TABLE 1.
Interpretive category errors associated with application of the proposed breakpoints to the strains tested in this study
| Antimicrobial agent (disk content in μg unless otherwise noted) | % Error for 50 strains tested in four laboratoriesa
|
% Error for 100 unique strainsa
|
||||
|---|---|---|---|---|---|---|
| m | M | VM | m | M | VM | |
| Penicillin (10 U) | 26 | 0.5 | 0 | 19 | 0 | 0 |
| Ampicillin (10) | 13.5 | 0 | 0 | 11 | 0 | 0 |
| Cefotaxime (30) | 0 | 0 | 0 | 0 | 0 | 0 |
| Ceftriaxone (30) | 0 | 0.5 | 0 | 0 | 0 | 0 |
| Meropenem (10) | 0 | 0 | 0 | 0 | 0 | 0 |
| Chloramphenicol (30) | 1 | 0 | 0 | 2 | 0 | 0 |
| Rifampin (5) | 0 | 0 | 0 | 0 | 0 | 0 |
| Trimethoprim-sulfamethoxazole (1.25-23.75) | 0 | 0 | 0 | 2 | 0 | 0 |
| Minocycline (30) | 0 | 0 | 0 | 0 | 0 | 0 |
| Azithromycin (15) | 0 | 0 | 0 | 0 | 0 | 1 |
| Ciprofloxacin (5) | 1 | 0 | 0 | 0 | 0 | 0 |
| Nalidixic acid (30) | 0 | 0 | 0 | 0 | 0 | 0 |
a
m, minor interpretive error (i.e., intermediate category versus susceptible or resistant categories); M, major interpretive error, susceptible by the reference MIC method, resistant by the disk test; VM, very major interpretive error, resistant by the reference MIC method, susceptible by the disk test.