Tuberculosis

Question 1

What is TB

Answer 1

An infection caused by Mycobacterium tuberculosis that may affect any part of the body but most commonly affects the lungs

Question 2

How is TB spread

Answer 2

By a person inhaling the bacterium in droplets coughed or exhaled by someone with infectious TB

Question 3

How many people have the active disease

Answer 3

15-20 million

Question 4

How many people have the latent disease

Answer 4

2 billion

Question 5

What ethnic groups is TB highest in

Answer 5

Black African
Pakistani
Indian

Question 6

What has caused the recent increase in notification rates

Answer 6

The patterns of immigration and increasing international travel

Question 7

What other groups of people have a high incidence of TB

Answer 7

Alcoholics, homeless, those misusing drugs, those coinfected with HIV

Question 8

What type of TB do young people get

Answer 8

Newly acquired TB

Question 9

What type of TB do older age groups get

Answer 9

Reactivation of latent infection

Question 10

What are the two main patterns of the disease

Answer 10

Primary and post-primary

Question 11

What is primary tuberculosis

Answer 11

The pattern of disease seen with first infection in a person (often a child) without specific immunity to TB

Question 12

How is primary tuberculosis acquired?

Answer 12

By inhalation of organisms from an infected individual

Question 13

What appears on the CXR in primary tuberculosis

Answer 13

Ghon focus ( a peripheral area of consolidation)

Question 14

What does healed primary focus appear as on a CXR

Answer 14

Calcified nodules

Question 15

Bronchiectasis in which lobe is a very typical outcome of hilar node involvement by TB in childhood

Answer 15

Middle

Question 16

What might haematogenous spread of infection result in

Answer 16

Early generalisation of disease that may cause miliary TB and the lethal complication of tuberculosis meningitis

Question 17

Describe post-primary TB

Answer 17

The pattern of disease seen after the development of specific immunity

Question 18

When would post-primary TB typically occur

Answer 18

Following direct progression of the initial infection or result from endogenous reactivation of infection or from exogenous reinfection in a patient who has had previous contact with the orgnaism and has developed a degree of specific immunity

Question 19

Where is the most common pulmonary site of infection for post-primary TB

Answer 19

The apices of the lungs

Question 20

What are the most typical chest symptoms of TB

Answer 20

Persistent cough, sputum production and haemoptysis

Question 21

What are the most typical systemic symptoms of TB

Answer 21

Fever, night sweats, anorexia and weight loss

Question 22

What is the most common appearance of TB on a chest xray

Answer 22

Cavitating apical lesions

Question 23

How should sputum samples be examined in the lab

Answer 23

By the Ziehl-Neelsen method looking for AAFB that appear as red rods on a blue background

Question 24

What is the disadvantage of using the Ziehl-Neelsen method

Answer 24

It takes a long time for the laboratory tests to come back

Question 25

What is the current standard treatment of TB

Answer 25

6 months of rifampicin and isoniazid supplemented by purazinamide and ethambutol for the first 2 months

Question 26

Why is rifampicin and isoniazid used for so long?

Answer 26

To eradicate bacilli that may be lying dormant

Question 27

What should be instituted for patients who have difficulty complying with TB treatment

Answer 27

Directly observed therapy - observed to ensure that he or she swallows the medication

Question 28

How is directly observed therapy sometimes achieved

Answer 28

By giving high doses of the anti-TB medication three times per week with the patient attending a hospital or GP clinic to be given the medication under the supervision of a doctor or a nurse

Question 29

What are the adverse effects of isoniazid

Answer 29

Hepatitis, neuropathy

Question 30

What are the adverse effects of Rifampicin

Answer 30

Hepatitis, rashes, enzyme induction

Question 31

What are the adverse effects of pyrazinamide

Answer 31

Hepatitis and rashes and elevated uric acid

Question 32

What are the adverse effects of ethambutol

Answer 32

Optic neuritis

Question 33

What are the adverse effects of ethambutol

Answer 33

Optic neuritis

Question 34

What should be checked before commencing ethambutol

Answer 34

Visual acuity

Question 35

What is latent TB

Answer 35

The situation where a person has been infected with Mycobacterium tuberculosis at some time but does not currently have the active disease

Question 36

What are the factors that increase the risk of reactivation of TB

Answer 36

``` Aging Alcohol misuse poor nutrition coinfection with HIV use of immunosuppressive drugs ```

Question 37

How is detection of latent infection carried out

Answer 37

Demonstrating an immune response to Mycobacterium tuberculosis using a tubercilin test or an interferon gamma based blood test

Question 38

What type of hypersensitivity response occurs during the tuberculin testing and what can be seen

Answer 38

Type 4 cell mediated - results in a raised area of induration and reddening of the skin

Question 39

How is the tuberculin solution injected in the Mantoux test

Answer 39

Intradermally

Question 40

What indicates a positive result to the Mantoux test

Answer 40

Redness and induration at least 10mm in diameter

Question 41

How is the Heaf test performed

Answer 41

With a spring loaded needled "gun"

Question 42

How is the reaction of the Heaf test graded

Answer 42

From 1- 4 according to the formation of papules and the extent of induration

Question 43

What does a negative tuberculin test indicate

Answer 43

BCG is recommended as it makes active TB unlikely and therefore there would be a lack of immunity

Question 44

What is the most useful and more specific diagnosis of a latent TB infection

Answer 44

Interferon Gamma blood tests but they should not be used as a routine diagnostic tool for active TB

Question 45

How long are sputum positive patients infectious for

Answer 45

Until they have completed 2 weeks of treatment

Question 46

What does screening of contacts consist of

Answer 46

Checking for symtpoms Chest Xray tuberculin testing interferon-gamma test and assessment of BCG status

Question 47

What reduces the risk of future activation of the latent disease

Answer 47

Chemoprophylaxis

Question 48

What does chemoprophylaxis consist of?

Answer 48

6 months with isoniazid alone or for 3 months with isoniazid and rifampicin

Question 49

Why are only 1 or 2 drugs used in the treatment of latent TB and 4 in active TB

Answer 49

there are a thousand times fewer bacteria than in active TB

Question 50

Describe the screening process of immigrants for TB

Answer 50

For immigrants from areas with a high prevalence of TB (africa, indian subcontinent ) should be screened for TB on arrival in a country of low prevalence sucha s the UK Adults have CXR and children have a tuberculin test.

Question 51

What is the BCG vaccination

Answer 51

A live attenuated strain of TB that provides about 75% protection against TB for about 15 years

Question 52

How is the BCG vaccination given

Answer 52

Intradermal injection