24. TB Flashcards
What organism is responsible for TB
Mycobacteria- slow growing species, very hard to get rid of
Mycobacterium tuberculosis
Mycobacterium bovis
Explain the pathology of TB?
Activated macrophages turn epitheliod cells into laghans giant cells
These accumulate with other leucocytes to form granulomas
They lead to central caseating necrosis
Explain the course of TB
Typically initial infection that sits and waits soemwhere sealed off (lungs, bone, bladder)- typically asymptamatic
in 1-2% they will progress very rapidly into seriosu disease (lobar collapse, widespread graulomas, meningeal TB)
For many others if may take 6 months-40 years for symptoms to come back
Describe post primary pulmonary tuberculosis
Progressive several months increasign symptosm of cough, sputum, haemoptysis, pleuretic pain, malaise, fever, weight loss, night sweats.
What groups are TB moer likely in
HIV/Immunosuppressed Diabetic Previous TB Alcoholics IVDA Immigrants from high incidence areas
How do you diagnose TB in the hospital?
3 sputum samples on successive days:
Ziehl-Neilsen stain
Sputum PCR
Sputum culture- may take 8 weeks
CXR- bilateral pathciness, may see cavitations and calcfications
What further tests should be done in sputum negatice
CT thorax
Bronchoscopy with bronchoalveolar lvage
Pleurall aspirationa dn biopsy in PE
Interferon Gamma release Assay (expensive)
What was the name of the old regime of treating TB?
The sanatorium regime
What is the current TB regiment?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol (for 2 months)
Rifampicin
Isonazid (for 4 months)
What are the side effects of rifampicin?
Orange piss
Renders prednisolone, anticonvulsants and OCP,amongst other drus innfective
Causes hepatitis
What are the side effects of Isoniazid
Hepatitis
Peripheral neuropathy
What are the side effects of pyrazinamide
Gout
What are the side effects of ethambutol
Optic neuropathy
What is a key part of TB treatment?
Contact tracign and notification to public health
How to you screen for TB
Either Mantoux or Heaf test
Mantoux- intradermal injection, check in 48-72 hours
Heaf- multiple puncutres, read after 4-7 days
