficult to clean and remove my clothes. So things that are in a spore form, regardless of why they got there, they're now basically more resistant to everything. Things that are in attached biofilm, regardless of why they got there, they're now much more difficult to remove. And so all of these different sort of pathways that we can push microbes down by exposing them to antimicrobials, they can be problematic for different reasons. - You know, this is something that I teach about and there's a final exam I'm giving a week from yesterday and one of the things will be modes of resistance. And two things that I really wanted my students to know is that many antimicrobials don't really kill the bacteria. They just keep them from growing. And I have some nice demonstrations for that that I'll share with you offline, that's just fun to see. But secondarily, E-flux pumps are a really big deal because they can, as you say, shoot out a lot of things and that's one of the problems that we deal with. So if I can change gears a little bit with you, how does your lab look for antimicrobial resistance in the inhabitants of the built environment? - We use a lot of different approaches. We do a lot of different things in my lab. So we do some basic microbiology, growing things on petri dishes, running around and collecting swabs and plating them out, doing enrichment cultures, that kind of thing. You know, it's the tried and true 100 year old methods and you know what, there's still a lot of really cool stuff to get from that. But we also do a lot of molecular biology. So for the antimicrobial resistance genes that we know about, we might develop targeted PCR-based methods to look for those specific genes. One of the cool things we can do with that is actually quantify. So I'm in an engineering department. We like to be quantitative. So we can actually say, you know, there's this many copies of this gene here and this many copies of that gene there. And you know, what's the difference between these systems? We also use a lot of sort of omics techniques and data science and bioinformatics. So we do things like metagenomics where we'll go around and collect samples and extract all of the DNA from those samples and sequence all of it and see sort of who's there in terms of what types of microbes there are but also what types of antimicrobial resistance genes they might be carrying. And yeah, I would say we try to couple the sort of field studies if you can call, you know, going to your bathroom sink or whatever a field study. It's not the most glamorous field site. It's a couple of these field studies with sort of microcosm or simulation studies so that we can say specifically like, oh, we find this type of organism or this type of antimicrobial resistance gene in your bathroom and we find it in these bathrooms more than those bathrooms and then we can specifically say, well, it's because of this chemical or this practice that we can then simulate if you did the exact same thing but used a slightly different cleaning product or a slightly different material that you would get a different result from the microbiology perspective. So having sort of both the field and the lab studies and using traditional microbiology and molecular microbiology, we sort of bring it all together. - You know, and it's so relevant to what I showed a little bit earlier because a gazillion years ago, Joe Handel's men involved me in a program that she was doing where she was teaching functional metagenomics to people and using this cloud forest library that I mentioned. And what's interesting to me is that when you get, for example, a phosamid containing an insert that has canomycin resistance, we don't know if that's similar or different than other canomycin resistance genes. And this whole issue of why antimicrobial resistance exists in nature is a whole can of microbial worms but absolutely I've got some things whether worth looking at now that sequencing is a little bit easier on phosamids even at a small undergraduate institution. I also was able to get rifamysin resistance which fascinates me because I wanna know what that is. If that's just a change in the RNA polymerase, that's, yeah, okay. But if it's something else, I wonder because there are several diseases that are treated with rifamysin and I've never done anything in my career that's benefited humanity. So, you know, it'd be nice on my way out to do something like that. So anyway, that. - Somebody say the education benefits humanity. (laughing) - That's nice of you to say, thank you so much. In any event, you know, I really find this really a fascinating topic in general and I appreciate the approaches that you use. I know some people that have been using cure-based approaches for people to look for antibiotic resistance in nature. We have a site here in Puget Sound where we had serious heavy metal contamination for years and years. And I'm really interested in what that looks like with regard to in the environment there, AMR genes. So, what you're talking about is really exciting. - Yeah, it's, I think. One of the reasons I think it's so important to use a variety of different approaches is because, you know, We know that there are certain antimicrobial resistance genes, the ones that are identified in the clinic that were like, "Oh, this one's really bad." You know, your extended spectrum beta-lactamases, for example, were like, "Oh, we know that. That's a problem." What we don't know is what the next problem is going to be, and what we don't know also, and this is to sort of turn the problem on its head, is what the next useful thing might be. And so one of the things I think is really cool about using these sort of untargeted approaches, or things like collecting microbes and just hanging on to them so that you can see what they can do later, is like, yeah, you might discover a new antimicrobial resistance gene, which would be cool just from the point of view of knowledge, and also might be useful from the point of view of medicine. But you might also discover an antibiotic production gene. You might discover an enzyme that does something, you know, industrially relevant. You might discover a new small molecule that has some cool properties. And so you may think like, "Oh, the bathroom sink is not that interesting of a habitat compared to, say, a coral reef or the rainforest or whatever." And I'm not saying we should get rid of coral reefs or rainforests. Those are amazing environments, and they deserve all of our protection and all of our studying. I'm just saying don't neglect the biodiversity that's right under your nose. Oh, absolutely. I mean, I love to tell students this, and this is a good opportunity. The name Hudson Freeze. Now, that is a fabulous name. It sounds like a super villain name, but that was an undergraduate in the 1960s who was working with Tom Brock, and that undergraduate helped discover thermosacquaticus Yellowstone National Park, and that organism has a DNA polymerase, which is thermostable, and was actually necessary for the process we call PCR. Yeah, it's changed. It's changed. It's not just microbiology. It has changed biology as we know it, so. I got curious what happened to Hudson Freeze. He got a PhD. He works in glyco biology as it relates to cancer in San Diego. Yeah, cool. So I tell students don't tell me you can't find something important. We have found water bottle denizens that clearly have antimicrobial activity. So I think they're battling for turf. Yeah, yeah. So could you talk about a couple of projects in your lab you're particularly excited by I would love to hear about the toothbrush story. Yeah, so the toothbrush story is actually a couple of different stories. So one started with some of the folks in my lab, and I love it when the people in my lab come to me with research questions rather than me imposing them. I'm here to foster research and to support people as they start out on their own journeys. So yeah, absolutely. You can discover something cool, and you can dream it. You can make a reality. So this was one of those types of things where someone was like, oh, I heard or I forget it was you know, my friend who's in dental school was told that you should always keep your toothbrush in the medicine cabinet not out on the vanity because when you flush your toilet, it generates aerosols, and then you get poop associated microbes on your toothbrush. When you flush your toilet, it does generate aerosols. This is true. And we do find sort of human gut associated microbes in bathroom environments and it's somewhat unsurprising. And perhaps it's a little unsavory to think about, but I don't necessarily know that even if that is the case, it's a problem. But we thought it would be interesting to actually go in and like, yeah, okay, so I guess dental school students are culturing E. coli off of toothbrushes, but I'm pretty sure you could culture E. coli off of just about anything in your home. And that doesn't necessarily mean there was a lot of it there to begin with. It just means there was one cell or whatever, you know. So we started what I sort of affectionately refer to as project potty mouth where we got people to send in their used toothbrushes. And we took a shotgun medigenomics approach. So we extracted all of the DNA off of these toothbrush bristles to see what types of microbes were in the sort of biofilms attached to those to those bristles. And we're interested in this A because of this this idea of like poop associated microbes on your toothbrush. But also because if you think about it as an environment, a toothbrush is really interesting. It undergoes like various cycles of wedding and drying. It gets a lot of really funky chemical exposures from your toothpaste or whatever oral products you're using oral care products. And then it goes in your mouth. So it's getting these really direct exposures to human associated microbes. But then it sits out and gets all of these sort of indirect exposures to whatever tiny amount of microbes might be coming in from your tap water or whatever's floating around in the air in your bathroom, so on and so forth. And so we did this study. It was a pilot study. So we only had about 35 samples or so. And overwhelmingly what we saw is that the toothbrushes had mostly human associated microbes on them and they were mostly from the human mouth. So we found a lot of human associated like putatively oral microbes on these toothbrushes. And then we wanted to compare that to what we would have expected if we had just looked at people's mouths. And so we went to something called the human microbiome project, which took a bunch of samples from a bunch of people and a bunch of body sites. And they have a bunch of oral samples. And so we looked at what types of microbes are there and also what types of antimicrobial resistance genes are there. So we looked at the diversity of microbes on toothbrushes and the diversity of microbes in people's mouths. And what we found is that toothbrush microbiomes, so the microbes on toothbrushes tended to be less diverse than what was in people's mouths. But the antimicrobial resistance genes, those ARGs, were actually sort of potentially more diverse. And we thought that was really interesting. And then we looked at specifically where those genes were coming from and we hypothesized that essentially what you get is there's like humans tend to share a lot of overlap in what types of microbes they have. And so we figured that there might be some antimicrobial resistance genes associated with those bugs, but they would probably be a lot of the same antimicrobial resistance genes. Whereas if you do have environmental microbes, environmental microbes are much more diverse and they might have much more diverse functions because they're encountering different habitats and different stressors and things like that. So we thought maybe the higher diversity of antimicrobial resistance genes would be coming from that environmental import. And when we sort of broke down the data, so what we saw is that where we had a lower fraction of potentially human derived taxa. So fewer of those mouth associated microbes and more potentially environmental microbes, we saw more and more diverse antimicrobial resistance genes. So that was one part of the toothbrush study. The second part had to do with the toothbrushes themselves. So I'm really interested in all of these antimicrobial chemicals and the various ways in which we incorporate antimicrobials into our built environments. And again, a toothbrush, you might not think of it as such, but it is a component of the built environment. And so we found these toothbrushes that actually have silver nanoparticles embedded in the bristles. So the idea there is that it would prevent microbes from growing on your toothbrush. There are a bunch of like different technological solutions for this supposed problem. Again, I'm not 100% sure it's a problem, but anyway. And we wanted to see basically what happens to the toothbrush associated microbes when they are exposed to these different toothbrushes. So from toothbrushes that people had donated to the lab, not the ones that were used for the study, but ones that were used basically for method development. We isolated a bunch of different different bacteria. And we picked two, we had stuff, stuff like caucus epidermis, which is often skin associated, but can also be oral associated. And Rathiadenta Cariosa, which is often oral associated. And we took these two microbes and we exposed them to two different toothbrushes, a sort of regular toothbrush. And then this antimicrobial toothbrush from the same manufacturer. And we looked at who survived and basically how well they did. So you can see the basically microscopy images. And we're showing who attaches to the surface and how well they survive using live dead staining. And it seems like the the nano-enabled toothbrush bristles. So the ones that did have those nano particles added retained more bacteria. And we think that's because it actually changes the surface roughness. Basically you have more little nooks and crannies for microbes to attach to. And where the nano particles were retained, they actually did kill bacteria. But often what would happen over time, if the toothbrushes were used, is that like I guess due to just mechanical shear, the nano particles would fall out and you would have more just basically more surface area and no added antimicrobial. And the last little point I'll say about this is that the staphlococcus epidermis seemed to survive better on these toothbrushes than Rathiadenta Cariosa. And when we looked at the whole genome sequence of the staff versus the Rathia, it had more more antimicrobial resistance genes and more metal resistance genes. And there's often these like metal and antimicrobial resistance genes can be sort of located together within the genome. And so there's a reason where you see an enrichment of one set of genes you might just by chance get this carryover effect on the other. So that's sort of a little bit of the work that we've done on toothbrushes. There's actually a third part to that story, which has nothing to do with antimicrobial resistance, but we went back to the same data set and decided to look just for fun to look for bacteria phage, which are the phage that infect bacteria to see who might be there. And we just found this like incredible amount of diversity of phage that we've never seen anywhere else before, which is possibly just because we know very, very little about phage. And no one had looked at phage on toothbrushes before. So that sort of feeds back to that maybe potential biotechnology or like new discoveries. So yeah, we've actually done quite a bit of toothbrushes. So you know, I make little stickers and buttons and all the rest. Do you have a logo for Project Pottymouth because you need one? I don't. I do feel like that is a thing that we are lacking. And I don't know. I feel like Project Pottymouth was sort of funny tongue in cheek, but I worry that it might be spreading that, that, you know, again, that what we don't necessarily see a lot of, you know, human gut associated microbes on toothbrushes, even if we did, I'm not sure that we would also, if we then did the study, find negative health impacts associated with it. And I think that's really the thing to think about is like, okay, we can find all these different things, but so what does it actually translate to some sort of health outcome, sort of environmental impact, some sort of like what is the thing that you actually care about when you're, when you get squicked out? This is, this is very similar to what I was talking about with swab stories. I mean, I've seen and so have you, I used to offer again extra credit for people to find the most outrageous examples of them. And there are people and I'm not a hater. I'm not drinking the Haterade or eating hater tots on this. There are people who spent their whole career kind of promoting this idea that there are bacteria you can find through swabbing and isn't that interesting. For example, your shoes or what you find in the bathroom or the subways in New York and I am not being negative about it because I know that's a lot of work. What I am trying to say is we exist in this microbial sea, this microbial cloud. It's everywhere. And so it's not a surprise that we'll find them because they, I have a saying, first evolved, plastic stink. Those are microbes and it's really true. And and and this is what's wonderful. Do you have another project that you can talk about that will excite listeners and viewers? I'm trying to restrain myself from talking about dust particles with you. I so maybe I'll just say we could save dust for another if you're allowed repeat dust because I could probably go on for another hour about dust and hopefully we'll have I just just a sort of teaser. One of the things that I'm really interested in that I didn't really mention is that we do some work on antelidical chemistry because if you're interested in antimicrobial chemicals, it helps to know something about the chemicals themselves. So for example, in the toothbrushes, we actually analyzed what types of metals were used in those nanoparticles and whether if they said they had silver nanoparticles, whether they actually do spoil it or they don't always. So yeah, I think we could have a whole thing about dust. It might get a little more into the chemistry, a little more into physics, but it's still super microbially relevant. I do have a funny little vignette about maybe a swap, not necessarily a swap story, but someone at some point did a study on the microbiomes of kitchen sponges. Yes. And my uncle emailed me and was like, "Hey, Erica, I just saw this study about kitchen sponges and I'm like, that's amazing." And he's like, "Should I be worried?" And I was like, "Well, how many decades have you been using a kitchen sponge now?" I probably wouldn't put it in my mouth, but that's probably just because it would taste bad. You know, like, you've been using it for this long. The microbes have always been there even before we knew they were there, they were there. And now knowing it doesn't really change that. So if it didn't have an adverse health outcome before, it won't now either. We just happen to know more. Or if there is something where we see an adverse health outcome and we're trying to understand it, understanding what types of microbes are there can be helpful. But it's not necessarily like the only conclusion we can draw from that. There's a lot of interesting stuff out there. It doesn't necessarily all mean that you're going to get sick or not. Oh no. I mean, this is exactly true. Actually I know some people that worked on the kitchen sponge project. And I got to tell you that at my home and all respect to my spouse who's smarter and better looking and anything else you want to think of, I cannot get that person to ever let the sponge dry out. So I finally realized the smart move is to keep putting it up to dry and then replacing them every week or two. That's my solution there, right? Now I would say is I think for a lot of things, especially in the built environment where you're concerned about microbes, the best thing that you can do if you're really concerned about microbes is to let something dry. Yeah. You know, it's life as far as we know requires water. I'm sure maybe there's some extreme planets out there or something that defy that. But on this planet, all life requires water. And so if you're worried about microbes on your sponge, if you're worried about microbes on your toothbrush, if you're worried about, you know, whatever it is, let it dry. Yeah. That should be a motto. You see, I need to come, I need to come to your lab and come up with PR for you because this is fabulous. You know, I make, I make, I make buttons and t-shirts for my classes all the time. I need to come out there and bring them all to you. But it's hysterical. I get the best time. Now, you did say something in one of your, okay, first off, folks, listeners and viewers, I'm going to be this website. Okay, Dr. Hartman's website is beyond awesome. And also, Dr. Hart is sending me a bunch of links. You definitely want to check these links. But you made a comment about a probiotic approach to being antimicrobial. Could you say a few words about that? There's definitely a lot of, a lot of reasons to avoid using chemical antimicrobials, especially in places where they're not needed. So, you know, we absolutely need to have antimicrobials that work really well so that we can keep, you know, operating rooms and intensive care units sterile. Like that's super important. And I'm not saying we should get rid of all antimicrobials, but there are a lot of cases where we probably don't need them and, in fact, by using them too much, we're actually doing harm. So I think a lot of people are sort of coming around to this, at least in a lot of different, you know, different spheres, different circles or whatever. There has been some reaction to this, which is like, well, what if instead of using an antimicrobial cleaning approach, we used a probiotic cleaning approach. And I think this is an interesting concept, but it's a little premature. So there are actually probiotic cleaning products out there that you can get. I'm not sure at this point that I would necessarily recommend them, but it's a thing that sort of exists. And so one of the things that we wanted to do in my lab was actually to look at whether or not they work and not necessarily whether or not they work, but whether or not they work the way that they are supposed to. So the idea here is that a lot of the built environment is a really hostile environment to microbes. So like I said, microbes need water. If they don't have water, they die. Some of them are more stress tolerant than others, but you know, if you don't have water for long enough, you will die. They also need things like carbon and nitrogen and other nutrients. And so if you think about, you know, a floor or a kitchen counter, this is a dry, barren surface. It is not a friendly environment for microbes. So the thought then is that if you already seeded this environment with a bunch of microbes and it's already very resource poor, that there would be something called competitive exclusion. Where if a new microbe came in, the ones who were already there would out compete and the new microbe wouldn't be able to establish. And so if you seeded these environments with potentially friendly microbes, then the incoming pathogens wouldn't be able to establish. And this is, you know, I think there's a lot of evidence for this in the human microbiome and things like your skin and your gut, which is all great. But I was a little suspicious of it actually happening on surfaces in terms of surface cleaning just because again, you have so little microbial activity. And most of the microbes that we actually see on surfaces, if you look at what they're doing, they're dying. They're just in a state of decay. And so we did this study where we basically competed a probiotic cleaning product against some pathogens. We took to approach to looking at what was happening. One was a culture-based approach where we just counted colony forming units of, in this case, a pathogen called Acinida Bactore Balmani, and then the probiotic, which was a mixture of basilis species. And if you look at the sort of culture-based results, one thing that you notice is that, whether you do anything at all or nothing over time, the pathogen dies. If you add a detergent over time, the pathogen dies. If you add the probiotic cleaner, it doesn't actually accelerate that process at all. But if you look at sort of the relative abundance of what types of cells you're recovering from that surface, you would see the basilis come to dominate. But actually, on an absolute scale, you haven't changed the amount of acinida bactore that's there. At all, you've just sort of masked it with an overwhelming signal of the probiotic basilis. The other thing that we looked at, and this will be the next slide, is we took a transcriptomics approach. And so we actually collected RNA from these, this is a microcosm study that we did. So we had painted drywall in this case. And we collected transcribes, so RNA, and we sequenced them, and we just mapped them back to either the acinida bactore or the probiotic cleaning. So the acinida bactore is the ABBL, and the probiotic cleaning product shows up in the panels three and four here. And essentially what you see is the mapping rate of transcribes is 100% to acinida bactore until we forced the basilis to germinate. So in the probiotic cleaning product, presumably the basilis is only present in spore form. And this is important because if you think about manufacturing a product, it does have a detergent in it, and you need something that can survive that detergent. And so a sporylated basilis is like a great choice. But then what happens is if it hits the surface and doesn't have the things to signal it to germinate, it stays as a spore, and it's not metabolically active, it's not competing for resources, it's not really doing anything. And the only way that we could see any transcripts mapping to that basilis is if we forced germinate it and then applied it as the vegetative cells. And so we essentially interpret this as evidence that if probiotic cleaning products do have any impact, it's not due to competitive exclusion. And so I think until we really understand how microbes are surviving in these environments, it's a little early to be taking this type of approach. There's a great quote by Mark Twain that it's not what you don't know that gets you into trouble. It's what you think you know that isn't true that gets you into trouble. And that's really true everywhere that we go. We have assumptions about science. I don't want to speak for you, but I have been fooled so many times by phenotypic screens because I want that to be due to a particular mutation. Bacterium doesn't care about that. It's just a red colony, right? And a friend of mine, Bill Metcalf used to say, your phenotypic screen is for your benefit, the microbes don't care. And that's true. And again, it's the past year in the end, microbes will have the last word and they do. They do. Yeah. I have to say one more thing that I'm old enough to have been very, very reductionist in my view. Here is a gene, I knock it out, what is the effect on phenotype? But that's not how life works. And now we have the ability to look at whole constellations of genes. And again, as you're talking about in community issues as well. And this is what makes microbiology such a great, great field to be in because it's, I don't want to say it's blooming, mixing my metaphors, but it absolutely, there's something new and exciting every day, which is one reason I enjoy talking to people like you. So Dr. Fauci was recently commenting on what he termed disinfectant theater during the awful COVID-19 pandemic. I wonder if you have any recommendations on the kinds of things we actually should disinfect and the best way to do so. Yeah, I think the thing that I really want, the cultural revolution that I would like to see happen when we're talking about things like disinfectants, is to actually think about what it is that we're trying to achieve. So for example, if we think about the kitchen counter, if I just got out a loaf of bread and cut that bread, and now there are breadcrumbs on the counter, all I need to do is sweep the breadcrumbs away. I don't need to disinfect that counter. There's no microbial hazards that are imparted by cutting bread and breadcrumbs. If on the other hand, I was say handling raw chicken, there I do have to be aware that there's a potential for some Ike microbes that I don't necessarily want on my counter. In that case, we should use some sort of disinfectant in our cleaning strategy, but remember that cleaning and disinfection are actually two different things. So the first thing you do is you wipe down the counter to remove any physical debris or any like oils or actual liquids that have pulled up. And then the second step is disinfection, which is to deal with any residual. And in that case, whatever disinfectant you use, make sure you use it correctly. So for example, if you're cleaning with something like bleach, you have to make sure that you're using a 10% bleach solution and that you leave it for the appropriate amount of contact time. You also want to make sure you're doing it in a well-ventilated area because some of those fumes are not so good for you. And so to think about disinfection, not as a thing that we're trying to achieve, but rather a means to an end. And so think about what am I actually concerned about? And how do I get to that endpoint and is disinfection a necessary step in that pathway? Related to that question, Erica, are there any antimicrobial products that you like? I think-- so for general consumers, the big thing that's missing in terms of that antimicrobial to me is really demonstrating the efficacy of why it's there. And so really thinking about if it's gym socks, for example, for me, if you see anything that's anti-owner, it probably contains some sort of antimicrobial. My answer is always going to be to wash the gym socks, you know. My answer is always going to be if it-- you know, if it needs to be washed, it needs to be washed, and no amount of added antimicrobial is going to change that. And so to really think about if you're adding an antimicrobial to something, if you're buying an antimicrobial something, what are you trying to achieve and does it actually do that? And in a lot of cases, there could be good applications. We just lack the data to show that it's actually doing that because we haven't agreed on what the endpoint is. No, I think that's really well stated. We had a podcast recently with Michael Schmitt about copper usage in hospitals for touch. And there's a lot of good benefits from that. And obviously you can't like build your home out of copper sheeting, but you get the idea. So again, it's like the context of it. And I was especially struck by your comment, what are you attempting to achieve? Because I think this factors into the germs idea so much. People aren't thoughtful about that at all. Yeah, and I think outside of, say, planetary protection, where you're really concerned about sending earth microbes to Mars or whatever, the outcome should never be zero microbes. Because it's not realistic. The outcome should be no Campalobacter on my kitchen counter. You know, and that is much more reasonable. That's a slogan we can all live with there. No Campalobacter on the kitchen counter. It's a liturative, too. I guess another question that comes up is with the rise of antibiotic resistance among microbes. And how antibiotics appear to be in a losing race no matter what. What do you think the prospects in the future are going to be? I really think the solution to antimicrobial resistance isn't the like silver bullet. It's not like, oh, we're going to discover the next antibiotic and that's going to solve the problem. We're going to discover the next antibiotic and that's going to solve some of the problem for a short period of time. I think the thing to really think about is, A, how do we continue to use our antimicrobials that we have most effectively? So antimicrobial stewardship. And B, when we develop new strategies for treating infections, how do we manage those in a way that disfavors the evolution of resistance? And so that could be, for example, if we keep developing antibiotic drugs to cycle through them, maybe to have them as cocktails, there just needs to be different ways of using them. The other thing that I think is really promising and really interesting is more sort of biological and ecological based strategies. So looking at things like phage therapy or other sort of more, uh, targeted approaches so that when you are getting some sort of treatment for infection, you're taking out the infectious organism and not the rest of your microbiome, which probably will help the system be more resilient, so then you have less of a risk of recurring infection or something like that. And so really thinking about not what is the next thing that's going to solve the problem or what is the thing that's going to solve the problem, but thinking how can we keep coming up with new ideas and keep cycling through things so that we get the most use possible out of the things that we have and that we anticipate evolution of resistance in the future. To me, antibiotics are doomed because the antibiotics don't change and the microbes that they're impacting are endlessly protean if nothing else we've learned. I again, trying to be overly clever, I'll say that the hand of Darwin is on all that lives and it's really true and that's why your ecological solution is I'm with you. I think that'll be the future. It's really amazing that it doesn't matter how toxic you think a particular chemical is or some sort of environment that some microbes will figure out how to live there. Dienicoccus radiatorans exist and that's wild. Would you say a few words about your path to becoming a microbial scientist before we close out? Yeah, sure. I think I was always sort of interested in nature and the environment and that's something that even as a little kid I was catching crayfish in a stream or whatever and I thought that was super cool. When I eventually got to college, I thought I would study biology because of this interest in nature. It turned out that what happens at least at the school that I went to in a biology track is very different from the sort of things that I was interested in. But while I was there, they had a first-year seminar and one of the professors who came to talk was talking about something called bio remediation which is the use of microbes to clean up toxic chemicals in the environment. I just thought that was the coolest thing. First off, these chemicals that were supposedly xenobiotic or foreign to life that everybody thought would just stick around forever. If you give microbes enough time, they will figure out how to degrade them and I was like, "That's incredible." Then that you could potentially use this to clean up the environment. I thought that was just the greatest thing. I went straight up to him after his lecture and said, "This is what I want to do. How do I do it?" He was like, "Well, ask around and see if anybody in my lab needs an intern." That's what happened. That's what happened. It turned out that he was in environmental engineering and public health. That's how I got to where I am now is I blended the molecular biology of my curriculum with this microbiology, environmental engineering, public health research. I took that and ran with it. I did an interdisciplinary PhD at Arizona State, which was super cool because it allowed me to pursue all of these different things to keep that molecular biology focused but also within the context of environmental engineering. What I was actually working on a lot was proteomics at the time. There was one experiment that I always wanted to do, but we didn't have the right instrument to do it. I ended up getting a postdoc actually in France, which was super cool. I went and lived in France for two years and did that experiment with that instrument and I felt like, "Oh, my life is complete. This is great." Then from there, I was like, "This is really cool, but I didn't want to be limited by instruments. If I was going to keep doing proteomics, I was going to get really tied into the types of questions that you can answer because, what is it if you have a hammer, everything looks like an nail?" I made the decision to radically switch gears so that I could use all of these different approaches and combine different ones instead of really specializing in one. I did a second postdoc the biology of the built environment center at the University of Oregon and that's where I started working on microbes in built environments. That was a really cool center. It was a merger between microbial ecologists and architects. They were really thinking about how does building design and operation influence indoor microbiology. I was like, "Hey, that's cool. Have you ever thought about antimicrobial chemicals?" They went, "What?" That's where we started looking at triplosan and antimicrobial resistance in indoor microbiomes and the rest is history as they say. I think, I say this in lots of different ways and it merits repeating. There are lots of paths to go into the microbial sciences and so many students I talk to, so many people I talk to were convinced there's only one way to do it. It's simply not true. I've always been interested in microbes and symbiosis and bioluminescence and all these things and I would try and deny it but I couldn't because the collar of the microbe was too much for me. There are lots of paths to get there. If you forgive this, I think that we need a big petri dish. Instead of a big tent, we need a big petri dish because the more we have different faces and voices and ideas, the better we are. That's what I hope to explore in this podcast and I'm glad that you've been part of it and I want to wish you and your co-workers and friends and family the very best and I am so happy to have met you. Well, thank you so much for having me. It's been a lot of fun and yeah, thanks for hosting. Thanks for exploring. You're welcome. This has been Matters Microbial, a weekly podcast about the wonders of our microbial world and the people who study it. You can send questions, suggestions or comments to me at [email protected]. Show notes from today's episode with epic links can be found at microbe.tv/MM. If you like our work, please consider supporting us at microbe.tv/contribute. I'm Doc Martin and you can find me in the biology department of the University of Puget Sound in Tacoma, Washington. Dr. Erica Hartman is in the McCormick School of Engineering at North Western University in Illinois. Many, many thanks as always to David Renata for superbedding and Reiber Clark for the wonderfully quirky music that makes me smile every time. I hope that you've all enjoyed being part of our quality quorum today. See you next time on Matters Microbial.