Tuberculosis Flashcards
Stages of TB Infection
How many have TB worldwide?
- 7 million
Mycobacterium TB Structure
- Mycobacteria
- Surrounded by waxy layer, rich in lipids
- Ziehl-Neelsen Stain
- Anaerobic
- Non spore forming
- Non-motile
- Bacillus
What is a Ziehl-Neelsen Stain?
- “Acid-fast stain”
What do we use to treat TB?
- 6 months of treatment:
- Intensive phase - 2 months of 4 drugs
- R, H,Z & E
- Continuation phase - 4 months of 2 drugs
- R, I
What is extra-pulmonary TB?
How does Rifampicin (R) work?
- Binds to RNA polymerase
- Inhibits DNA transcription into mRNA
- Thus inhibits protein synthesis
- Bacteriocidal
- CYP 3A4 inducer
What are the complications of Rifampicin?
- NEVER give it on its own
- It has loads of drug-drug interactions
- Reduces plasma drugs such as methadone and warfarin
- Therefore, patients are often prescribed lots of methadone alongside it.
How does Isoniazid (H) work?
- Inhibits mycolic acid synthesis (fatty acids are part of Mycolata cell wall)
- Bacteriocidal
- CYP inhibitor (not as strong as Rifampicin)
How does Ethambutol (E) work?
- Bacteriostatic - stops TB growing, but does not kill it altogether
- Cell wall inhibitor
- Inhibits arabiosyl transferase which polymerases arab….
How does Pyrazinamide (Z) work?
- Officially unknown
- Inhibits fatty acid synthesis
- Acidifies inside of bacillus
Complications of Pyrazinamide?
- Myalgia
- Gout
- Hepatitis
What is Streptomycin?
*
What are the 4 subpopulations of M.TB within the host?
- Extracellularly rapidly dividing
- Organisms that grow more slowly
- Organisms characterized by spurts of growth with periods of dormancy
- Dormant/persistent bacilli
Treatment of latent TB
- 6-9 months of Isoniazid
Problems with latent TB?
What is TB Chemotherapy?
How do we get patients to adhere to TB Chemotherapy?
- DOT
- Directly
- Observed
- Therapy
Explain the pharmacology of treating TB
What are the precautions before giving TB treatment?
(x3)
- Base-line LFTs (including transaminases, bilirubin…)
- Nephrotoxicity: Renal function, creatinine
- Snellan chart for optic neuritis, Ishiara Eye Chart
Types of Drug Resistance?
- Drug resistant TB
- Multi-resistant drug TB (Rifam and Ison)
- Extensively multi-drug resistant TB (Rifam, Ison, Fluroq, or 1 of 3 injectables: Cap/Kan/Am)
By when do scientists predict are we going to eliminate TB?
- 2035
Which genes are involved in drug resistant TB?
- rpoB (Rifampicin)
- rpoB encodes beta subunit of RNA polymerase
- katG (Isoniazid)
What is MDR TB?
- Multi-drug resistant TB
- Only Rifampicin and Isoniazid
