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
what are the advantages of microscopy?
o Done on any type of sample
o More quickly than culture
what are the disadvantages of microscopy?
o Low pick up rate
o Not very specific
what solid medium is used to culture TB?
Lowenstein-Jensen
what liquid medium is used to culture TB?
Kirchner
how does TB look in a CXR?
• Right apical cavity
• Collapsed right upper lobe
• Horizontal fissure displaced superiorly secondary to collapse of right upper lobe
• Consolidation and loss of right border
o Consolidation = filling with fluid leading to swelling.
• Elevation in right hemi diaphragm (acute).
-
erythropoeisis and microcytic anaemia82
-
applied anatomy of the heart62
-
macrocytic and haemolytic anaemia65
-
development of the heart52
-
haemostasis81
-
haemostasis and inherited blood disorders22
-
ecg1
-
angina34
-
atherosclerosis and coronary artery disease80
-
applied anatomy of the thorax63
-
hypertension69
-
venous thromboembolism86
-
oxygen, respiratory failure and oxygen therapy49
-
clinical anatomy of the larynx98
-
cardiomyopathies36
-
white blood cells86
-
obstructive lung disease54
-
restrictive lung disease42
-
shock82
-
upper respiratory tract infections39
-
lower respiratory tract infection36
-
respiratory function tests19
-
acute myocardial infarction35
-
valvular heart disease41
-
tuberculosis20
-
stroke77
-
type 1 hypersensitivity23
-
haemoglobinopathies76
-
respiratory acidosis54
-
lymphatics60
-
heart failure33
-
chest x-rays25
-
exercise physiology71
-
blood groups and transfusions38
-
physiology of high altitude53
-
nitric oxide56
-
anterior abdominal wall and inguinal region46
