TB

Question 1

what pathogen is responsible for the cause of most tb

Answer 1

M. tuberculosis causes most TB cases.

Question 2

name the type of mycobacteria that can cause TB

Answer 2

M. tuberculosis 
M. bovis
M. africanum
M. microti
M. canetti

Question 3

name a mycobacteria that does not cause TB

Answer 3

M. avium complex

Question 4

how is TB spread

Answer 4

TB is spread person to person through the air via droplet nuclei

M. tuberculosis may be expelled when an infectious person:
Coughs
Sneezes
Speaks  
Sings

• then the transmission occurs when another person inhales the droplet

Question 5

what does the probability that TB will be transmitted depend on

Answer 5

Infectiousness of person with TB disease
Environment in which exposure occurred
Length of exposure
Virulence (strength) of the tubercle bacilli

Question 6

what is the best way to stop transmission

Answer 6

Isolate infectious persons

Provide effective treatment to infectious persons as soon as possible

Question 7

what is latent TB

Answer 7

this is when a person is infected with TB but the TB is not yet active

Question 8

How do you diagnose those with latent TB

Answer 8

• Mantoux test with PDD

- gamma interferon release assays (IGRA)

Question 9

how long is the incubation period of active TB

Answer 9

incubation period of active TB typically 3-9 months and almost always under two years

Question 10

most people who have active TB are…

Answer 10

reinfected with TB it is not latent TB becoming activated

Question 11

How many people have latent TB

Answer 11

About 1.7 billion people, 23% of the world’s population, are estimated to have a latent TB infection

Question 12

what are the breakthrough drugs in the 1940s and 1950s that can kill TB

Answer 12

Streptomycin (SM) discovered in 1943

Isoniazid (INH) and
p-aminosalicylic acid (PAS) discovered between 1943 and 1952

Question 13

what is the treatment of drug sensitive TB

Answer 13

RIPE

• Rifampicin
• Isoniazid
• Pyrazinamide
• Ethambutol
• Rifampicin and Isoniazid for 4 moths
• pyrazinamide and ethambutol for 2 months
• daily therapy (or 3 times a week)
• orally
• 12 months for TB meningitis

Question 14

what are the baseline checks for TB

Answer 14

• chest x ray
• liver function tests
• fasting blood sugar test
• urea and electrolyte test
• c reactive protein test

Question 15

what are the countries high in TB in the EU

Answer 15

Armenia, Azerbaijan, Belarus, Bulgaria, Estonia, Georgia, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Moldova, Romania, Russia, Tajikistan, Turkey, Turkmenistan, Ukraine and Uzbekistan

Question 16

what is MDR tb

Answer 16

this is multi drug resistant to TB 
- Resistant to INH and RIF (“ MDRTB)
PLUS 
Resistance to amikacin, kanamycin or capreomycin (injectable agents)
AND
Resistance to any fluroquinolone

Question 17

what 3 countries account for almost half the worlds cases of MDR

Answer 17

• india
• china
• Russian federation

Question 18

who usually gets XDR-TB (extensively drug resistant TB)

Answer 18

Most were pulmonary
Most were male
Most aged 20-50
Most had had previous TB
Most born abroad.
Distributed

Question 19

how do you improve diagnosis of TB

Answer 19

• Improve diagnostic capacity: infrastructure, training
• Export patient materials to central facilities
• Improve transport
• Improve stability of biomaterials
• Combination of above
  Lateral thinking
• Clinical
• Radiological
• Laboratory-Diagnosis TB
• Laboratory-DST
• Microscopy, culture, molecular

Question 20

how is the TB culture use

Answer 20

Solid + rapid liquid systems

Sensitive for diagnosis

Slow but faster for liquid eg approx 10-21 days for smear positive sputum specimens

Also for drug resistance

• more expensive
• supply chain is critical

Question 21

how do you do rapid diagnosis of resistance to RIF and INF

Answer 21

molecular line probe assays

Question 22

how do molecular line probe assays work

Answer 22

1, DNA extraction from cultures and clinical specimens (sputum);
2, PCR amplification of fragments of genes associated with drug resistance;
3, Hybridization with the DNA probes on membranes;
4, Development, reading and interpretation of results