Table 3.
Limit of detection determination for all Listeria SYBR®Green qPCR assays. The results are based on 36 repetitions with genomic targets as DNA template. Average, standard deviation and percentage of positive signal of C q values obtained at each dilution point
| Mean C q value ± SD (% positive) | |||||
|---|---|---|---|---|---|
| Listeria spp. (except L. grayi) assays | Listeria monocytogenes assays | ||||
| Theoretical copy number/assay | iap-50-deg | prs-2-deg | hlyA-177 | hlyA-146-deg-tronc | |
| Serial dilution points | 10 | 32.96 ± 1.02 (100) | 31.18 ± 0.74 (100) | 32.85 ± 1.12 (100) | 33.23 ± 0.87 (100) |
| 5 | 34.11 ± 1.45 (97.2) | 32.19 ± 0.92 (100) | 33.79 ± 1.31 (100) | 33.93 ± 0.79 (97.2) | |
| 2 | 34.75 ± 1.01 (80.6) | 33.43 ± 0.70 (72.2) | 35.2 ± 1.13 (75) | 34.96 ± 1.2 (75) | |
| 1 | 35.44 ± 1.02 (75) | 34.23 ± 1.08 (55.6) | 35.63 ± 0.97 (61.1) | 34.18 ± 3.78 (50) | |
| 0.5 | 35.51 ± 0.86 (44.4) | 34.67 ± 0.52 (44.4) | 36.04 ± 1.20 (36.1) | 35.57 ± 1.20 (44.4) | |
| 0.2 | 35.99 ± 1.05 (19.4) | 34.61 ± 0.69 (27.8) | 36.08 ± 1.09 (22.2) | 35.62 ± 1.69 (22.2) | |
| 0.1 | 35.85 ± 0.98 (22.2) | 34.59 ± 0.48 (16.7) | 36.46 ± 0.21 (8.3) | 35.64 ± 1.62 (11.1) | |
| Negative controls | Dilution buffer control | Below LOD | Below LOD | Below LOD | Below LOD |
| Water control | Below LOD | Below LOD | Below LOD | Below LOD | |
LOD limit of detection