TB - clinical presentation and management*** Flashcards
What are the risk factors of getting a TB infection?
Non-UK born - Asia, africa
HIV
Immunosuppressed
Young-middle aged adults
What are the symptoms of TB?
Fever
Night sweats
Weight loss, anorexia
Tiredness
Cough
Haemoptysis
Breathlessness, pleural effusion
What investigations are done for a patient with TB?
Chest X ray
Sputum samples
Culture
Biopsy, histopathology
Tuberculin sensitivity test
Interferon gamma test
What is seen on a chest X-ray of a patient with TB?
Consolidation in upper parts of lungs
Cavitation within consolidation
Pleural effusion
What does consolidation on a chest X-ray look like?
White areas
What does cavitation on a chest X-ray look like?
Dark areas within white areas of consolidation
Why is consolidation seen on a chest X-ray of a patient with TB?
Fibrosis of lungs
takes over air spaces of lungs
Why is cavitation seen on a chest X-ray of a patient with TB?
Empty areas within lung
due to destruction of lung tissue
What part of the lung is most commonly affected by TB?
Upper parts of lungs
Why are the upper parts of the lungs most commonly affected by TB?
Because mycobacterium TB needs high levels of oxygen to grow and replicate
and the upper parts of the lungs are most oxygenated
What does pleural effusion on a chest X-ray look like?
White areas
What is done to sputum samples of a patient with TB?
Auramine staining, look at using a fluorescent microscope
Ziehl Neelsen stain, look at under microscope
What does TB look like with a Ziehl Neelsen stain under a microscope?
Pink elongated structures
If a patient with TB isn’t coughing up sputum, how is sputum obtained?
Induce sputum via exercise
Bronchoscopy
How is a sputum sample obtained from children with TB?
Children swallow sputum
so do gastric aspirate
What is seen in a sample of lung tissue under a microscope of a patient with TB?
Caseating granuloma
caseous necrosis in centre
surrounded by macrophages, Langhans giant cells, T cells
What is tuberculin?
Mycobacterium TB antigen
What is the tuberculin senstivity test?
Prick person’s skin with tuberculin
wait 2-3 days
measure induration, that’s the clear skin between the redness
What happens when tuberculin is injected into a person’s skin?
Inflammatory cells and immune cells accumulate there
skin becomes red
What are the disadvantages of using the tuberculin sensitivity test?
False positives
False negatives
Does not differetiate between primary infection, latent infection, post primary disease
What are the advantages of using the tuberculin sensitivity test?
Cheap
When might the tuberculin sensitivity test give a false positive? Why?
BCG vaccine
because T cells have seen antigen before
react to it
When might the tuberculin sensitivity test give a false negative? Why?
HIV
Immunosuppressed
insufficient T cells and other immune cells to mount a response
How is the interferon gamma test carried out?
Take blood from patient
add mycobacterium TB antigens to it
measure interferon gamma levels produced by T cells
