Hello and welcome to the zero to finals podcast. My name is Tom and in this episode I'm going to be

talking to you about tuberculosis or TB. And if you want to follow along with written notes on this

topic, you can follow along at zero definals.com in the infectious diseases section or in the

zero to finals medicine book.

So let's get straight into it.

Tuberculosis or TB is an infectious disease that's caused by the mycobacterium tuberculosis bacteria.

And this is a small rod-shaped bacteria, which we call a bacillus, because it's rod-shaped.

And it has a waxy coating that makes gram staining ineffective.

So if you try and do a gram stain on a tuberculosis bacteria, it won't show up.

Because they're resistant to the acids that are used in the staining process, because of this

waxy coating. And this property of being resistant to the acids is called acid fastness.

Therefore, the TB bacteria are often described as acid-fast bacilli. They require a special

staining technique, which uses something called a Zal Nielsen stain

and this turns the bacteria bright red against a blue background. So a quick Tom tip straight

away, a common exam question involves a patient coughing up sputum that grows acid fast bas bacilli that stain red with the Zahilinilson staining.

And remember these key words because this is a description of tuberculosis in your exams.

TB is more prevalent in non-UK-born patients, for example from South Asia,

and those people who are immunocompromised, for example,

HIV. And of course, you're more at risk if you have close contacts with TB, so taking a family

and a social history to see where the patient lives and whether they have any unwell contact

is very important.

Multi-drug-resistant TB, or MDR-TB, are strains that are resistant to more than one anti-tB drug, and this makes them very difficult to treat.

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