Tuberculosis Flashcards
(40 cards)
1
Q
Common areas for TB
A
- Asia
- Africa
- South America
- Eastern Europe
2
Q
Pathogenesis of TB
A
- Aerosol inhalation
- = Pulmonary infection
- Then spreads via blood
- Initial infection can be asymptomatic
- Can lie dormant for many years –> latent TB
- But can then reactivate (risk 10-15% of activation)
3
Q
How is latent TB identified?
A
- CXR
- Interferon gamma (Quantiferon test or T spot)
4
Q
What is QuantiFeron?
A
- Assess amount of interferon gamma released by T cells when they are exposed to proteins found on mycobacterium
- Pre-exposed cells release more interferon
5
Q
Key points about Quantiferon
A
- Does not differentiate between active and latent TB
- Not used to diagnose active TB
- Can be negative during infection (esp if immunosupressed)
6
Q
What is T spot test?
A
- Similar to Quantiferon
- But just T lymphocytes are isolated instead of testing whole blood
- If there is deficiency of lymphocytes quantiferon can be negative but T spot can be positive
7
Q
When is screening used for TB?
A
- Interferon gamma tests used in asymptomatic patients with these risk factors:
- Immigrants from high prevalence countries
- Healthcare workers
- HIV positive patients
- Patients starting immunosupression
8
Q
Treatment of latent TB
A
- 3 months of Rifampicin and Isoniazid OR
- 6 months of Rifampicin alone
9
Q
Risks of treatment of latent TB
A
- Need to balance risk of reactiviation with risk of hepatotoxicity
- Pts aged older than 35 at increased risk of hepatotoxicity
- Current guidelines advice not treating these pts for TB unless they have other RF eg healthcare worker or HIV
10
Q
Active TB symptoms
A
- Non-resolving cough
- Weight loss
- Drenching night sweats
- Unexplained peristent fever (low or high grade)
11
Q
Signs of TB
A
- Clubbing
- Cachexia
- Lymphadenopathy
- Hepato/splenomegaly
- Erythema nodosum
- Crepitations/bronchial breathing if lung changes
- Pericardial rub if involved
12
Q
Investigations for TB and findings
A
- CXR - mediastinal lymphadenopathy +/- cavitating pneumonia or pleural effusion
- CT chest - lymphadenopathy, nodes with central necrosis, can see lesions in viscera
- MRI head - leptomeningeal involvement
13
Q
Samples for TB - gold standard
A
- Culturing bacteria is current gold standard
- Treatment should be delayed if possible until samples taken
- Culture can take up to 6 weeks so therapy started after samples taken
14
Q
How can we culture pulmonary TB?
A
- Sputum culture
- Induced sputum - after nebuliser of 7% hypertonic saline
- Bronchoscopy +/- EBUS of pulmonary lymph nodes if sputum negative
Endobronchial US guided biopsy
15
Q
How to culture meningeal TB?
A
Lumbar puncture for TB culture and TB PCR
16
Q
How to sample lymph node TB?
A
- Core biopsy of lymph node
- Fine needle aspirate not enough
17
Q
Pericardial TB - how do we sample?
A
- Pericardiocentesis - but not often practical
18
Q
How to sample GI TB?
A
- Colonoscopy and bowel biopsy
- OR Ultrasound guided omentum biopsy
19
Q
Histology of TB
A
Caseating/necrotising granulomatous inflammation
20
Q
What can occur when starting treatment for TB?
A
- Paradoxical reaction - as bacteria die increase in inflammation can cause worsening symptoms
- If TB occurs in place that cannot tolerate swelling (eg meningeal, spinal, pericardial), steroids are given at start of treatment
21
Q
What should all patients with miliary TB have?
A
Lumbar puncture to exclude TB meningitis
22
Q
Symptoms og TB meningitis
A
- Subtle at first - slight personality change and headache
- Then more meningitic
- Finally comatose over several weeks
- More slower onset than viral/bacterial
23
Q
Findings of MRI and LP for TB meningitis
A
- MRI - leptomeningeal enhancement (brighter)
- LP - high protein, low glucose, lymphocytosis
24
Q
Why do we need to make sure TB meningitis is not present?
A
- Paradoxical reaction to therapy can be fatal
- Given steroids when starting treatment
- Treatment is also longer (12 months)
25
Complications of pericardial TB
* Effusion
* Tamponade
26
Signs of pericardial TB
* Pericardial rub
* Kussmauls sign (increase in JVP during inspiration, in normal - usually decreases)
27
Miliary TB on CXR
Widespread throughout patient
Also found in CNS, bone marrow, pericardium
28
What should all patients with miliary TB have?
* Neuroimaging - CT/MRI head +/- LP to exclude CNS involvement
* Treatment should never be delayed while awaiting biopsies too
* Therapy started as soon as it is determined whether or not there is CNS involvement
29
MDR and non-MDR resistant TB
* Consider in patients who have had incomplete TB treatment previouslt
* Usually seen in patients from abroad
* Treatment based on sensitivities - consultant led
* **Infection control is paramount** - negative pressure rooms, staff for PPE
30
Treatment for TB
2 months of:
* Rifampicin
* Isoniazid
* Pyrazinamide
* Ethambutol
(RIFATER drug when combined) + pyridoxine (Vitamin B)
Then 4 months of:
* Rifampicin
* Isoniazid
(RIFINAH when combined)
+ pyridoxine
31
Side effects of Rifampicin
* Urine/tears to turn orange
* Drug induced hepatitis
32
Side effects Isoniazid
* Peripheral neuropathy
* Colour blindness
* Drug induced hepatitis
33
Side effects Ethambutol
* Optic neuropathy/reduced visual acuity
34
Side effects of pyrazinamide
Drug induced hepatitis (biggest risk)
35
Moniting before and during treatment of TB
* Before - LFTs and visual acuity baseline (if using ethambutol)
* During - LFT monitoring
36
What to do if LFTs derange during treatment for TB?
* Stop treatment and then gradually reintroduce once normalised
* OR can use a liver friendly regime but treatment duration is longer (24 months)
* Liver friendly - Amikacin, Levofloxacin, Ethambutol
37
Contact tracing fot TB
* Once patient diagnosed --> refer to TB nurse
* They will perform contact traving and wil test household conatcs with CXR or Quantiferon test and will treat latent TB
* If household conacts were going to catch TB it would be before pt was admitted so visitors are allowed - unless pt has resistant TB
38
Infection control for TB - rooms and discharge
* Side room if non resistant TB
* After 2 weeks of treatment - considered non-infectious to immunocompetent individuals
* If ward manages immunosupressed patients - pts need to be in side room until discharge (regardless of smear-ve/+ve)
* Smear positive patients can still be discharged but need to quarantine at home until 2 weeks of treatment is complete
39
Infection control - PPE
* Staff do not need to wear masks/aprons unless MDR TB is suspected or they are performing aerosol generating procedure
* Patients with smear +ve TB do need to wear a mask when leaving their room until they have completed 2 weeks of treatmet
40
