Tuberculosis (summary)
Updates to Article Attributes
This is a basic article for medical students and other non-radiologists
Tuberculosis (TB) is a mycobacterial airborne infection that is typically asymptomatic in children but can reactivate in later life causing a destructive cavitating contagious pneumonia. Occasionally TB spreads through the bloodstream to infect the brain and other organs.
Reference article
This is a summary article; read more in our article on tuberculosis.
Summary
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epidemiology
According to the WHO 2023 report:
developing nations - adolescents and young adultsdeveloped nations - immigrants, homeless and HIV-infectedglobally TB causes more deaths than any other infectious disease
in 2022 it is estimated that 10.6 million became ill with TB
most cases were in SE Asia (46%), Africa (23%) and W Pacific (18%)
around 6.3% of cases occurred in people living with HIV
diagnosis and treatment was disrupted by the COVID pandemic
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presentation
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usually asymptomatic
may feel generally unwell or have a small pleural effusion
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non-specific systemic symptoms
malaise
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pulmonary symptoms
productive cough (mucopurulent or blood-stained)
shortness of breath
chest pain
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extrapulmonary symptoms
depends on location of disease
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pathology
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aerobic mycobacterium
Gram staining ineffective due to waxy coating
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primary infection
first exposure to M. tuberculosis
the lung infection may be occult or may be visible as an area of consolidation in the mid or lower zone (Ghon focus)
more commonly hilar and/or paratracheal lymphadenopathy are seen
most primary infections are asymptomatic and are contained remaining dormant (latent TB)
occasionally the host immune system does not contain the bacterium
leading, and this leads to progressive primary TB or haematogenous spread (miliary TB)
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post-primary TB is due to reactivation of infection when the immune system is impaired due to old age, immunosuppressive drugs, etc.
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dormant bacteria are no longer contained and multiply in the lungs causing:
a contagious destructive cavitating pneumonia
endobronchial spread within the lungs
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disseminated disease spreads through the blood
tuberculomas in brain, kidney, bone, etc
tuberculous meningitis
may follow primary or post-primary infection
poor prognosis
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TB in HIV-AIDS presents with a primary pattern
due to; immune compromise means that the body responds as if it is a first exposuremiliary disease is common
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investigation
chest X-ray
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sputum sample
Ziehl-Neelsen stain for acid-fast bacilli
culture for confirmation of diagnosis and sensitivity testing
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blood tests
interferon gamma release assay (IGRA)
GeneXpert nucleic acid amplification test and antibiotic sensitivity
HIV serology
brain MRI (miliary TB)
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lumbar puncture
investigation for TB meningitis
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treatment
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active TB
four-drug regimen of rifampicin, isoniazid, pyrazinamide and ethambutol (2 months)
continuation of rifampicin and isoniazid (4 months)
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latent TB
rifampicin and isoniazid (3 months)
OR isoniazid alone (9 months)
OR rifampicin alone (4 months)
multidrug-resistant TB is an increasing problem
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screening and prevention
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screening for latent TB
Mantoux test (tuberculin skin test)
interferon gamma release assay (IGRA)
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recommended for high-risk groups
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Radiographic features
Chest radiograph
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parenchymal consolidation
lymphadenopathy - most frequent manifestation
pleural effusion
Ghon complex (consolidation plus lymphadenopathy)
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patchy consolidation and cavitation (upper zones)
cavitationhealing results in fibrosis and calcification
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innumerable 1-3 mm diameter miliary nodules
uniform size and distribution throughout both lungs
thoracic spine infection may be apparent as bone destruction and paraspinal mass
CT chest
CT is far more sensitive and demonstrates lesion characteristics which are helpful in diagnosis:
central necrosis in lymph nodes
areas of consolidation which may be occult on CXR
effusions
cavitation
endobronchial spread (tree in bud opacities)
miliary nodules
signs of latent disease such as calcified granulomata and upper zone fibrocalcific disease
- +<p>According to the WHO 2023 report:</p>
-<li><p>developing nations - adolescents and young adults</p></li>-<li><p>developed nations - immigrants, homeless and HIV-infected</p></li>- +<li><p>in 2022 it is estimated that 10.6 million became ill with TB</p></li>
- +<li><p>most cases were in SE Asia (46%), Africa (23%) and W Pacific (18%)</p></li>
- +<li><p>around 6.3% of cases occurred in people living with HIV</p></li>
- +<li><p>diagnosis and treatment was disrupted by the COVID pandemic</p></li>
-<li><p>occasionally the host immune system does not contain the bacterium leading to progressive primary TB or haematogenous spread (miliary TB)</p></li>- +<li><p>occasionally the host immune system does not contain the bacterium, and this leads to progressive primary TB or haematogenous spread (miliary TB)</p></li>
-<p>TB in HIV-AIDS presents with a primary pattern due to immune compromise</p>- +<p>TB in HIV-AIDS presents with a primary pattern; immune compromise means that the body responds as if it is a first exposure</p>
-<li><p>patchy consolidation (upper zones)</p></li>-<li><p>cavitation</p></li>- +<li><p>patchy consolidation and cavitation (upper zones)</p></li>
-<li><p>spine infection</p></li>- +<li><p>thoracic spine infection may be apparent as bone destruction and paraspinal mass</p></li>