TB

Question 1

1. IX for acute TB
2. how long do sputum culture results take?
3. When is PCR performed?

Answer 1

• -> 3 early morning sputum samples on 3 consecutive days for Acid Fast Bacilli Stain & Culture
• -> Chest xray

2. upto 4-6 wks
   (Ref: Infectious Diseases Check 2014)
3. PCR is routinely performed on new smear positive cases as it can confirm that the AFB seen are M. tuberculosis complex and not non-tuberculosis mycobacteria.

Question 2

T or F

Tuberculin test and Inteferon Gamma should be performed in acute disease investigation?

Answer 2

False –>
can have false negative in acute disease
(Ref: Infectious Diseases Check 2014)

Question 3

1. What’s the mx of close household contacts?

Answer 3

1. test with tuberculin test + inteferon gamma test

Treatment with isoniazid can prevent progress of TB disease
Ref: Infectious Diseases Check 2014

Question 4

What % of infected individuals will develop active disease?

Answer 4

10%,
Approximately 90% of individuals infected with M. tuberculosis do not develop active disease.

(Ref: RACGP Check 2017 and etg)

Question 5

In Aus what are the groups @ highest risk of TB?

Answer 5

–> recent migrants and returned travellers from high-incidence countries
–> contacts of active TB cases
–> ATSI in NT, QLD, NSW
(Ref: RACGP Check 2017)

Question 6

1. What is the BCG vaccination for?
2. What is the use BCG in adult population?
3. Is it affective after a person has been infected?

Answer 6

1. protect against severe disseminated disease in young children (miliary and meningeal TB).
2. variable protection against adult pulmonary disease (0–80%)
3. It is not effective once a person is infected with M. tuberculosis
   (Ref: RACGP Check 2017)

Question 7

Risk factors for progression to active TB include:5

Answer 7

1. infection within 5 yrs
2. <5 yrs + elderly
3. HIV, renal failure, head+bneck cancer,
4. Smoker, pulmonary comorbidities
5. medications such as tumour necrosis factor alpha (TNF-α) inhibitors, glucocorticoids, immune modulators used in organ transplantation and immune-compromising chemotherapy agents.
   (Ref: RACGP Check 2017)

Question 8

Sputum collection guidelines

Answer 8

–> in a well-ventilated place, away from other people
–> NOT in restroom facilities.
–> For highly suspected clinical presentations of active TB a spot sputum should be collected and referral made to a hospital with respiratory isolation.
(Ref: RACGP Check 2017)

Question 9

Side effects of the following drugs for TB (ref: BMJ)

Isoniazid 
Pyrazinamide 
Rifampicin
Streptomycin 
Ethambutol

Answer 9

Isoniazid - peripheral neuropathy, psychosis, hepatitis

Pyrazinamide - hepatitis, gout

Rifampicin - hepatitis, orange discolouration of urine and tears, interaction with contraceptive pill

Streptomycin - ototoxicity, renal tubular damage.

Ethambutol - visual problems with loss of visual acuity, colour blindness, and restriction of visual fields being well documented side effects.