TABLE 1.
Breakpoints (current and proposed) for three tetracyclines with the summary of intermethod error ratesa
| Antimicrobial agent (no. of tests/no. of resistant strains) | Current CLSI (2006) breakpoints
|
Proposed CLSI (2007) breakpoints
|
||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Criterion (mm)
|
Error rate (%)
|
Criterion (mm)
|
Error rate (%)
|
|||||||
| Susceptible | Resistant | VM | Ma | Mib | Susceptible | Resistant | VM | Ma | Mi | |
| Tetracycline (504/140) | ≥19 | ≤14 | 0.0 | 0.8 | 14.9 | ≥15 | ≤11 | 0.0 | 0.0 | 4.4 |
| Doxycycline (504/120) | ≥16 | ≤12 | 0.0 | 0.4 | 11.5 | ≥14 | ≤10 | 0.2 | 0.0 | 5.6 |
| Minocycline (288/60) | ≥19 | ≤14 | 0.0 | 0.7 | 30.6 | ≥16 | ≤12 | 0.3 | 0.0 | 8.3 |
a
VM, very major (false-susceptible) error; Ma, major (false-resistant) error; Mi, minor errors (discords involving an intermediate interpretation).
b
Underlined error rates indicate unacceptable levels of intermethod discord (NCCLS, M23-A2) (17).