TABLE 3.
PCR hybridization and real-time PCR of IncF, IncI1, and IncI2 plasmids and intI1 and tet(A) from TC-DNA extracted from produce before and after enrichmenta
| Produce | DNA isolation | Time point (day) |
IncF |
IncI1 |
IncI2 |
intI1
|
tet(A) |
|||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| RT-PCR | Blot | RT-PCR | Blot | RT-PCR | Blot | RT-PCR | Blot | RT-PCR | Blot | |||
| Mixed salad | Direct extraction | 0 | − | − | − | − | − | +++ | + | (+++) | − | (++)1 |
| 7 | − | − | − | − | − | +++ | + | (+++) | − | (+++)2 | ||
| Enrichment | 0 | + | (+++) | + | (++) | + | +++ | + | (+++) | + | (++)2 | |
| 7 | + | (+++) | + | (++) | + | +++ | + | (+++) | + | +++ | ||
| Arugula | Direct extraction | 0 | − | − | − | − | − | (++)3 | + | (++) | − | (+++)2 |
| 7 | − | − | − | − | − | (++)1 | + | (++) | − | (+++)1 | ||
| Enrichment | 0 | + | (+++) | − | − | + | +++ | + | (++) | + | +++ | |
| 7 | + | (+++) | − | − | + | +++ | + | (++) | + | +++ | ||
| Cilantro | Direct extraction | 0 | − | − | − | − | − | − | (+)1 | (++) | (+)1 | (+++)3 |
| 7 | (+)1 | (++)2 | − | − | − | − | (+)3 | (+++) | (+)2 | (+++)3 | ||
| Enrichment | 0 | (+)2 | (+++)2 | (+)1 | (++)2 | − | − | (+)3 | (+++) | (+)2 | (+++)3 | |
| 7 | (+)2 | (+++)2 | (+)2 | (++)2 | − | − | (+)3 | (+++)3 | (+)3 | (+++)3 | ||
a
Superscript numbers indicate number of positive replicates; −, not detected or no signal; (+), positive (RT-PCR); (++), medium signal; (+++), strong signal.