TABLE 5.
NG-Test Carba 5 medium comparison study by isolate, pre-discrepant analysisa
| Plate | Organism group (total no. of isolates) | NG-Test Carba 5 carbapenemase target (no. of expected positives) | No. of results |
PPA | 95% CI |
NPA | 95% CI |
|||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| TP | FP | FN | TN | Low | High | Low | High | |||||
| Blood agar | Enterobacterales (101) | KPC (n = 26) | 26 | 0 | 0 | 75 | 100.0 | 87.1 | 100.0 | 100.0 | 95.1 | 100.0 |
| OXA-48-like (n = 15) | 15 | 0 | 0 | 86 | 100.0 | 79.6 | 100.0 | 100.0 | 95.7 | 100.0 | ||
| VIM (n = 7) | 7 | 0 | 0 | 94 | 100.0 | 64.6 | 100.0 | 100.0 | 96.1 | 100.0 | ||
| IMP (n = 6) | 6 | 0 | 0 | 95 | 100.0 | 61.0 | 100.0 | 100.0 | 96.1 | 100.0 | ||
| NDM (n = 27) | 27 | 0 | 0 | 74 | 100.0 | 87.5 | 100.0 | 100.0 | 95.1 | 100.0 | ||
| OXA-48 + NDM (n = 3) | 3 | 0 | 0 | 98 | 100.0 | 43.9 | 100.0 | 100.0 | 96.2 | 100.0 | ||
| OXA-48 + VIM (n = 1) | 1 | 0 | 0 | 100 | 100.0 | 20.7 | 100.0 | 100.0 | 96.3 | 100.0 | ||
| Overall (n = 85) | 85 | 0 | 0 | 16 | 100.0 | 95.7 | 100.0 | 100.0 | 80.6 | 100.0 | ||
| P. aeruginosad (9) | VIM (n = 1) | 1 | 0 | 0 | 8 | 100.0 | 20.7 | 100.0 | 100.0 | 67.6 | 100.0 | |
| IMP (n = 3) | 3 | 0 | 0 | 6 | 100.0 | 43.9 | 100.0 | 100.0 | 61.0 | 100.0 | ||
| Overall (n = 4) | 4 | 0 | 0 | 5 | 100.0 | 51.0 | 100.0 | 100.0 | 56.6 | 100.0 | ||
| Enterobacterales + P. aeruginosa (110) | Overall (n = 89) | 89 | 0 | 0 | 21 | 100.0 | 95.9 | 100.0 | 100.0 | 84.5 | 100.0 | |
| MacConkey agar | Enterobacterales (101) | KPC (n = 26) | 26 | 0 | 0 | 75 | 100.0 | 87.1 | 100.0 | 100.0 | 95.1 | 100.0 |
| OXA-48-like (n = 15) | 15 | 0 | 0 | 86 | 100.0 | 79.6 | 100.0 | 100.0 | 95.7 | 100.0 | ||
| VIM (n = 7) | 7 | 0 | 0 | 94 | 100.0 | 64.6 | 100.0 | 100.0 | 96.1 | 100.0 | ||
| IMP (n = 6) | 6 | 1b | 0 | 94 | 100.0 | 61.0 | 100.0 | 98.9 | 94.3 | 99.8 | ||
| NDM (n = 27) | 27 | 0 | 0 | 74 | 100.0 | 87.5 | 100.0 | 100.0 | 95.1 | 100.0 | ||
| OXA-48 + NDM (n = 3) | 3 | 0 | 0 | 98 | 100.0 | 43.9 | 100.0 | 100.0 | 96.2 | 100.0 | ||
| OXA-48 + VIM (n = 1) | 1 | 0 | 0 | 100 | 100.0 | 20.7 | 100.0 | 100.0 | 96.3 | 100.0 | ||
| Overall (n = 85) | 85 | 1 | 0 | 15 | 100.0 | 95.7 | 100.0 | 93.8 | 71.7 | 98.9 | ||
| Enterobacterales + P. aeruginosa (110) | Overall (n = 89) | 89 | 1 | 0 | 20 | 100.0 | 95.9 | 100.0 | 95.2 | 77.3 | 99.2 | |
| Mueller-Hinton agar | Enterobacterales (101) | KPC (n = 26) | 26 | 0 | 0 | 75 | 100.0 | 87.1 | 100.0 | 100.0 | 95.1 | 100.0 |
| OXA-48-like (n = 15) | 15 | 0 | 0 | 86 | 100.0 | 79.6 | 100.0 | 100.0 | 95.7 | 100.0 | ||
| VIM (n = 7) | 7 | 0 | 0 | 94 | 100.0 | 64.6 | 100.0 | 100.0 | 96.1 | 100.0 | ||
| IMP (n = 6) | 5 | 0 | 1c | 95 | 83.3 | 43.7 | 97.0 | 100.0 | 96.1 | 100.0 | ||
| NDM (n = 27) | 27 | 0 | 0 | 74 | 100.0 | 87.5 | 100.0 | 100.0 | 95.1 | 100.0 | ||
| OXA-48 + NDM (n = 3) | 3 | 0 | 0 | 98 | 100.0 | 43.9 | 100.0 | 100.0 | 96.2 | 100.0 | ||
| OXA-48 + VIM (n = 1) | 1 | 0 | 0 | 100 | 100.0 | 20.7 | 100.0 | 100.0 | 96.3 | 100.0 | ||
| Overall (n = 85) | 84 | 0 | 1 | 16 | 98.8 | 93.6 | 99.8 | 100.0 | 80.6 | 100.0 | ||
| Enterobacterales + P. aeruginosa (110) | Overall (n = 89) | 88 | 0 | 1 | 21 | 98.9 | 93.9 | 99.8 | 100.0 | 84.5 | 100.0 | |
These data are for 50 isolates from the Washington University isolate collection and 60 isolates from the challenge panel provided by Hardy Diagnostics. Testing was performed at site 4. TP, true positive; FP, false positive; TN, true negative; FN, false negative; 95% CI, 95% confidence interval.
One P. mirabilis isolate was mCIM negative, IMP positive by NG-Test Carba 5, and characterized to harbor blaIMP-27 by whole-genome sequencing.
One P. rettgeri isolate was mCIM positive, IMP negative by NG-Test Carba 5, and characterized to harbor blaIMP-27 by whole-genome sequencing.
The performance with P. aeruginosa was the same for each agar type, so only data for blood agar are shown.