Microbiology PDF

So the patient needs to understand what this is because sometimes they're not aware of that. They don't understand. Sometimes they just freak out thinking, oh my god what kind of diseases that in my gums. And other times they don't pay the proper attention. So we need to explain to them what's happe...

So the patient needs to understand what this is because sometimes they're not aware of that. They don't understand. Sometimes they just freak out thinking, oh my god what kind of diseases that in my gums. And other times they don't pay the proper attention. So we need to explain to them what's happening, why is it happening and what we can do to treat control whatever we need to do for the disease. So these next few lectures will be a series of understanding what's happening sub clinically with bacteria. The host response, the whole cascade and game that's being played between those two, how these are being affected by other factors, what you see clinically and how you transition eventually from health to disease and vice versa. Okay. So today we're going to start with microbiology. And we will talk about the normal flora how bacteria cause disease, the complexes you will see. Or you may have heard about those that we talk about impaired ontology and the most common bacterial species that we have in periodontitis that you need to be aware of. So some information is that the the human body contains ten times more bacteria than human cells. You can imagine how many of those we have. And that's actually part of our normal flora and balance. We're going to see in a few slides that we need those to survive. Right. In a our environment is not sterile and we cannot function or we cannot like live and survive if we don't. Everything okay? Yeah, okay. If they say something wrong? No. Okay. Um. So it wasn't because of the kilos. I'm trying to understand what's going on. This is just, like. Extra strong. So this is, like, the. Most. Simple slide, like I said. Okay. It's inspiring. Anyways, let's start with more important things. You may have heard about Louis Pasteur. He's the. He was like the pioneer for inventing, like, the principles of vaccination. Microbial fermentation. Pasteurization. We used the techniques that he used for those things. So he assumed and theorized that foreign microorganisms were responsible for infecting animals and humans and causing diseases. So he discovered the process of all these things that we mentioned the pasteurization, the vaccines, the fermentation in order to help the and the humans, the people, in order to prevent that microorganisms to develop and infect humans. And based on this process, you may have heard about this name, Joseph Lister. So he was a pioneer of antiseptic treatment and based on his techniques and everything. So actually, Joseph Lawrence and Jordan Wheat were the ones that developed the antiseptic techniques based on Joseph Lister. And that's where Listerine, the name comes from. Yeah, some information on that. So I said about that before, how bacteria are in our body, on the skin, the mouth, mucous membranes, respiratory tract, digestive tract. So the majority of bacteria, normal flora is found on the exposed surfaces of the body. And each surface, depending on where bacteria are being found, have a characteristic biological and physiological proper and physical properties, and the composition varies significantly within the mouth. So this is all about a balance. And I will be saying that thing again and again about a balance. That's also a huge concept in our life to have balance. And that happens in the bacteria and the host response as well. So we have a normal flora that we have learned how this works and we survive without and any imbalances in that either because this flora becomes more pathogenic, has other species of bacteria, more numbers, etcetera, or the host vice versa becomes more susceptible for various reason reasons. So this imbalance creates whatever we see as clinical signs of inflammation and disease, not only in the mouth, also in other like in the GI tract, all those inflammatory bowel diseases, IBS that patients are having is like imbalances of these flora as well. So when do we start having a flora in the normal flora in the oral cavity? And that's actually, as you may have heard, that we are born, the teeth start to erupt and we get through phases and all those phases and ecological situations with age and maturation and different environmental. Effects that we have. We have the changes in composition in the normal flora. So obviously in the uterus, the oral cavity sterile. The moment we are born, we have the first like ours, the first ours like this streptococci species. We're getting our first first nutrition, etcetera. As the teeth are out, we start seeing more species around the erupting teeth. That's a key phase, like the puberty. We talked about that number of teeth is increasing different configurations, habits of the people at that age, other factors in diet, in ecological and environmental effects that may have habits that kids and adolescents may develop at that time. And then as we go through the adult age, we have this biofilm, the dental plaque that we have talked about in a few lectures ago, and how this may influence periodontal diseases and eventually with a loss of teeth. We are expecting that the bacteria, the number of bacteria decreases. Now, what I need you to keep in mind is that even in completely identical patients, you can still find some bacteria in the mucous membranes. Patient is wearing prosthetic devices from removable dentures or fixed. They obviously have bacteria obviously nowadays with the implant treatment and everything even. If teeth are missing, we are replacing those with dental implants, and those can be affected by same bacteria as well and develop similar diseases. This is another big chapter, but letting you know about that as well. So usually the oral flora has aerobic and anaerobic species, some Candida species, some protozoa. So there's a lot of bacteria as you see here, that they try to communicate and live together. And as I mentioned just mentioned. So teeth and implants have similar like composition of bacterial flora that can be found around them, especially implants that suffer from forms of disease, either just inflammation or also inflammation and loss of bone per implant mucositis per implant virus. They have similar bacterial species and need specific treatment as well, the same that we do around teeth. So we've been talking about the different species, or we have almost like 700 different species of those. They are capable of colonizing. Bless you. The oral cavity and the metabolic environment that the bacterial needs need can be determined by the temperature, the moisture, the nutrients, oxygen levels and several metabolic inhibitors. So as we said, the majority of the oral bacteria that we all have in our mouth, we are all sitting here. We are all having bacteria, because that's something as a notion. When we used to talk about period disease in the past, we say that's caused by bacteria. And people were going around thinking, oh my God, what do I have in my mouth? So they need to understand what we all have this bacterial flora that we call like the commensal. They are harmless and they provide benefits to the host. Remember from the previous lectures when we started with the gingivitis, when you always get a little bit of maybe some biofilm forming there, and you always have this first line of defense being ready, but this kind of prepares your host knowing how the balance of the specific flora that you have in the mouth, in the oral cavities. Right. And any changes in that, that's what triggers the host. And then we start having the whole cascade of immune response. And we can understand like how important those comments are, like bacteria, at least when we see that when we reduce, for example, a normal microbiota, we have yeast infections. They can happen anywhere in the body that bacteria reside. So we can understand the importance of that under specific conditions. They can cause disease. And as we said, they can have more mass, more numbers, more pathogenicity, suppression of the commensal beneficial bacteria and reduced host response. And usually it can be a combination of those depending on the situation. Now, what triggers what according to the knowledge we have is more like the chicken and the egg question. Because you have you can see, like in more recent studies, what they are calling us this inflammatory like friends of inflammation environment where depending on changes that may happen in the course, they allow the bacteria to multiply and become more numbers and more pathogenic. And then these increase in number and size and mass etcetera triggers the host response more as a reaction. So it's like kind of a vicious, if I can say cycling though. So what we are trying to do in terms of treatment is to bring this back to balance. And if you see, like recent studies on this approach and understanding of perio diseases, one of very good speakers, in case you haven't heard him, I would really advise you to listen to any of his lectures. Is Dr. Van Dike. He's also in Boston, has done a lot of lectures over here, like how he targets the immune response because even if you eliminate bacteria, if you have a susceptible host, you're always at risk getting those flare ups again with the disease. Right? So it's about a balance with that. So as we said about the bacterial habitat obviously we can have some class and pros and cons when we have the normal flora being healthy. And as we know it, you obviously do not allow other microorganisms and bacteria, non-indigenous species to become established, which is a protection over there you can have the host nutrition with the synthesis of vitamins. They contribute to immunity. We said this constant response over there and obviously they have microbial antagonism for again for non-Indigenous species. So it's kind of a constant battle to make sure we have the normal flora. On the other hand, these flora, when it becomes pathogenic it can cause oral diseases. And they can gain sometimes like entrance to deeper tissues. And they can cause other form of diseases from abscesses in other extremities. These bacteria. Me that we say so. This is something to keep in mind as well. And since I've talked, I've been talking a lot about the balance thing. We see all those nice rocks we do every summer. Every single summer. Go to a Greek beach. There's always something like that. So health is a state of balance where you're having those multiple bacteria that coexist with a host, they do not occur any damage. They do not create or cause any host issues. On the other hand, in disease we have disruption of this balance and that causes alterations to the host and bacterial biofilm, which eventually can result in destruction of the T, the connective tissues of the periodontal and everything that we know about diseases. And that's a brief. Like representation to understand what's happening when we're having homeostasis and we're having the health and we're having community stability. And obviously with either caries or dental diseases, depending on which disease you may come across with, you have different bacteria that become more pathogenic, increase the number and pathogenicity, and they cause the disease and obviously can be influenced by other factors, dietary factors, host factors, and have the impact of the host. We will have more understanding of this in our next lectures. When we're going to talk about the host and how everything comes together. So just giving you a little bit of a small information over there. So regarding the adherence, we have six major niches. We have super and sublingual areas soft tissue epithelium the tongue the tonsil the saliva. Why do we mention those things. You may have heard about some protocols. They call them like this full mouth disinfection. They were developed for specific situations patient wise, health wise, treatment wise. That should just disinfect the whole oral cavity. And this even included disinfecting like the tonsils, the tongue with antiseptic rinses. It was like a whole approach in that. So we need to understand that they can reside over there. Yes, obviously the areas around the teeth are more important about us and that's where we focus. But something else, when we give oral hygiene instruction and everything of what we talk today comes to the answer. Okay, good. I learned about the bacteria. So what do I do with this information is first how you explain to the patient. What's going on in their mouth. Why? They may have those signs of disease. And what's the role of bacteria in the disease and the clinical signs? And secondly, what can we do about that? And one part is the treatment that you're going to be providing depending on the patient's needs. The other one is the work or the care that the patient needs to take of the teeth in terms of brushing, oral hygiene, etcetera. And very often, for example, I remember I was a student dental student and they were saying, yeah, we don't say about brush, for example, your tongue. And obviously that's a huge habitat of bacterial species that you may reinforce the patient's like brushing the whole oral cavity to maintain that balance. So obviously when you're having those microorganisms that can eventually cause disease, they attach to the two surface they colonize. And they can either cause the carious lesions. As you know, we're not going to talk about those obviously, and other inflammatory changes in the periodontal. So depending on what the patient has, they may either have more carious lesions than periodontal issues or vice versa or both. So we need to be able to address both. So there are differences in the supra and sub gingival environments, especially in the metabolic environments different nutrient sources and oxygen level oxygen levels and the environment kind of dictates the ecology. And I'm saying that here we you've heard it maybe 3 or 4 weeks ago with a lecture of plaque and biofilm, and I have it here as well. So this ecological pattern plays a lot of role. And it's being mentioned in also the theories of the ecological plaque hypothesis, the keystone pathogen hypothesis. So all those changes play a role because a lot of the times when we're thinking about what's happening, let's say in the periodontal around the specific tooth site or the whole dentition, we're thinking systemically, which is right, but we're also thinking what's happening locally in that specific pocket area like site, and how is this environment over there? And this question of having more bacteria, this inflammatory, like, as I said, environment like friends of inflammation causing the disease and disruption. That's how the whole concept of everything comes together. And that's how we understand the differences of having supra versus gingival plaque and calculus, the importance and how sub gingival plaque and calculus develops and how bacteria can become more pathogenic, and why we see specific forms of of destruction sub gingival and why by removing and creating an a balance with inflammation on the host, we take all these pieces and we do not allow those sub gingival species that need those specific requirements in this specific environment survive. We make it difficult for them to survive and eventually cause disease. Makes sense. Okay. And just as a comparison here, as we said, we have different environments. We have different page. In. A more acidic. In the super, gingival can be more acidic and more neutral. In the sub gingival, we have different nutrient sources with a dietary sources that can be affected. Supra gingival. Obviously, although sub gingival you have more the gingival fluid the tissue breakdown by products and metabolic activity and obviously the oxygen level. You will be hearing that again and again. Whatever is above the sulcus, the pocket is having access to the oxygen. That's why we call it aerobic. Whatever is below has reduced oxygen and or even zero oxygen. That's why more anaerobic bacteria survive. And that's why those we don't want those to be there. Because anaerobic bacteria, when cluster creating communities can create these pathogenic issues that we have seen clinically. Okay. So what do we know as dental plaque or biofilm. As we say we can define it as a complex microbial community. You had a whole lecture about that. So I'm not going to stress too much on that. We have bacteria that are embedded in the matrix of polymer and are structurally and functionally organized. Just for your reference, I need you to biofilm. You will definitely get questions on that. So I need you to know their structures, their abilities, what protects them, what how you can address it, how they can be resistant in some environmental changes because of the community that they form over there. Okay. So how do bacteria cause disease? It all has to do with a process of acquisition, adhesion and retention, the survival, then the prosperity, avoidance or elimination, multiplication and eventually elaboration of virulence factors. So let's see all those things steps by step by step in terms of acquisition, interference and retention. It's all about the ability of an organism to attach to a surface. Okay. So when we are able to do that and that's why we talk about biofilms biofilm, that's not only in the oral cavity. It's the ability of a microorganisms to attach on the surface. You have a glass surface. The bacteria can attach there and form a community. So we have the ideal surfaces with crowns and teeth in the mouth. That's how bacteria can attach over there. We usually have the early colonizers, and I want you to keep in mind those names so I can differentiate that we have the early colonizers that are usually gram positive cocci, bacteria that produce like those extracellular polysaccharide that will glue the cells together. So the first complexes that try to form and make the biofilm are those early colonizers, usually gram positive. They're the ones that are aerobic, creating those complexes over there. The biofilms are responsible for the interaction of microbes with each other as well with the interfaces, and the initial adhesion is dictated by specific physicochemical variables. How the situation environment is over there. And obviously these adhesion is mediated by nonspecific like interactions and accomplished through specific molecular mechanisms. And it's all about creating a community together. So as we produce let's say we allow this to develop, we start having specific like cell to cell adhesion mediated by specific adhesions or cell surfaces modifications. And we start having like this Co aggregation of bacteria. And this is like genetically of genetically distinct bacteria in specific molecules. And we have seen that in mixed species biofilm. That's what we have in the oral cavity how those bacteria can come together. So this is the first thing that happens. You brush within hours that happens. Right. And that's why another that's another reason we say to our patients, you know, brush twice a day because this thing the moment you clean it, because we do have those planktonic commensal bacteria in our mouth, they start to form these communities again. And when they form that what we what we're doing with a brush, because that's what has been shown that we need the mechanical force. So we just break this community and then they have to start all over again. And we break the community and we start all over again. And obviously we manage us patients depending on our risks, etcetera, to maintain, maintain that balance and that to disrupt this community with our brushing, oral hygiene techniques. But we cannot be 100% efficient, especially in difficult areas of gingival. That's why we need to go to the dentist. So I'm saying all those things because that's what I'm saying to the patients, because yes, they are coming, they're doing the treatment. And then I tell them, excellent. And now I need to see you every three months, every four months, every six months. And they do not understand why this needs to happen. So we need to keep this story, let's say, together. So after this happens we have the initial. Yes of course. So one and biofilm are two different entities. Yeah. So we start with the biofilm. So the bacteria as terminology. And if you go back to the lecture of plaque biofilm that you had maybe 3 or 4 weeks ago. So the bacteria that start colonizing the surface causing and forming that biofilm. So as these matures forms eventually the plaque that, you know. Just one more thing that could be helpful. Next. Yep. Yeah yeah yeah yeah. It's the same thing. Yeah, yeah. Nothing has changed with that with the pellicle. So bacteria requires also not only the stable surface to be able to adhere and create the community, but also a source of nutrients. We talked about that that the gingival fluid is a great source of nutrients. And obviously that helps with sub gingival bacterial colonization and growth over there. And eventually when this is being continued, we should have like this prosperity and long term survival. So this is how the biofilm develops and the mature biofilm as it matures. It has a complex architecture provides niches specific like physicochemical conditions. Again differences in the oxygen availability, the aerobic versus anaerobic. As we talked about metabolic side products the pH, everything that we talked about becomes more organized. And the cells in specific regions of a biofilm can have different properties, different patterns of gene expression. These quorum sensing you talked we talked about that again in this biofilm plug lecture about the communication between the bacteria. So they form like a great community, like these chaotic communities that we form as humans. It's exactly the same thing. We have a complex, highly differentiated, multicultural community, different species. Communication happens in order to communication happens in order for those bacteria to survive, in order to create the resistance that we know about the biofilm. And this is like super, super dynamic. We call it like the mixed species. They can stay and live on purpose. They can do whatever they want to say, okay, now I have to live from here, create a different or change the structure that's happening over there. They they compete or cooperate. They share their genetic material. So it's very like organized on how they are able to survive there. And that's why because of those mechanisms that they have specific approaches of just giving antibiotics, for example, or just giving antiseptics has been proven that it's not working right, because they create that resistance to all those external environmental factors, and that's why they can survive and withstand those. So a key survival strategy for all pathogens is how they can eliminate the threads. So the avoidance of elimination and as we see here, they can have different mechanisms in order to protect themselves from the threats. Just an example over here for different like from iron acquisition mechanism, the artesian everything that we know of how biofilm and bacteria work together. And as a summary here, in terms of the survival strategies for the bacteria they can have. They can sequester themselves within the host tissues and create, as we said, like the pool for colonization of periodontal pockets, the specific environment around the pockets. And as I mentioned before, the use of antibiotic is counterproductive in those patients with Titus. Right. They become resistant they to antibiotics. There was a notion in the past, oh it's an infection with bacteria give antibiotics. And it has been proven that it does nothing in terms of treating the disease. It actually what's the word trained the bacteria of the biofilm to become resistant. And if you do need the antibiotics with proper treatment later on, they're not going to be effective. Right? So if somebody says, yeah, I was given to take antibiotics to treat my gum disease or so that's something that's not right and actually will cause harm eventually in the future, was a question. Nope. Then obviously an important part of these bacterial and community is the multiplication. So specific like those parental pathogens can reach like a critical mass numbers, a lot of bacterial tests that are being done, they not only detect the presence or absence absence of the specific bacteria, but they also examine the number and the mass, like how much of those you have. And they have evaluated with specific studies that are above a critical level. This patient may be at higher risk getting these pathogenic biofilms and eventually clinical features that you may see in the oral cavity. So in order to survive they need to have a critical mass. That's why. If you leave them alone, they multiply, they develop. And obviously further multiplication is required for disease to occur. And that goes back to those theories that we're going to revisit again today for these like nonspecific or specific black hypothesis, like the presence of of a specific bacteria, just because it's there, it doesn't mean necessarily that it's going to cause or contribute to the disease. Right? They need to have specific product specific properties. They need to have specific mass, have a critical like number in order for disease to occur and overcome like this pathogenicity overcome the host response and mechanisms that we know and eventually what you may have heard about or not, but you will hear now it's about this virulence factors, virulence factors, which comes from the Latin word virulence, which means full of poison. As we see over here. And what are those? Those are like typically like proteins or other molecules of bacterial origin that are produced in order to cause disease to the host and allow these pathogens to thrive and survive over there. And they can be enzymes, metabolic products or toxins. We will have a huge list. I have a couple of slides on that. Obviously, I don't want you to get lost and remember everything by heart, but just the more important ones are coming more and more. So how do they cause disease? They produce like toxic cell constituents, like endotoxins, specific surface components, capsular components, enzymes. They disrupt the host cell membranes. We will see that how this connects in our next lecture with the host response and how the virulence factors affect the host cells and how they stimulate them, and they also inhibit the host immune system defenses. So it's a whole well orchestrated thing that's happening over there. You're going to learn more on that in our next host response lecture. So as I told you, there's tons of them over here. So what I need you to remember is that there are virulence factors. What they can do, they can have impact on the adhesion colonization, the evasion of the host response and the tissue destruction. So those three different properties and among those we're going to see in the bacteria, we're going to see later on, there are specific ones like the LPs that like over here. Bless you, the LPs and specific other virulence factors. I'm going to mention them in the next slides, of which ones you need to remember as a name, so that you're not getting lost with all those huge lists of them. So as a summary, the ability of bacteria to cause disease is based on the number and type of bacteria, the root of the entry in the body, the effects to the host defense mechanism of the host defense mechanism, extrinsic characteristics and increasing characteristics. So all those things together contribute to the ability of bacteria to cause the disease. So let's see what happens during periodontal disease. Our assumption in theory based on what we know so far today, which is Tuesday the 24th of October 2023, is that I'm saying that because we've changing well, everything is changing. So our assumption is that primary etiology is bacteria for our periodontal diseases. And eventually untreated gingivitis can advance to burden. Titus, as we mentioned, remember these four stages of patients, rather with initial the early the established in the advance, they have seen the stages from the initial to the established in days and how long it takes for hours days for them to develop. But the transition from established to advance. I had a question mark, if you remember there, because we don't know how and when it happens. Right. And our assumption is you have gingival inflammation. This cascade happens. So eventually it goes down to the host response further losing attachment and bone. And the question for that comes like if you remember we talked about this aggressive burden tides or what we call now the stage for grade C or stage three grade seabird Antilles. Those patients usually won't have a lot of plaque or calculus that you may see clinically. Right. So but they will still indeed have a lot of destruction. And that's the question like okay, what caused over there? Obviously there are different host response mechanisms that play a role and have these specific features. But based on our understanding, we know that bacterial is etiological prime. We consider that the primary theology, with a host playing a significant role of how the host reacts to this bacterial challenge. Obviously, there are other environmental factors. We're going to learn about those, either local or systemic, that affects what you're seeing clinically. And eventually you're having these biofilm forming, dental plaque extending, sub gingival secretion of toxins, irritation of the gingival irritation of the host response, inflammation showing up initially as redness. All those early signs that we know where we are bleeding, etcetera. And if this progresses, we're having continuous attachment breakdown of attachment loss, bone loss and deep pockets colonized by bacteria continuing this process. So that's what our understanding, which makes sense. And that's why we like it because it makes sense. But maybe after 2030 years new things will come into the light, especially these times. A lot of research is a lot of actually even funding is being given to research on inflammation generally. And guess what is predictable? Disease. Inflammation. Right. So we may have way more information of how things are happening. So something that you need to know. These bacterial complexes. Okay. So Kerensky here in Boston, Forsyth Institute, very famous. If you haven't been there you can go and check it out. They have very nice things over there. So he identified he did a lot of research on this microbiology. And he's like one of he's the first one who developed who identified those for the bless you sub gingival microorganism sub gingival with different complexes. And he found that those complexes colonize and proliferate at an early age. And you see they're colored here. And I have the next slide for your reference as well. So the first species, like the early colonizers we talked about are more like those streptococci, the green species, these orange one. Everything in the orange we consider like the bridging species, like a bridge that connects the early and eventually the late colonizers, which are the red complex pathogens. So PGA Valley standard, forsythia and tentacle. So you need to remember which ones are in. So it's easy because you see like 40 species. Remember the three bad ones. So you know what's not a bad one. And then you will try to understand and remember from the orange the bridging species like the intermedia and the bacterial atom. And we're going to talk about those in a few minutes. So the red complex bacteria. There is a constant whisper from that side. I will. I will lecture like this now. So. So the red complex bacteria have been associated with bleeding and probing, deeper pockets, attachment loss. And a lot of we're going to talk about those bacterial tests in future lectures as well. But a lot of those tests target of identifying especially red complex bacteria and specific other bacteria from early and colonizers and bridging species, and a lot of studies have shown, because what we seen about that is patients with disease, we take bacteria and in presence of inflammation and destruction and deep pockets, we have increased numbers of these red complex. And in presence of health we have decreased numbers or even absence of those bacteria. Right. That's why we have this correlation. And bringing back to connect these information. We learned a few slides ago regarding the critical mass and the numbers. I'm part from the presence. We also have to have a pathogenic like mass quantity of bacteria to be able to have those properties and be able to cause the disease, and as I have over here. So the composition and everything is color coded for your reference. So blue and purple complexes persist of gram positive cocci and roads the yellow are more gram positive facultative cocci. The green ones as you see over here, gram positive. So those first ones are usually those gram positive, the early colonizers. Right. I'm not going to be asking you like specific streptococci Gordon. Where is it in which color? But if I talk to you about colors, that's why we have it color coded. I need you to understand what we're talking about. So the first ones, the early colonizers, which are more gram positive rods or cocci, non motile, usually species. Some of them may be like facultative depending on their composition. But that's what you start having in the beginning. If this becomes like this structural biofilm that we talked about and develops, that's when you're starting having the orange complex which starts having more a higher concentration of gram negative of rods and cocci, some more motile species being present. And that's what we call this, the bridging species. Right. It's like the bridge connecting the early to the late colonizers. And eventually you're leading to the red complex, which is exclusively gram negative, motile, anaerobic. So if I have a question about a red complex, which you need to know, those three ones at least pigeon Duvall's forsythia and troponin identical like which complex they are they red. And what's the difference is they're gram negative, anaerobic, motile species. Okay. And it makes sense. Like the more pathogenic the bacteria. We have some gingiva. We have no oxygen. Anaerobic okay. Gram negative. That's what we have in pathogenesis. And also motile. The more pathogenic you have you have more mobility and movement on the species to be able to create their whole structure that we know clear. And that's another representation that you may see as a pyramid. And you see like the first blue, purple, green and yellow there in the bases, like the first ones. And I have it written over here, what you may be seeing of those. And then eventually going to the second layer of the pyramid, which are the orange complex, and eventually the top of the pyramid, which is the red complex. And why do we have it like this? Because I need you to understand how these biofilms work more frequently. You will see a lot of those early colonizers being present, or early colonizers and bridging species being present or everything being present. So seeing just the top of the pyramid, either the red or the orange and the red without the bottom, it's very rare to see that, right? You need these early colonizers a structure to be able to multiply, just to see the early colonizers, and then suddenly on top of these pathogenic red complex, it's very rare because you don't have the bridging species over there. And the same thing just to see like random orange or red species by themselves, it's very rare. You need to have this community of the biofilm as we talked about. Make sense and question. Yes, Buck. Up, down, through to the. Disease or no. What do you mean by that? If you just have the early colonizers. Plus the red, the red ones. We have down here. So. Yeah. So that's what we're saying here. That's very rare to find something like that, to find suddenly like early colonizers and suddenly like in specific numbers, pathogenic numbers, red complex. In order for disease to occur, you need to have a organized structure with all those complexes, the way we see here. And for disease to cure periodontal disease, you will see that. I think I have a couple of slides on that, that in gingivitis you mainly have this structure. Maybe sometimes you can get some red ones. In periodontitis you definitely get red complex okay. That's why we associate that. There is according to the studies that we have over there, they haven't found, like you have inferred disease with the absence of periodontal bacteria over there. The pathogenic bacteria. Yes. Wait a second. Yep. Yes. So let me bring it back to you over here so that you can see. So for the you said orange and yellow, right. So the orange is what we call the bridging species. And they usually have gram negative. They can have some gram positive but usually gram negative cocci and rods. The yellow are usually gram positive. So the basis of this pyramid is usually gram positive. Very few of those. Of those green ones you can have a random negative, but usually this is gram positive aerobic cocci and rods. Here you start becoming more negative and more motile species. And that's why based on those characteristics and you can see over here that's how they clustered them, because they collect each species of patients with different forms of the disease. And they found that in disease sites, that's what they were having and how they were grouping. So that's how they group those together, make sense? Yep. This one is a mixed speech. I'm sorry. You. Mum. Can I do this? Okay, so if I understand the question you're asking, if those are resistant to the antibiotic specifically. Is it the typical one? Like 25%? It's not. Okay, okay. I think I understand your question and let me know if I haven't. So the question is that because we talked about resistance of the bacteria of the biofilm to the antibiotics, etcetera. So once you have established even the red ones, if I understand correctly, if you have resistance to the antibiotics. So the answer to that, because I'm not sure how you have it in your mind, just giving antibiotics, it's not going to do anything. Even. If you do not debride mechanically, just giving the antibiotic is not going to do anything. Everything is in combination with your mechanical debridement. As of now, the treatment that we're doing, number one is mechanical debridement with scaling, scaling and root cleaning, removing the biofilm, the bacteria and everything. We have targeted the host response, you know, with some host modulation. That's another topic. But that's not that. We do it routinely, but giving antibiotics, you can even give systemic antibiotics to patients that have are diagnosed with severe forms of periodontal disease, even aggressive forms. And they definitely have all of those okay. But you need to combine it. So I don't want you to leave here saying we never give antibiotics to patients. That's not what I'm saying. I'm saying the treatment is not okay. I have those clinical findings pockets, attachment loss, bone loss, bleeding, inflammation, calculus, whatever you may have. And the treatment that you do for your patient is take this course of antibiotics and you're going to be fine. That's not what you do because this is not going to solve the disease. Right. What. But do we give antibiotics to patients that have. Yes, we do either local or systemic and are specific indications we're going to learn about those as well. But I don't want you to leave here saying we never give antibiotics. We just have to be careful when we choose to give them and how we give them. And we can't just say, okay, you have that. Let me do a debridement in a patient and take antibiotics. There's a whole concept how you deliver those either locally or systemically. If those will be resistant to that, you have to do bacterial tests and see if there are specific species resistant to those antibiotics. Usually not. But obviously there are patients like that. Clear. Clear. Okay. So. And as. And as a brief slide from transition from health disease. You're going to have a lecture on that. So that which is going to bring everything together. You will see that in the beginning. You start with those early colonizers, the bridging species, the red complex and from gram positive to gram negative, from aerobic to anaerobic, from non motile to motile. So as a concept to know where things are transitioning from health to disease. So let's see briefly about those these bacteria. Do you need a break. Yeah okay. Eight. No okay. Ten minutes break ten minutes. 959 okay. Yes. Yeah. It's afterwards. I'm sorry. Yeah. Lucky you. You got three extra minutes. Okay. Okay. It's not going to be too long. We're just going to talk about this bacterial composition that we find in the oral cavity. So. Regarding periodontal health as we said we do have bacteria when tissues are healthy. And usually you're having those early colonizers the Cryptococcus species. ET cetera. And it's all in a balance with a host. I think it was a question that I answered. Now we're going to understand this way better the role of the host in our future, our next lecture, and why this misconception was about, okay, what causes periodontal disease and we used to say in the past it's, you know, bacteria. And it made sense if you were to ask periodontist or, you know, dentists 100 years ago, they would say, yes, you're having bacteria, you're having an infection in your gums, you're having bacteria, you're having an infection in this part of your body. Right. So this made sense as research progressed. Then we started realizing that there are other factors. Yes, because you can have bacteria, but you may not have the disease that you're expecting. Right. And that's where the host got incorporated. That's where environmental factors got into the game. Genetic factors got into the game. And that's why I told you a few slides before that. According to our knowledge so far, we say yes, bacteria. We consider that to be the primary theology of initiating like not bacteria, just the presence. Because they're here present. Right? Doesn't mean that you have disease. It's becoming this pathogenic culture of bacteria that having your breeding species and your late colonizers and your anaerobic species, and this organized biofilm with all those properties and everything like that, that triggers the host response. Now, sometimes you may have this and the patient gets susceptibility in the host for x, y, z reasons from diseases, for treatment, from treatments, whatever. And you can still get the multiplication of that because bacteria now they have a way more favorable environment for them to advance because before they had the resistance from the host, as you see in the health. But now they don't. So let's say a little bit of that's why I call it as a balance, because you're starting thinking of those different things. But when you start, when we will talk about the host, next time, you will start understanding how the one affects the others. And that's why I'm saying, according to the knowledge we have so far, what makes sense to us is we assume we're having the bacteria becoming pathogenic that triggers the host and then could be affected by other factors. And if this is not being controlled, inflammation gets produced. And if this is not controlled, then it can get exacerbated and continue and go to further progression of attachment loss and bone loss. It could easily stay in a state of those like severe or moderate gingivitis, as we said, for months or even years, and nothing progresses. So what makes that click and changes? We can't know. We assume that at some point this happens and something triggers that. And keep in mind you just see your patients cross sectional, which means that specific periods of time, right. You don't see them every time, every day. You don't do examinations and evaluations clinically and sub clinically every day. Yep. So how accurate or helpful can be those saliva testing that are out on the. Okay. I'm not going to go too much into that detail. We have a lecture on that coming up. I think in the next semester you have to consider, especially the saliva ones. You have to take them with a grain of salt because you just take bacteria from the whole mouth. If you want to be more precise, you're going to go to the site. And then if you do find things in that specific site grade, I learned what happened in that site. But what does it mean for the rest? So it's way more complicated. A lot of companies try to bring those tests that can be helpful. I don't disagree with that, but we're not taking anything. Oh, because the test tells me that that's what it is. Okay. And what we're going to learn about those. Nothing to worry about at the moment. So as we go to gingivitis, you will be able to see in those patients the combination of the first early colonizers and eventually orange complexes. You may see that's the bacterium. And we're going to talk about that in a little bit. You may see some random red complex species, especially in more severe forms. But again, that's another question. Like if this is a gingivitis clinically or your findings are saying gingivitis, and you take a bacterial test and you find out, let's say pidgin devalues, does it mean that because you have that you have pertinent theories? No. Right. You can have the association, but you understand how it progresses from early colonizers to breeding species to late colonizers, and eventually to bird entities, where you're having a bunch of all the bacteria, you know, the red complex, depending on the disease, we're going to learn in a little bit that with what we used to call aggressive predators, you have more the A being associated. So there are specific diseases that specific species are more prominent, more prevalent. And we understand that. And we're expecting does it mean that we need to do testing for our patients? No. Would you consider that in specific cases? Sure. Would you consider that if you want to give antibiotics? Yes and no, because usually you wait for the test and the test. The antibiotic test says, okay, you will give the antibiotic you would give anyways, right? So there are specific indications of when to do those. But it's important to understand what we have in each form of the disease. So I think you went briefly over those hypotheses in our in the biofilm and plaque lecture. But let's wrap it up as a reminder. So we started, remember, with a nonspecific plaque hypothesis which said that quantity mattered over quality because they said you just need to have bacteria. If you're having bacteria, then you will have disease. But then what they said over there is like they believed that periodontal disease occurs because of accumulation of plaque over the period of time, and those elaboration of noxious products of the entire plaque flora can cause the disease and periodontal tissue breakdown. So they updated that later on and said that any microbial colonization of sufficient quantity in the gingival crevice can cause at least gingivitis, and these were supported by the fact that even non pathogenic plaque was never observed. But then the questions came like why do some patients have plaque and calculus for years and they may just developed in devices without any attachments as we said. Right. Or why do some patients show severe attachment loss with relatively good oral hygiene. That was like the aggressive forms that we used to call of the disease. Right. And why do the severity and speed of progression differ from 2 to 2 in the same individual or from side to side. And they have a different pattern. So this hypothesis wouldn't satisfy those questions. That's when they said, okay, we're going to go to the specific plaque hypothesis where quality matters more than quantity. So you need to have specific microorganisms that are necessary for the development of periodontal disease. So the hypothesis was that only specific plaque bacterial like bacteria in the plaque are pathogenic. And the pathogenesis depends on the presence of the amount of the specific bacteria. So is this wrong? No. Right. We talked about that. It's not only about being present because we can have like planktonic bacteria and stuff like that. You only have to have a critical mass to have pathogenic properties of the bacteria. So that's not wrong per se. But that's not the only thing that happens for disease to occur. Right. And some suspected periodontal pathogens can be isolated even by clinical healthy sites and oral cavities. And for example, this was accepted, as I said, with the AA, this specific species that was associated with the aggressive, especially the localized, what we used to. Localized, aggressive, early juvenile, what they used to call predators for the younger population. And even now, the fact that we changed how we say the disease we were staging and grading and fancier and stuff like that hasn't changed the disease, right? If you still do in a patient with grade stage four, grade C bacterial test, you would still find most probably the A if you're suspicious of that aggressive form of the disease or anything like that. So the questions with this hypothesis where like, why can't some suspected periodontal pathogens can be isolated from clinical healthy sites, right. If you consider that those pathogens are associated with the disease per se, you can still find them in healthy sites that you see clinically. And obviously, not all the genotypes of the same pathogen can have the capacity to induce the disease. They did analysis on all those different genotypes. So this brought them eventually to the ecological plaque hypothesis where they said a change in the key environmental factors can cause a shift in the balance. Again, this word it's all about balance between the bacterial species that reside there and then that predispose a side to disease. So it's also what happens in the environment. And some researchers with their studies found that these pathogenic flora can occur because of environmental changes and disturbances. And the selection of pathogenic bacteria is related to changes in the environment. And when I say environment, I'm saying also this local microenvironment that you can have in the oral cavity in the specific site that can become the make the area more susceptible to the disease. And any species with a specific and relevant traits can cause the disease process. And this was even more advanced. What we follow and consider right now, the keystone plaque hypothesis, which kind of summarizes everything that we're seeing so far. Yes, you need to have specific pathogenic bacteria and critical mass. With all those pathogenic activities, you need to have ecological changes and you need to have specific host specific changes. This kind of wraps up the story and understanding of what we have right now. So going back somebody asked me about, oh, why don't we know how we shift from gingivitis to Titus and things like that. Like some years ago, they said, you just need to have plaque and you have the disease. And now, you know, we just know that we need to have a combination of things and orchestrated like response of everything in order to have the disease. And obviously what we call here is we if you're having those changes, those specific bacterial pathogens can orchestrate the inflammatory disease. And they make from the switch the environment to a this biotic one. Again another Greek word, it's difficult to live. That's what it means. This is difficult biotic survival live. So they make those changes those shifts. And obviously because of the changes that are happening environmentally, locally, in the periodontal pocket, specific cost related factors can make this shift from health to disease. And it's all about shifting in the ecology that can result in the. The ecology of this environment, of this microenvironment, as we say, that can change and lead to high numbers of specific keystone pathogens that are associated with the disease. And this goes back to my very, very first thing that I said today. Like it's kind of the chicken and the egg thing, like it's a, you know, it's an inflammation, like an environment that creates bacteria, like keystone pathogens to increase. And but those bacteria also trigger the host response. And that's how the cycle works. Okay. So the three top bacteria that are causing periodontal diseases that are recognized by the American Academy of Dermatology are gingival forsythia and aggregate bark. They're acting in competence. I'm not expecting you to know that by heart. You can say AA. I will be happy with that. I'm not gonna test you in writing this long bacteria over there. And obviously, you can have some spider kids that intermediate and fuzzy bacteria. And these are the ones generally as bacteria that I need you to be aware of. These are coming off in several questions. They're coming in whatever you're reading. I know we identified about those 40 species. I'm not expecting you to know for this species by heart, but these are the ones that I need you to know. And I have some slides here for your references for your reference. So PGA values for gingivitis, as you see over here, it's black pigmented gram negative anaerobic. And there is. Like increased evidence that of the role that it plays in the pathogenesis of burden theory. So a lot of studies when you're having patients with diabetes and you're taking a sample, you're expecting that you will see pigeon values over there. So you see like how the nicely pigeon goes with cell surface adhesion molecules and goes to the inflammatory cells. And how this causes the disease. This is a pic of next week's lectures about host response. You're going to get more information on that next time. I have a lot of information here which I'm not going to just read over here. It's for your reference to summarize everything in a couple of slides, instead of getting lost in the textbook and everything. But what I need you to keep in mind is that it's found very often sub gingival. It's gram negative as we said anaerobic. Remember where how the plaque is super versus how gingival it can. It is thought to spread through the tissue, destroy and invade evade the host defenses and be familiar with the microbial and biochemical properties of being non motile, gram negative and road shape. And that's why we say about the pigmentation, because they are anaerobic and forms blood colonies of agar samples and pigments. Those we have found in several studies that it's elevated in periodontal lesions very rarely you will find that in health because what do we have in health. Aerobic right. We have gram positive. So if you don't have a bridging species to to connect those aerobic gram positive to the red ones, you can't find it survive by itself right. If it's planktonic it's a different thing. We're talking about organized biofilms around teeth and sites. And a lot of studies have shown, especially studies that started with identifying bacteria before treatment and after treatment. They showed that elimination or suppression resulted in a successful treatment outcome and therapy. This is a bunch of all those virulence factors I have highlighted, like the ones that are over here. What do you need to keep in mind is mainly the capsule, the LPs. This will come again and again, so keep that in mind. A specific protein is don't get like lost with all of those. It's further information what all those virulence factors are. But you will see this name again and again with the LPs. So just keeping that in mind tonight. Forsythia again in the red complex we used to call it Bacteroides for situs is gram negative normal tile and aerobic non pigmented compared to the PGA valleys. It's difficult to culture. And it was first I mentioned about that isolated here in the Forsyth Institute in Boston. And that's why they gave this name as well with the forsythia. You may also see that in other indoor infections and burying plant as well, keeping those properties in your mind about the anaerobic and gram negative, as we said, about these bacteria and about the virulence factors obviously again, several things. But just remember these surface protein nothing to get lost in that the AA they used to call it active. They change it to aggregate it back to economic competence. As we said, just call it AA. Nothing to worry about that. Remember the association of AA and aggressive periodontitis especially the localized. So if I get for you, for example, a question that has clinical features of. Let's say deeper pockets and attachment loss and bone loss in molars first molars and incisors. Right. And I describe that in your question. And I say what is your diagnosis. And you come up with your diagnosis with a 1999 I would call it localized aggressive with a 2017 localized stage four, let's say, or stage three, grade C, depending on what you have. And then my other question, because that's clinically what you see. Right. And my other subclinical question was if I were to take a bacterial sample, what bacteria would you expect to see more prominently there? The answer would be a right. On the other hand, if I had a case where you're having like a typical, you know, stage three, grade B, like what you used to call chronic bronchitis. And I would say, what bacterial species are you expecting there to be very prevalent? You could easily say among the choices p g values make sense or read complex bacteria make sense. That's how you understand what you see clinically. If you were to do a test, what you would see is a clinical and this will build up next time with your host host response lecture. So again remember in the past they used to call it like juvenile periodontitis. This localized aggressive. And they changed the name in 2006. I hope they not change it again. We have a thing with changing names. So remember the microbial and biochemical properties. It looks like a star. It can be facultative anaerobes. Remember it in the table of kids on the lower left side over there if you're trying to find it. And the other thing is that this bacteria, these AA can invade the tissue. So sometimes in cases like that, that's why in aggressive cases it's we usually consider even giving antibiotics that after our herpes we can give antibiotics systemically that to address the bacteria. And we do have different serotypes. What you need to keep in mind that the serotype B is the one that's more associated with these aggressive entities. And obviously we have this intra familial transmission. So things try to connect together. Remember when we talked about the tightest classification that in the aggressive form the features I told you were like significant like rapid progression of the disease, absence of other systemic factors. And the third bullet was like familial aggregation, right. So now those things connect together because you have the species that are being highly associated with the disease. We found that this intra familial transmission. And that's why patients that exhibit those signs of early loss of teeth or severe destruction at a young age, in absence of other factors and other systemic diseases, can have these bacterial species too. Okay. And again, virulence factors don't get lost. You can see again the LPs that plays a significant role. We're going to talk about that next time as well. So and again AC we can it will be brought up as well. But just to have it here together for you and I just. Categorized how the virulence factors what they do. So you're having factors that promote th