TABLE 3.
Plaque area, infectivity, and association with food or humans as the source for eight common L. monocytogenes ribotypes
| Ribotype | No. of isolates | Plaque area (%)a | CFU/PFU (%)a | Source associationb |
|---|---|---|---|---|
| DUP-1038B | 8 | 119* | 95 | H > F**** |
| DUP-1039B | 5 | 97 | 99 | H > F*** |
| DUP-1039C | 11 | 100 | 83 | H = F |
| DUP-1042B | 14 | 126*** | 78 | H > F**** |
| DUP-1042C | 5 | 110 | 129 | F > H*** |
| DUP-1043A | 6 | 101 | 90 | F > H* |
| DUP-1053A | 7 | 94 | 135* | H > F* |
| DUP-1062A | 11 | 97 | 78 | F > H**** |
Plaque area and CFU per PFU (a measure of infectivity) are expressed relative to those of the reference strain, 10403S (2). High values indicate a large plaque area and low infectivity, respectively. Asterisks represent P values for comparison of a specified ribotype versus all other plaque-forming isolates. *, P < 0.05; ***, P < 0.001.
Based on analysis of 502 food isolates and 492 human isolates (Table 2). H > F, ribotype more common among human isolates than among food isolates, H = F, no significant difference in occurrence, F > H, ribotype more common among food isolates than among human isolates. Asterisks represent P values. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001.