TABLE 6.
Expt no. | No. of E. coli cells inoculated
|
Preenrichment culture
|
Solution used for:
|
After IMS
|
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---|---|---|---|---|---|---|---|---|---|---|---|---|
MacConkey agar (cells/ml ± SD)
|
MacConkey agar (cells/ml ± SD)
|
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O157KB2 Rifr | Non-O157 E. coli cellsb | Total cells | Rifampin selection | Nalidixic acid selection | Ratio of cells (Rifr:Nalr) | IMS | Washing | Total cells | Rifampin selection | Nalidixic acid selection | Ratio of cells (Rifr:Nalr) | |
A | 85 ± 28 | 74 ± 3 | (1.9 ± 0.4) × 107 | (4.8 ± 1.4) × 105 | (3.0 ± 0.8) × 105 | 1.6:1 | BPW | PBS-Tween 20 | (4.2 ± 0.1) × 105 | (5.4 ± 1.4) × 104 | (1.0 ± 0.1) × 103 | 5.4 × 101:1 |
CMQ | CMQ | (1.6 ± 0.2) × 104 | (5.6 ± 1.3) × 103 | 0a | >5.6 × 103:1 | |||||||
B | 85 ± 28 | (74 ± 3) × 101 | (3.8 ± 0.2) × 107 | (4.4 ± 0.6) × 104 | (2.6 ± 0.2) × 105 | 1.7 × 10−1:1 | BPW | PBS-Tween 20 | (1.4 ± 0.4) × 105 | (7.6 ± 1.5) × 103 | (9.4 ± 2.3) × 102 | 1.8 × 101:1 |
CMQ | CMQ | (1.1 ± 0.1) × 104 | (1.6 ± 0.3) × 103 | 5 ± 10 | 3.2 × 102:1 | |||||||
C | 85 ± 28 | (74 ± 3) × 102 | (2.2 ± 0.2) × 107 | (8.0 ± 1.0) × 104 | (3.4 ± 0.4) × 106 | 2.5 × 10−2:1 | BPW | PBS-Tween 20 | (8.1 ± 1.1) × 104 | (1.2 ± 0.04) × 104 | (6.8 ± 0.3) × 103 | 1.7:1 |
CMQ | CMQ | (6.3 ± 0.7) × 103 | (2.7 ± 1.0) × 102 | 0a | >2.7 × 102:1 | |||||||
D | 60 ± 2 | (97 ± 2) × 102 | (4.0 ± 0.6) × 107 | (9.0 ± 4.6) × 104 | (1.8 ± 0.4) × 107 | 5.1 × 10−3:1 | BPW | PBS-Tween 20 | (2.2 ± 0.4) × 105 | (5.4 ± 1.0) × 104 | (4.2 ± 0.3) × 104 | 1.3:1 |
CMQ | CMQ | (4.3 ± 0.6) × 103 | (3.2 ± 0.7) × 102 | 5 ± 10 | 6.4 × 101:1 | |||||||
E | 60 ± 2 | (97 ± 2) × 103 | (9.4 ± 0.6) × 107 | (4.6 ± 1.0) × 104 | (1.1 ± 0.1) × 108 | 4.3 × 10−4:1 | BPW | PBS-Tween 20 | (4.2 ± 0.4) × 105 | (1.9 ± 0.1) × 104 | (3.7 ± 0.02) × 105 | 5.0 × 10−2:1 |
CMQ | CMQ | (7.3 ± 0.3) × 103 | (2.1 ± 0.1) × 103 | (3.1 ± 0.9) × 102 | 6.8:1 | |||||||
F | 0 | 0 | NDc | NDc | NDc | NDc | BPW | PBS-Tween 20 | (8.5 ± 0.9) × 104 | 0a | 0a |
There were no cells in the 0.2-ml cell suspension.
In experiments D through F, the non-O157 E. coli strain used was V9 Nalr.
ND, not determined.