hey everybody dr. L in this video I want to review the differential stains so slammed you'll hear me call these diagnostic stains because I like about these as you know there are simple stains that just color something stain something to make it easier to see differential stains they answer questions they tell you something as well so that's why I like to use the word diagnostic stains but differential stains is just fine so I'm gonna jump right in here and cover all these so let's go ahead and dive in the first one is the Gram stain I did a separate video on the Gram stain because it is so important but the Gram stain is generally the first stain you're gonna use on any organism any unknown organism because it'll help you determine what kind of cell wall it has so gram positive cells are gonna have big thick peptidoglycan cell walls gram-negative cells are gonna have a thin peptidoglycan cell wall with a lipid outer membrane that that can make them a lot harder to deal with in a lot of cases so I don't want to spend any more time on that because just watch the separate video on the Gram stain so here we see just a close-up of the the purple organisms would be gram positive the red or pinkish organisms will be gram negative here the acid fast stain is very important so now the key thing I want you to know is which types of organisms we're looking for when we do a stain like this now with the Gram stain I do expect you to know the the the actual stains you use in the order to use them in but that's the only one so acid fast organisms there's going to be two types and that is the Mycobacterium and the nocardia so you here you see an example of Mycobacterium tuberculosis obviously the causative agent of tuberculosis the other big micro bacterium is Mycobacterium leprae which causes a Hansen's disease or leprosy so acid fast Thane is used to determine if you're looking at a micro bacterium a nocardia or anything else you see how their Gram stain tells you something about almost every organism the acid fasting is not going to do that so if you want to know the real quick basics of the of the acid fasting you use here it says to use basic fusion that's fine but I prefer kinyoun's carbo fusion I feel like it's a more effective and then you use acid alcohol as your decolorizing agent and then you add the counter stain methylene blue so here we see a close-up of that organism so the red organisms would be acid fast positive and the blue organisms would be acid fast negative so what looking for specifically is what organisms have a waxy material in their cell wall called my Kolok acid and that would be your Mycobacterium and your nocardia so that's the acid fasting next we have the spore stain or the Endo's for stain so when would you use this well you'd use this anytime you're concerned that you're dealing with a spore forming organism and that would be the Clostridium and the bacillus so bacillus you think like bacillus anthracis the causative agent of anthrax bacillus cereus bacillus subtilis these can sometimes cause foodborne illness but the Clostridium are to me the really big ones you have Clostridium difficile a or C diff anyone that works in healthcare knows that's a big concern Clostridium tetanus the cause the causative agent of tetanus Clostridium botulinum the causative agent of botulism so spores are very very scary much harder to kill them vegetative cells but the spore stain will highlight them so there are multiple staining techniques to look for spores but primarily what you're going to what you're going to use when you're looking for spores is you're going to use malachite green as the stain that should stain the actual spores green and then whatever technique you use you're going to counter stain with safranin this is the same grant this afternoon using the Gram stain so so here we see a close-up so you see the green spores inside the regular bacterial cells then you see some vegetative bacterial cells that don't have spores so that's the spores stain just a reminder it's useful when you're looking for a Clostridium or a bacillus as far as the two genus here all right next we have the flagella stain so like the name implies the flagella stain is going to try to identify organisms or help you see flagella if they're there so this would be an example of a of a mordant I don't care if you know what the Mortons are but mordant's are generally used to attach stain to an organism and the flagella stain is where we need a mordant actually thicken so it makes the flagella more visible by layering the mordant the chemical compounds on them so the flagella stain is useful if you are trying to identify organisms that have flagella which were used for movement we cover that in a separate video as far as bacterial Anatomy here you see a more close-up of a really awesome one obviously when you think of lardelli with human cells you think of that kind of one whip like flagella on this on a human male sperm but the flagella is a very powerful very complex system in bacteria pretty awesome so we'll cover that in other places and then the last thing we have the capsule stain so here's the key with the capsule stain this is actually not a great image but capsules can't be stained so a capsule stain is an example of a negative stain so very important understand that term and negative stain is where you stay in the background you stain everything else but what you are trying to identify which is the capsule so you can go a little bit closer here there actually we have two images here now the one the right is better so notice the white the clear areas around those microorganisms those are the capsule so you stain the organism inside the capsule you stay in the environment outside the capsule but you couldn't stay in the capsule itself that's why it's called a negative stain you stain the background and what you see is what isn't stained so alright so that is the capsule stain