TABLE 3.
Chlorine resistance as measured by extended lag phase among strains of the nine different E. coli O157:H7 clades
| Clade | No. of strains | Lag phase extension (h) | Tukey's groupinga |
|---|---|---|---|
| 6 | 5 | 9.73 | A |
| 4 | 1 | 9.45 | AB |
| 9 | 5 | 9.24 | AB |
| 2 | 6 | 9.03 | ABC |
| 1 | 3 | 8.36 | BCD |
| 3 | 5 | 8.31 | CD |
| 7 | 6 | 7.78 | CD |
| 8 | 8 | 7.69 | D |
| 5 | 3 | 7.59 | D |
a
Groups with the same letter designation showed no significant difference in extended lag phase; therefore, strains in such groups showed no significant difference in chlorine resistance. Groups with different letter designations indicated significant difference in chlorine resistance.