TABLE 1.
Comparison of Phoenix and Vitek 2 results to reference BMD oxacillin MICs
| System testeda | % Categorical agreement | No. of resistant isolatesb | No. (%) VM errorsc | No. of susceptible isolatesb | No. (%) major errorsd | % Essential agreemente | No. of instrument oxacillin MIC results within the following log2 dilution of reference method MIC
|
||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| >−2 | −2 | −1 | Same | +1 | +2 | >+2 | |||||||
| Phoenix | 99.8 | 448 | 1 (0.2) | 172 | 0 (0) | 91.6 | 5 | 3 | 10 | 491 | 67 | 42 | 2 |
| Vitek 2 | 99.7 | 448 | 1 (0.2) | 172 | 1 (0.6) | 94.7 | 6 | 2 | 10 | 511 | 66 | 25 | 0 |
a
A total of 620 isolates were tested with each system.
b
As determined by the reference BMD method.
c
A VM error was resistance by the reference method but susceptibility by the automated method; percentages are based on the number of resistant isolates.
d
A major error is susceptibility by the reference method but resistance by the automated method; percentages are based on the number of susceptible isolates.
e
Essential agreement is an MIC determined with the Phoenix or Vitek 2 system that is ±1 log2 dilution of the MIC determined by the reference method.