Hi class, Dr. Jim here. In this lecture we're going to be looking at how we can actually control microorganisms from growing. So in the past couple lectures we've been talking about how bacteria grow, how they can divide, how they make their DNA, how they can regulate, and a lot of other things.
Today we're going to be looking at how do we stop them. Okay, and this is obviously a very important lecture because we want to know how we're going to be able to control these microorganisms. especially in environments where we don't want them to grow, like in hospitals. OK, so this is going to be really important when you start to think about where you're going to find these things growing in nature. And so we're going to figure out ways to make things clean and basically sterile so that you don't infect your patients.
OK, so that's what we're going to be thinking about today, because really we have to think about that there are microbes everywhere. They're in the air. They're in the water. They're in the food we eat. Most of the time with a good immune system, we don't have any problems.
However, when we don't have a good immune system, that's where the problems start to arise. And so when we're in a hospital situation, that can be really bad. What is hospitals filled up? Sick people.
So that's why we need to make sure that we control the microorganisms so we don't make our patients even sicker. Okay. So that's what we're going to be looking at today.
So how do we control the microorganisms? So first I'm going to show you. What are the methods of controlling microorganisms growth? So we're going to take you through some real basic ones. Really, it boils down to two different things, physical control and chemical control.
Physical control includes things like heat. So when we talk about moist heat, which is an autoclave, or dry heat, like your incinerator that you use in the lab, or a dry oven, things like that, those things will actually kill microorganisms so that you can now do things either in the lab. or use sterile instruments in hospital settings.
So that's what we're talking about there. Other physical controls include things like being cold or using radiation, radiation is a newer one, newer technique. And I'll show you some pictures using that. And then finally, using bacteriological filters, which actually you can filter fluids and other things like this through so we can eliminate the bacteria.
So things don't get bad. Okay. Chemical controls, there's lots of different chemicals out there. I'm not expecting you guys to know the different chemicals.
I just want you to know that there are chemical controls out there, and we're going to be looking at those as well. We'll take a look at it and kind of survey through the different types of chemicals. Another thing we're going to be looking at are what are the most resistant and what are the least resistant microbes to deal with. I can give you a hint.
The most resistant are going to be those wonderful endospores that we talked about back in Chapter 4. The least resistant are going to be like the microbes that we deal with in our lab. the ones that grow on the plates and also some of these viruses that are around because they're easily a lot of them need hosts to live on and so once they're outside the host they don't have much of a chance of surviving so we'll look at that as well we'll talk about the modes of action for cell death and so we'll talk a little bit about how the cells die what are important things to look at when you think about what what do these physical or chemical controls target And then finally, we'll look at some of the different types of mechanical and chemical control or physical and chemical control that we're talking about here. Okay. So we'll look at a number of different things as well.
So lots and lots of things about how to prevent bacteria or microbes in general from getting out of control. All right. So controlling microorganisms, like I said, is the physical, chemical, mechanical methods. And again, the physical are going to be heat, cold, radiation, chemical. are basically using chemicals in the mechanical or the filters, but I kind of put physical and mechanical together here.
And that you'll see on the next slide, I show you all those different things. And again, the idea is to destroy and reduce the number of microbes. Okay. And again, these are the different microbes that we target, the vegetative, bacterial cells, endospores, fungal hyphae, protozoans, worms, viruses, and pre-ants, everything that we've talked about already.
These are the things that we're trying to control. Okay. Again, here's a number of the different methods. Here's the physical agents.
I've talked about the heat. The heat can be divided into two groups, the dry and the moist. The dry, we talked about incineration and the dry oven, which some people still use the dry oven. The moist really consists of the autoclave if you use the steam autoclave.
However, we can also include things like boiling water, pasteurization, where we heat things up and then cool them down, but we don't get them to the point where we sterilize things. Radiation is another type of thing. Radiation is included in physical agents. And again, we're talking about the difference between ionizing, which is deep penetrating radiation, and non-ionizing, which is UV. And we'll show you some of those things as well.
Then we get into the chemical agents. The chemical agents include gases and liquids. And again, we'll talk about those different things and where we use them. And then finally, the mechanical non-clipped, we'll talk about filtration. And again, I include this in the physical agents too, because we use filters all the time.
And that includes the air and liquids. And again, depending on what you're using now, air is, you can't sterilize the air, but you can pretty much disinfect it. You can pretty much get everything out of there using those HEPA filters. There are also liquid filters, which you can run through that will actually sterilize. And so you see these words, what are these words really mean?
Sterilization, disinfection, antisepsis, disinfection. So that's really the next step to understand these terms. And a lot of people get these really confused and they flip them around and use terms that they really shouldn't be using. Okay.
So today, hopefully I set the record straight so that you kind of understand the differences between sterilization, disinfection and antiseptic. Okay. Alright, so really we have to talk about what is the relative resistance of microorganisms. Now the highest resistance have really two main contributors. These are the prions, which we talked about, those infectious protein particles, which are really, really tough to destroy.
In fact, normal sterilization techniques do not get rid of prions and bacterial endospores. This is where you actually have to use sterilization to get rid of these things. Normal chemicals.
washing your hands, things like this do not eliminate endospores. And when we talk about Lysol killing 99.9% of the germs, these are not touched, the endospores. Very tough, chemically resistant, heat resistant, lots of different things. Now we have a group of organisms that have a moderate resistance. And so they put more of a fight up with some of these different controls, the heat, the chemicals, and things like this.
And this includes Pseudomonas, Mycobacterium tuberculosis, which causes TB. Staph aureus and some protozoan cysts they can actually survive the digestive enzyme So high acid content and make it through and into your intestines and then that's where they get released And so we'll look at these again in chapter 23 and look at how these guys work But I wanted to give you an idea that they can survive some pretty harsh conditions They can survive the acid of your stomach and make it to the intestines now the least resistance These are the ones that don't really put up much of a fight These things are pretty much wiped out with the use of soaps, chemicals, and other things that you use around your house. And so we really don't worry too much about them.
But again, they're so numerous that you're not going to be able to eliminate everything. I've had students in the past who have been germaphobes. And again, there's really nothing you can do. You could wash your hands until they are bloody raw and they will not, you'll still have microbes on them.
You cannot eliminate all the microbes out there. They are pretty easy to eliminate. What you're going to find out throughout this class as we go on is that eliminating some of these microbes actually does you more harm than good.
So I'm trying to tell you that having microbes on you are a good thing. It helps you fight the bad things that are out there. So we'll talk about that and we can even have a discussion about that at some point in time in the class. So that's what we're looking at.
So the highest resistant endospores and prions, lowest are going to be the vegetative bacteria, viruses, and really the ones that don't put much up a fight. All right. And so we look here.
These are, again, how hard it is to kill endospores versus the vegetative forms. These are the hardest. These are the easiest. And you can see the difference in the amount of temperature that you have to use to kill endospores versus vegetative.
How much radiation you have to put up, sterilizing gas and how many how long you'd have to let the sporosile liquid to actually sit on waste type of thing or the bacteria to actually kill it. And you can see that every one of these categories requires more heat, more radiation, more gas, more liquid, more time saturating the liquid than it does for the vegetative. Just showing you how tough it really is to get rid of the endospores. And obviously this is a huge problem when we're talking about hospitals. And so you don't have quite the time to do these things.
And so You have to think about what is going to be beneficial. Obviously, you're not going to be able to eliminate every pathogen out there, but you want to try and keep things as clean. And so, again, you have to make decisions as you go along of what are you going to use to control and what are you going to use to just say, you know what? It's not going to cause that much harm. We can let it go.
Okay. And so that's going to be one of the biggest things. So again, I talked about terms in controlling microorganisms. And again, I think these are really important to understand the difference between the terms. What does sterilization mean versus disinfection versus antiseptic or asepsis?
Okay. So the first term is sterilization. Sterilization is the process in which you destroy all viable microbes.
So sterilized means no life. Sterile means no life. And so when you eliminate all life, you've eliminated everything, including the endospores.
So when we say that this process is sterilizing or sterilization, we mean we're eliminating everything. We're eliminating the vegetative bacteria, the moderate, and the highest resistance, the endospores and even the prions. And so we'll call that sterilization when you eliminate everything, okay?
Even the top guys. The second one is disinfection, and this is pretty much what we do in our houses. When you go home and you see a dirty toilet or you see a dirty countertop where you may have prepared food and now you want to wipe it down, you go and reach for the Lysol, the Pine Sol, these different chemicals, and basically what you're doing is trying to eliminate as much bacteria so you don't get sick.
We call this disinfection. So disinfection is the reduction of microbes by using chemicals or other methods but not getting rid of all. all the microbes. You're not getting rid of the endospores. You may not even get rid of all the moderate pathogens or moderate microbes out there like the pseudomonas and things like this.
But you're killing a number of the bacteria. You're getting rid of a lot of the vegetative bacteria and viruses. And so you're doing a really good job of reducing the numbers. And so by reducing the numbers, you prevent yourself from getting sick.
Okay, we call that disinfection. Now what does antiseptic mean? So you may see these words used interchangeably and again they mean pretty much the same thing. All the differences is where you put it.
Okay so disinfection is all about putting it on surfaces inanimate objects. So you put it on your toilet, your your countertop, your refrigerator, things like that. That would be a disinfectant. When you put it on your body that is called an antiseptic. So you see here with Listerine Listerine is listed as an antiseptic because you actually put it in your mouth.
Now, I don't recommend drinking it because it does have alcohol in it, but it will kill a lot of the germs that are growing in your mouth. And so it does a very good job. When chemicals or other things that we put on our bodies kill microbes, again, the vegetative forms, we call that an antiseptic.
So when you see the word antiseptic, that means it kills microbes on your body. So it's safe to put on your body. You see disinfectant, you want to stay away from that. Well.
You can use it on your countertops and things like that, but you don't want to put it on your body, obviously. Okay, you're not going to douse yourself in Lysol or things like that. All right, and then sanitization is any cleaning technique that mechanically removes microbes. And again, we sanitize our houses.
We do a lot of different things. And so this is just another terminology to use to talk about the process of removing microbes. But really the three that I want you to know is sterilization, disinfection, and antiseptic. And really knowing the difference between disinfection and antiseptic.
and where those things are found. Okay, the last thing is de-germination, and this reduces the number of microbes through mechanical means. So this would be using a UV light.
So obviously I like this picture because obviously this is someone who's had their first, this is their first child. And so they have a baby bottle and they're eliminating all the germs on the baby bottle with the UV light. Now the second child, you don't care.
You basically just wanna make sure the dust and dirt is off of it. and make sure that it's clean enough, you know, type of thing. But obviously, someone's going to the extra effort of actually adding these things. And we call that de-germination, using a mechanical mean to decrease the number of microbes.
All right? Again, here's the terminology. I've talked about this already. Again, the biggest thing to know is the difference between antiseptic, disinfection, and then sterilization. Those are really the three terms that I want you to know, and I ask those on the test.
Okay? All right, when we describe microbial death, it's hard to detect. Okay, so what does microbial death mean?
What does it mean when we're killing bacteria? Again, a lot of people would say, well, you wouldn't see the bacteria move, or maybe, you know, things like this, and we'd all have different definitions. The scientific definition for microbial death means that the bacteria still can be metabolizing, making ATP, going through cell respiration. If it can't reproduce, that means we've killed it.
Okay, so if you've eliminated the ability of that bacteria to reproduce and pass its genes on to the next generation, we have effectively killed the microbe. And so that's what microbial death means, is that you've eliminated the way for the bacteria to reproduce, you've effectively killed it, even though it's still metabolizing. Okay, so that's the big caveat.
It could be still metabolizing, making ATP, could still be eating. As long as it can't reproduce, you've effectively killed the microorganism. And so the idea is the permanent loss of reproductive capability, even under the best growth conditions out there.
So that's what it means. All right. Because it's real tough about how you know there's no heartbeat in a bacteria. There's nothing that you can otherwise say.
I mean, I guess you could look at measuring ATP, but that's really tough. It's easy to tell. Can the microbe grow and basically make new bacteria? If they can't do that, we know that we've effectively killed it.
All right. So that's what we're looking for. All right, and so factors that affect the death rate, we can look at the numbers of microbes. Obviously, the more microbes you have, it takes longer to kill them all. So you can see here, low load versus high load, and it takes longer to sterilize.
The nature of the microbes in the population, again, are they the lowest, are they the medium, or are they highest? The temperature and pH environment play a huge role with proteins and things like this. And again, the higher the temperature and the pH, either more acidic or basic.
can obviously kill microbes faster the concentration or dosage a lot of times we look at these things and the more the better but not always the case the mode of action of the agent what does it go after what does it kill and then the presence of solvents organic matter and other inhibitors which can affect the chemical agent okay and so all these things play a huge role and so again this just determines how or the effects of the death rate and so i'm just giving you an idea and again These are just good to know and types of things like this where, again, these can all affect how fast the microbes actually die. All right. So when we're in the hospital setting, we have to think about what are the best, best things to kill microbes. And so, again, we have to think about the choices that we make and how are we going to eliminate microbes.
And so the first thing we need to ask is, does it, does the application need to be completely sterile? If it does, you're going to go into another category rather than disinfection or antiseptic. If you have to eliminate everything, obviously you're going to be moving on to the next level so that you can get rid of those endospores.
Because the chemicals you use are not going to touch it. So you have to get a situation where, or maybe more expensive for sterilization. So that's one of the key questions to ask.
Another thing is, do you have to reuse the item? If you don't, then you might have an easy choice of using something that's plastic. Plastic can be used one time. We throw it away and then you don't worry about having to sterilize it or do other things or worry about microbes on it. Okay.
Can the item withstand heat, pressure, radiation, or other chemicals? And obviously this is going to be a huge issue. You're talking about a very sensitive liquid.
You're going to have to do something different than something that's made out of solid steel. Okay. Solid steel can go in an autoclave where the liquid may not be able to go into the autoclave. You might not be able to heat the liquid because you may destroy the liquid, the chemical formula.
Okay. Is the method suitable? Is it going to do the job that you want it to do? Is the agent going to penetrate?
So there are obviously things that are out there like gases and other liquid chemicals. Are they going to be able to get all the way to the inside? So that's something you have to think about. And obviously, whenever you're talking about hospitals, you always have to think about money and safety. Is it going to be cost effective?
And is it going to be safe for the patient? So again, that's another big question. When you're thinking about these things, you always have to think about, I have to keep the place clean, but at what cost and what is it going to do to the patient? Okay.
And so that's the ultimate questions that you have to answer. And so that's, that's the biggest thing. So you want to think about costs and what is it going to mean to the patient? Okay.
And so that's the idea with these things. All right. So what are some of the agents or modes of action of the chemicals and physical control, like heat and other things?
Well, there's a couple of targets, and so we're going to bring this up today. And if you go and then watch the next lecture on the antibiotics, you're going to see that there are a lot of the same things. And so kind of keep these guys, remember these guys, because you're going to see it again in chapter 12. So the targets of the physical and chemical agents include the cell wall. Obviously, if you start poking holes in the cell wall, you're going to make it more able to be or less likely to withstand osmotic pressure. So you start poking holes in the walls.
you can obviously destroy the bacteria so that's a good thing there and so obviously lysine bacteria getting antimicrobial drugs detergents and alcohol all affect the cell wall another thing is the cell membrane this is the job of surfactants surfactants are soaps and so what soap does is when you wash your hands you're washing not only layers of skin off but you're effectively washing the bacteria that are by destroying the cell membranes and so that's one of the things that's why i have a lot of dead skin on her hands and that stuff When we wash our hands with soap, you're effectively washing layers of skin off your hands. So you want lots of layers on your hands. If you don't, you start washing all those layers off.
They become raw, bloody, cracking, things like this. And that's obviously a bad thing. You don't want to do that. All right. Another thing is the protein and nucleic acid synthesis.
So obviously destroying proteins, destroying DNA. If you can eliminate those things, the bacteria can't grow. Okay.
And so if it doesn't have proteins, it doesn't have DNA. It's not going to be able to grow. And then finally the proteins itself, you know, talking about proteins and destroying enzymes, breaking things down. So this is where we see a lot of our modes of action, especially with the heat and the chemicals denaturization of proteins. and then also the acids and bases that affect the protein shape and structure.
So think about those things. And again, we've talked about these before, but now we really want to destroy these things. How can we destroy them?
All right, and this shows you again just a picture of an enzyme with a substrate. Remember the active site. And again, heat will change or pH will change the shape, cause denaturation will come unfolded. Sometimes the heat will cause it to change a different shape and make it inactive.
And then sometimes like when we talk about heavy metals or inhibitors, we can block the active sites and it no longer uses. And so these are all different examples of how we can destroy proteins and affect enzymes. OK. And so, again, we've talked about it before in Chapter two.
We've talked about it again in Chapter seven and eight and nine. How can we eliminate these things or how can we block these things? And so this is really all tying together. All right.
Here's your con chip. Concept check. If you wipe your hands with an antimicrobial cleaner, what are you accomplishing?
Are you accomplishing sterilization, disinfection, antisepsis, or sanitation? I'll give you a second. If you said antisepsis, you would be correct.
Remember, antiseptics are on the skin. Anytime you put something on your skin that's antiseptic. Disinfection surfaces, so you're thinking countertops, your toilet, your refrigerator, and sterilization would be a process of eliminating everything.
And typically you don't sterilize your skin is almost impossible unless you use some agent and that would kill you too. So you don't want to do that, obviously. So if you're thinking about putting stuff on you, that's going to be an antiseptic. Good job.
All right. So let's take a look at some of the physical methods of physical control. And this includes heat, cold, desiccation, radiation, and filtration.
So again, this was again, the mechanical. And I just put this in here to kind of just make it easy because it's really the only mechanical, but we can easily put it in the physical control. So with the heat, we're going to talk about moist and dry heat, and then talk about cold, radiation, and then filters.
So let's take a look at these different types of physical control. All right, so the difference between moist heat and dry heat, obviously moist heat is thinking about steam and water and using pressure. Obviously with moist heat, you can use lower temperatures. Shorter exposure time and you get coagulation and denaturation of proteins earlier because you're affecting it by the pressure and the steam.
And so this prevents, this again, kills the microbes this way. Dry heat is an example of very dry. You don't have any moisture added and this will require much higher temperatures.
So what happens at this case, use higher temperatures and longer exposure time. But essentially what you're doing is desiccating or drying out everything. And so you, again.
dehydration altered proteins and you incinerate and so this is what we do with our little loops and that stuff that's an example of dry heat all right so let's move on again here's the difference how long it takes to sterilize you can see moist heat lower temperatures smaller amount of time compared to dry heat which again if you use higher temperatures and again much more time involved to sterilize so again moist heat is the the way to go But some things can't get wet, so that can be a problem. So then you might have to go after the dry heat. Moisture, the example would be using the autoclave and that stuff. And I'll show you what an autoclave looks like here in just a second.
All right, now this is something we're going to actually be doing in the lab. So if you're watching this after we've done the physical and chemical controls, we've already done this in the lab. If you haven't seen this yet. are, if we haven't done this in the lab yet, this is going to be something that we're going to be doing.
So there are two labs out there that are both the physical and chemical control. And in the physical control, what we're going to actually be doing is actually boiling things for different amounts of time and looking to see how long it takes. Okay. And so the example of that is going to be the thermal death time.
So really what we're going to do is use the same temperature all the time, and we're going to use different amounts of time to see how long it takes to eliminate all the bacteria. Okay. So that's what these things are measuring. So we can say with the thermal depth time, this is basically keeping the temperature constant, okay, but changing the amount of time at that temperature. So let's say we pick the temperature of 100 degrees C or 212 degrees Fahrenheit boiling water, okay, and we set up a number of test tubes.
This is what you guys are going to do in the lab. You're going to do one as a control with no time, so that should have all the growth. You might then pick one minute, five minutes, 10 minutes, 12 minutes, 15 minutes, 20 minutes.
Okay. And so you have all these different tubes lined up. And so then what you do is then you take those tubes, you boil them for the amount of time, then you pull out the solution and then you put it onto a plate.
And what you're looking for is, did you eliminate all the bacteria? Whichever time. whichever is the smallest amount of time that eliminates all the bacteria on that plate is your thermal death time. So let's say we do the 1, 5, 10, 15, and 20. When we do those tubes, let's say we get bacteria at the 0, we get bacteria at the 1, we get it at the 5, and at the 10. At 15 minutes, we don't see any bacteria growing on our plate after we plated them out and grew them up.
We know we've effectively killed all the bacteria that were in that tube. So we would say 15 minutes is the thermal death time at 100 degrees C or 212 degrees Fahrenheit, which is the boiling point of water. OK, so that would be the thermal death time. Now, the thermal death point works very similar.
The thing is, is now you're going to keep the time constant, but change the variable in the temperature. So you might set up things saying like something at 95 degrees. 100 degrees, 105 degrees, 110, 115. And then what you do is then put each solution at those temperatures for 10 minutes.
And then what you do is plate them just like you would do with the thermal death time. And whatever is the lowest temperature that kills all the microbes at 10 minutes would be your thermal death point. Okay. So let's say again, we have 95, 100, 105, 110, 115. Okay. 10 minutes each we go.
We bake them all for that amount of time. We pull them out and we plate them the same way that we do with the thermal death time. And again, let's say we have bacteria within 95 degrees after 10 minutes. We have bacteria at 100 degrees after 10 minutes. At 105, we don't see any bacteria.
And after that, no bacteria at all. So we'd say 105 degrees is our thermal death point because that is the time where we've killed. That is the temperature in which we killed all the microbes in 10 minutes.
Okay, so. It's all about which one are you keeping constant, which one is going to be the variable. So we're talking about thermal death time. In this case, you are basically using time as the variable.
So think of time and time as the variable. In this case, the temperature remains the same. In this one, the thermal death point, the time is constant, but now you're changing the temperature. So very similar to what they do. It's just a little bit different.
It's easier to do thermal death time just because, again, changing temperatures means you got to do a lot of setups. You got to make sure that the temperatures are all correct, everything else, where time is a little bit easier to do the variable with. So in the lab, we're going to do thermal death time.
Thermal death point's a little bit harder because you need specific equipment to make sure that you're at the right temperature for the right amount of time for 10 minutes, okay, whereas time is much easier to do. So that's what we're doing in the lab, okay? All right, so here's the first one. This is the moist heat method.
And again, this is the steam under pressure. This is the autoclave. And what it is, is basically it runs your stuff through at 15 psi, so pounds per square inch, which is very high pressure, 121 degrees C, anywhere from 10 to 40 minutes. That's the typical amount of times to run. Typically for most tools and things like this, we do about 15, 20 minutes, sometimes a little bit longer if you want to make sure that everything's getting sterilized.
Again, the steam is used and really the steam is what causes these things to get killed. Basically what this is, is a gigantic pressure cooker. And so that's what you're seeing here.
It's a big pressure cooker turned on its side. You use that to cook your food a lot faster. Same type of principle, more pressure, heat, steam, cooks these things and basically kills these things in a short amount of time. So this is the way to go.
And so a lot of the offices, so if you go and work in a doctor's office or maybe a dental office, they're going to have mini autoclaves on the desk. And this is how they sterilize their tools every night. What you do is you take the tools that you use during the day, you wrap them up, you throw them back into the autoclave, you let it run overnight. And in the morning, you pull it all out, ready to go and use on the next patients.
And so that's the way they do it. Again, eliminates a lot of different things, proteins, membranes, and DNA. So.
does a very good job of sterilizing even the endospores. All right, another type of measurement is tendalization. This is a intermediate sterilization for substance that can't withstand autoclaving.
And so what you do is, again, a free-flowing steam for anywhere from 30 to 60 minutes. Then you incubate for 23 to 24 hours. And then you give the high steam again. And you repeat this cycle for three days. And this is how a lot of our canned foods and things like this and our media can be done.
And again, a lot of our canned foods are steamed, steam pressure and that stuff. So you don't lose the nutrients on the inside, the nutritious value of the food, but you can sterilize it so that when you open it up, you know, you're not going to get a bunch of bacteria right in your face and eating it up. So that's why canned food can stay for a long, long time on your shelves because they pretty much eliminate everything inside of those things. So again, not a very big proponent of canned food, but again, um, I typically use the frozen vegetables and that stuff. That's just personal choice.
But that's, again, canned food is just perfectly safe, nutritional value and things like this. But you got to remember that that canned food could be sitting around for a long time. That's just one of the caveats there.
All right. Another one is boiling water. And again, 30 minutes will destroy most pathogens at this point in time.
So a lot of times you guys will hear, especially now with it being cold out, you'll hear about these water main breaks. Water main breaks happen, places shut down because the water isn't useful. What happens in these situations is when you have a water main break, the water rushes out and can mix with dirty soil and dirty wastewater.
When that happens, we think of E. coli and other things getting into the water and it's not safe to drink. So what you might get is a boil band, it's called, that says that you need to boil your water before it's safe for at least 10 to 15 minutes.
And then it will be safe to drink. And essentially when you boil the water, you're heating it up enough to kill the bacteria there. And so you want to make sure that you keep it boiled for about 10 to 15 minutes. Same principle works if you're out camping.
If you take water from a stream. or other where other places maybe a lake and you want to drink that water you should at least boil it or do some other mechanism like iodine tablets or or filtration to make sure that the water is safe boiling will work for you know killing most of the pathogens and make pretty much everything safe doesn't eliminate endospores but it does a pretty good job with all the vegetative bacteria all right another thing is the pasteurization and again this is the process that louis pasteur developed And again, this is bringing things up to a temperature and then cooling them down really quick. The idea behind it, again, is to heat it up to kill microbes and then to cool it down pretty quickly so that you don't destroy the nutritional value.
So this works out very well. It's not a sterilization technique because there are still microbes growing in. But as long as you don't open that milk and expose it to the outside air, that milk will be pretty much bacterial or basically, I shouldn't say bacterial free, but at least.
It will be pathogen free. And so that would be one of the things. Now, a lot of people may hear about these things about raw milk.
Raw milk is basically milk taken right from the udder. Here in Wisconsin, that's a big thing because we have a lot of dairy farmers and people that grew up on dairy farms. You may be one of them.
And so you may drink raw milk and not have anything happen to you. But raw milk is essentially one that hasn't been pasteurized. Now, if you are a big proponent of getting all your microbes from the cow and everything else, then go ahead and drink raw milk. However, if you've been growing up on pasteurized milk for your whole life and then you drank some raw milk, you'll probably get pretty sick the first couple of times because you're going to be introducing yourself to a lot of new bacteria that your body hasn't seen before.
So there are people out there that think that, you know, pasteurization destroys the nutritional value of milk and that we should be drinking milk straight from the udder. If you expose yourself enough times to it, You shouldn't have any problems, but I'm just going to tell you now, if you decide to switch to a raw milk diet, you're really going to have some issues the first couple of times you drink it. And this is not even with the lactose part of it.
So a lot of people become lactose intolerant as they get older because they don't have the enzyme to break down lactose. And that causes a lot of issues, digestive issues. I'm talking purely on a micro basis.
So raw milk can potentially lead to some serious problems like listeria and other bacteria problems. because it is impasteurized. So that's your one word of warning there.
So if you've ever thought about drinking raw milk or maybe serving it to your family, just word of advice. You might get pretty sick from it the first couple of times just because your body has not seen those microbes before. If you've drank it all your life, you shouldn't have any problems. And you know, I'm not here to dissuade you from those things, but there's always the potential if there's something like listeria or something else that gets into the milk and it's not impasteurized, that could lead to problems. Okay.
That's your warning. but just that's just me. Okay.
So that's pasteurization. All right. Another thing we use is dry heat.
Dry heat again is basically using high temperature to kill things. You guys are very familiar with this. This is what we use in our lab all the time. These little incinerators, these are very high heat. If you went and touched it, you could burn your finger pretty badly and that stuff.
So that's why I always say, be mindful of what you're doing in the lab and that stuff. Loops get very hot. If you leave the handle in there, it can get very hot and you can burn yourself. pretty badly in that stuff doing that. So incineration, what it does is it heats things up to a very high temperature and then you sterilize and kill anything in the, on your loop at that time.
And so this will even get rid of the endospores because it's such a high, high heat. This gets up to about 500 degrees pretty quickly. And so it's really, really hot.
So again, avoid touching it. Another thing we have in the lab and in other places you might see like in offices, like doctors and dental offices that are these dry ovens. And again, these are higher heat than the autoclave, but again, you don't need a steam cooker to cook it. You don't need a steam hookup per se.
So if your office doesn't have the steam or the steam pressure in order to run an autoclave, what they might have is a dry oven. And then what you would do is throw all your stuff in there, turn up the temperature and let it sit overnight. And then by the morning, that should be more than enough time to sterilize the equipment.
So depends on how the setup of the office is, but you might see something like this, a dry oven. in your place of work depending on whether you have a steam hookup or not. Alright, the next thing is cold.
Now cold is not really a way of controlling microorganisms other than basically what you're doing is slowing down their metabolism. Cold will never eliminate any microbes. It never reduces the number of microbes. It never eliminates the microbes like sterilization. So we call this microbe static because basically it keeps the numbers in check.
So when you keep things cold in your refrigerator, you know that basically microbes won't grow and they don't spoil. But over time, if you let that sit for long enough, you will see those things start to grow and then they will start to get moldy and spoil and things like this. And so that tells you that cold is not a very effective method of getting rid of microbes.
Whatever microbes have landed on that food and then you put in the refrigerator, remember those microbes aren't going anywhere. All you've done is basically put them to sleep for a little while. As soon as you bring them out of the refrigerator, they come back on again. And that's why things spoil.
Okay, so things get old as you leave them in there. And again, good recommendation for leftovers in that only about three to four days. Otherwise, you better pitch it because you're going to start to get some funky stuff growing on those things, including fungi and other things like this. And so you might as well just pitch it after about three or four days that are in the refrigerator. Okay, and again, preserve fruit, media and cultures, and we use this a lot.
But again, this is not a method of sterilizing or disinfecting or anything. All you're doing is keeping. The microbes basically in a hibernation, they're not going to grow at this level. All right. Another thing is desiccation.
This is the freeze drying process. And so again, we talk about freeze drying. So food that goes up to the space station and other places like this like to be freeze dried. And again, that helps eliminate microbes.
Not only is it a space saver, but it also eliminates microbes. These things can last for a long time once they're freeze dried, because essentially what you've done is remove the water. When we remove the water. you've removed the ability for the microbe to grow. And so again, you're preserving the food.
Once water gets put back in, the microbes can grow again. So again, it's again, not something that's going to eliminate bacteria, but what you effectively do is preventing them from growing or making another generation on there. You're not killing all the bacteria.
You're just basically allowing them to sit there. And once the water returns, they can start growing again. So again, it's not a sterilization, a disinfection or antiseptic.
This is just something where you're kind of microvastatic, where you just kind of keep them at a certain level and you don't change the number. All right. So which of the following accomplishes microbicidal effects? And this means basically killing bacteria.
Which one of these actually kills bacteria? OK, is it boiling, pasteurization, incineration, freezing or desiccation? And really, let's say sterilization in this case, because really all of them you could argue and say a lot of there's a couple of these things that would actually kill bacteria.
But let's let's say sterilized bacteria. Let's say we're going to eliminate everything. What would be the one that does that? You said C incineration.
You got it right. So, again, incineration, that's what we use in our benchtops. It effectively kills everything, kills the vegetative, the moderate and the endospores.
Good job if you got it right. All right, another tool or method that we use is ionizing radiation, and this is going to be very intense radiation. This is stuff that really penetrates through. So we've talked a little bit about UV.
I haven't really discussed a whole lot about UV, but UV damages DNA. Same thing with ionizing radiation. Ionizing radiation can get in and bust up and destroy DNA using the...
different types of rays. And again, you see this in the ultraviolet levels and the x-ray and the gamma rays. These are where you're going to see them. The x-rays and gamma rays and cathode rays are very deep penetrating, which means they have a lot of energy. They can penetrate deep and they can cause serious effects.
And so when you're using these things, gamma rays and x-rays, you can destroy the microbes very deep. UV doesn't do a very good job of getting very deep. UV only does surfaces, and we'll talk about that in a minute. So ionizing, think of very deep penetrating rays. This is going to eliminate even surfaces and very deep into material because it's going to be able to pass through and kill a lot of different things.
Now, one of the things that's interesting is this is being introduced into our foods. And so what basically is going on here is that you can irradiate food and actually keep it for a longer shelf life. Now, everyone's bought raspberries and blueberries and blackberries before.
And it seems like as soon as you bring them home from the store, you have to throw them out because they're already moldy. Well, one of the things we can do to make things last longer is actually irradiate them. And so when we irradiate these things, and if you see this symbol on your fruit, this means your fruit has been irradiated. Now, this doesn't mean that these things are nuclear now and that you can't touch them or radioactive or anything like this.
Essentially, what it is is that they've been treated with ionizing radiation, either gamma rays or X-rays, and they've eliminated. the, the fungal spores that have been growing there. And you can see same amount of time.
Here's the raspberries that have been irradiated. Here are the raspberries that have not been irradiated and you can see the big difference. And so if you see this symbol, it's perfectly safe.
You can eat these raspberries. I would eat these raspberries with no problem. Another thing where they're, uh, ionizing radiation is our male.
So obviously if you remember back, maybe you're a little young, but if you remember back in the year 2001, we had the problem with the, um, Spores getting to Washington DC. So we're talking about anthrax spores and things like this. So one of the ways that we've eliminated Senators and Congress and the president from getting these spores is that in Washington DC all male goes through basically a radiation Technique so basically what it goes in through is an x-ray machine It radiates the mail and will eliminate all the spores. And so this is one of the things that Again tries to help and prevent and so you might see this as well in the mail And so some places may do this especially when you're talking about big figureheads like the the government and things like this They might do it out in Hollywood too because obviously the big heads out there and that stuff So again, this is just a technique to eliminate lots of things And again, this is going to be sterilization because you're going to be able to eliminate everything because of the deep penetration rays Alright, another thing is not I see the non ionizing is basically UV ray.
The problem with UV, it does destroy and nick the DNA and causes the thymine dimer. So when you have two thymines together, it will create these dimers and destroy the DNA. The problem is, is UV radiation doesn't penetrate surfaces.
So if I hold a piece of paper over a UV light, none of that UV rays are actually going to get through. Okay, and we talked about the different things, you know, you wear sunglasses and that stuff to block the UVA, the UVB. and that and those are different types of UV radiation.
Most glass will block UVA light so most things are going to be UVA protected. UVB is a little bit more penetrating and UVC is even more penetrating. When those things say that it's all UV blocking that means it eliminates all the UV light. So if you go and buy the cheap $2 sunglasses at Target or whatever they're probably just going to be as effective as if you spent a hundred dollars on a pair of sunglasses because they're pretty much all the same UV radiation doesn't get in very quick or very far doesn't penetrate that's why you don't get sunburned when you basically look out a window all the time you see the Sun you stuck your hand out the window yeah you could burn get your hand burned but if you have the windows closed you're not going to get any sun because the UV light cannot penetrate the glass and so that's one of those things so UV is great for air and surfaces but it doesn't penetrate very deeply so you do see some of these things and i like to show this next slide which kind of shows you here's a clean room and you can see these are probably servers or something else that are being used and you can see the uv lights around them these are going to again keep the surfaces clean but it's not going to be very deep in penetration and penetration here's something you can actually buy online if you want to irradiate your toothbrush and so again uv light which will effectively kill the germs in your toothbrush And this would be one way to do this.
Now, what I would just say is save your money in that stuff and probably just throw out your toothbrush after every couple months. Especially if you've been sick. If you've been sick, just throw it out type of thing.
Get a new toothbrush. This UV light will be nice. It's kind of a nice little thing to have. But it really isn't going to do much because you're not going to get very deep into the brushes and that stuff.
And so it's more of a gimmick than anything else. But you may have seen hospitals are using these blue light robots and things like this. And again, it's sterilizing the air. So they do a pretty good job of getting the air in the surface part of it, but it's not going to get deep into the beds or anything like this. So it does a good job of controlling microorganisms in the air and on the surface.
But again, deep penetration is not going to happen. All right, the last type of physical control is filtration. And again, filtration removes microbes by blocking the microbes and allowing water to go through. So here you can see the setup. Here's the setup of the filter.
You have the liquid up here, the non-sterilized liquid up here, and then you have it being pulled through with a vacuum and you get sterilized fluid. The fluid is small enough to fit through the pores, but the bacteria is too big to actually fit through. Here's an example of this. Here's the bacteria on the filter.
Here are the tiny pores that allow the water through. So you can see these holes are so small. And a lot of times these things are...... They basically say on the filter, if it's a bacteriological filter, it means bacteria will be too big to get through the filter itself.
So that's what you're looking for. Another place you see this is in the air with the HEPA filters. So you may have a help of filter on your furnace and that, and what it does is it collects a lot of the bacteria and that stuff. Same idea that the air air can get through, but the bacteria and other things get trapped by the filter.
Now you have to be smart and change these all the time for these to work because once they get dirty again. a lot of times they become very faulty and things can get through. But as long as you change them on a regular basis, you shouldn't have a lot of problems.
And so again, you see this with both liquids and air with the filtration. All right. So the next thing we're going to look at is the chemical controls.
And again, I'm not going to worry for you guys to write all these things down. The chemicals, there's a lot of different chemicals. There's about 10 different types of chemicals out there and how they work.
I'm just going to go through them real quickly. I don't expect you guys to write these down. I don't want you to know them. There might be something in here that you think, oh, I use this all the time, like in alcohol.
What is the alcohol, you know, the little alcohol rub do or whatever. And you want to see the mode of action. But again, I'm not going to ask specific questions about any of the chemicals. I'm just going to go through them real quick to kind of show you some of the different types of chemicals and what they do.
Okay? And so, like I said, I will not ask any specific questions about any of these chemicals on here. So, if you want to put your pencil down and just kind of follow along, I'm perfectly fine with that. All right. So, let's talk about the chemical agents.
And again, this is your disinfectants, antiseptics, sterolants, de-germers, and preservers. Okay, so again, the desired quantities or qualities are, again, rapid action and low concentration. So the lower concentration, it's still killing is good because you don't want to make it toxic.
You want to have solubility either in water or alcohol so it's stable. Kills lots of things, so broad spectrum means that it kills a lot of different things. Low toxicity to you.
You don't want to kill yourself with these things. You want it to be able to be penetrating, but you don't want it to be corrosive or staining the materials that you're doing. Obviously, you don't want to ruin your...
countertop you don't want to ruin your toilet your refrigerator things like this and again obviously as a consumer you want to make sure that it's affordable if i give you a chemical and say this will kill everything and you're like great how much does it cost 100 bucks you're going to be like yeah dr jim i'm not paying 100 for this chemical when i can buy a lysol on the shelf for 3.99 and so i would agree with you on that even though it might kill everything if it's not worth it you know you're not going to buy it okay And so that's the idea. So you want to make sure that when you're thinking about these things is how effective does it kill and what is the cost, obviously. All right.
And again, we can talk about the high versus intermediate and the low. And this refers to what are these things going to kill? So when we're talking about high-level germicides, these are going to kill the endospores.
These are going to kill everything that can be basically considered the high end, the prions and the endospores. Okay. And again, these are used on devices that can't be, uh, heat sterilized in the, in the autoclave or something like this, or body tissue. You have the intermediate level, which will kill the fungal, the, the tubercle, bacillus, the pseudomonas, and some of these other things, the medium level.
And then finally the low level, which most of us own in our houses, the Lysol and that, these are going to be the low level. These are the vegetative, the viruses, things like this. A lot of things, clean surfaces that touch skin, but not on the skin.
Okay, and so these are the, again, different types of chemical decontamination. All right, and so we're going to look at the nature of the material, the degree of the contamination, the time and exposure, and the strength of the chemical. These are the factors, just like when we talked about the factors that affect the growth, these are the factors that affect the skin.
the chemical control. So how well are the chemicals going to work? And again, we're doing something in the lab looking at chemicals. You picked four disinfectants looking at those things.
And again, we're going to see how effective they are. And again, if you've watching this after the fact, then you probably have already done the lab and you know which ones are effective, which ones aren't. But if you haven't done the lab yet, we're going to definitely do this in the lab as well. So we're going to do a physical with the heat and we're going to do a chemical one looking at some of the disinfectants as well.
All right. Here's a list of the different chemicals we're going to quickly go through. Again, most of them in this situation are going to be intermediate to low. There are a few that are high, and we'll talk about those. So again, it just depends on the type or the strength of the solution, and we'll see those things.
And again, we'll talk a little bit about these. But most of the time, they're going to be low to intermediate in this case and what they're going to kill. Most things do not touch the endospores.
All right, here's a list of the chemicals. Again, we'll go quickly through them, talk about some of the chemicals that you might use in the house or in your office or in the doctor's office that you might be working at or the hospital. And so we'll talk about some of these things real quickly and just, again, mention where you might see these things. Okay, so the first one we're going to look at is the halogens.
Halogens include things like chlorine and iodine. Chlorine bleach is obviously the one most common thing that most people use. And again, this denatures proteins by breaking disulfide bonds.
It's intermediate. It will kill up to, again, about the 99.9%. Problem with it is that it's unstable in sunlight.
So you don't want to keep it out in light. That's why it comes in the cloudy bottles and that stuff. It's not a clear bottle, but a cloudy bottle because it can be inactivated.
And again, organic matter can also inactivate it. Okay, we use this in the water, sewage, wastewater, and inanimate objects. And so we chlorinate the water.
That's the idea. Okay, so we chlorinate these things to eliminate a lot of the bacteria and other things. However, some things do not get eliminated by chlorination, and Milwaukee does know this because we've had the problem with cryptosporidium.
So we'll talk a little bit about that when we get to one of the other chemicals here in a little while. Another type of halogen is iodine, and again, most of you guys are probably aware of this. If you've worked in the hospital or worked at a doctor's office, a lot of times the pre-opted scrubs and things like this contain iodine in them.
and they do an effective job of killing intermediate. So this, again, is found on the skin and other agents that a lot of times mucous membranes and that stuff. And, again, it's not so toxic to us, but it does a good job of killing the microbes.
All right, so here's a concept check. Which of the following is not true about hypochlorites? And, again, kills by denaturing proteins.
It's light sensitive. It's often used in disinfecting water. It slows the release of iodine, which one is not correct.
Okay, I talked about all three of these things up above. So D is the one. I didn't really talk about that release of iodine at all. And it really isn't that.
It does, again, kills by denaturing. It is light sensitive. Remember, bleach, you have to have it in the dark bottle. And then disinfecting water. We use this all the time to chlorinate our water.
The release of iodine is not correct. All right, another one is phenolics. Phenolics are found in your thing. So the most common one you probably have seen is Lysol. Another one that you see is this triclosan.
Now what's interesting is, is there's now a real big push, especially by the FDA to eliminate triclosan. Because what we're finding is that people when they're exposed to it, and again, this is found in a lot of our antibacterial soaps, actually can get sick from it. So we're actually learning to actually get rid of this.
And so if you have soap that has triclosan, I would recommend not using that soap anymore. Now, I'm not saying you should go and throw everything out and that stuff. But what they're finding is that it can cause more problems than actually do good. And what they're finding is that it's actually not very effective in killing things.
And so what we're finding now is a big push to eliminate this triclosan from a lot of the different soaps and things like this. So if you use an antibacterial soap at home, check it out and see if you have triclosan in it. And again, if it does, it's probably not the best thing for you.
Like I said, I'm not telling you to go throw it away, but the next time you go shopping or whatever you're going to buy soap, find something that doesn't have the triclosan in it that will work better for you and it's a little bit safer. So just a word of advice. And again, you might see this in the next couple of years where they're going to eliminate it altogether.
And there might be a big push, especially in places where, you know, they really regulate heavily, especially like California and New York and things like this. So again, that's just one of those things. The phenol, we always think of the phenol rings and things like this. And again, they precipitate proteins, destroy cell membranes and cell walls.
And so a lot of different things out there. Okay. Another one is chlorhexidine. This is something, the Hibiclens. So you may have used this again in the doctor's offices.
It's a soap with the protein denaturant and microhibicidal properties. Again, it's low to intermediate levels and it's used for skin de-germing. Again, you might use this on the skin as a pre-optive scrub.
skin cleaning burns if you have burn patients and things like this. And so you may use this, the chlorhexidine, which is kind of a mix of the two. And so it's the chlorine and the phenol mixed together in that.
And so that's the chlorhexidine. Alright, another one that we use a lot of hand sanitizers is alcohols. These work very effectively when they're between 50 and 95%. And again, what it does is it's used as a surfactant to dissolve membranes, coagulating proteins and vegetative bacteria, cells and fungi. A lot of times it's intermediate.
However, there are things that do not get killed by these hand sanitizers. So that's one thing to remember. So one of the nasty guys is the norovirus that goes around that causes people to get diarrhea and that. Those do not get eliminated by hand sanitizers. So your best way, so if you hear about noroviral breakouts, wash your hands with soap, okay?
Don't rely on the hand sanitizers because the norovirus isn't touched by that. So that's something that they don't tell you a lot of times, but hand sanitizers don't work. Also, we're seeing now that kids are starting to abuse these things, and we're actually seeing that kids are using this to get drunk off of, and that's not a good thing because they add more than just alcohol to these things. So...
If you have teenage kids that are thinking about it and you're starting to see your hand sanitizer disappear, that might be something to think about. But again, there's a lot of problems associated with that. So I'm not going to get into it today, but I just want you to be aware of those things. All right, another one that we have in our house and a lot of you guys will use is hydroperoxide. So if you get a wound, what it does is it decomposes the O2 gas and this is toxic to anaerobes.
So this is really good for these deep puncture wounds. And so if you get a deep puncture wound, I definitely recommend hydrogen peroxide because this will eliminate any of those spores. It won't eliminate the spores, but any of the vegetative bacteria, because what it does is it gets in there and destroys the anaerobic bacteria.
They don't have mechanisms to destroy it. Now, what happens when we put hydrogen peroxide on us, we bubble. And the reason why we bubble is we have the enzyme catalase. Catalase breaks down the hydrogen peroxide. And so again, it doesn't do much to us, but Again, because we have the catalase, but it can really destroy the anaerobic.
And again, we're going to see this is with the clostridium. And I'll talk about that in a couple of weeks when we get into the different things that can kill you. This is going to be an important one where hydroperoxide is actually probably good. So if, again, you have a deep puncture wound, highly recommend hydroperoxide, especially when you're at home. Hey, another one is the aldehydes, glutaraldehyde and formaldehyde.
These were things that were used to involve people in that stuff. And again, they do a very good job of killing bacteria. The problem with these things, though, is that they can be cancerous or mutagens. And so now we're trying to push away to more safe things.
So if you've done any dissection in the past, like an A&P or biology, you've used things where now these chemicals are less harsh. They still stink pretty bad. but they're less harsh.
They're more alcohol based because we want to try and eliminate the glutaraldehyde and formaldehyde. Now I've had some students in the past that have been actually in the funeral services program. And again, a lot of times they're still using some of these chemicals, but they're trying to become safer because obviously the more that you guys breathe these things, this can be an issue as well.
And so again, they do a very good job of killing microbes, but they also do a very good job of killing you too. So it's not being used as an high in concentrations anymore, but you do see these things use. Now these are high level because they will kill endospores and everything else.
And when we're talking about preserving bodies, we want to preserve them for a long, long period of time. These are the things that will actually do it. So there you go.
All right. Another one is the gases and aerosols. Probably the biggest one is ethylene oxide or propylene oxide. These things are used on your plastics. So anything that you open up in the hospital that is in a bag that has a plastic and it's been sterilized has been treated with this gas.
This gas will eliminate everything and eliminates endospores. It's highly toxic. And so that doesn't mean that when you open up the bag, you should breathe it or anything else and that you're going to die from it because they've removed the gas.
But it is something that again, when the, at the time of doing these things, this is highly, highly toxic gas. So you don't really want to live next to a factory that is sterilizing plastics because if the gas gets out, it could kill you. So again, there's lots of things that go on, but this thing, you don't want to be bringing this stuff in.
But it does eliminate microbes really well. All right, another one that we use is detergents and soaps. This is very, very low level. The soaps don't do a lot.
What they do is they basically break up cell membranes. Problem is, is you got to get to the cell membrane for these to actually do any good. Now, why we use it to wash our hands.
The reason why we use it to wash our hands is we can eliminate a lot of our skin cells that will then get washed, wash the bacteria down. So it doesn't necessarily effectively kill the bacteria that are on our hands. But what we do is eliminate a lot of the skin cells that have the bacteria on them and then wash those down. So soaps do a good job in the sense that they help wash the bacteria away, but they're not really going to eliminate the number of bacteria.
bacteria that you have. Alright, it shouldn't say kill the bacteria that are on your hands, it's more about washing them away. Alright, and again you can see the difference between a non-germicidal soap, so something that's like a Dove bar or maybe an ivory soap type of thing that doesn't have antimicrobials.
Here's one that's germicidal, so this would be your antibiotic soap. So you can see that those are obviously more effective and kill things longer because you have antibiotics added to. added to the soaps.
And we'll talk about this in the next chapter here, but this is just showing you the difference between one that's non-germicidal versus a germicidal. And again, in my opinion, yeah, this is great, but what it's setting up is now you're eliminating the stuff that's on you. Okay. Which can be bad, not getting, not getting wrong.
There's obviously pathogens that get on you, but you're also eliminating good bacteria that can be there too. And so what happens is that we start to build resistance and this can lead to some problems and so the more that we use antibacterial soaps the tougher it is it's going to be to kill the ones that we want to really get rid of because they get stronger and stronger through mutations so just a word word of a little advice there i guess all right here's another concept check so which of the following kills by producing oxygen radicals is it alcohol hydrogen peroxide aldehydes gases or soaps so i'll give you a second Okay, you may have heard me talk about it before, but hydrogen peroxide is the answer. Hydrogen peroxide produces toxic radicals that kill anaerobic bacteria.
We have catalase that eliminates those toxic radicals, and so any organism that breathes oxygen and can produce hydrogen peroxide in that as a byproduct has enzymes that get rid of it. One of those enzymes is catalase. So good job if you got it right. Okay, another one is heavy metals. Metals are actually a good thing.
So. There are studies which show that silver and gold actually have antimicrobial properties. And so these are used in a lot of things.
So if you have a lot of gold jewelry and silver jewelry on and that stuff, they're actually antimicrobial. They'll actually keep you protected a little bit. There's even hospitals, and this is an interesting article.
I forgot which magazine what is in, but what I would do is Google this. Look at the hospital that's made of copper. So Google in hospital made a copper and they'll show you a hospital down in Colombia where they've outfitted all the metal with copper. And what copper does is another or another metal that prevents micro microorganisms from growing. And so they've lined a lot of the hospital, a lot of the instruments.
And of course, they're right next to a copper mine that helps. And so kind of reduces the cost of that. But when they've done that, they've lessened the amount of people getting infections once they come to the hospital.
So that's something to think about. These heavy metals could be used in those types of things. Another thing we've used before in our life is the silver, the silver nitrate.
They used to use that as eye drops. So when babies were born, they would put silver nitrate in the eyes. Obviously, they don't do that anymore.
But this was one of the ways to eliminate any bacteria that may have gotten the eyes during natural childbirth. Another one that people... take is sometimes they'll drink the silver.
And so you may see some of these stories. And so you can, um, Google this as well and see blue people. And so if you type in blue people or people that drink silver, what you're going to find out is that this guy has been drinking, or these people have been drinking silver for a long period of time.
Like they drink it every day. And what is what it's done is change their skin to a bluish tint. And so they're actually referred to as blue people due to drinking the silver. the silver solutions and that stuff.
They think that it's going to keep them from getting microbes, but what it really does is just change into blue and it probably does something. But again, it's all about balance and that stuff. So you have to think about the normal flora as well.
All right. Some of the other ones are these dyes, the aniline and dyes and things like this. Sometimes we see this in wound treatment in that, but it's very low level, low level spectrum and narrow spectrum.
So we don't really use this very often unless in some very bizarre cases in which people get some of these gram positive bacteria and some fungi infections you may see these dyes used in wound treatment but otherwise doesn't isn't used very often Okay. And then else acids and alkalized. So again, anything that has a low level, again, these things have low level of activities, but when we talked about Lysol and things like this, a lot of people are going back to the good old white vinegar again.
And so I know my wife uses this as with a mixture of water as a cleaner, and it does a very good job of eliminating bacteria. We use it in our bathrooms and our countertops and that. And the nice thing about it is the idea of the vinegar smell.
But you don't have to worry about chemicals. There's no harsh chemicals that are going to get you sick. And so that's one of the ways it works just as well as a lot of the chemicals that you can buy at the store.
And vinegar is cheap. You can buy gallon buckets of it very cheaply. And so, again, it's one of those things. But you can see there's other acids out there. Acetic acid, that's the vinegar.
Proponic acid retards the molds. Lactic acid prevents anaerobic bacterial growth and benzoic and sorbic acid inhibit yeast. So these are all natural methods.
So if you're thinking about, I want to drop the chemicals and go to a natural method, I highly recommend the vinegar route and trying that mixture of 50-50 mixture of water and vinegar and use that as your disinfectant. And it works really well. Gets rid of a lot of the bacteria and it doesn't smell too bad.
Okay. So again, here's a list of a lot of different chemicals that you may have used. Here's the products and you can look to see what is the specific agent. And again, what is the antimicrobial category? I just show this again, because some of you guys are interested in, you're saying, I use this all the time and I didn't know this is what, what it was for or why I had to worry about it.
So this just kind of gives you an idea. Again, knowledge is power and just gives you an idea of what you might be using in your household. So you want to pause it here and kind of look, you can do that, but otherwise don't worry about it. I'm not going to ask any questions on these things.
All right, so we've come to the end of this lecture. And so I think this is a pretty fun lecture just looking at the different things that are out there. You've probably used a lot of the different chemicals and some of the physical things.
I know you use the physical heat in the lab and you talk about boiling things and getting rid of bacteria and that stuff. But this is always something you really don't know the full information until you really kind of sit through it. So I think this is really a knowledgeable one.
You might get something out of this one. that you haven't out of any of the other lectures, you know, not to say that you haven't gotten anything out of it, but you might get something just for general knowledge to take with you out of this class. So again, we looked at the types of control. This includes the physical and chemical controls. And again, in physical we talked about the moist and dry heat, the cold, the radiation, filtration, and the chemical controls.
There's a variety of chemicals that do a lot of different things. Okay, so again, I'm not going to ask you about the various types of chemicals that are out there. I went through them pretty quickly and that stuff, just to kind of give you an idea of what's out there.
What I just want you to know is think about the targets. Now I don't have the targets down, but if you think about the main targets of bacteria, what are they going to target? Cell walls, cell membranes, proteins, and DNA and RNA, nucleic acids.
Okay. So if you think of those are the four main things, those are going to be the targets for all these things. And I'll include it in on the video here. just to show you so that you're kind of write those down because those are important cell wall cell membranes uh proteins and dna or nucleic acids all right and we'll see that again in the next chapter so don't worry talk about the difference between disinfectant versus antiseptic and i should also put sterilization so disinfectant means chemicals that kill bacteria but you apply them to inanimate objects antiseptics are going to be chemicals that kill bacteria that are applied to the skin And then sterilization means eliminating all life.
So when you talk about sterilization, you eliminate everything. So you're going to eliminate bacteria, the moderate, and then you're also going to eliminate the endospores. So that's important. Sterilization means you're going to get rid of everything.
So don't mix up those words. I do a lot of times when I say, oh, we're going to sterilize it. But really what you mean is disinfect things because you're not getting rid of the endospores.
And again, that what goes along with this is the relative resistance. Know which ones are the highest. the highest or the highest resistant ones this is the endospores and prions and then finally the vegetative bacteria and the viruses are the lowest okay so we've come to the end of the lecture if you have any questions please feel free to ask me in class send me an email talk to me after class i'm happy to answer anything for you guys glad you're watching the videos and again if you have any questions let me know thanks for watching and i'll see you next time