TABLE 5.
Comparison of Phoenix to reference method MICs and interpretive category errors for viridans group streptococci
| 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 | 329 | 92.7 | 14 | 1 (7.1) | 294 | 0 (0) | 23 (7.0) | 90.9/91.2 | 1 | 16/15 | 82/83 | 192 | 25 | 9 | 4 |
| Cefotaxime | 329 | 96.7 | 17 | 1 (5.9) | 304 | 0 (0) | 10 (3.0) | 91.5 | 2 | 18 | 73 | 207 | 21 | 6 | 2 |
| Ceftriaxone | 330 | 96.7 | 15 | 0 (0) | 307 | 0 (0) | 11 (3.3) | 92.4 | 1 | 11 | 62 | 214 | 29 | 9 | 4 |
| Clindamycin | 327 | 99.1 | 22 | 1 (4.5) | 302 | 0 (0) | 2 (0.6) | 96.3 | 1 | 2 | 55 | 214 | 46 | 7 | 2 |
| Erythromycin | 333 | 94/95.5 | 199/198 | 10 (5.0)/7 (3.5) | 133/134 | 7 (5.3)/4 (3.0) | 3 (0.9)/4 (1.2) | 84.7/85.9 | 13/12 | 20/19 | 86/89 | 171 | 25/26 | 9 | 9/7 |
| Gatifloxacin | 333 | 98.2/98.5 | 15 | 0 (0) | 315/317 | 2 (0.6) | 4 (1.2) | 91.6/92.2 | 2 | 7/6 | 71 | 163/165 | 71 | 14/13 | 5 |
| Levofloxacin | 334 | 98.5 | 17 | 1 (5.9) | 316 | 2 (0.6) | 2 (0.6)/3 (0.9) | 96.4/96.7 | 1/0 | 4 | 98 | 189/190 | 35 | 4 | 3 |
| Linezolid | 328 | 99.4 | 0 | 0 (0) | 328 | 2 (0.6) | 97.9/98.2 | 0 | 3/2 | 124/125 | 169 | 28 | 2 | 2 | |
| Meropenem | 330 | 98.2/98.8 | 38/37 | 4 (10.5)/2 (5.4) | 292/293 | 2 (0.7) | 0 (0) | 89.1/89.4 | 5/4 | 18 | 77/78 | 180 | 37 | 11 | 2 |
| Penicillin | 329 | 86.9 | 30 | 0 (0) | 188 | 0 (0) | 43 (13.1) | 86.9 | 10 | 14 | 54 | 165 | 68 | 10 | 8 |
| Tetracycline | 323 | 90.4/92.0 | 102/101 | 9 (8.8)/5 (5.0) | 207 | 6 (2.9)/3 (1.4) | 16 (5.0)/18 (5.6) | 83.3/85.1 | 15/11 | 12/11 | 55/56 | 172/176 | 42/43 | 13 | 14/13 |
| Vancomycin | 329 | 100 | 0 | 0 (0) | 329 | 0 (0) | 96.0 | 1 | 8 | 155 | 147 | 14 | 1 | 3 | |
| Challenge | |||||||||||||||
| Cefepime | 11 | 90.9 | 0 | 0 (0) | 11 | 0 (0) | 1 (9.1) | 100 | 0 | 0 | 2 | 7 | 2 | 0 | 0 |
| Cefotaxime | 10 | 90 | 0 | 0 (0) | 10 | 0 (0) | 1 (10.0) | 100 | 0 | 0 | 0 | 7 | 3 | 0 | 0 |
| Ceftriaxone | 11 | 90.9 | 0 | 0 (0) | 11 | 0 (0) | 1 (9.1) | 100 | 0 | 0 | 0 | 8 | 3 | 0 | 0 |
| Clindamycin | 9 | 100 | 0 | 0 (0) | 9 | 0 (0) | 0 (0) | 88.9 | 0 | 0 | 0 | 7 | 1 | 1 | 0 |
| Erythromycin | 8 | 87.5 | 3 | 1 (33.3) | 5 | 0 (0) | 0 (0) | 75 | 0 | 1 | 0 | 4 | 2 | 1 | 0 |
| Gatifloxacin | 10 | 100 | 1 | 0 (0) | 9 | 0 (0) | 0 (0) | 100 | 0 | 0 | 1 | 5 | 4 | 0 | 0 |
| Levofloxacin | 11 | 100 | 1 | 0 (0) | 10 | 0 (0) | 0 (0) | 100 | 0 | 0 | 3 | 7 | 1 | 0 | 0 |
| Linezolid | 9 | 100 | 0 | 0 (0) | 9 | 0 (0) | 100 | 0 | 0 | 3 | 5 | 1 | 0 | 0 | |
| Meropenem | 9 | 100 | 0 | 0 (0) | 9 | 0 (0) | 0 (0) | 88.9 | 0 | 0 | 1 | 6 | 1 | 1 | 0 |
| Penicillin | 11 | 90.9 | 1 | 0 (0) | 8 | 0 (0) | 1 (9.1) | 90.9 | 0 | 0 | 1 | 4 | 5 | 1 | 0 |
| Tetracycline | 10 | 80 | 1 | 0 (0) | 8 | 0 (0) | 2 (20.0) | 80 | 1 | 0 | 2 | 3 | 3 | 0 | 1 |
| Vancomycin | 10 | 100 | 0 | 0 (0) | 10 | 0 (0) | 100 | 0 | 0 | 3 | 6 | 1 | 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.