Table 6.

Interlaboratory percent agreement by interpretive category among four laboratories of Etest results for seven antimicrobial agents against M. abscessus, M. chelonae, and M. fortuitum group

Drug% Agreementa for isolate
M. abscessusM. chelonaeM. fortuitum group
1801180218071814183118661351135213531359
Amikacin91.7 (S/I)88.9 (R)75.0 (S/I)91.7 (R)66.7 (R)66.7 (R)100 (S)100 (S)100 (S)100 (S)
Cefoxitin69.4 (R)100 (R)91.7 (R)100 (R)100 (R)100 (R)80.5 (S/I)100 (R)100 (S)91.7 (S/I)
Ciprofloxacin100 (R)100 (R)91.7 (R)100 (R)86.1 (R)100 (R)100 (S)100 (S)100 (S)100 (S/I)
Clarithromycin100 (S)100 (R)b 91.7 (S)100 (S)100 (S)100 (R)b 75.0 (R)94.4 (R)100 (S)100 (S)
Doxycycline100 (R)100 (R)100 (R)100 (S/I)100 (R)100 (R)100 (R)100 (R)100 (S)100 (S)
Imipenem97.2 (R)100 (R)100 (R)100 (R)100 (R)100 (R)80.5 (R)72.2 (R)72.2 (R)55.5 (S/I)
Trimethoprim-sulfamethoxazole100 (R)100 (R)100 (R)100 (R)100 (R)100 (R)75.0 (S)100 (S)100 (S)100 (S)
  • a Interpretive category suggested in Table 1. S, susceptible; I, intermediate; R, resistant.

  • b Strain contains 23S rRNA gene mutation at position 2058 or 2059 that confers high-level resistance to clarithromycin (11, 15).