Flashcards in Myobacteria Deck (20):
What type of bacteria are mycobacteria?
Gram positive, bacillus
Whats different about mycobacteria to normal bacteria
-very waxy cell wall
-poor update of gram stain 'ghost cell'
What is the difference between infection and disease?
Mycobacterium (i.e. TB) = intracellular pathogen (requires ingestion by host immune system)
Infection - host = carrier of disease but without symptoms
Disease - carrier with associated symptoms
Is treatment for TB long or short?
Long - 6 moths using combinational therapeutics (prevents resistance)
What are the bacterium that cause TB and leprosy (most of the time)?
M tuberculosis/M Bovis - TB
M leprae - leprosy
Whats the main mode of transmission?
Respiratory droplets - most pulmonary disease
What is mean by primary TB?
Acquisition of disease
Inhaled bacilli phagocytosed my macrophages (unable to kill)
Macrophages carried back to Hilar lymph nodes
Disseminated via lymph system/bloodstream
Where is the most common site for primary TB in the lung?
Periphery of lung mid-zone
What is it called when machrohages carry TB to Hilar lymph nodes?
What is the bodies response to primary TB infection?
- Cell mediated immune réponse - antibodies not really involved
-Central area of epithelia cell, giant cells - central region of caseous necrosis
- Fibrosis and calcification of lesions
-Bacilli slowly die/remain viable for 20 years
What are the symptoms of primary TB?
Usually asymptomatic, flu like, chest X-ray = normal
- Tuberculin skin test - positive (after acquisition)
What condition predisposes individuals to reactivation TB?
Immunosuppressed e.g. malnutrition, alcoholics, HIV
Individuals taking anti TNF alpha medication (immunosuppression) - infliximab
What are the symptoms of reactivation TB?
Chronic productive cough (2-3 weeks) - haemoptysis
What are the main characteristics of reactivation TB?
- coalescing TB - central caseous necrosis
- Cavitation - results in greater viral load - risk of transmission
Where does reactivation TB usually occur in the lung?
Apices of the lung (highest O2 tension - require O2 to survive)
What is miliary TB?
widespread infection (primary or secondary with erosion of necrotic tubercle) - immunocompromised or young/old
What characterises TB meningitis
May lack constitutional 'quartet' e.g. fever, anorexia, weight loss, night sweats
What stain is used in TB Diagnosis?
Acid fast bacillus
What is the standardised therapy for TB?
'Directly observed therapy short' (DOTS) - course
For pulmonary - 4 antibiotics (RIPS):
1st 2 months