9.0 Anti-Mycobacterials Flashcards
Which drugs are 1st line anti-mycobacterials? (5)
- Isoniazid
- Rifampin
- Rifabutin (1st line in HIV +ve patients)
- Ethambutol
- Pyrazinamide
Which drugs are 2nd line anti-microbacterials? (4)
- Streptomycin
- Ethionamide
- Levofloxacin
- Amikacin
Which anti-mycobacterial agent is the sole drug for latent infection?
Isoniazid
What is DOT?
Directly Observed Therapy: regiments are recommended in noncompliant patients or resistance strains.
-Healthcare worker is physically present when pt takes medicine
What is the MOA of Isoniazind?
- Pro-drug (activated by a mycobacterial catalaseperoxidase- KatG)
- Targets enzymes involved in mycolic acid synthesis:
- enoyl acyl carrier protein reductase (InhA)
- B-ketoacyl-ACP synthase (KasA)
How does Isoniazid resistance via mutations occur?
- mutation of deletion of KatG
- mutations of acyl carrier proteins
- overexpression of inhA
What is the most important adverse effect of Isoniazid?
Peripheral Neuritis
How is peripheral neuritis as a result of isoniazid corrected?
Pyridoxine supplementation
Besides Peripheral Neuritis, what are the other A.E. from Isoniazid?
- Hepatotoxicity: clinical hepatitis & idiosyncratic
- CYP P450 inhibitor
- Lupus-like syndrome: rare
What is the MOA of Rifampin?
• Blocks transcription by binding to B subunit of bacterial DNA-dependent RNA polymerase
-> leading to inhibition of RNA synthesis
What are the clinical uses of Rifampin?
- TB
- Latent TB in INH intolerant patients
- Leprosy
- Prophylaxis for individuals exposed to meningitis
- MRSA (with vancomycin)
How does Rifampin gain resistance?
• Point mutations in rpoB, the gene for the B subunit of RNA polymerase
-> decreased affinity of bacterial DNA-dependent RNA polymerase for drug
• Decreased permeability
What is the DOC for HIV patients with TB?
Rifabutin
Which Drugs would cause an orange/red body fluid discharge?
Rifampin
Which anti-mycobacterial drug is specific for strains of M.tuberculosis & M.kansasii?
Ethambutol
