TABLE 3.
Comparison of Phoenix to reference method MICs and interpretive category errors for beta-hemolytic streptococcus groups A, C, and G
| Isolates and antimicrobial agent | No. of isolates | Initial/resolved
|
|||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| % CA | No. of resistant isolatesa | No. (%) of VM errorsb | No. of susceptible isolatesa | No. (%) of major errorsc | No. (%) of minor errorsd | % EAe | No. of Phoenix MICs within specified log2 no. of dilutions of reference method MIC
|
||||||||
| >−2 | −2 | −1 | Same | +1 | +2 | >+2 | |||||||||
| Clinical | |||||||||||||||
| Cefepime | 266 | 100 | 0 | 0 (0) | 266 | 0 (0) | 0 (0) | 98.9/99.6 | 0 | 3/1 | 2/3 | 261/262 | 0 | 0 | 0 |
| Cefotaxime | 267 | 100 | 0 | 0 (0) | 267 | 0 (0) | 0 (0) | 99.3/100 | 1/0 | 1/0 | 0/1 | 265/266 | 0 | 0 | 0 |
| Ceftriaxone | 266 | 99.6/100 | 1/0 | 1 (100)/0 (0) | 265/266 | 0 (0) | 0 (0) | 99.2/100 | 1/0 | 1/0 | 2/3 | 262/263 | 0 | 0 | 0 |
| Clindamycin | 268 | 96.6/97.0 | 3 | 0 (0) | 264 | 7 (2.7)/6 (2.3) | 2 (0.7) | 93.3/93.7 | 0 | 2 | 24 | 87/88 | 139 | 8 | 8/7 |
| Erythromycin | 266 | 97.7/99.2 | 25 | 0 (0) | 241 | 4 (1.7)/0 (0) | 2 (0.8) | 92.9/94.4 | 0 | 0 | 30 | 145/147 | 72/74 | 15/14 | 4/1 |
| Gatifloxacin | 268 | 98.9 | 0 | 0 (0) | 268 | 0 (0) | 3 (1.1) | 85.1/85.4 | 0 | 1 | 4 | 33 | 191/192 | 33/32 | 6 |
| Levofloxacin | 268 | 99.3/99.6 | 0 | 0 (0) | 267/268 | 0 (0) | 2 (0.7)/1 (0.4) | 95.9/96.3 | 0 | 2/1 | 13 | 108 | 136/137 | 8 | 1 |
| Linezolid | 268 | 96.3/99.3 | 10/2 | 10 (100)/2 (100) | 258/266 | 0 (0) | 95.9/98.5 | 1 | 9/2 | 145/152 | 103 | 9 | 0 | 1 | |
| Meropenem | 267 | 100 | 0 | 0 (0) | 267 | 0 (0) | 0 (0) | 99.6/100 | 0 | 1/0 | 1 | 264/265 | 1 | 0 | 0 |
| Penicillin | 267 | 98.9/100 | 3/0 | 3 (100)/0 (0) | 264/267 | 0 (0) | 0 (0) | 97.8/98.5 | 3/1 | 3 | 8 | 251/253 | 2 | 0 | 0 |
| Tetracycline | 247 | 98.0/98.4 | 31/30 | 1 (3.2)/0 (0) | 212/213 | 1 (0.5) | 3 (1.2) | 91.5/91.9 | 1/0 | 1 | 24 | 140/141 | 62 | 14 | 5 |
| Vancomycin | 267 | 100 | 0 | 0 (0) | 267 | 0 (0) | 99.6 | 0 | 1 | 69 | 190 | 7 | 0 | 0 | |
| Challenge | |||||||||||||||
| Cefepime | 20 | 100 | 0 | 0 (0) | 20 | 0 (0) | 0 (0) | 100 | 0 | 0 | 0 | 20 | 0 | 0 | 0 |
| Cefotaxime | 20 | 100 | 0 | 0 (0) | 20 | 0 (0) | 0 (0) | 100 | 0 | 0 | 0 | 20 | 0 | 0 | 0 |
| Ceftriaxone | 19 | 100 | 0 | 0 (0) | 19 | 0 (0) | 0 (0) | 100 | 0 | 0 | 0 | 19 | 0 | 0 | 0 |
| Clindamycin | 17 | 94.1 | 3 | 0 (0) | 14 | 0 (0) | 1 (5.9) | 88.2 | 0 | 0 | 1 | 5 | 9 | 1 | 1 |
| Erythromycin | 17 | 94.1 | 12 | 0 (0) | 5 | 0 (0) | 1 (5.9) | 82.4 | 0 | 0 | 0 | 11 | 3 | 2 | 1 |
| Gatifloxacin | 19 | 100 | 0 | 0 (0) | 19 | 0 (0) | 0 (0) | 89.5 | 0 | 0 | 0 | 0 | 17 | 2 | 0 |
| Levofloxacin | 20 | 100 | 0 | 0 (0) | 20 | 0 (0) | 0 (0) | 100 | 0 | 0 | 0 | 9 | 11 | 0 | 0 |
| Linezolid | 19 | 100 | 0 | 0 (0) | 19 | 0 (0) | 100 | 0 | 0 | 5 | 14 | 0 | 0 | 0 | |
| Meropenem | 20 | 100 | 0 | 0 (0) | 20 | 0 (0) | 0 (0) | 100 | 0 | 0 | 0 | 20 | 0 | 0 | 0 |
| Penicillin | 20 | 100 | 0 | 0 (0) | 20 | 0 (0) | 0 (0) | 100 | 0 | 0 | 0 | 20 | 0 | 0 | 0 |
| Tetracycline | 20 | 100 | 6 | 0 (0) | 14 | 0 (0) | 0 (0) | 85 | 0 | 2 | 0 | 10 | 7 | 1 | 0 |
| Vancomycin | 20 | 100 | 0 | 0 (0) | 20 | 0 (0) | 100 | 0 | 0 | 0 | 18 | 2 | 0 | 0 | |
a
Based on reference method result.
b
VM error, resistant by the reference method but susceptible by Phoenix; percent based on the number of resistant isolates.
c
Major error, susceptible by the reference method but resistant by Phoenix; percent based on the number of susceptible isolates.
d
Minor error, intermediate by the reference method but resistant or susceptible by Phoenix or intermediate by Phoenix but susceptible or resistant by the reference method.
e
EA, Phoenix MIC ±1 log2 dilution of reference method MIC.