tuberculosis Flashcards
what bacteria can cause TB?
M tuberculosis
M. tuberculosis, M. bovis, M. africanum, M. microti, M. canetti
what mycobacteria dont cause TB?
M. avium complex
how is TB transmitted?
- Spreads through the air via droplet nuclei
- M. tuberculosis expelled when an infectious person coughs, sneezes, speaks, sings
- Transmission occurs when another person inhales the droplet nuclei
what does the probability of transmission depend on?
o Infectiousness of person with TB disease
o Environment in which exposure occurred
o Length of exposure
o Virulence (strength) of the tubercle bacilli
what is the best way to stop transmission of TB?
o Isolate infectious persons
o Provide effective treatment to infectious persons as soon as possible
what % of the world have latent TB infection?
23%
what is the replication time of TB?
replicates once every 24 hours
how can you prevent latent bacteria becoming active?
through diagnosis and preventative treatment e.g. chemoprophylaxis = medication to prevent latent infection from becoming active
- good ventilation
what is chemoprophylaxis?
medication to prevent latent infection from becoming active
what is the incubation period of TB?
Incubation period of active TB typically 3-9 months + almost always under two years
what is the chance of developing TB if you have HIV?
30-50%
how do you diagnose latent TB infection?
Mantoux w PPD or gamma interferon release assays (IGRA)
how do you treat drug sensitive TB?
• Isoniazid, Rifampicin, Pyrazinamide + Ethambutol for 2 months • Rifampicin and Isoniazid for 4 months o Daily therapy (or 3 x weekly), orally • Total 6 months • 12 months for TB meningitis
what are multi-drug resistant bacteria?
resistant to isoniazid and rifampicin (MDR)
what are extensively drug resistant bacteria?
MDR + Amikacin, kanamycin and resistant to any fluoroquinolone
