TB

Question 1

define tuberculosis?

Answer 1

Granulomatous disease caused by Mycobacterium tuberculosis

Question 2

what is primary TB?

Answer 2

initial infection is often pulmonary

Question 3

what is miliary TB?

Answer 3

results from haematogenous dissemination of TB via the pulmonary venous system

Question 4

what is secondary TB?

Answer 4

o If the host is immunocompromised the initial infection can become reactivated
. Often the reinfection occurs in the lungs, although can occur in the CNS, vertebral bodies, cervical lymph nodes, renal or GI tract.

Question 5

causes of immunosuppresion?

Answer 5

immunosuppressed: HIV, steroid treatment, malnutrition.

Question 6

epidemiology of TB?

Answer 6

• Asian immigrants are the highest risk group

* Annual mortality = 3 million

Question 7

typical signs of TB?

Answer 7

fever, fatigue, weight loss, blood stained sputum and night sweats.

Question 8

typical skin change in TB?

Answer 8

o Erythema nodosum

Question 9

examples of where non pulmonary TB can infect?

Answer 9

• Lymph Nodes leading to abscesses or sinuses
• CNS - meningitis, tuberculoma
• Skin - lupus vulgaris
• Heart - pericardial effusion, constrictive pericarditis
• GI - Subacute obstruction, Change in bowel habit
• Genitourinary - UTI symptoms, Renal failure, Epididymitis
• Adrenal insufficiency
• Bone/Joint - osteomyelitis, arthritis, vertebral collapse

Question 10

how to screen latent TB?

Answer 10

Mantoux test:
• Main technique looking for latent TB
• 0.1ml of Purified protein derivative is injected intradermally
• The result is read 2-3 days later
• The PPD will respond if the tuberculin protein is present >15mm

Question 11

which test used to be used to screen for latent TB?

Answer 11

The Heaf test used to be used

Question 12

how can TB be actively diagnosed? gold standard

Answer 12

Sputum Culture

Question 13

how can active TB be diagnosed?

Answer 13

Chest X-ray:
• Upper lobe cavitation is the classical finding of reactivated TB
• Bilateral hilar lymphadenopathy

Sputum smear:
• 3 specimens are needed
• Rapid and inexpensive
• Stained for the presence of acid- fact bacilli (Ziehl-Neelsen stain)
• Sensitivity is 50-80% and less for those with HIV

Nucleic acid amplification tests:
• Allows rapid diagnosis (24-48 hours)
• More sensitive than smear but less sensitive than culture.