Tuberculosis Flashcards
Tb is an _________ pathogen
Airbourne
What is the difference between Tb infection and disease?
Infection means the pathogen cannot be cleared and disease means symptoms are experienced
Where will Tb normally be more prevalent in the lungs?
Apices
Why does Tb usually grow preferentially in the lung apices?
Tb is an aerobic pathogen
In the apices of the lungs there is generally more ventilation than perfusion meaning inhaled aerobic pathogens will thrive most here
Which type of bacteria is Tb?
Bacilli
Why does Tb involve gramuloma formation?
Tb can enter alveoli and enter macrophages.
To respond, the body walls off the infected macrophages in a granuloma
In people experiencing Tb symptoms, the body cannot hold the ________ within the _________
Infection
Granuloma
How long can a granuloma hold the infection of Tb at bay?
It can vary from days to years
A Tb infection can remain “dormant” for many years
Systemic symptoms of Tb include?
Weight loss, malaise and night sweats
Respiratory symptoms of Tb include?
Cough, haemoptysis, breathlessness and upper zone crackles
If lower lobes are infected with Tb, what does this suggest?
The infection occured through blood spread (sepsis)
Tb does not just infect the lungs. What are some other complications of Tb?
- Meningeal Tb
- GI Tb
- Spinal Tb
- Cold abscesses
- Lymphadeopathy
- Pericardial - cardiac tamponade
- Renal
- Septic arthritis
- Adrenal - hypoadrenalism
Which type of stan can detect Tb?
Ziehl-Neelson
Describe the process by which Tb is identified through staining
- Tb is stained
- Alcohol and acid are added to remove the stain as far as possible
- The sample is washed with blue stain
- Any areas still red show presence of Tb which retains the original stain
Tb can be identified by staining, how else can it be identified?
PCR (polymerase chain reaction)
Culturing
The histology of Tb includes ___________ giant cell _________, _________ necrosis and potentially visible ___________
Multinucleate
Granulomas
Caseating
Mycobacteria
What is the treatment for Tb?
6 month antibiotic course
- 2 months of
- Rifampicin
- Isoniazid
- Pyrazinamide
- Ethambutol
Followed by
- 4 months of
- Rifampicin
- Isoniazid
What is a side effect of rifampicin?
It colours everything orange
(Bodily fluids, urine etc)
Metabolism is sped up in the liver leading to enhanced breakdown of steroid molecules (hormonal contraception) and opiates due to increased production of cytochrome enzymes
What is a side effect of ethambutol?
It can cause optic neuritis
Why does Tb treatent take so long?
There are two Tb populations:
- The replcating bacilli
- The trapped bacilli
What are the different types of Tb resistance?
- Single agent
- Multi-drug resistance
- Extensive drug resistance (rifampicin, isoniazid and quinolone plus an injectable)
What is latent Tb disease?
Symptomless Tb - Tb is in a dormant state
How can it be determined that Tb is active?
- Symptoms present
- Cues through history
- X-rays (can show previous Tb by calcification)
- Culturing is positive
What are two tests for previous Tb exposure?
- Interferon gamma release
- Mantoux (tuberculin test)
Tuberculin is a protein taken from mycobacteria which can prvoke a hypersensitivity reaction so it involves two visits, one for administering the tuberculin, another for measuring the response
