TABLE 2.
Virulence of S. typhimurium strains for 3- to 4-week-old Friesian-Holstein calves
| Strain | Genotype | Result for infection with 1010 CFU/animal
|
||
|---|---|---|---|---|
| No. dead/no. total | Avg time to death (days) | Avg fecal scorea | ||
| IR715 | Wild type | 8/8 | 3.1 | 3.1 |
| STN61 | hilA | 0/4 | NAb | 1.9 |
| STN119 | spiB | 2/2 | 2.3 | 3.8 |
| STN162 | prgH | 0/2 | NA | 2.1 |
| STN166 | rfaJ | 1/2 | 3 | 3.4 |
| STN272 | spvR | 2/2 | 1.2 | 4 |
| SVM255 | sopB | 2/2 | 4 | 3.8 |
| BA1567 | sopB | 2/2 | 4 | 3.1 |
| CL1509 | aroA | 0/2 | NA | 2.1 |
a
Fecal scores were used to assess the severity of diarrhea, where 1 = normal feces; 2 = soft feces with loss of distinct conformation; 3 = diarrhea, loose feces with reduced solid matter; and 4 = diarrhea, aqueous feces with markedly reduced or little solid matter, blood, or fibrin.
b
NA, not applicable.