Table I.
Expression of virulence of 16 L. monocytogenes strains and their VBNC forms, by formation of plaques in the human adenocarcinoma cell line HT-29. The results are expressed as the number of plaques obtained for 7 log CFU deposited per well.
| Strain | Source | Virulence (mean log + SD) culturable strains | Virulence (mean log + SD) VBNC |
|---|---|---|---|
| EGDea (control) | Reference strain | 5.23 ± 0.40 | ND |
| Scott A | Reference strain | 6.38 ± 0.03 | 0 |
| EGDeb | Reference strain | 5.18 ± 0.11 | 0 |
| L1069 | Patient | 5.75 ± 0.34 | 0 |
| L1371 | Patient | 5.18 ± 0.27 | 0 |
| L1372 | Patient | 6.70 ± 0.13 | 0 |
| L3365 | Patient | 6.18 ± 0.47 | 0 |
| L3368 | Patient | 5.35 ± 0.23 | 0 |
| L3371 | Patient | 5.66 ± 0.14 | 0 |
| L839 | Salmon | 5.44 ± 0.37 | 0 |
| L1272 | Salmon | 5.81 ± 0.26 | 0 |
| L1338c | Salmon | 4.28 ± 0.24 | 0 |
| L2663 | Salmon | 4.98 ± 0.16 | 0 |
| L2735 | Salmon | 5.56 ± 0.21 | 0 |
| L1317 | Drainpipe | 4.88 ± 0.27 | 0 |
| L2842 | Salmon waste | 5.61 ± 0.31 | 0 |
| L1232 | Seawater | 5.88 ± 0.13 | 0 |
ND: Not done.
a
Control used in the plaque cell test.
b
Used in the VBNC experiments.
c
Examined in a immunocompetent mouse assay and shown to be virulent.