Tuberculosis: Diagnosis, Treatments & Latency

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Strep Throat: Cause, Symptoms & Treatments

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
Your next lesson will play in 10 seconds
  • 0:07 Mycobacterium tuberculosis
  • 1:57 Tuberculosis
  • 2:53 Latent and Active Tuberculosis
  • 5:02 Diagnosis and Treatment
  • 6:41 Lesson Summary
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Speed Speed

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

This lesson will discuss the disease known as tuberculosis. We will talk about mycobacterium tuberculosis, latent TB, TB disease, mycolic acid, and the symptoms, signs, and treatments used for this terrible disease.

Mycobacterium Tuberculosis

In 1986, the worst nuclear disaster in world history occurred at the Chernobyl nuclear power plant, in what is now the Ukraine. Dozens of people died as a direct result of this accident, and certainly thousands more were negatively affected for many years to come. In order to try and stem the flow of poisonous and radioactive material coming from the plant, a giant sarcophagus was built over the nuclear reactor.

In a similar way, your body also builds sarcophagi-like structures to entomb dangerous things such as bacteria. One type of bacterium your body tries to entomb is called Mycobacterium tuberculosis, and this is an acid-fast, aerobic bacterium responsible for causing a disease known as tuberculosis.

The reason this bacterium is called acid-fast is because a fatty acid in the cell wall of acid-fast bacteria, known as mycolic acid, gives these cells the ability to resist decolorization with acid alcohol in certain staining procedures that are used to identify this bacterium. In addition, this mycolic acid also makes these bacteria impermeable to a lot of stains, such as those used in the Gram stain.

You can basically think of the mycolic acid as a type of wax coating applied to the cell wall of Mycobacterium tuberculosis. If you were to take a little drop of olive oil and put it on a wax cookie sheet, the oil would slide right off. It wouldn't be absorbed. Likewise, many stains would slide right off of this bacterium in a very similar fashion.


As I mentioned, this bacterium causes a condition known as tuberculosis, or TB for short. This is a respiratory disease that may cause everything from a bloody cough to death. The fact that this is a respiratory disease, meaning it is associated with air, should make perfect sense.

I mentioned the fact that Mycobacterium tuberculosis is an aerobic bacterium, meaning it needs air to survive. Therefore, it follows that, as a general rule, this bacterium will probably be associated with something like the lungs, which obviously help you breathe in air.

If a person has an infection of tuberculosis and they cough or sneeze or even talk around you, they may spread this bacterium around. Once you inhale it, it will enter your lungs and, in 90% of cases, will thankfully not cause an active infection.

Latent and Active Tuberculosis

This means that it will cause a latent TB infection, or an infection by Mycobacterium tuberculosis that does not cause an individual to fall ill. The reason this occurs goes back to our introductory scenario. If tuberculosis-causing bacteria enter your lungs, they will be immediately attacked by cells called white blood cells.

These cells are important in something known as your immune system. This is basically the force that protects your body from infection and disease. As soon as these white blood cells, such as macrophages, see these bacteria in your lungs, they will surround these bacteria on all sides.

By doing so, your white blood cells will wall off, or entomb these bacteria within the immune system's equivalent of a sarcophagus. This sarcophagus is more technically called a granuloma and causes these bacteria to go latent. The nodule that forms in the lungs as a result of a granuloma is called a tubercle, and is obviously what gives this disease its name.

However, if a person's immune system is compromised due to something like an HIV infection, then these granulomas will be unable to form. This is equivalent to that sarcophagus never being built around the Chernobyl nuclear power plant. That means the radiation would be able to continue to leak out of it, causing serious disease.

Likewise, with no granuloma formation, the tuberculosis-causing bacteria will be able to multiply and spread about, causing the active form of tuberculosis to occur. We term this active form more technically and unsurprisingly as TB disease.

The disease-causing form of tuberculosis can cause signs, or objective identifiable things, such as:

  • A bloody cough
  • Fever and
  • Scarring of the lungs

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back
What teachers are saying about
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create an account