TB Flashcards
Approximately what percentage of the worlds population carry the causative bacteria, mycobacterium tuberculosis
1/3
Travel to which countries would raise suspicion of TB?
India, China, Indonesia, Pakistan, Bangladesh (essentially any asian country)
What is the causative bacteria?
Mycobacterium tuberculosis
When should TB be considered infectious?
When tested positive for ziehl-neelson sputum test showing alcohol fast and acid fast bacteria
When in children under 12 does it tend to be infectious or not?
Unlikely to be infectious
What are the symptoms of primary infection of adults?
No, patients are almost always asymptomatic
Children may suffer symptoms on primary infection which are?
Local pulmonary hilum lymphadenopathy which can cause bronchial narrowing and pleural effusion
Clinical features of reactivation and primary infection (occurs when there is hypersensitivity to TB or bacilli spread before immunity can contain them)
Weight loss, fever, night sweats, malaise, anorexia, cough, purulent sputum and haemoptysis
Post primary and non pulmonary TB can effect a large number of different areas such as?
Kidneys, joints, abdomen (ascites), female genitals and CNS (TB meningitis)
What are he two key tests for confirming diagnosis of TB?
Auramine and ziehl-neelson sputum screening and culturing to find mycobacterium tuberculosis
What other test can confirm TB?
PCR (can confirm before full sputum sample can be achieved). Very poor sensitivity if non-pulmonary TB and in some cases biopsy and culture are required
What might CXR reveal?
Consolidation, cavitation, calcification
Cavitation is less likely in which group of patients?
In those who are co-infected with HIV (10% of TB infections)
If sputum sample and PCR cannot be done and TB is suspected what must be done?
Bronchoscopy and culturing of bronchial Washington to ensure it is mycobacterium tuberculosis
Which patients with TB are not infective?
Those who have non-pulmonary TB
Name 5 risk factors for getting TB
First gen immigrants from high incidence countries, overcrowded housing, homelessness, primary infection less than a year previously, smoking, corticosteroid therapy, HIV, malignancy (esp leukaemia and lymphoma), diabetes, silicosis
What are the manifestations of TB 3-8 weeks post infection?
Primary complex forms and tuberculin skin test positive
What are the manifestations 3-6 months post infection
Meningeal, milary, pleural disease
Up to 3 years what can manifest?
Gi, bone, joint, lymph node disease
By 8 years what can develop?
Renal tract disease
What happens in most patients post initial infection?
M. tuberculosis is contained in a lesion in the apices of the lung and it calcifies (visible on x ray) and usually doesn’t reactivate
What might cause reactivation of TB?
Diabetes, malnutrition, HIV, immunosupression or corticosteroid therapy
What happens to normal tissue once infected?
It is replaced by macrophages which transform into langerhans and epithelial cells to form a tuberculous granuloma
What is milary TB
It is when M. tuberculosis disseminates I to the blood and affects other areas of the body and multiple disperse lung areas. Anaemia and leukopenia may occur with bone marrow involvement
What preventative action can be taken?
Give BCG vaccine
Management of patients with TB
Isolate for 2 weeks, notify, HRZE treatment (h=isoniazid R=rifampicin Z=pyrazinamide E=ethambutol) given once daily for 2 months while drug sensitivities and diagnosis confirmation is awaited, after it is simplified into two drugs for a further 4 months to make a total treatment time of 6 months
What disease has played a large role in allowing TB to persist into he 21st century?
HIV
