Tuberculosis Flashcards

(39 cards)

1
Q

What happens in primary TB?

A

1st encounter
Host macrophages in the lung engulf the organisms + carry them to hilar lymph nodes in an attempt to control infection.
Small granulomas (tubercles) are formed around the body to contain the mycobacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the outcome of primary TB?

A

80% heal spontaneously + bacteria are eliminated
20%: bacteria encapsulated in a defensive barrier but persist in an otherwise healthy individual where disease is dormant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is secondary TB? What is it usually precipitated by? Where does it usually occur?

A

Reactivation of semi-dormant TB
Precipitated by impaired immune function: malnutrition, AIDS or immunosuppressive therapy.
Occurs in lung apices

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

List 7 risk factors for TB

A

Close contact with TB patient
Ethnic minority groups (sub-saharan Africa + S. Asia)
Homeless, alcohol dependent, drug misusers
HIV+, immunosuppressed
Elderly
Co-morbidities
Children

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How do primary and secondary tuberculosis patients present?

A

1: usually asymptomatic.
2: variable + nonspecific

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

List 8 general symptoms a patient with TB may complain of

A
Fatigue
Malaise
Fever
Weight loss
Anorexia
Night sweats
Clubbing
Erythema nodosum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What pulmonary symptoms occur in TB?

A

Chronic, productive cough/ Haemoptysis

Purulent ± bloodstained sputum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What genitourinary, musculoskeletal, CNS, and GI symptoms may arise from caseous tubercles spreading in miliary TB?

A

GU: Sterile pyuria, Infertility
MSK: pain, arthritis, osteomyelitis, Pott’s disease, spinal cord comp. + abscess formation
CNS: meningitis + tuberculomas: headaches, vomiting
GI: Subacute obstruction, COBH, Weight loss, Peritonitis, Ascites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is TB?

A

Granulomatous disease caused by Mycobacterium tuberculosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the 3 subtypes of TB?

A

Primary: initial infection; pulmonary or GI (rare)
Post-primary: Reinfection/ reactvation
Miliary: Haematogenous dissemination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Give 4 features of Mycobacterium Tuberculosis

A

Intracellular organism
Acid fast bacilli
Survives after being phagocytosed by macrophages
Aerobe: prefers upper lung lobes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the epidemiology of TB

A

Annual mortality = 1.5 million (95% in developing countries)
Annual UK incidence = 8000
Asian immigrants = highest risk group in UK

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

List 6 signs and symptoms in primary TB

A
Mostly ASYMPTOMATIC
Fever  
Malaise  
Cough  
Wheeze  
Erythema nodosum 
Phlyctenular conjunctivitis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

List 7 symptoms in post-primary TB

A
Fever/ night sweats  
Malaise  
Weight loss  
SOB 
Cough with purulent, blood streaked sputum  
Pleuritic chest pain  
Clubbing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

List 6 signs and symptoms in miliary TB

A
Fever  
Weight loss  
Cough
SOB
Meningitis
Yellow caseous tubercles spread to other organs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What investigations should be performed for TB?

A
Sputum/ Pleural Fluid MC+S 
CXR
Raised WCC + Anaemia
HIV Testing 
CT, lymph nodes, pleural biopsy, sampling of other affected systems
17
Q

What is seen on CXR in primary TB?

A

Peripheral consolidation

Hilar lymphadenopathy

18
Q

What is seen on CXR in post-primary TB?

A
Upper lobe shadowing  
Streaky fibrosis + cavitation  
Calcification  
Pleural effusion 
Hilar lymphadenopathy
19
Q

What is seen on CXR in miliary TB?

A

Fine shadowing

Nodular

20
Q

What group of antibiotics are used to treat TB?

A

Rifampicin (6months)
Isoniside (6months)
Pyrazinamide (2months)
Ethambutol (2months)

21
Q

What is extra pulmonary TB? In which patients does this most commonly occur?

A

TB involving organs other than the lungs

Immunocomprimised

22
Q

What lymph, dermatological, CVS and adrenal signs and symptoms may arise from caseous tubercles spreading in miliary TB?

A

Lymphadenopathy
Skin: lupus vulgaris
Heart: pericardial effusion, constrictive pericarditis
Adrenals: Addisons

23
Q

How does primary TB present?

A

Mostly asymptomatic

May have vague flu like symptoms

24
Q

What is the gold standard investigation for TB? What is the issue of relying on this?

A

Sputum culture + Ziehl-Nielsen staining

Culturing TB takes a long time (~ 6 weeks)

25
When are IGRAs useful? What occurs?
Useful in latent TB (high specificity) Negative in BCG vaccine Exposure of host T cells to TB antigens leads to release of interferon
26
Why is IGRA testing preferred to TSTs?
Single patient visit | BCG does NOT give false positive
27
What are the 2 forms of testing for TB?
Tuberculin Tests: Mantoux test +Heaf Test | Interferon Gamma Tests (IGRA)
28
How should cultures be taken in suspected TB?
Sputum acid-fast bacilli smear (3 samples 8 hours apart, with 1 being in early morning)
29
What is shown by tuberculin skin tests?
Positive if previous exposure to TB or BCG | Negative TST doesn't rule out TB
30
What is the Mantoux test? What does it identify?
Erythema after 72hrs of PPD injection suggests patient has previously been exposed to TB. Identifies those exposed to TB DOES NOT distinguish between active + latent TB.
31
What is the Heaf test? How is it interpreted?
PPD on forearm. Graded according to papule size + vesiculation (ring-shaped induration)
32
What is the limitation of the IGRA test?
Does not differentiate between latent + active TB
33
What is a Gohn focus?
Granuloma in which central tissue has died due to caseous necrosis Sequela of primary TB infection
34
What is a Ghon complex comprised of? What may this progress to if calcified?
Ghon focus + ipsilateral mediastinal lymphadenopathy | Ranke complex
35
What is a Ranke complex?
a Ghon lesion that has undergone calcification + an ipsilateral calcified mediastinal node
36
Which anti-TB antibiotic causes optic neuritis? How may this present?
Ethambutol | Loss of colour vision + visual acuity
37
Which anti-TB antibiotic is an enzyme inducer? Thus what drugs need to be considered?
Rifampicin | OCP
38
Which anti-TB antibiotic causes peripheral neuropathy?
Isoniazid
39
Which anti-TB antibiotics are hepatotoxic?
Rifampicin Isoniazid Pyrazinamide