TUBERCULOSIS IN HIV

Question 1

What is the difference in lifetime chance of reactivation of latent TB between an individual who is HIV positive and another who is HIV negative?

Answer 1

HIV positive: 10% chance per annum

HIV negative: 10% chance over lifetime

Question 2

How much more likely is a HIV positive individual to develop active TB than a HIV negative individual?

Answer 2

20-40 times more likely

Question 3

What proportion of AIDS related deaths around the world are attributable to TB?

Answer 3

Around one quarter

Question 4

What are the clinical features of TB?

Answer 4

Fever

Night sweats

Weight loss

Haemoptysis

Question 5

How does HIV change the typical appearance of chest radiograph in someone with HIV?

Answer 5

Lacks characteristic upper zone cavitatory disease

Replaced by pulmonary infiltrates, mediastinal lymphadenopathy and pleural effusions

Question 6

Are HIV positive patients with pulmonary TB more or less likely to be AFB sputum negative?

Answer 6

More likely which makes this inexpensive and rapid test less sensitive.

Question 7

What does MODS stand for in the context of TB diagnostic tests?

Answer 7

Microscopic observation drug susceptibility assay

Question 8

What does the microscopic observation drug susceptibility assay tell you about TB?

Answer 8

Information on drug resistance

Question 9

How does HIV affect ease of diagnosis of TB?

Answer 9

Tends to make it harder and render tests less sensitive

Question 10

Which TB diagnostic tests are rendered less sensitive by HIV?

Answer 10

Sputum smear for AFB

Sputum liquid culture

NAAT

Histology of granulomas - less AFB present

TST - tuberculin skin test

Rapid immune-based tests

Question 11

Which TB diagnostic tests are unaffected by HIV?

Answer 11

MODS (Microscopic observation drug susceptibility assay)

Question 12

Which TB diagnostic tests are rendered more sensitive by HIV?

Answer 12

Urine LAM (lipoarabinomannan)

Question 13

What is the prevalence of drug resistant TB in HIV positive patients when compared with HIV negative patients?

Answer 13

2-3 times higher

This is not due to increased susceptibility to these strains, but more because HIV positive patients will rapidly develop active disease

Question 14

What is the anti-TB drug that TB is most commonly resistant to?

Answer 14

Isoniazid

Question 15

How does HIV affect anti-TB drug resistance?

Answer 15

Increases likelihood of rifampicin resistances

Question 16

How does HIV co-infection affect the anti-TB treatment regimens?

Answer 16

It doesn’t in itself although there may be indirect increase in resistance to certain drugs.

Question 17

What is the standard and reliable anti-TB treatment regimens for those with pulmonary TB or extrapulmonary TB without cerebral involvement?

Answer 17

Rifampicin for 6 months

Isoniazid for 6 months

Pyrazinamide for 4 months

Ethambutol for 4 months

Question 18

Which anti-TB drug is a potent P450 inducer which therefore has an effect on cART doses?

Answer 18

Rifampicin (a type of rifamycin)

Question 19

What is alternative to rifampicin that has less of inducing effect of P450 enzymes and is therefore often safer when given in conjunction with anti-HIV cART?

Answer 19

Rifabutin

Question 20

By how much does effective use of cART reduce risk of developing active TB?

Answer 20

60-90%

Question 21

Are those with an undetectable HIV load and a good blood CD4 count at increased risk of TB than the general population?

Answer 21

Yes

Question 22

Which cART drugs should be especially avoided with rifampicin?

Answer 22

Protease inhibitors

Question 23

Why is a combination of protease inhibitor (as cART) and rifabutin (instead of rifampicin) still not a particularly good regimen to use in a HIV/TB co-infected patient?

Answer 23

Because protease inhibitors inhibit rifabutin metabolism.

Question 24

What are the risk of starting early (within 2 weeks of diagnosis) concomitant use of cART and anti-TB treatment?

Answer 24

Risk of drug interaction

Overlapping toxicities and additive adverse effects

High pill burden

Risk of reduced patient adherence

Immune reconstitution inflammatory syndrome (IRIS)

Question 25

What are the most commonly experienced additive adverse effects seen with concomitant use of cART and anti-TB treatment?

Answer 25

Hepatotoxicity

Peripheral neuropathy

Rash

Persistent nausea and vomiting

Question 26

What is immune reconstitution inflammatory syndrome (IRIS)?

Answer 26

When cART actually worsens existing disease due to an inappropriate response by the newly invigorated immune system. Mechanism is unclear.

Question 27

What are the risk factors for developing immune reconstitution inflammatory syndrome (IRIS) when cART is started too soon after administration of anti-TB medication?

Answer 27

Very low CD4 count

Disseminated TB

Question 28

What are the clinical features of immune reconstitution inflammatory syndrome (IRIS)?

Answer 28

New or enlarging lymph nodes, cold abscesses or other focal tissue involvement eg tuberculous arthritis

New or worsening radiological features of TB

New or worsening CNS TB

New or worsening serositis (pleural effusion, ascites or pericardial effusion)

Worsening of constitutional symptoms

Worsening of respiratory symptoms (cough, dyspnoea or stridor)

New or worsening abdo pain accompanied by peritonitis, hepatomegaly, splenomegaly or abdominal adenopathy

Question 29

How do we treat immune reconstitution inflammatory syndrome (IRIS)?

Answer 29

Normally can be managed without stopping cART or anti-TB medication

More serious disease especially when associated with cerebral or mediastinal disease is likely to cause compression of vital structures. In these cases, corticosteroids should be given. These patients need close monitoring.