TB Flashcards
TB microbiology
a) features of mycobacterium TB
b) form what histological feature?
c) microbiological tests done and culture medium used
d) transmission
e) prevalence of latent TB, prevalence of clinical infection
a) Aerobic, non-motile, non-sporing, slightly curved rods
b) Granulomata (caseating)*
- Caseating: TB, RA
- Non-caseating: Crohn’s, sarcoid
c) Acid-fast bacilli (Ziehl-Nielsen stain) from samples (eg. sputum, urine, LN biopsy)
- Culture medium: Löwenstein–Jensen
d) Aerosol
e) 1/3 world pop (95% do not show disease)
TB: risk factors
- Close contact of TB-infected person
- Born in high prevalence area (eg. South Asia, Sub-Saharan Africa)
- IVDU, homeless, alcoholics, prisoners
- Immunosuppressed, especially HIV+
- Butchers/abattoir workers at risk of m. bovis and abdominal TB
Pulmonary TB
a) Primary granulomatous lesion is called the…?
b) Most common site (+ differentials)
c) Large granulomas form a…?
d) Other CXR features
e) Pulmonary symptoms
f) Systemic symptoms
a) Ghon focus
b) Apex of lung (as there is more air and less blood supply)
- Sarcoidosis (usually peri-hilar), histiocytosis, apical lung tumour (Pancoast)
c) Cavity
d) - Mediastinal/hilar lymphadenopathy (when combined with a primary focus, called a Ghon complex)
- Consolidation, collapse
- Pleural effusion, pericardial effusion
e) (productive) Cough > 3/52, Chest pain, SOB, Haemoptysis
f) Weight loss, Anorexia, Fever, Night sweats, Malaise
If TB is not contained within a cavity and successfully treated can lead to haematogenous spread:
a) Within lung
b) Systemic (features of each)
c) In vertebrae - ?
a) Miliary TB
b) - Pleural (pleuritis)
- Meningitis (headache, vomiting, altered mentation; LP - low glucose, raised protein, monocytosis)
- Bone and joints (pain or swelling of joint, Potts disease with spinal cord lesion)
- Genito-urinary (epididymitis, frequency, dysuria and haematuria)
- Abdominal (ascites, abdominal lymph nodes, ileal malabsorption)
- Lymph nodes (swelling, pain)
- Skin (erythema nodosum, erythema induratum)
c) Potts disease
Diagnosing TB.
a) Pulmonary
b) Non-pulmonary TB
c) Latent TB
d) Other investigations to perform
a) 3x sputum samples for MC+S:
- Microbiology ZN + culture; Histopathology caseating granulomata + ZN, CXR for lesions
- Note: if spontaneous samples not possible, do bronchoscopy and lavage
b) Any specific site affected (Urine, CSF, Pleural fluid, Biopsy specimen
c) Tuberculin skin test - ‘Mantoux’ or IGRA
d) - Bloods: HIV, hepatitis B and hepatitis C
- Imaging: CXR
Managing active TB.
a) Non-drug
b) Normal drug regime
c) Drug regime if CNS affected
d) Also, must notify…?
e) Ensuring good compliance
a) - Suspected TB in hospital - manage in side room until proven non-infectious
- Managed by TB specialists
- Notify PHE
- Protect immunocompromised contacts
b) 6 months R and I, 2 months P and E
c) 12 months R and I, 2 months P and E
d) Public Health England
e) Community TB nursing team, ‘directly observed therapy’ (DOT)
Anti-TB therapy: (MoA and SEs)
a) Rifampicin
b) Isoniazid
c) Pyrazinamide
d) Ethambutol
e) In patients on isoniazid at risk of neuropathy (eg. DM, HIV, pregnant), what prophylactic treatment may be given?
f) 2 reasons why anti-TB therapy may be stopped/changed
g) Example second-line therapies
a) Bacteriocidal, blocks protein synthesis.
- SE: red secretions, hepatitis, cytochrome P450 induction (affects: COCP, steroids, warfarin)
b) Bacteriocidal, blocks cell wall synthesis.
- SE: hepatitis, neuropathy
c) Bacteriocidal.
- SE: hepatitis, arthralgia/gout, rash
d) Bacteriostatic.
- SE: optic neuritis
e) Pyridoxine
f) - Liver toxicity (particularly associated with rifampicin)
- Optic neuritis and vision loss - stop ethambutol straight away and vision should recover
g) - Amikacin*, capreomycin, cycloserine
- Macrolides (azithromycin, clarithromycin)
- Quinolones (moxifloxacin, levofloxacin)
*note: streptomycin is no longer licensed for TB
Drug resistance
a) Single drug - most common
b) MDR - define
c) XDR - define
d) Risk factors for drug resistance
a) Single agent, Isoniazid = 7% in UK
b) Rifampicin + Isoniazid resistance = 1%
c) R + I + quinolones
d) Previous treatment, high risk area, contact of resistant TB, poor response to therapy
TB prevention
Active case finding – reduce infectivity
Detection and treatment of latent TB
Community TB nursing team using Mantoux
Vaccination:
- Neonatal BCG in high-risk groups
Any chronic illness with fever and weight loss
especially if from endemic country
‘Think TB!’
Latent TB.
a) Tests used
b) How is active TB excluded?
c) Who should receive treatment
d) What is the treatment regimen if indicated?
a) - Mantoux test
- IGRA
b) CXR and examination
c) Anyone < 35, or HIV+, or healthcare workers who are:
- Mantoux positive (6 mm +) without BCG vaccine, or;
- Strongly Mantoux positive (15 mm +) and IGRA positive (even if BCG vaccinated)
d) - 3 months of rifampicin and isoniazid, or
- 6 months of isoniazid monotherapy
