TABLE 2.
Results for retrospective specimens
| Target and specimen type | No. of specimens with BD Max EBP result with reference to culture/EIA confirmed by alternate PCR |
Total no. of specimensa | PPA (95% confidence interval) | P value for PPAb | NPA (95% confidence interval) | P value for NPAb | |||
|---|---|---|---|---|---|---|---|---|---|
| True positive | False negative | False positive | True negative | ||||||
| Campylobacter | |||||||||
| Total | 129 | 4 | 2 | 372 | 507 | 97.0 (92.5–98.8) | 99.5 (98.1–99.9) | ||
| Preserved | 64 | 2 | 0 | 151 | 217 | 97.0 (89.6–99.2) | 1.000 | 100 (97.5–100) | 0.657 |
| Unpreserved | 65 | 2 | 2 | 221 | 290 | 97.0 (89.8–99.2) | 99.1 (96.8–99.8) | ||
| Salmonella | |||||||||
| Total | 166 | 1 | 1 | 450 | 618 | 99.4 (96.7–99.9) | 99.8 (98.8–100) | ||
| Preserved | 105 | 1 | 0 | 213 | 319 | 99.1 (94.8–99.8) | 1.000 | 100 (98.2–100) | 1.000 |
| Unpreserved | 61 | 0 | 1 | 237 | 299 | 100 (94.1–100) | 99.6 (97.7–99.9) | ||
| Shigella | |||||||||
| Total | 91 | 1 | 0 | 451 | 543 | 98.9 (94.1–99.8) | 100 (99.2–100) | ||
| Preserved | 50 | 1 | 0 | 187 | 238 | 98.0 (89.7–99.7) | 1.000 | 100 (98.0–100) | 1.000 |
| Unpreserved | 41 | 0 | 0 | 264 | 305 | 100 (91.4–100) | 100 (98.6–100) | ||
| Shiga toxins | |||||||||
| Total | 66 | 0 | 0 | 90 | 156 | 100 (94.5–100) | 100 (95.9–100) | ||
| Preserved | 41 | 0 | 0 | 79 | 120 | 100 (91.4–100) | 1.000 | 100 (95.4–100) | 1.000 |
| Unpreserved | 25 | 0 | 0 | 11 | 36 | 100 (86.7–100) | 100 (74.1–100) | ||
a
The number of specimens varies by target due to differences in compliance with the protocol and unresolved results.
b
P value for testing of the significance of the difference between preserved and unpreserved specimens.