TB II

Question 1

typical clinical manifestations of TB

Answer 1

Fever, fatigue, weight loss, night sweats

Question 2

What causes the typical symptoms of TB?

Answer 2

It is due to effects of cell mediated immune response to TB

Question 3

what are the clinical manifestations of pulmonary TB. Explain each.

Answer 3

Productive cough
Blood stained sputum due to tissue destruction
Haemotysis due to the TB infection eroding into the blood vessels and causing rupture of the vessels. Can also cause significant fatal haemorrhage

Question 4

Common sites of extrapulmonary TB (6)

Answer 4

TB meningitis: serious can cause brain damage and death
Bone and joint disease (Arthritis, osteitis affecting spine and other joints)
Isolated lymphadenopathy
Peritoneal TB, pericardial TB
Urogenital TB

Question 5

Clinical features of TB in pts with advanced HIV

Answer 5

Inadvanced HIV infection
* Don’tdevelop characteristic granulomas
* Unable tocontrol dissemination (spread) of TB bacilli throughout body
* Somorelikely to have extra-pulmonaryTB

Question 6

Why is it hard to make a diagnosis of TB in pts with advanced TB

Answer 6

Specifically in the lungs
* TBinfection occurs throughout the lungs not just in the upper zones
* Doesn’t cavitate (or form cavities)
* Therefore, often sputum is pauci-bacillary (few bacilli)
* So more difficult to diagnose from sputum samples

Question 7

How do people with miliary TB present?

Answer 7

They are usually very weak and sick, but they do not have typical TB symptoms like fever, cough, haemoptysis, etc.

This is because they do not have cell mediated response to the TB (failure of host response to control infection)

Question 8

Pts at risk of miliary TB

Answer 8

advanced HIV, young infants, other immunocompromised individuals

Question 9

Principles for TB Tx (3)

Answer 9

Importance of multi-drug combination treatment
* Use drugs that kill mycobacteria effectively and or act at different sites or stages of infection
* Treatment needs to be prolonged

Question 10

What is the reason for using multi-drug combination Tx?

Answer 10

This is to reduce chances of resistance forming. In a TB pt, there is a high mycobacterial load, with a small percentage consisting of resistant strains.
Monotherapy selects out those resistant organisms, thus causing them to thrive.

Question 11

What is the first line regimen for TB tx in SA?

Answer 11

Rifampicin, Isoniazid, Pyrazinamide, ethambutol

Question 12

Why should TB Tx be prolonged?

Answer 12

Because of slow replication of Mycobacteria, and because most antimicrobials work on replicating or

Question 13

How does SA ensure adherence to TB regimen?

Answer 13

DOTS strategy (directly observed therapy short course)

Question 14

How does resistant TB occur?

Answer 14

Non-adherence - susceptible strains are killed first, and then resistant strains that were not fully killed regrow.

Question 15

Mono-resistant TB

Answer 15

Resistance to only one anti-TB drug, without resistance to other drugs

Question 16

Multi-drug resistant TB

Answer 16

Resistance to Isoniazid and rifampicin with or without
resistance to other anti-TB drugs

Question 17

Extremely resistant TB

Answer 17

MDR-TB with resistance to any fluoroquinolone as well as
one or more of the three second-line injectable drugs (Capreomycin, kanamycin or amikacin).

Question 18

why is resistant tb more difficult to treat?

Answer 18

Second line drugs are not as effective as first line drugs  must be given for longer up to 2
years, some patients fail treatment
* Can be more toxic and cause long term side effects, e.g. hearing loss
* Some must be given by injection
* Drugs are more expensive problems for TB control program

Question 19

Vaccines for TB

Answer 19

Live attenuated M. bovis strain - Bacillus-Calmette-Guerin (BCG) Vaccine

Question 20

Disadvantages of BCG vaccine

Answer 20

Offers limited protection- doesn’t protect adolescents and adults

Live attenuated - can cause disease in immunocompromised babies

Question 21

Term used for use of drug to prevent disease

Answer 21

Chemoprophylaxis

Question 22

Who should get chemoprophylaxis for TB

Answer 22

For infected but asymptomatic persons (i.e. latent infection) AND at high risk of developing active
disease

Question 23

What is the current prophylactic regimen for TB?

Answer 23

Isoniazid for 6 months

Question 24

Who is at high risk?

Answer 24

children under 5 who are close contacts of newly diagnosed TB patients, since they have likely
been exposed to MTB and their immature immune systems are less likely to control infection
* High risk people with evidence of latent infection since their impaired immune system means that
spread or reactivation of TB is likely. This includes all children under 5 or persons living with HIV

Question 25

How is latent TB confirmed?

Answer 25

Tuberculin skin test