Tuberculosis Flashcards Preview

Respiratory (LECTURE NOTES) > Tuberculosis > Flashcards

Flashcards in Tuberculosis Deck (52):
1

What is TB

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

2

How is TB spread

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

3

How many people have the active disease

15-20 million

4

How many people have the latent disease

2 billion

5

What ethnic groups is TB highest in

Black African
Pakistani
Indian

6

What has caused the recent increase in notification rates

The patterns of immigration and increasing international travel

7

What other groups of people have a high incidence of TB

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

8

What type of TB do young people get

Newly acquired TB

9

What type of TB do older age groups get

Reactivation of latent infection

10

What are the two main patterns of the disease

Primary and post-primary

11

What is primary tuberculosis

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

12

How is primary tuberculosis acquired?

By inhalation of organisms from an infected individual

13

What appears on the CXR in primary tuberculosis

Ghon focus ( a peripheral area of consolidation)

14

What does healed primary focus appear as on a CXR

Calcified nodules

15

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

Middle

16

What might haematogenous spread of infection result in

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

17

Describe post-primary TB

The pattern of disease seen after the development of specific immunity

18

When would post-primary TB typically occur

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

19

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

The apices of the lungs

20

What are the most typical chest symptoms of TB

Persistent cough, sputum production and haemoptysis

21

What are the most typical systemic symptoms of TB

Fever, night sweats, anorexia and weight loss

22

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

Cavitating apical lesions

23

How should sputum samples be examined in the lab

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

24

What is the disadvantage of using the Ziehl-Neelsen method

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

25

What is the current standard treatment of TB

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

26

Why is rifampicin and isoniazid used for so long?

To eradicate bacilli that may be lying dormant

27

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

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

28

How is directly observed therapy sometimes achieved

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

29

What are the adverse effects of isoniazid

Hepatitis, neuropathy

30

What are the adverse effects of Rifampicin

Hepatitis, rashes, enzyme induction

31

What are the adverse effects of pyrazinamide

Hepatitis and rashes and elevated uric acid

32

What are the adverse effects of ethambutol

Optic neuritis

33

What are the adverse effects of ethambutol

Optic neuritis

34

What should be checked before commencing ethambutol

Visual acuity

35

What is latent TB

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

36

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

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

37

How is detection of latent infection carried out

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

38

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

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

39

How is the tuberculin solution injected in the Mantoux test

Intradermally

40

What indicates a positive result to the Mantoux test

Redness and induration at least 10mm in diameter

41

How is the Heaf test performed

With a spring loaded needled "gun"

42

How is the reaction of the Heaf test graded

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

43

What does a negative tuberculin test indicate

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

44

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

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

45

How long are sputum positive patients infectious for

Until they have completed 2 weeks of treatment

46

What does screening of contacts consist of

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

47

What reduces the risk of future activation of the latent disease

Chemoprophylaxis

48

What does chemoprophylaxis consist of?

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

49

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

there are a thousand times fewer bacteria than in active TB

50

Describe the screening process of immigrants for TB

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.

51

What is the BCG vaccination

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

52

How is the BCG vaccination given

Intradermal injection