13. Drug Susceptibility Testing

Drug Susceptibility Testing

  • Primary drugs (for M. tuberculosis)
    • Bactec system
    • Rifampin, Isoniazid, Streptomycin, Ethambutol, Pyrazinamide
  • Secondary drugs
    • Agar proportion method
    • Disk diffusion method
Growth control
3+
Agar Proportion Method
Control (1/100 dilution)
8 col
Clarithromycin 15ug/ml
0
Doxycycline 6ug/ml
3+
Trimeth/Sulfa30ug/ml
3+
Cefoxitin 30ug/ml
13 col
Tobramycin 8ug/ml
3+
Amikacin 6ug/ml
3+
Amikacin 30ug/ml
0
Ciprofloxacin 8ug/ml
3+

Disposition

  • Final Interpretation
  • Mycobacterium chelonae complex with susceptibility pattern consistent with Mycobacterium abscessus

    • Susceptible only to
      • Amikacin
      • Clarithromycin