Flashcards in Tuberculosis Deck (21)
What are the different outcomes after the first exposure to the bacteria?
Elimination of the bacteria
Control and then elimination of the bacteria
Control - latent tb
Unable to control, active TB -> primary infection
Describe the TB granuloma
Consists of central caseous necrosis surrounded by epithleiod histiocytes, lymphocytes, and langhans giant cells
(Giant cells are multi-nucleated macrophages. Langhans have a horseshoe arrangement of nuclei and abundant cytoplasm)
What is meant by the primary or Ghon's focus?
The primary focus is formed by the deposition of tb bacilli in the alveoli, followed by the development of sub-pleural granulomas
What is meant by the primary complex?
The primary focus drains in to the hilar lymph nodes to form the primary complex
What is the presentation of a patient with a TB infection?
Persistent cough, NIGHT SWEATS, fever, haemoptysis, weight loss, sob, fatigue, enlarged lymph nodes, crackles due to the consolidation
n.b Children present in a similar way to adults
What can be seen on a chest x-Ray of a patient with a TB infection?
Enlarged hilar lymph nodes, consolidation, cavitation, healing leading to fibrosis, shadowing, calcification and cardiomegaly
What is meant by miliary TB?
What investigations need to be done if miliary TB is suspected?
The bacilli have spread through the blood stream
If suspected, must perform MRI brain/spine and LP. This is due to the high rate of blood borne spread to the meninges
What is the management of TB?
Rifampicin, ethambutol, isoniazid, pyrazinamide for 2 months
Continue Rifampicin and Isoniazid for a further 4 months
Pyridoxine (vitamin B6) given for 6 months to reduce peripheral neuropathy
Compound therapy used to reduce emergence of MDR
What are the side effects of pyrazinamide?
What can be done to monitor the side effects?
Hepatitis, rashes, vomiting, gout (increases uric acid levels)
Liver function tests
What are the side effects of ethambutol?
What can be done to monitor this side effect?
Base-line visual test, and during the course of the drug, check each eye independently
Colour vision is the first to deteriorate
Dose decrease needed with renal impairment
What three events can occur if a person has latent TB?
They may eliminate the bacteria
They may have life-long containment of the bacteria
They may have re-activation when the immune system can no longer contain the bacteria, this is post-primary/secondary TB
What is meant by latent TB?
The bacilli are contained and controlled by the immune system by being enclosed in a barrier shell of macrophages
It should be suspected with positive testing (Mantoux and Quantiferon)
If positive Quantiferon - 3 months of Rifampicin and Isoniazid or 6 months of Isoniazid
and close contact with active/latent
These patients need regular CXR to look for active TB
What are the side effects of Rifampicin?
Hepatitis - monitor liver function tests
Bodily fluids become orange/red (n.b. Contact lenses)
What are the side effects of isoniazid?
Hepatitis (monitor LFTs), rashes, peripheral neuropathy (pyridoxine can be given as prophylaxis for the full 6 months of treatment), psychosis
What are the risk factors for TB?
Past history of TB
Known history of TB contact
Born in a country with a high TB incidence
Travel to a country with a high TB incidence
Who should be screened for latent TB?
What does this involve?
People who are younger than 35, HIV positive or HCW who have been in contact with a person infected with TB
What happens with DOT (Directly Observed Treatment)?
Risk assessment for treatment adherence consider in
History of poor adherence
All prisoners with active or latent TB
Three times a week dosing
Name 3 conditions that increase the risk of latent TB becoming active
Solid organ transplant
Anti-TNF alpha treatment
What type of micro-organism is Mycobacterium tuberculosis?
How can they be identified?
Aerobic, acid and alcohol fast bacilli
They can be demonstrated on smears stained by the Ziehl-Nielsen method - within 24 hours, 3x sputum samples (ideally early morning samples)
TB culture can take 6-8 weeks to assess Abx sensitivity
Spread from person to person by aerosol droplets
What is the treatment for meningeal TB?
All 4 (RIPE) for 2 months
Then Rifampicin and isoniazid for 10 months (continuation phase)
Dexamethazone or Prednisolone should be offered for 4 weeks, then a steroid reducing regime