Lecture 1 Flashcards
What tests are you required to do if you enter the UK for, a country with common TB infections ?
Sputum test and x-ray
Define latent
You are infected with the bacteria but do not have the signs or symptoms
What patients are at more risk if they develop TB?
HIV patients
What are the symptoms of TB?
More than 3 weeks cough that is getting worse persistent and productive, temperature,fever, night sweats and chills - occurring at different times of the day, unexplained weight loss and coughing up blood
How do we diagnose TB?
X-rays, clinical examination, PCR test (rapid within 2 hrs)
How do we diagnose latent TB?
Tuberculin Skin Test (Mantoux test), molecular tests (interferon gamma release assay)
What is the tuberculin skin test ?
Tuberculin injected sc into forearm possible if skin lesion >10 mm diameter post 48-72 hrs
Describe stage 1 of TB
Inhaled in droplets, settle in alveoli of the lung, start to grow, stimulates an immune response and macrophages come out,they are phagocytosed by macrophages but they do not kill the bacilli
Describe stage 2 of TB
Asymptomatic/ mild fever, body isn’t effective at removing TB, bacteria multiple in size, macrophages in lungs 7-21 days, macrophages burst and incoming macrophages phagocytose release M.TB and the cycle repeats. This continues for 3-4 weeks
Describe stage 3 of TB
At 6 weeks symptoms of disease start to appear, cell mediated response initiated (T cell, B cell, fibroblasts), collagen fibres form around affected sites, granulomas (tubercules) formed in lung
Describe stage 4 of TB
Bacteria multiply inside macrophage, granuloma burst - uncontrolled lysis. Bacteria spread - new sites of infection process repeats. Enzymes released - destroys local tissues causing lesions
What is disseminated TB?
Spreads throughout body and can infect multiple organs
Name the 1st line treatments for active TB
Combination of 4 drugs over 6-9 months
Rifampicin and isoniazid - 6-9 months
Pyrazinamide and ethambutol for the first 2 months
Name the 1st line treatment for latent TB
Isoniazid 6 months or Rifampicin and isoniazid for 3 months
Describe the MoA of Rifampicin
Bactericidal to all metabolising cells
Targets mRNA production
Inhibits RNA polymerase
Oral
Absorption affected by food