TB Flashcards
What organisms cause TB?
Mycobacterium tuberculosis
Mycobacterium bovis
Mycobacterium africanum
What is the appearance of mycobacterium?
Non-motile rod bacteria
What stain is used for mycobacteria?
Ziels-Neilson stain
How is TB spread?
Respiratory transmission via droplet spread
What is the pathogenesis of TB?
Inhaled aerosols are engulfed by alveolar macrophages
Spreads to local lymph nodes
Forms primary complex
EITHER
- progesses to active disease
- initial containment to become latent infection
What are the features of a latent TB infection?
Inactive contained bacilli in body TST tests usually positive CXR normal Sputum cultures negative No symptoms Not infectious
What are the features of active TB?
Active multiplying bacilli in the body TST tests usually positive CXR abnormal Sputum cultures positive Symptoms Infectious
What are the symptoms of primary TB?
Cough Fever Weight loss Night sweats Malaise
What are risk factors for TB reactivation?
HIV infection Substance abuse Immunosuppression TNF-a antagonists Low BMI
What is the pathology of TB?
Creates a caseating granuloma in lung parenchyma and mediastinal lymph nodes
Langhans giant cells
What are risk factors for TB infection?
Recent travel HIV Immunocompromised Homeless Drug users Close contact with those with TB
What are the investigations for suspected TB?
CXR
Sputum - 3 early morning samples
Microscopy
What is the tuberculin skin test?
Tuberculin injected into skin
Size of lump measured 72 hours later
AKA Mantoux test
What is seen on a CXR in TB?
Apex often involved
Cavitating lesion (ghon focus) Patchy consolidation
How is TB managed?
Rifampicin 6/12
Isoniazid 6/12
Pyrazinamide 2/12
Ethambutol 2/12
