TABLE 3.
Effect of enrichment conditions on recovery of E. coli O157:H7 from foods inoculated with freeze-injured cells
| Inoculum size (CFU/25 g) | Food | Recovery with direct platinga
|
Recovery with IMS platinga
|
||||
|---|---|---|---|---|---|---|---|
| mEC+n methodb | b-mEC (b,n) methodc | TSB (b,n) methodd | mEC+n methodb | b-mEC (b,n) methodc | TSB (b,n) methodd | ||
| 22 | Radish sprouts | NTe | 0/10f | 0/10 | NT | 2/10 | 1/10 |
| Strawberries | NT | 6/10 | 3/10 | NT | 9/10 | 4/10 | |
| Salted cabbage | NT | 10/10 | 10/10 | NT | 10/10 | 10/10 | |
| 43 | Radish sprouts | 0/5 | 5/5 | 1/5 | 0/5 | 5/5 | 5/5 |
| Strawberries | 0/5 | NT | NT | 0/5 | NT | NT | |
| Salted cabbage | 0/5 | NT | NT | 0/5 | NT | NT | |
a
Direct plating, direct plating of enrichment culture; IMS plating, plating of immunoseparated fraction of enrichment culture.
b
Preparations were incubated for 18 h in modified E. coli broth containing novobiocin at 42°C.
c
Preparations were incubated for 2 h in modified E. coli broth without bile salts at 25°C and then for 18 h in the presence of bile salts and novobiocin at 42°C.
d
Preparations were incubated for 2 h in Trypticase soy broth at 25°C and then for 18 h in the presence of bile salts and novobiocin at 42°C.
e
NT, not tested.
f
Number of samples in which E. coli O157:H7 was detected/number of samples tested.