TB Flashcards
What is the risk of TB in HIV
16-27 times more likely to contract TB
What are the types of TB ?
active and latent
What is the pathophysiology of TB ?
Aerosolized M Tuberculosis droplets are inhaled into the lungs and the bacilli will replicate within the alveolar sacs in macrophages. This causes T cell mediated healthy macrophage response to bacilli infected macrophages. This process leads to casseating grnaulomas (Ghon’s focus). The necrotic centre of a granuloma may liquify and cavitate where it empties into the airway and spread the infection. Infected macrophages can cause lymphatic spread of disease leading to extra-pulmonary TB. 5% of the patients clears Bacilli post infection and the remaining patients have latent TB in which the bacilli remain dormant in Ranke focus.
What is the sputum marker of risk for TB ?
positive for acid-fast-bacilli
What are the symptoms of pulmonary TB?
TB has an insidious onset and symptoms are usually present for several weeks to many months. Typical symptoms include:
*Drenching night sweats
and Weight loss.
*Fever,Productive cough and Haemoptysis.
What are the commonest locations of extra-pulmonary TB?
*Lymph nodes (TB lymphadenitis)
*Bone (TB osteomyelitis)
*CNS (TB meningitis)
But it can occur anywhere in the body including the eyes (ocular TB)
What are the symptoms of extra pulmonary TB ?
- TB lymphadenitis
- TB osteomyelitis
- TB meningitis
What are the signs of pulmonary TB ?
- cachexia
- digital clubbing
- Coarse crackles on auscultation of the lung filed affected.
What are the signs of extra-pulmonary TB ?
*Palpable enlarged lymph nodes
*Tenderness over site of *Bone involvement
*Signs of meningitis include
What is Tuberculin test (Mantoux test) in latent TB?
It involving intradermal injection of tuberculin which the body will recognise as TB and cause a visible reaction if positive within 72 hours.
What is Quantiferon test for latent TB?
It is a blood test measuring the body’s immune response to TB. Those that have had prior TB exposure will have a positive test.
What are the work-ups in active TB?
- Blood culture and microscopy for M. tuberculosis.
- TB GeneExpert ( PCR) for detecting DNA of M.tuberculosis
- A definitive TB diagnosis could be made in 2 hours rather than days to weeks
- GeneXpert can detect TB DNA even in microscopy negative samples
What is the test to detect M. tuberculosis sensitivity to Rifampicin ?
Rifampicin is the backbone of standard TB treatment and resistance to it can be detected using PCR( TB GeneExpert).
What is the pharmacological Tx of latent TB ?
A patient with latent TB should be offered treatment but they are not obliged to accept. It consist of Rifampicin for 4 months or Isoniazid for 9 months.
What is the problem of treating TB using only on drug ?
Guaranteed drug resistance development.
What is the pharmacological protocol in active TB ?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
* Typically 2 months of all medications, followed by 4 more months of rifampicin and isoniazid.
* Pyridoxine / B6 vitamin to prevent neuropathy.
What is the side effect of Rifampicin ?
Drug interactions and
Turns body fluids orange.
What is the side effect of Isoniazid?
Sensory neuropathy.
What is the side effect of Pyrazinamide?
Altered LFT.
What is the side effect of Ethambutol ?
Ocular toxicity causing red-green colour blindness or total blindness in extreme cases.
What are the additional tx strategies in TB ?
*Directly observed therapy (DOTS) to ensure compliance
*Screening high-risk populations (homeless)
*Treatment in isolation (negative pressure room)
* Primary prevention using BCG
what is the problem of BCG vaccine ?
May result in a positive Mantoux test
What are the pulmonary complications of developing TB ?
*Extensive lung destruction / Bronchiectasis
*Permanent lung cavitation leading to occupancy by fungus such as aspergillus.
What is the main side effect of Amikacin used to treat multi-drug resistant TB ?
multi-drug resistant TB treated with at least 3 months of IV Amikacin, resulting in at least some degree of sensorineural hearing impairment
