Hi, welcome to our video on Antimycobacterial Agents.
Now, really, it’s easy to remember.
We think we’re talking about the treatment of tuberculosis.
Well, let’s start off with what are Mycobacterium?
It’s just a genus of actinobacteria.
Well, in case microbiology brings back bad memories for you,
they’re classified into several major groups.
Two you might recognize are M. leprae that causes leprosy and M. tuberculosis
which is what we’re gonna talk about today.
So, M. tuberculosis infection is what causes tuberculosis or what we know as TB.
So, what is Tuberculosis? Well, it’s a disease caused by the Mycobacterium tuberculosis, right?
We just talked about that. It’s spread by droplets in the air, so, another human coughs or sneezes
and then, someone else inhales them, that’s how it’s spread.
Now, usually, it infects the lungs and when we think about TB,
that’s usually what we think about is what happens in the lungs
but it can also infect the brain, the kidneys, or the spine.
So, kind of keep that in mind. We tend to focus on the lungs because that’s what usually happens
but it can also disseminate to the brain, kidneys, or spine.
Now, TB can be either latent or active.
And that’s a really important concept.
So, latent or active TB, we treat them a little bit differently.
So, latent TB, these are the things that the patient doesn’t.
The patient doesn’t feel sick, so, this is kind of a difficult discussion to have to some people
because they don’t understand. They think, how can I have a form of TB if I don’t even feel bad?
They won’t even have the symptoms of TB, so, they don’t feel sick, they don’t have the symptoms of TB,
and actually, they’re not infectious and cannot spread TB.
So, a healthcare worker could take care of patients if they have latent TB because they’re not infectious.
Now, here’s the thing that the patient will have or does experience.
They are infected with M. tuberculosis but they don’t have the disease.
They’ll have a positive reaction to the TB skin test or blood test but they don’t actually have the disease tuberculosis.
Okay, so, latent TB according to the CDC, why do we care about it if they’re not infectious,
they don’t have the symptoms, they don’t feel bad. Well, because latent TB can turn into active TB
and then, we’ve got a big problem.
So, the CDC says without treatment, five to 10% of the people with latent TB
will develop the active disease at some point.
Now, look at this cool graphic to help you understand this next statistic.
Bing, yeah, look at that.
See how they took that little tiny pie shape, the 5 to 10%, 50% of those will develop TB
will do so within the first 1 to 2 years.
So, if you’re someone who has latent TB, you have about a five to 10% of developing TB
and a 50% chance it’ll probably happen within one to two years.
Now, what are the things that cause someone to develop latent TB into active TB?
Well, people that are immunocompromised are at an increased risk to develop TB.
Also, if you have any other chronic conditions like diabetes or heart disease,
you’re also somewhat immunocompromised and could have a higher risk for going from latent TB to active TB.
Okay, so, we’ve talked about TB being this mycobacterium, it causes that,
you can have it in your body and it’s latent. It hasn’t taken over yet
but you do have the risk of turning into active TB.
So, let’s talk about how would I know if I have latent TB if it’s becoming active?
Well, when we say active, that means the TB bacteria have overcome the person’s immune system
and they have multiplied in the body.
So, they might see symptoms like respiratory, they’re coughing for like three weeks or longer.
They have hemoptysis, that means they’re coughing up blood or they have chest pain.
They also might have some GI symptoms like they’ve lost weight and they just know why.
Now, usually, we’d celebrate but if it’s active TB, that is not the way you want to lose weight.
It doesn’t help matters; they probably have lost their appetite too.
It really can kind of impact how they feel all over in their GI system.
They’ll also have night sweats. They’ll just wake up drenched. They’ll be running a little bit of a fever,
they may have chills, and they’re just really, really tired.
So, when latent TB becomes active TB, they don’t feel good.
Latent TB, they don’t have symptoms, they don’t think they feel sick.
When it becomes active, they’re gonna know there’s a difference.
Coughing, coughing up blood, chest pain, GI disturbances, losing weight and they’re not really trying
but they don’t feel like eating and they have these horrible night sweats and the fever, and chills,
and they are just uber, uber tired.
That’s when we know this person’s starting to show us symptoms of active TB.
Now, when you’re working with a patient with latent TB, they need to understand, “Hey, you have latent TB.
If you start to have any of these symptoms,
you need to contact your healthcare provider immediately so you can get the right kind of treatment.
Now, how do we diagnose active TB?
Well, the initial screening is something you probably went through before nursing school.
If you work in a hospital, we have to do it every year but it’s a TB skin test.
It’s called the PPD for purified protein derivative.
Yeah, don’t bother memorizing that, we all just call it the PPD.
Now, how this works is if you have an intact immune system and we expose it to M. tuberculosis as PPD,
we’ll have a local immune response.
You read it after about 48 to 72 hours.
You know, you go, you have a slight injection,
very little bee sting and if you have an induration or a hardness around the injection site after 48 to 72 hours,
that’s considered a positive test if you have an active immune system.
People who are immunocompromised, they don’t have to have as big a response to that PPD
because they don’t have the immune system that can respond.
But someone with an intact immune system,
a healthy immune system is gonna have a pretty good size induration or hardness reaction to the PPD test.
Now, we can also do blood tests.
There is an interferon gamma release assay or an IGRA, it’s one of the blood tests that can be used.
So, initial screening TB test or a blood test.
If one of those comes back positive, then, you’ll be referred for a chest x-ray or sputum microbiology
because there’s a couple things we can do with sputum microbiology.
If we culture for M. tuberculosis, it takes two to six weeks.
Now, if I’m worried about having active TB, I don’t wanna wait that long.
That seems like too long a time or we can do an NAA, nucleic acid amplification,
we can get those results in 24 to 48 hours.
I don’t think I need to tell you which test is more expensive but if I was worried about it,
I sure would hope I could get an NAA instead of waiting for that culture for two to six weeks.
Now, again, talking about latent TB versus active TB.
We’ve got these in two different sides of your notes there so you can kind of see them laid out right next to each other.
Latent TB might have a positive scanner blood test.
They’ll have a normal chest x-ray and a negative sputum test.
If I have active TB, I’ll have a positive scanner blood test
and I might have an abnormal chest x-ray or a positive sputum smear or culture.
Now, in latent TB, TB bacteria are alive in the body but they’re inactive.
Okay, so, underline alive and circle inactive.
In active TB, TB bacteria are alive but they’re active in the body, that’s the difference.
Both of them have alive bacteria but in latent TB, they’re inactive, in active TB,
they are very active hence the name active TB and they overwhelm the patient’s immune system.
Now, the latent people, they won’t feel sick.
Active TB usually feels sick, they have cough, and fever, and weight loss, and night sweats,
and they don’t feel like eating. But latent TB doesn’t have those symptoms, active TB usually does.
Latent TB can’t spread it, they’re not infectious but someone with active TB can spread TB to others.
Now, latent TB, people would benefit from treatment to minimize the risk of them converting to activating
or reactivating they’re talking about that.
We wanna minimize the risk of latent TB becoming active TB.
So, if we can educate them like, “Hey, you don’t have to take the medication but if you do,
you’re gonna have a much lower risk of developing active TB.”
And the more cases we can avoid becoming active, the whole society and community is safer.
Someone who has active TB, treatments, not optional, you need to have treatment for the TB.
Now, if the patient has been exposed to multi-drug resistant TB or extensively drug-resistant TB,
preventative treatment is essential.
These bugs, these types of TB are much harder to treat because just look at their name.
They’re multi-drug resistant meaning the drugs that we have,
it’s not gonna response to. If they’re extensively drug resistant, that’s even worse.
Now, look at those letters there.
I want you to be familiar with those if you’re gonna be a nurse and a professional practicing,
MDR TB just stands for multi-drug resistant TB and XDR TB just means extensively drug resistant TB.
So, in case you see those terms in your readings or you hear people discussing it, that’s what they mean.
Now, in active TB, your lungs can even develop like necrosis and these big deep cavities,
so, you gotta know, those aren’t doing what lungs are supposed to do
and it’s taken that kind of a hit from those mycobacterium.
So, make sure you’re very clear on the difference between latent TB and active TB.
Now, we’re hanging out today.
We’ve kind of talked through those
but it’d be a great time for you to pause the video, think through those lists
and make sure you’re very clear on the differences and the similarities between latent TB and active TB.