Pulmonary Tuberculosis Flashcards
What is TB?
Respiratory infection caused by Myobacterium Tuberculosis
- Pulmonary TB is the only type of TB that is infectious
What are the two main forms of active tuberculosis
- Pulmonary Tuberculosis
- Non-pulmonary Tuberculosis (Extra-pulmonary)
What are the different types of non-pulmonary tuberculosis?
- TB Meningitis
- TB Gastro
- TB Genitourinary
- TB Skeletal (reactive arthritis)
What are the risk factors of pulmonary tuberculosis?
- HIV
- Immunosuppression
- Exposure to infection
- Birth in an endemic country
- Smoking
- Age (under 5 or elderly)
- Alcohol
- Diabetes
What are the clinical features of pulmonary tuberculosis?
- Unexplained weight loss
- Drenching night sweats
- Lymphadenopathy
- Fever
- Coughs
- Haemoptysis
- Pleuritic chest pain
- Crackles on auscultation
What are the clinical features of TB Meningitis?
- Headache
- Fever
- Mental State Changes
What are the clinical features of TB Skeletal?
- Back pain and stiffness
- Bone pain
- Arthritis
What are the clinical features of TB Genitourinary?
- Dysuria
- Haematuria
- Frequent infection
- Flank Pain
What are the clinical features of TB Gastro?
- Difficulty swallowing
- Non healing ulcers
- Abdo pain
- Hepatomegaly
What is the differential diagnosis of pulmonary TB?
- Pulmonary oedema
- Lung cancer
- Sarcoidosis
What are the two main types of tuberculosis?
=> Active infection:
- Can arise from primary infection or by reactivation of latent infection
=> Latent TB:
- Evidence of infection but the patient is asymptomatic
What is the pathophysiology of pulmonary tuberculosis?
- Macrophages migrate to lymph nodes, lung lesion and affected lymph nodes is referred to as a Ghon complex
- This leads to the formation of a granuloma which is a collection of epithelioid histiocytes
- Presence o necrosis in centre
- Inflammatory response is mediated by a Type 4 hypersensitivity reaction
=> In healthy individuals the disease may be contained, in immunocompromised military TB develops
What are the investigations in suspected Active Pulmonary TB?
PATIENT MUST BE ISOLATED IN SUSPECTED CASES
=> Ziehl-Neelson Staining - first line
=> NAAT:
- Rapid diagnosis in less than 8 hours
=> Sputum culture:
- More sensitive than smear but takes 4-8 weeks
=> Sputum smear
=> CXR:
- Ghon complexes
- Miliary TB
What is the affect of HIV on TB infection?
HIV infection leads to depletion of myobacterium tuberculosis specific CD4 lymphocytes, promoting activation of latent TB
What is the screening of latent TB?
=> Mantoux testing:
< 5 mm - Negative
6-15 mm - Positive
> 15 mm - Strongly positive for latent TB
=> Interferon-gamma releases assays:
- Diagnosing latent TB by measuring the release of interferon-gamma from T cells
What is the treatment regime for active TB?
R - Rifampicin (inhibits RNA polymerase)
I - Isoniazid (inhibits mycolic acid synthesis)
P - Pyrazinamide (inhibits fatty acid synthase)
E - Ethambutol (inhibits enzyme which polymerises arobinose to arabinan)
First 2 months (initial phase)- Rifampicin, Isoniazid and Pyrazinamide and Ethambutol
Next 4 months (continuation phase) - Isoniazid and Rifampicin
If there is central venous involvement, the continuation phase is extended to 10 months making a 12 month treatment programme
Meds are taken all together on an empty stomach one hour before breakfast
What is direct observed therapy?
- HCP, DOT observer or family member ensures patient adheres to treatment
- Incentives include free meals and cash rewards
Who is made available to the BCG vaccine in the UK?
- All infants living in areas of the UK where annual TB incidence is > 40/100,000
- All infants who have at least 1 parent or grandparent born in a country where the annual TB incidence > 40/100,000
- Previously unvaccinated tubercullin-negative contacts of cases of respiratory TB
- Previously unvaccinated tubercullin-negative < 16 year old who were born or of have lived for longer than 3 months in a country with an annual TB incidence > 40/100,000
- Healthcare workers
- Prison staff
- Staff or care home for the elderly
- Those who work with homeless people
=> Contraindications for the BCG vaccine:
- Previous BCG vaccination
- Past history of TB
- Pregnancy
- Positive tubercullin test
What stain is typically used in the diagnosis of tuberculosis?
Ziehl-Neelson
What are the most common side effects of the drugs in the treatment regimine of tuberculosis?
=> Rifampicin:
- Orange body fluids
- Rash
- Hepatotoxicity
- Drug interactions
=> Isoniazid:
- Peripheral neuropathy
- Psychosis
- Hepatotoxicity
=> Pyranzinamde:
- Arthralgia
- Gout
- Hepatotoxicity
- Nausea
=> Ethambutol:
- Optic neuritis
- Rash
How does Military TB spread through the lung parrenchyma?
Pulmonary venous system
What set of investigations are most appropriate to check whether starting treatment for tuberculosis does not cause problems?
LFTS
U&ES
FBC
Vision testing
What is the treatment regime for latent TB?
3 months of Isoniazid with Pyridoxine and Rifampicin for those < 35 where hepatotoxicity is a concern
OR
6 months of Isoniazid with Pyridoxine where Rifampicin toxicity is a concern
