Tuberculosis Flashcards
Social factors that will contribute to infections
Immigration Poverty Alcoholism Close contact with large populations Poor nutrition IV drug use
Age groups at risk of TB
Very young
Elderly
Type of immunity at risk of TB
HIV
Gamma interferon
SCID
Immunosuppression
Varying pathology of TB
TB infection + TB diseases
TB infection doesn’t mean you have the disease - immune system has fought it off.
Mycobacteraemia
Entry of infection in to blood
Site of tuberculosis infection
Lungs
Consequence of tuberculosis infection
Symptomatic illness - Disease
Primary TB
Silent, formation of granuloma of Ghon focus
(X-ray / mantoux skin test for antibodies against TB)
Infected via inhaled micro-droplets containing bacteria from infectious TB
Taken up by alveolar macrophages - not activated - bacteria replicates - T-cells induce a cell-mediated response to infection
Small foci of inflammation induced by bacteria with spontaneous healing - forming granuloma
Ghon focus - may be reactivated/release bacteria
- centre of granuloma undergoes caesation necrosis forming semi solid cheesy like consistency
- mycobacteria cannot proliferate in enviro.
- clinically silent - latent TB
Post primary TB
Infectious TB
Expanding granulomata (tubercles) releasing numerous mycobacteria + lesions
Lung is site of TB disease
In active disease, caseous centres of granulomata liquefy and facilitate proliferation and spread of bacteria, locally in the lung but also other tissues
little spontaneous healing of the granulomata , causing cavities and extensive damage to the lung tissues including airways and blood vessels
Signs + symptoms of Primary/Post-primary TB
Induce fever Night sweats Weight loss / anorexia - fever production Dry coughs - lungs Wheezy cough - airways
PPTB - sputum with blood
First line antibiotics of TB
Rifampicin Isoniazid Pyrazinamide Ethambutol - (Streptomycin)
Pathogenicity of TB
Aerosolized droplets (spread)
Cell wall components
- Mycolic acid (immune evasion
- impermeability / resistance to anitmicrobials
- Cord factor = glycolipid causing cells to grown in serpentine cords + toxic to mammalian cells + inhibitor of neutrophil migration
- Antigen 85 = bind to host; involved in tubercle formation
Immune privileged site/ ‘deactivation’ of some immune response
- inhibit phagosome function
- heat shock proteins
Detoxification of oxygen intermediates produced during phagocytosis
- catalase
- superoxide dismutase
Cell entry
Second line antibiotics of TB
Ciprofloxacin
Clarithomycin
Amikacin
Miliary TB
Disseminated TB with spread of bacteria from ruptured tubercles/granuloma to blood and reaching many tissues
Spread through blood/circulation
Tuberculosis meningitis
- Complication in children with primary TB
- Adults with extensive TB in other parts of body
- AIDS suffers
- Immunosuppressed
Renal tuberculosis
- May present as a genito-urinary tract infection
- Can form abscesses in kidney cause extensive damage
Tuberculosis of bones + joints
- Affects cartilage with caseation lesions and spread to adjacent bones causing marked damage
In spine causes deformity – Pott’s disease
What does primary TB affect
Lungs(persistent dry cough)
Airways (wheezy cough),
Pleura (fluid on lungs, with pain, shortness of breath)
Can affect lymph nodes near lung/airways causing obstruction, cough
