Tuberculosis Flashcards
What causes TB?
Mycobacterium Tuberculosis
Mycobacterium Bovine
Among others.
What is mycobacterium tuberculosis
Non-motile bacillus
Slow growth
Aerobic- predilection for APICES of lung
TB causing organisms are AAFBs, what does this mean?
Acid-Alcohol fast bacilli.
Don’t decolourise in acid or alcohol during staining techniques
Often resistant to absorbing the dye
ZN stain is used
Why cant our body overcome TB?
The mycobacteria are resistant to macrophages and neutrophils.
How is TB spread?
Airborne - pulmonary & laryngeal spreads
M. Bovis spread by infected cow’s milk
Deposited into the cervical & intestinal lymph nodes.
How does TB occur?
Invading mycobacterium trigger Th1 cells which activate macrophages.
1. Macrophage activation-> epithelioid cells-> Langhan’s giant cells
2. Indigestible material produces Granuloma
3. Central caseating necrosis
(Caseating Necrosis = causes tissues to become “cheese-like” in appearance)
How does a primary TB infection affect the body?
Often asymptomatic but can have fever, malaise, erythema nodosum and chest signs.
Spread from alveoli -> Hilar lymph nodes -> blood to all organs.
How does a primary TB infection resolve?
85% reach a primary complex then heal (initial lesion and lymph node).
Can be progressive, latent or cleared.
What happens when primary infection progresses to tuberulous bronchpneumonia
Primary focus enlarges- cavitation
Enlarged hilar l.n compress bronchi- lobar collapse
Enlarged l.n discharges into bronchus
What is miliary TB
Hematgenous spread of bacteria to multiple organs
Fine mottling on X-ray
Widespread granulomatoma
CNS TB in 10-30%
What does post-primary TB refer to?
Infection after latent disease
Reinfection after original disease
Can affect almost any tissue
What is miliary TB
Hematgenous spread of bacteria to multiple organs
Fine mottling on X-ray
Widespread granulomatoma
CNS TB in 10-30%
What are the symptoms of post primary pulmonary TB?
Cough with sputum and haemoptysis Pleuritic chest pain SOB Malaise & Weight Loss Fever & Night Sweats
Maybe crackles/bronchial breathing
What are the clinical symptoms of TB
Cough
Fever
Sweats (at night)
Weight loss
Fever absent in 37%
Sweats asbent in 39%
Weight loss absent in 38%
What are the risk factors for post primary pulmonary TB?
History of diabetes, immunosuppression or TB.
Immunosuppresive Drugs
History of alcohol, IV drug abuse, poor living standards.
Immigration from a high risk area.