TB Flashcards
How many people are infected with TB worldwide
2 billion
How many new cases of TB are there annually
8.6 million
How many of the new annual cases are in HIV positive patients
1.1 million (75% in Africa)
How many of the new annual cases are in children
530,000
How many deaths occur annually due to TB
1.3 million
How many of the annual deaths are in HIV positive patients
0.3 million
How many of the annual deaths are in children
74,000
How many TB cases in the UK are in London
39%
45 cases per 100,000
How many TB cases in the UK are in the West Midlands
11%
20 cases per 100,000
What is the responsible organism for TB
Mycobacteria
Where is mycobacteria ubiquitous
Soil
Water
Name two of the main TB causing organisms
Mycobacterium Tuberculosis
Mycobacterium Bovis
Is Mycobacterium Bovis still an issue
No
It has been eradicated through the pasteurisation of milk
In how many UK isolations is Mycobacteria other than tuberculosis (MOTT) found
30%
When does MOTT tend to be an issue
In patients with an underlying lung condition
Name 4 organisms that are classed under MOTT
Mycobacterium avium-intracellulare (HIV)
M. kansasii
M. malmoense
M. xenopii
What bacteria causes leprosy
Mycobacterium Leprae
What is mycobacteria
A curved non-motile bacillus
Very slow growing
How long is TB treatment
6 months
How can mycobacteria grow
Aerobically
This is why it favours the apices of the lungs
State 4 properties of mycobacteria
Very thick cell wall
Lipids
Peptidoglycans
Arabinomannans
What is mycobacteria resistant to
Acids, alkalis and detergents
Neutrophil and macrophage destruction
What type of dyes can complex with mycobacteria cell wall
Aniline based dyes such as carbol fuschin
What other type of staining can be used on mycobactera
Acid and alcohol fast bacilli (Ziehl Neilson stain)
What is open pulmonary TB
Cavity in the upper lobe of the lung
Which mycobacterium causes ‘open’ pulmonary TB, coughing and sneezing
Mycobacterium Tuberculosis
What do the respiratory droplets of M. tuberculosis contian
Droplet nuclei containing mycobacteria
How many nuclei are expelled from one cough
3,500
How long do droplets remain airborne for
Very long periods
What can eliminate mycobacteria
UV radiation
Infinite dilution
What do the larger droplet nuclei impact on
Large airways
They can be cleared
How big are the small droplet nuclei
Under 5 micrometers
What do the small droplet nuclei have
1-3 organisms which can impact the alveoli and slowly proliferate
Where can mycobacterium bovis be consumed from
Infected cow’s milk
Where is mycobacterium bovis deposited
Cervical and intestinal lymph nodes
How to macrophages in the alveoli become activated
Th1 cells
What can the activated macrophage kill
Bacterium but causes tissue damage at the same time
What do activated macrophages transform into
Epithelioid cells and then transform into Langhan’s giant cells.
What is a granuloma
Accumulation of macrophages, epithelioid and Langhan’s cells
What is an identifying factor of TB
Central caseating necrosis
What 2 things does the Th1 cell mediated immunological response cause
Eliminates/reduces the number of invading mycobacteria
Tissue destruction due to the activation of macrophages
Why must the outcome of infection be very finely balanced
As any tip of the scale can cause active disease
What factors can affect susceptibility
Genetics Race Nutrition Age Immunosuppression
What factors can affect infecion
Virulence
Number
