Tuberculosis Flashcards
What are the symptoms of primary infection TB?
Usually asymptomatic
Cough, fever, erythema nodosum, malaise , rarely chest pain
in primary TB, where are most of the infections focused?
80% of infections are focused in the alveoli, lymph nodes and gut.
Describe briefly what the primary infection TB can be like in a minority of patients.
In a minority of patients (1%) the primary focus doesnt heal and continues to enlarge causing cavitation.
The enlargement of the hilar lymph nodes compresses the bronchi causes a lobar collapse.
The hilar lymph nodes may discharge into the bronchi.
It may also develop into TB bronchopneumonia which has a poor prognosis.
6 months after infection some may develop Millard TB, meninges TB or TB pleural effusion.
Describe what Millard TB presents like.
Millard TB presents with fine mottling on X ray. Shows wide spread small granulomatous and pleural effusion.
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What are the symptoms of post primary infection TB?
Cough with sputum Haemoptysis Pleuritic chest pain Breathlessness Fever, malaise, might sweats, weight loss
What are the clinical signs of post infection TB?
Usually present with no signs.
Signs may be crackles and bronchial breathing. Clubbing is rare but only in severe disease.
What is the treatment for TB?
4 drugs for 2 months then 2 drugs for 4 months. Total of 6 month treatment
Rifampicin, isoniazid, ethambutol and pyrazinamide for 2 months
Rifampicin and isoniazid for 4 months
What are the side effects of the TB treatment?
Rifampicin - orange ‘iron bru’ tears, urine and stains contact lenses. Hepatitis. Induces liver enzymes so makes certain drugs ineffective such as prednisolone, anti-convulsants and contraceptive pill.
Isoniazid - hepatitis and peripheral neuropathy
Ethambutol - optic neuropathy
Pyrazinamide - gout
what species make up the mycobacterium tuberculosis complex?
M. Tuberculosis
M. Bovis
M. Africanum.
M. Microti
what type of immunological response occurs when infected by M. tuberculosis?
T cell mediated immunological response
Describe the granulomas present with TB.
granulomas contain activated macrophages and are surrounded by epitheliod cells and Lang hans giant cells
the granulomas have central caseating necrosis
there is cavitation in advanced disease
what type of bacteria are mycobacterium tuberculosis?
they are facultative intracellular aerobes
they are slow growing
have high lipid content
acid fast bacilli
why are M. tuberculosis termed as acid fast bacilli?
when stained with dye + phenol and washed with acid they resist decolourisation
what is the generation time of M. tuberculosis?
12-18 hours
what are the risk factors for infection from TB?
poverty low socio economic background malnourished immigrants sub saharan africa / asia immunosuppressed diabetes HIV
how is M. bovis contracted from and where does it deposit the infection?
contracted from cows milk.
the infection is usually deposited in cervical and intestinal lymph nodes
what symptoms and signs are present with primary progressive TB?
usually asymptomatic pyrexia malaise erythema nodosum Ghon focus on CXR, usually found in the mid zones and/ or in regional draining lymph nodes
describe what meningeal TB presents like.
high CSF protein
what are the symptoms/ signs of post primary TB?
may be asymptotic for months.
respiratory: cough with sputum and/ or haemoptysis, SOB, pleuritic chest pain
malaise, pyrexia, weight loss, night sweats
Crackles and Bronchial breathing may be heard over area of consolidation.
in latent primary TB, what can develop after 6-12 of infection?
Miliary TB
meningeal TB
TB pleural effusion
what 3 investigations should be carried out for diagnosing TB?
sputum samples taken on 3 successive days.
- sputum culture
- sputum PCR
- sputum smear
Chest X-ray
CT scan of thorax
Bronchoscopy with bronchoalveolar lavage and transbronchial biopsy
Pleural aspiration and biopsy if pleural effusion.
For the treatment of TB, single agent treatment leads to drug resistant organisms within how many days?
14 days
when patients start treatment for TB, when are they rendered non-infectious?
after 2 weeks
what is the vaccine for prophylaxis of TB infection?
BCG vaccine
how is screening for TB carried out?
If under 16 and no BCG = Tuberculin test and CXR
If over 16 and BCG = CXR for reassurance
In TB screening, if someone is under 16, no BCG and IGRA is positive but X ray is normal, what does this mean and what is done?
This means that they are at risk of disease
- chemoprophylaxis to kill mycobacterium : rifampicin + isoniazid prophylaxis therapy for 3 months and IPT for a further 6 months
What can be used for diagnosis of latent TB?
IGRA
What are the symptoms of progressive primary TB?
Usually none Progressive productive cough with haemoptysis Erythema nodosum Pyrexia Malaise (Ghon focus seen on mid zones on CXR)
What are the 3 sputum tests carried out for investigation of TB?
Sputum culture
Sputum smear
Sputum PCR
Where in the lungs is TB most commonly found?
Upper lobe
What can miliary TB sometimes present with?
Pleural effusion
