Tuberculosis

Question 1

What is tuberculosis?

Answer 1

An infection caused by Mycobacterium tuberculosis. It can affect any organ system. It is a rod shaped gram positive bacillus. Slow growing- can be dormant then active. Extra pulmonary tB is not infectious.

Question 2

What are the risk factors of TB?

Answer 2

> Exposure
> Endemic country
> HIV and immunosuppression
> Silicosis
> Malignancy
> IVDU
> Alcoholism
> Homelessness
> Age
> Smoking
> Dialysis

Question 3

What is the epidemiology of Tb?

Answer 3

Higher in immigration centres from high risk countries (Asia)

Question 4

What are the signs and symptoms of TB?

Answer 4

Cough
Fever
Anorexia
Weight loss
Malaise 
Lymphadenopathy
Haemoptysis, pleuritic chest pain, dyspnoea, clubbing (chronic), erythema nodosum, night sweats 
Uveitis, conjunctivitis 
Lupus vulgaris

Question 5

What investigations do you do for TB?

Answer 5

Chest x ray
> Pulmonary symptoms 
Mediastinal lymphadenopathy
Pleural effusions 
Lobar consolidation
Miliary 
> Reactivation 
Classically in apices and mid zone 
Upper zone fluffy disease
Cavitating pneumonia 

Tuberculin skin test (may be positive if BCG has been given)
takes a few months

Interferon gamma release assays
ELISpot (cell specific)
ELISA (total IFN)
3 Sputum culture/ smears to rule out infective TB

FBC
CSF microscopy (TB meningitis)
Lymphocytic 
High protein
High glucose