Tuberculosis Flashcards
Describe the groups vulnerable to getting TB in the UK.
-HIV positive individuals
-Immunosuppressed individuals
-People from high prevalence countries
-Elderly, neonates, diabetics
-Homeless
-Alcoholics
-Prison
What proportional of all TB cases in the UK are alcoholics/homeless/in prison?
1 in 10
TB kills more than which two diseases together?
Malaria and HIV
What ranking is TB on deaths of commuincable diseases?
2
after Covid-19
How many people worldwide are estimated to have TB?
2 billion
List some countries where TB is more prevalent.
Nigeria, Pakistan, China, Philippines, Bangladesh, India, Indonesia
Where are mycobacteria found?
Soil and water
Name some species of mycobacteria responsible for TB.
M. tuberculosis, M.africanum, M. bovis
M= mycobacteria
What mycobacteria causes leprosy?
M.leprae
Describe mycobacteria.
Non-motile bacillus, very slowly growing, aerobic
What can be frustrating about diagnosing/treating TB?
Disease is slow and long to treat
Which part of the lungs does TB affect?
Upper part of the lungs- aerobic
Describe the cell wall of mycobacteria.
Thick and fatty cell wall
Due to the thick and fatty cell wall, what are mycobacteria resistant to?
Acids, alkalis, detergents
Neutrophil and macrophage detruction
What is the route of transmission for TB?
Airbourne
What is the one exception to the transmission of TB being airborne?
thanksjacquelinewilsonforwritingqueenie
Cows milk- unpasteurised and infected by Mycobacterium bovi
List some ways TB is NOT spread.
- Shaking hands
- Sharing food
- Touching surfaces
- Sharing toothbrushes
- Kissing
How can someone get TB via the air?
TB bacteria attached to aerosol droplets which can remain suspended in air for many
hours, especially if there is poor air circulation
Someone else breathes these bacteria in
What is usually required for someone to develop TB?
Prolonged contact
How is mycobacteria eliminated outdoors?
UV radiation and dilution
What % of all TB cases are in the lungs?
50%
What is the second most likely part of the body to get infected by TB after the lungs?
Lymph nodes
Does post-primary TB occur in humans or animals?
Only in humans
What is DOT?D
Directly observed therapy
Nurse goes into the home of individual infected w TB to watch them take their medication to reduce likelihood of spreading it to others.
Often happens with people who may struggle to remember to take medication.
What happens to TB bacteria in alveoli?
Macrophages recognize it and ingest the bacteria
T helper cells are activated and come from the lymph nodes.
Lymph nodes secrete various cytokines
Macrophages become activated
What do activated macrophages turn into?
Langhan’s giant cells
What forms when there is an accumulation of Langhan’s giant cells, macrophages and epithelioid?
Granuloma
What can the granuloma lead to?
Necrotic tissue, which may calcify later and tissue damage
Why are there pros and cons to Th1 cell mediated immunological responses?
Eliminates / Reduces number of invading mycobacteria
Tissue destruction is a consequence of activation of macrophages
What does the outcome of a TB infection depend on?
Infection and Susceptibility
What is meant by infection in terms of the outcome?
Virulence of infection
Number of infections
What is meant by susceptibility in terms of the outcome?
Genetics
Nutrition
Age
Immunosuppression
What are the three paths that a primary infection of TB could go down?
Progressive disease
Contained/ latent
Cleared/cured
What can primary infection lead to?
Tuberculous bronchopneumonia
Miliary TB
What is Bronchopneumonia?
Bronchopneumonia is a type of pneumonia that causes inflammation in the alveoli.
What can happen in Tuberculous bronchopneumonia?
Enlargement of hilar lymph compresses bronchi which can lead to lobar collapse.
Enlargement of lymph node can discharge into the bronchus
What happens in miliary TB?
Hematogenous spread of bacteria to multiple organs
Looks like millet seeds on autopsy
What are the two hypotheses for why humans develop post-primary TB while animals do not?
- TB bacteria entering a dormant stage with low or no replication over prolonged
periods of time - Balanced state of replication and destruction by immune mechanisms
How long can Miliary, Meningeal, Pleural TB last?
6-12 months
How long can post primary TB last?
1-5 years
But could be 30-40
How long can Genitourinary, Cutaneous TB last?
10-15 years
But could be 30-40
What is the clinical presentation for someone w TB?
- Cough
- Fever
- Sweats (mainly at night)
- Weight loss
What is important to note about the presenting symptoms?
A lot of people don’t have all of them and some don’t have any.
What may a chest xray look like in someone w TB?
Apices, soft ‘fluffy/nodular upper zone- like cotton wool
Cavitation in 10-30%
When might you consider CT for a patient with suspected/confirmed TB?
*Normal CXR but clinical suspicion
* Miliary TB
* Cavitation & other differential
* Lymphadenopathy, alternative diagnosis
* targets for BAL
Are mediastinal lymphadenopathy usually bilateral or unilater?
Unilateral
List some of the investigations used to diagnose TB
- Sputum; 3 samples, 8-24hrs gap, at least 1 early morning sample
- Induced sputum
- Bronchoscopy with BAL
- Endobronchial ultrasound (EBUS) with biopsy
- Lumbar puncture in CNS TB
- Urine in urogenital TB
- Aspirate/biopsy from tissue ( lymph-node, bone, joint, brain, abscess …)
Multi drug treatment is used when treating TB.
Why?
Single agent treatment leads to drug resistant organisms within 14 days
In terms of treatment for TB, how can you remember number and types of treatment?
4/2:2/4
Describe 4/2:2/4
Four drugs for two months
Two drugs for four months
Which two drugs do you have for the whole six months of treatment?
Rifampicin and isoniazid,
Which two drugs do you add in, alongside Rifampicin and isoniazid,, for the first two months of treatment?
Pyrazinamide and ethambutol
What can be given to reduce risks of isoniazid induced poly neuropathies?
Vitamin B6
Which vaccine is given to selected groups to help reduce risks of TB?
BCG vaccine
