Table 1.

Suggested broth microdilution breakpoints for rapidly growing mycobacteriaa

DrugMIC (μg/ml) for category:
SusceptibleIntermediateResistant
Amikacinb ≤1632≥64
Cefoxitin≤1632 [32–64]≥64 [≥128]
Ciprofloxacinb ≤12≥4
Clarithromycinb ≤24≥8
Doxycycline≤12–8≥16
Imipenemb ≤48≥16
Sulfamethoxazoleb,c ≤32≥64
Tobramycin (M. chelonaeonly)≤48≥16
  • a Breakpoints recommended by the American Society for Microbiology Clinical Procedures Handbook (3). Proposed new breakpoints are in brackets.

  • b NCCLS recommended breakpoint for bacteria that grow aerobically (8a).

  • c NCCLS recommendations are for trimethoprim-sulfamethoxazole at similar but not identical concentrations.