Tuberculosis Flashcards
Describe the global distribution of tuberculosis and its impact on tuberculosis in the UK.
- The disease burden from
- High prevalence countries (India, China, Indonesia, Philippines, Africa)
- 70% are non UK born, aged 15-44
- London is a risk factor (39% of TB cases in UK)
TB globally is falling.
- TB is the number one killer of communicable diseases
- TB is the leading killer of people with HIV
- Kills more than HIV and malaria together.
Describe the histopathology of tuberculosis.
- Granulomatous inflammation
at risk
- HIV positive, immunosuppressed
- Elderly, neonates, diabetics
outline the pathogenesis of tuberculosis in its primary, post- primary and fibrocaseous forms in the lung.
- M. tuberculosis, M.africanum, M. bovis (bovine TB, BCG strain)
“Infection - inhalation of droplet nuclei.
M. tuberculosis is deposited in alveoli & engulfed by alveolar macrophages.
Proliferating bacilli kill macrophages & are released.
”
describe mycobacteria tuberculosis.
- Non-motile bacillus, very slowly growing (disease is slow, the treatment is long)
- Aerobic (has a predilection for apices of lungs)
- Uniquely has a very thick fatty cell wall (Resistant to acids, alkalis and detergents
neutrophil and macrophage destruction)
what do Th1 cells do in response to M. Tb, and what does this cause?
Th1 cells & macrophages form a granuloma to prevent further growth - latent TB
-Eliminates the number of invading mycobacteria but causes tissue destruction because of the activation of macrophages
Describe the pathogenesis of tuberculosis in its primary, post- primary form.
- No preceding exposure or immunity
- Progressive or latent or cleared.
- Mycobacteria is spread via lymphatics and drains to hilar lymph nodes
In the majority (>85%)
Initial lesion + local lymph node (Primary complex)
Heals with or without scar. May calcify (Ghon focus + complex)
Associated with development of immunity to tuberculoprotein
- Primary infection progresses to Tuberculous bronchopneumonia
- Primary focus continues to enlarge - cavitation
- Enlarged hilar lymph compress bronchi, lobar collapse
- Enlarged lymph node discharges into bronchus
- Poor prognosis
- In a small number (1-3%)
- Miliary TB (looked like millet seeds on autopsy) develops, with hematogenous spread of bacteria to multiple organs
- Fine mottling on X-ray, widespread small granulomata
- CNS TB in 10-30%
hypotheses behind post-primary disease
- TB entering a dormant stage with low or no replication over prolonged periods of time
- Balanced state of replication and destruction by immune mechanisms
Describe the common clinical presentations of tuberculosis.
Usually presents with no symptoms
- Cough
- Fever
- Sweats (mainly at night)
- Weight loss
- malaise
Describe the public health duties of doctors managing cases of Tuberculosis.
- CXR should be obtained
- 3 sputum samples
- nucleic acid amplification test (NAAT) should be performed on at least one respiratory specimen.
Define the major groups of antituberculous drugs, their pharmacological profiles and side effects, and their practical application in the management of tuberculosis.
- Isoniazid (H)
- Pyrazinamide (z)
- Rifampicin ( R)
- Ethambutol (E)
- R and H for the entire 6 months
- -E and z for the first two months
side effects of isoniazid
- Hepatitis
- Peripheral neuropathy
side effects of pyrazinamide
- hepatitis
side effects of rifampicin
- orange pee
- hepatitis
how can active tb occur
-progression of primary disease or reactivation of latent disease
