Tuberculosis COPY Flashcards
1
Q
Why was there a decline in TB incidence pre 1980s?
A
There was advancements in housing, better diets and hygiene.
2
Q
Where in the UK is TB a major problem?
A
- West Midlands
- London
3
Q
What bacteria is responsible for TB?
A
Mycobacteria
4
Q
Where do mycobacterium live?
A
In soil and water
5
Q
What species of mycobacterium are responsible for TB?
A
- Mycobacterium tuberculosis
- Mycobacterium bovis
6
Q
What species of mycobacterium is responsible for leprosy?
A
Mycobacterium leprae
7
Q
What other species of mycobacterium are there?
A
- M. avium-intracellulare
- M. kansasii
- M. maimonese
- M. xenopii
8
Q
What kind of disease is TB?
A
Very slow grow growing, progressive disease that requires long treatment
9
Q
What kind of bacteria is mycobacterium?
A
- Non-motile bacillus
- Aerobic
10
Q
Where does mycobacterium have a predilection for?
A
Apices of the lungs
11
Q
Describe the structure of mycobacteria.
A
- Very thick cell wall
- Contains lipids, peptidoglycans and arabinomannans
12
Q
What is mycobacteria resistant to?
A
- Acids, alkalis and detergents
- Neutrophil and macrophage destruction
13
Q
What test is used to identify mycobacteria?
A
Acid and alcohol fast bacilli using a ZN stain
14
Q
What is the source of transmission of mycobacteria?
A
- Respiratory droplets evaporate
- Droplet nuclei contain mycobacteria
- Droplets remain airborne for very long periods
15
Q
How are outdoor mycobacteria eliminated?
A
By UV radiation and infinite dilution
16
Q
What happens when mycobacteria droplets are inhaled?
A
- Larger droplet nuclei impact on large airways and are cleared
- Small droplet nuclei organisms impact in alveoli and slowly proliferate.
17
Q
How is TB contracted through mycobacterium bovis?
A
- Consumption of infected cows milk
- Deposited in cervical and intestinal lymph nodes
18
Q
How do activated macrophages cause necrosis?
A
- Activated macrophages can kill off TB organisms but at the same time they release enzymes and free radicals which cause tissue damage
- Acculmulation of macrophages, epithelioid and Langhan’s cells cause granulomas
- Central caseating necrosis which may later calcify
19
Q
What mediates the immunological response?
A
Th1 cells
20
Q
What does the Th1 mediated immunological response lead to?
A
- Elimination/ reduction in number of invading mycobacteria
- Tissue destruction as a consequence of activation of macrophages
21
Q
What factors affect susceptibility?
A
- Genetics
- Race
- Nutrition
- Age
- Immunosuppression
22
Q
What affects outcome of infection?
A
- Virulence
- Number of organisms
23
Q
How might a resistant host become a susceptible host?
A
With age
24
Q
How might a susceptible host become a resistant host?
A
With a better diet
25
Who is usually affected by primary infection?
Usually children with infected focus in alveolus
26
How is mycobacteria spread in the body?
- Spread via the lymphatics to draining hilar lymph nodes.
| - Haematogenous seeding of mycobacter to all organs of the body
27
What are the symptoms of primary infection TB?
- Usually no symptoms
- Can be fever
- Malaise
- Erythema nodosum
- Rarely chest signs
28
What occurs in most people with primary infection?
- Initial lesion and local lymph node creating primary comlex
- Heals with or without scar which may calcify creating Ghon focus
29
What is primary infection associated with?
Development of immunity to tuberculoprotein
30
What does intra-dermal administration of tuberculoprotein result in?
Lymphocytic and macrophage based area of inflammation after 48 hrs
31
What are the 3 outcomes of primary infection?
- Progressive disease
- Contained latent
- Cleared and cures
32
How can a primary infection progress?
- Primary focus continues to enlarge and forms a cavity
- Enlarged hilar lymph compress bronchi causing lobar collapse
- Enlarged lymph node discharges into the bronchus causing tuberculous pneumonia
33
What occurs in some individuals 6-12 months after infection?
- Miliary TB fine mottling on X-ray, wide-spread granuloma
- Meningeal TB, severe, CSF high protein, lymphocytes
- tuberculosis pleural effusion
34
What are 2 mechanisms of post primary disease?
- Reactivation of mycobacterium from latent primary infection disseminated by the blood stream around the body
- New re-infection from outside source, susceptible previously infected host
35
What tissues can TB affect?
Just about any
36
When may post primary pulmonary tuberculosis occur?
At any age but there may be no symptoms for many months
37
What are the respiratory symptoms of post primary pulmonary tuberculosis?
- Cough
- Sputum
- Haemoptysis
- Pleuritic pain
- Breathlessness
38
What are the systemic symptoms of post primary pulmonary tuberculosis?
- Malaise
- Fever
- Weight loss
- Night sweats
39
Past medical history of post primary pulmonary TB.
- Diabetes
- Immunosuppressive diseases
- Previous TB
40
Drug history of post primary pulmonary TB.
Immunosuppressive drugs
41
Personal/social history of post primary pulmonary TB.
- Alcohol
- IDVA
- Poor social circumstances
- Immigrants from high incidence areas
42
What are the signs of post primary pulmonary TB?
- May be none
- Advanced: crackles, bronchial breathing
- Finger clubbing very rare unless in chronic infection
43
Who is included in high index of suspicion?
- Immunosuppressed
- Malnourished
- Alcoholics
- Vagrants
- Previous gastric surgery
- Malignancy
- Diabetes mellitus
- Adolescents, elderly
- Recent migrants from high prevalence countries
44
What essential investigations are there?
- Sputum sample
| - Chest X-ray
45
How is sputum sampling carried out?
- 3 sputum samples on successive days
- Sputum smear- ZN stain- immediate answer if AAFB
- Sputum culture which can take 8 weeks
46
What might be observed on a chest x-ray?
- Patchy shadowing, often apices/upper zones or apex of lower lobe
- Cavitation if advanced
- May calcify if chronic or healed TB
47
What further investigations can be carried out if the sputum samples are negative?
- CT scan of thorax
- Bronchoscopy with bronchoalveolar lavage, transbronchial biopsy
- Pleural aspiration and biopsy if pleural effsuion
48
What was the treatment of TB up until 1950?
- Fresh air
- Sunshine
- Bed rest
- Good food
- Improving immunity
- Vitamin D and cathelecidin
49
What surgery was used to treat TB?
- Collapse down the cavity
- Anaerobic conditions- phrenic crush
- Artificial pneumothorax
- Pneumoperitoneum
- Thoracplasty
- Lung resection
50
What are the rules for modern treatment of TB?
- Multiple drug therapy is essential
- Single agent treatment leads to drug resistance organisms with 14 days
- Therapy must continue for at least 6 months
- TB therapy is a job for committed specialists only
- Legal requirement to notify all cases
- Low threshold for HIV testing, AIDS defining condition
51
What drugs are patients on for 2 months?
- Rifampicin
- Isoniazid
- Ethambutol
- Pyrazinamide
52
What drugs are patients on for 4 months?
- Rifampicin
| - Isoniazid
53
When is TB rendered non-infectious?
After 2 weeks
54
What are the side effects of rifampicin?
- Orange urine
- Tears
- Induces liver enzymes which alter metabolism of prednisolone and anticonvulsants
- OCP ineffective
- Hepatitis
55
What are the side effects of isoniazid?
- Hepatitis
| - Peripheral neuropathy
56
What are the side effects of ethambutol?
Optic neuropathy
57
What are the side effects of pyrazinamide?
Gout
58
What does likelihood of infection with TB depend on?
- Duration of contact
| - Intensity of infection
59
Who should be screened first?
Close household contacts
60
If the close contacts have been infected who should be screened?
Casual contacts
61
What are the tuberculin tests?
- Mantoux
| - Heaf
62
Who should have no immunity to tuberculoprotein?
-Younger than 16 with NO BCG
63
What should be carried out if there is a positive heaf test?
Chest x-ray
64
If the chest x-ray is normal what should be done?
Chemoprophylaxis to kill mycobacteria
65
If the chest x-ray is abnormal what be done?
Treat as TB
66
If the heaf test is negative, what should be done?
- Repeat test after 6 weeks
- If 2nd test negative= BCG
- If 2nd test positive= recent infection
67
If someone is over 16 and has a BCG then how should they be screened?
- Chest x-ray
- Normal= reassure and discharge
- Abnormal= investigate and treat
