Cram The Pance - S1E28 Tuberculosis

Episode Date: June 26, 2021

Tuberculosis review for your Pance, Panre and Eor’s.►Paypal Donation Link: https://bit.ly/3dxmTql (Thank you!)--- Support this podcast: https://anchor.fm/scott--shapiro/supportBecome a supporter of this podcast: https://www.spreaker.com/podcast/cram-the-pance--5520744/support.

All right, so tuberculosis. This is not a hard topic. The difficult part about tuberculosis, at least from an exam standpoint, is just that there's so many little things that they can test you on. So I'm going to focus like I always do on the things that I feel like you may be asked and the most important things. So we don't waste your time with all the excess stuff that I don't think is very important. So let's get started with tuberculosis. As always, thank you so much for the comments. I've gotten a few emails thanking me, the people taking their pants that really found this helped in. That just makes my day. So thank you so much for that. And please, if you haven't checked out the YouTube page, please do it's cram the pants on YouTube. And subscribe if you haven't yet. I'm releasing all the videos there at the same time I do with the podcast just with added visuals and things like that to help. So let's get started with tuberculosis. I'm sure all of us are pretty aware with, you know, at least familiar with some of the basics. So it's an infection with an organism called mycobacterium tuberculosis. It's most common for this infection to present in the lungs, like a pulmonary infection.

But it can actually infect anywhere in the body. So we'll go over some less common extra pulmonary infections in a bit. But lungs is going to be the most common place. And that's why the blueprint, the NCCA blueprint, puts this under pulmonary, because pulmonary tuberculosis is the most common manifestation. You may also see this as an infectious disease, but as far as the blueprint, this is a pulmonary topic. And that's why we're doing it in line with all of our other pulmonary topic.

So let's start with risk factors because these are kind of important. And this is going to be your key to the vignette. So the two presentations, I remember, member as far as the risk factors that I saw that I feel like are really important are crowding and low socio-economic status. So crowding would be patients that are coming from prisons, jails with, you know, obviously a bunch of other people, homeless shelters, and that also goes in line with the low socio-economic status. So a lot of times you'll see a homeless patient that comes in with hemoptosis weight loss and they're kind of guiding you towards tuberculosis. So remember crowding for any reason,

and whatever it is, if they're a prison, homeless shelter, and low socioeconomic status, like a homeless patient. So those are two really big risk factors, especially on the boards. And then a couple other ones that are important for you to know as well as HIV. That's a really big one too. And other immunocompromise states as well. So remember if they're on chemo and other medications that may compromise their immune system. And then also birth in a TB endemic area.

So there's a bunch of countries you can look this up. but India, China, Philippines, Africa are some TB endemic areas. So if they're born in that area, that's another key in a vignette you might want to look for. The way that they may ask it is just saying this patient comes over. They're coming over from South Africa and they present with, you know, hemopthesis, etc. Like I went over before. So that's another key there that you should be looking for in a vignette. So risk factors focus on crowding low socioeconomic status, birth in a TB endemic area,

and then HIV and other immunocompromised states. So next I'm going to go over the stages or the different types of tuberculosis infection. So let's run down a scenario to see how it actually plays out so I can explain each stage that you're going to find with tuberculosis going over latent infection, primary, etc. So you have a healthy patient, normal immune system. They're exposed to TB. In this healthy patient, what's going to happen after TB exposure? And most patients actually about 90%. So in a healthy patient, their immune system will respond.

Macrophages will swoop in granulomas form around the tuberculosis and essentially surround and trap the TB infection in this little granuloma. It's almost like a cage keeping the TB from spreading elsewhere in the body. And they go on to develop what's known as chronic or latent infection. So that's what's going to happen in the majority of the population. Around 90% are going to go on to develop chronic latent infection. So again, immunocompetent patients, they have no history of HIV, diabetes, chronic steroid use. They essentially, their body creates this granuloma, this cage for the TB infection to be trapped in.

The TB is actually still alive in there. It's just essentially walled off and can't spread or infect the body. So that's chronic or latent infection. That's most of your patients is how they're going to, what they're going to progress to. So let's go over the same scenario. But this time the patient that's exposed to TB is immunocompromised. Maybe they have HIV, maybe they're on chemotherapy. These patients can't fight off that infection.

They're not going to build that little cage I keep talking about, that granuloma around the TB infection. And they're going to develop what's known as progressive primary TB disease. So they may have TB pneumonia, expansion of infiltrates. It's even possible to get like TB meningitis. So there's a lot of things that can develop in these patients that do. don't have a strong enough immune system to fight off the TB infection. So that's patients that are immunocompromised. Now let's go for one other type.

So the last type of TB, let's go back to the patient in the first group. They're healthy, their body did what was supposed to walled off the TB infection. They're living their lives, no problem, all is good. They don't even know they have TB maybe because it doesn't have any problems. It's contained in there. What happens if one day these patients, for some reason, have a weakening of their immune system? Maybe they develop HIV. they have to go on chronic steroids for a long period of time.

They become diabetic or even just aging. Obviously, as we get older, we know our immune system declines. What's going to happen to these patients that were at one time able to trap this infection? Well, remember, like I said before, TB is still active in these granulomas. It's there. The body just trapped it and the immune system has kept it under control. But now these patients have a waning immune system. It's weakening.

and the walls, the body's built to keep this TB trapped and those granulomas break down. And now they have what's known as reactivation or secondary TB. So those are the three stages you need to be familiar with. There are three outcomes. So chronic latent infection, that's your majority of patients who fight off the infection, walled off in these granulomas, primary infection for the small portion of the population who can fight off the infection, you know, the immunocompromised. And then reactivation or secondary TB in those patients who initially fought off the

infection, but later on became immunocompromised for whatever reason. So those are the three outcomes that you need to know about. Okay. Now clinical manifestations, they're going to be cough, weight loss, night sweats, hemoptosis, fatigue. You can even get chest pain from the enlarged bronchial lymph nodes. And you're going to have a lot of these constitutional symptoms that you see. And a lot of the symptoms that patients with TB present with sound a lot like a patient. with a malignancy, hemophtysis, weight loss, cough. So you have to be really careful when you're reading the vignette and really careful, obviously, in real life, too.

The keys, at least to a vignette are going to be that they mentioned something in the history to kind of zone you into TB rather than a malignancy. They may mention they were traveling internationally. And of course, you're going to know that it's a TB endemic country. They may mention that this patient is a non-smoker, which obviously is very rare to have a lung malignancy if you're a non-smoker, or even that they're young. which we know is uncommon to see in a young patient with pulmonary carcinoma. So you're going to see all these keys that kind of lead you to TB rather than a malignancy.

Because, again, these symptoms are, they both share that in common, a lot of the symptoms with the malignancy as well as TB. So you need to look for those key factors in the vignette. So those are the clinical manifestations when the patient has tuberculosis that affects the pulmonary system. But like I said before, it can actually affect anywhere in the body. And there's a couple, there's a lot of extrapulmonary manifestations, but there's really two that I feel are high yield that you should be familiar with. So the two, and I remember getting one of these on an exam question. So the two extra pulmonary manifestations that you should know about are Pots disease and something known as scrofula. It's very weird names, but that also helps you to remember them. So Pots disease is, just to put it simply, is TB of the spine. It's of the vertebrae. So you get tuberculosis infection of the vertebrae. The way that I used to remember this, and this works a lot better. with a visual like I'll have on my YouTube page, but if you stack pots on top of each other, they actually look like vertebrae. It sounds weird, but if you see a picture and I have a picture

on my YouTube video that I'm going to put up, but if you stack pots vertically, they look like vertebrae. So that's how I used to remember it. I'd see pots disease. And then in my head, I just thought of like pots stacked on top of each other. And to me, I visualize like vertebrae. That's how I remember pot's disease was TB of the spine. Hopefully you can create that, you know, that visual in your head. Now, Scrope. Ccula is tuberculosis lymphadenitis in the cervical region. So it's TB of the cervical lymph nodes. The way that I remember that is scrofia sounds like Dracula.

Scrofila, Dracula, Dracula, Dracula. So when I would think of Dracula, where does Dracula bite you in the neck? So this is TB in the cervical region, the neck. And the funny thing is, or not funny, but if you actually look up scrofula and you see the pictures, it almost looks like bites of the neck. it's it's kind of odd but sometimes it'll see enlargebone when it heals it almost looks like these bites so scrofula think of Dracula dracula bites you in the neck this is tb of the neck of the cervical region lymphadenitis of the cervical region all right so hopefully those help you um let's move on to

to diagnosis how are we going to diagnose these patients so first i'm going to go over diagnosing an acute patient that has signs and symptoms of TB they're sick and then we'll go over the screening ppd all the things that you're probably somewhat familiar with so you have a patient with signs and symptoms of TB. They're coming into the ER wherever you're at. What are you going to do first? So chest x-ray by far is going to be your first test you're going to do. So what are you looking for in a chest x-ray with, in a patient with TB? So most people when they think of chest x-ray findings in a patient with TB, the assumption, the thing that we all kind of just learn about or maybe heard about is that TB always presents in the apices or the upper part of

the lung. So that's true, but it's only true in reactivation or secondary TB. Primary infection actually presents like all of their pulmonary infections, and it's generally seen in the middle to lower lobes. So in primary pulmonary tuberculosis, you're going to see your radiographic signs of TB infection in the lower middle lungs, and that's solely based upon the fact that when these patients inhale the TB infection,

it's just where the respiratory droplets tend to deposit in these lobes. So primary, lower to middle lobes. And now reactivation secondary, that's going to be your classic finding that you probably have heard of the apacee. So the reactivation secondary TB is going to follow the classic pattern that we're familiar with. And that's it favors the upper lungs within the lung apex, the upper lobes. And the reason is that the apices have higher oxygen tension.

And that facilitates the growth of this oxygen loving aerob, which tuberculosis is. It's, it's an aerob. So it favors oxygen. It loves oxygen. So it's moving up to the apices where you have that higher oxygen tension. So remember reactivation secondary TB is going to be. In the apices or upper lobes, primary you're going to find more commonly in the middle or lower lobe consolidation. And you're looking for those granuloma findings, different things.

There's something known also as a caceating granuloma. That's where you have the central necrosis that's seen a lot of times in latent infection. So again, you're just looking on the chest x-ray. It may just look like a regular infiltrate, but sometimes you'll see those granulomas and things like that. So that's your chest x-ray. Those are the findings in a patient with TB. Now there's one other chest x-ray finding that I think you should be familiar with. And it's something known as Milliary TB.

So don't waste too much time on this one. But know if you see a chest x-ray that has a bunch of small nodular lesions, almost like somebody got shot in the chest with like a shotgun spray, all the little BBs in there. Then you should be thinking of Milliary TB. It's actually named after millet seeds, which is bird food. I don't know if you've ever seen like the bird food, those little seeds. Because that's what it looks like in the lungs.

just like a bunch of little seeds. So if you see a chest x-ray or they mentioned, they describe it to you, and it has a bunch of little, small, little tiny nodular lesons just spread throughout. Think of milliary t-b. That's really the only other chest x-ray finding I think you should know about. Don't waste your time with all the other excess stuff. So that's your first initial test. Somebody comes in with, you feel like maybe an acute infection with tuberculosis.

Next thing you're going to get, or maybe at the same time, depending on the hospital protocol, is something known as, as an acid-fast bacilli smear and then also a micro-bacterial culture. So acid-fast bacilli smear, which I'm going to call an AFB smear as it's commonly called. It's a fast, cheap test. It's fairly sensitive. It's not as sensitive as a culture or PCR testing, which I'll go over. So it's a good test, but if they ask you the best, this isn't it.

It's fast, it's cheap, which is important. And that's going to be one of your first things that you're going to see that you can get back. Don't worry about all the, you know, some of these you need three separate, you know, sputum test at this time, this time. They're not going to ask you that. So don't worry about those things. So again, remember acid fast bacilli smear. This is a good test. It's not the most sensitive test, but it does work well.

It's cheap and it's fast. The next one I'll go over is something known as a nucleic acid amplification test, also known as PCR testing. So this test isn't used that much. You probably won't even get an exam question on it, but just know about it. It's mainly used to confirm that the bacteria that's isolated in a positive AFB smear is actually from mycobacterium and not a non-tobacterious mycobacteria. So it's more sensitive than an AFB smear, but it's less sensitive than a culture. It's just not commonly used. Really, you're going to focus on your acid-fast bacilli smear.

And then we have the last one, your best test, your micobacterial culture. So this is the most sensitive tool for detection of TB. It's up to 98% sensitive for tuberculosis. But the bad thing about it is it's super slow. It can take up to eight weeks to get the results. So if you get a negative acid fast bacilli smear, you're obviously going to send out your culture. You're always going to send out a culture because you want this as a confirmatory test. But it's not anything that's going to guide your treatment while the patients in the hospital.

Because again, it can take up to a couple months to find out. So it's something you want for confirmation. You'll send it out no matter what. But remember, even though it's your best, your most sensitive test, it takes a very, long time. So really you need to see your chest x-ray findings, your AFB smear results, and if you do a PCR testing those as well. So really quickly, let's just review what we went over. So obviously your chest x-ray is going to be your initial test. Then you can do a sputum acid-fast bacilli smear, your AFB smear. It's a good test, fast and cheap, but it's the least sensitive. Then you have your

nucleic acid amplification, your PCR test more accurate than AFB smear, but not as sensitive as a culture. It's really good for just ensuring the organism that's isolated is from mycobacterium and not a non-tobacterious, mycobacteria. And then culture, your best, most sensitive test, but it can take weeks to come back. So those are your ways to actually diagnose tuberculosis. Now let's go on to screening. So screening, the one you'll hear about the most that you'll probably get a question on is your PPD testing. So there's only a couple things I think you need to know about PPD testing. So first, just the basics of the test, if you're not familiar with it, it's known as a question.

a purified protein derivative it's injected into the skin and then the results are interpreted between 48 to 72 hours it has to be within that time frame and then you measure the area of induration you don't look at the area of redness or you know if you have any you know sometimes they'll come back and you'll have a a PPD test and you have like this big area that's all just red this erythema but you don't measure that you actually feel for the area of induration and that's what you measure so there's a lot of there's a lot of room for error with this test. So, you know, because somebody's actually interpreting and measuring it. So there can be

problems, but it's a cheap test. And this is the most commonly used one. So the most important thing I think you need to know about for a PPD testing that I got asked is the reaction size and who's positive with each size. This is really what you should focus on. So there's three different iterations that are measured. And it all depends on the patient population being tested to decide whether or not they're positive. And the way you should think about it is the less of a risk you are for having to TB, the greater size of in duration you can get away with and still be able to be negative. So there's three sizes that you need to know. It's 15 or more millimeters, 10 or more millimeters, and then five or more millimeters.

So if you have a patient that has 15 millimeters or more to be determined positive at that level, like big enough to be all the way up to 15 and now you're diagnosed as positive for TB, this is only in healthy patients. No risk factors, healthy individuals. they can get away with having up to 14 millimeters, because again, this is 15 or more. So up to 15 millimeters or higher area of induration is a patient with a healthy patient, no risk factors. Next, you drop down a little bit more and you get to 10 millimeters or higher.

These are going to be patients that have more risk factors. These are going to be residents or employees of prisons, health care facilities, patients with like immunocompromise systems like diabetes, but not as severe as HIV. and then some malignancies as well. So remember when you get to 10 more millimeters, it's patients with more risk factors like people that are being exposed, residents, employees of prisons, healthcare facilities, patients with diabetes, malice,

and then some malignancies. Then when you get to 5 millimeters, these are the really sick patients. So to be diagnosed at 5 millimeters or higher, this is going to be a patient with HIV. It's going to be a patient with an abnormal chest x-ray with changes suspicious for TB, immunocompromise patients like patients,

on chemo, chronic steroid use, organ transplantations, and then patients with close contact that has active TB. So like if you're living in a house and your mom has TB, then you're only going to get away with 5 millimeters of in duration and you're positive. So really just remember that 15 or greater healthy, no risk factor is completely normal. And then 5 or greater is going to be your really sick patients, your HIV immutable suppressed or patients that have really close contact. with positive TB and then 10 millimeter is going to be everything in between so I'd really just

focus on the 5 and the 15 you should probably be able to get the question right remember 5 millimeters question they'll probably ask you is going to be a patient with HIV and then 15 or greater no risk factors perfectly healthy okay so then the other thing I would know about ppd just remember that you can do a two-part test this is really just a way of making sure that the patient's negative so you do the first test it's basically just to wake up the immune system to kind of remind the immune system. And then it's almost like knocking on the door and waking it up and saying, all right, we're checking you for TB because maybe they've had latent TB for 20, 30 years and the body's just forgotten about it. I guess you could think of it. So the second test

that you do two weeks later just confirms that they're indeed negative. So that's really what a two-part test is just to make sure in case for some reason when you did the first one, you know, whatever it was, the antibodies weren't awake. So you do a second test after you woke it up with the first one. to make sure that they are in fact negative. The other screening tests that you should know about is something known as interferon gamma release assay. So this test is it has a lot of positives over a PPD, but it's really expensive. So it's a one-time blood test. So the patient doesn't have to come back to have it read. There's no reader bias because there's nothing there's no area of in duration to measure. It's a lab test.

So it's either positive or it's negative. So you're not going to have any of these screw-ups with people measuring it and then maybe getting wrong, maybe measure the area of redness instead of the area of induration. So no reader bias. And that it's also not affected by the BCG vaccine, which I didn't mention. But the BCG vaccine is a vaccine that in TB endemic countries, they receive this vaccine to prevent some of the complications of TB. And in a PPD test, the BCG can make the PPD test falsely positive. So the only caveat, of course, like I said,

with the interferon gamma release assay is that it's much more expensive. So it's not commonly used. So those are the two screening tests that you need to know about and just the basic things that you should be aware of. So let's move on to treatment, which is going to be, you know, kind of wrapping it up here. And this is, treatment's actually pretty easy. For active infection, you're using ripe. So that's the mnemonic. Ripe stands for refampin, isosinized, pyrozinamide, and then ethambutal.

So active infection, ripe. The therapy is typically for about six months. Not all the meds have to be taken for the full six months. So like after two meds, pyrazinamide and a thambitol can be stopped. Anyways, don't focus on that. They're likely not going to ask you the length of treatment for each specific drug. Just remember ripe six-month-long regimen for active TB. The question you're going to ask, they're going to be asked, is likely not about how long you treat and which medications.

What they're probably going to ask you about is the adverse drug reactions of these meds. They're really high yield, these TB meds with their adverse drug reactions. They love to ask about ADRs or TB meds for some reason. So let's go over the high-yield ADRs that they're probably going to ask you and just some good ways that I've come up with to remember them. And another thing, just note that all of these TB drugs are hepatotoxic. So I'm not going to list that with each one. I'm just going to go over the unique ADR. So no, each one of these drugs can completely screw up the liver because I'm not going to mention that with each one.

So let's focus on these high-yield ADRs with TB medications. So let's start with refampin. That's your R and RIP. So refampin, it's the only TB med that starts with an R. So why does that matter? Because R, in my mnemonic, is going to stand for red. So why red? Because refampin has this very unique ability to turn all of your secretions reddish orange. Your tears, your urine, your sweat, your saliva, can all turn reddish orange. And that's why patients on refampin really can't even wear contact lenses because they'll get tinted orange or red. So refampin, remember, secretions are going to turn red.

orange where Phampan starts with an R. That's how you remember that next one. This is probably the highest yield I would say of all of these because they love to ask about this because it has one unique characteristic. So isonized it. I used to remember isonized it. Instead of remembering isonized I would remember isonum. Isonized it. Isoninum like numb NUMB. And why am I so numb? Because I have peripheral neuropathy. It's one of the main adverse effects of isonized. And it can be prevented by taking isinized with periodoxine, which is B6. So remember that. If they ever say you're going to prescribe isonized it, they will almost definitely have periodoxine combined with it. And if they have one without periodoxin, it's wrong. You never take isonized it without B6 or periodoxine.

You have to know that. It has a very high occurrence of peripheral neuropathy and it's prevented by giving them B6 or periodoxine. So remember that. Isonized it. Isonum. Isonum. because I have peripheral neuropathy. Next one is pyrazinamide. So this one, you have to be a little bit creative in your mind, but it helped with my visual that I used to have in my head on my exams. And I remember getting a question, and I had this visual, and I was so happy I remembered this.

So be a little bit creative here with me. We're going to paint a picture. So pyrazinamide, I want you to think of the pyramids being built. So the pyramids are being built stone by stone in the middle of this hot desert. And the people that are building these pyramids are in the middle of the desert, they're obviously getting sunburn. So let's go over why, you know, have that visual for you, these people building the pyramids, stone by stone, and getting a sunburn.

So when you think of pyrozynumide, remember you're thinking of the pyramids, and then they're built from stone. So stone because pyrazinamide can cause hyperurisemia. So uric acid stones that can be formed in the urinary tract, remember, patients with hyperurisemia can get stones, they can get kidney stones and then also the crystallized stones and the joints with gout. So remember the pyramids were built with stones. You think of stones. You start thinking of your uric acid stones, your crystallized stones and the joints with gout, hyperurisemia. Next part is people building the pyramids in the middle of the desert, the blazing hot sun, they got sunburn. So what are we thinking about with sunburn? That's the second ADR of pyrazinamide. That's going to be photosensitive dermatologic rash. So again, when you hear of

Pyrozynamine, think pyramid, pyramids building being built with stones. That's your hyperurisemia, your gout crystallized stones in the joints and in the urinary tract. And then pyramids being built in the middle of the hot desert, they're getting sunburn. That's because pyrazinamide also causes a photosensitive dermatologic rash. All right. So your last one, a thambutal. It's the only TB drug that starts with the letter E. And that's important because the ADR of a thambutal are all about the eye.

So a thambutal can cause optic neuritis. and that leads to visual changes, problems with color perception, et cetera, all the things with optic neuritis. So a thambutal, much easier than pyrazinamide. Starts with an E, think of the eye, and then you remember optic neuritis. One last side note about the meds as far as ripe, be aware that if a patient has a contraindication to a thambutal, they have an allergy, whatever the case, you can use streptomycin in its place. So the mnemonic would be rips instead of ripe.

So RIPS for streptomycin instead of ripe. So just I doubt they'll ask you that, but just so you know. Now, latent TB treatment, that was for acute TB treatment. Latent TB treatment is pretty straightforward. There's really just two meds that you need to know. And that's isonized and a rifamicin-based medication. So either refampin or rippantine. So that's for latent infection.

None of the treatment regimens for latent TB have been shown to be superior to one another. So whatever you choose, because you can either. treat for latent TB with isonized by itself. You can use ref. Um, refampin by itself. You can use a combination of isonized with refampin. You can use a combination I think of isonizing with rifapentin. It doesn't matter. There's not one that's better than the other. Therefore, they can't ask you which would be better. You're probably just going to get a question with, um, just make sure you don't pick something that says like pyrazidamide. They're probably just going to ask you if you're treating latent TB and they'll have the one that says that isonize it. So you just need to know that you

can use isonized it and then one of the rifamysin base med so either refampin or rifapentin combined or by themselves again one is not better than the other so they're not going to ask you that just know that those are the treatments those are the medications for latent TB all right so that's really it for tuberculosis let's do five quick questions and then we'll wrap it up so question one tuberculosis of the vertebrae is known as tuberculosis of the vertebrae is known as potts disease remember pots stacked on top of each other to look like a vertebrae question two patients with secondary or reactivation TB will most well most commonly have localization of the cavatory legions of in which region of the lungs so patients with secondary or reactivation

TB will most commonly have localization of cavitory lesions in which region of the lungs that's going to be your apices your upper lungs upper lobes with the higher oxygen tension question three which TB medication can cause reddish orange secretions your tears your urine all turning reddish orange. That's going to be refampin with an R. Remember Raphon red? Question four, a patient who is currently living with his brother who has active tuberculosis

would have a positive PPD at what size of induration. So you have a patient who is currently living with his brother who has active TB. He would have a positive PPD at what size of induration. That's going to be 5 millimeters or greater. Remember close contacts with active TB, as well as your HIV immunosuppress patients like on chemo. are all going to be at five or greater.

Question five, chest x-ray with diffuse small nodular lesions likely has which type of TB. So you have a chest x-ray with diffuse small nodular lesions. What type of TB should you be thinking? And again, that's going to be your milliary tuberculosis. Remember, that's your millet seeds on the chest x-ray, all those little tiny little lesions. All right, so that is tuberculosis. Hopefully that was helpful. Again, thank you so much for all of the comments and everything.

And if I can ask you just one favor, if you don't mind, go on the YouTube page and just subscribing I'm trying to get the word out about the YouTube channel and the more subscribers I have the more people that can find the page so that would be one thing I could ask if I could ask one favor of you so thank you so much please let me know if this is helping and good luck on your pants your panery your EORs and good luck in PA school