TABLE 4.
Comparison of ability of APEC strain χ7122 and derivatives to induce colibacillosis lesions and persist in internal organs and blood of chickens experimentally inoculated via the air sacsa
| E. coli strain | Mean lesion scoreb ± SD
|
Mean no. of bacteriac ± SD
|
Mean no. of bacteria in blood ± SD
|
|||||
|---|---|---|---|---|---|---|---|---|
| Air sacs | Heart and liver | Lung | Liver | Spleen | 6 h | 12 h | 24 h | |
| χ7122 | 3.0 ± 1.3 | 3.1 ± 0.9 | 5.04 ± 1.3 | 3.96 ± 1.1 | 4.54 ± 1.0 | 3.00 ± 0.6 | 2.98 ± 0.5 | 2.41 ± 1.4 |
| χ7273 | 1.5 ± 0.5* | 3.4 ± 0.7 | 4.55 ± 1.3 | 3.08 ± 0.9 | 3.81 ± 0.6 | 3.21 ± 0.3 | 2.65 ± 0.4 | 1.55 ± 0.5 |
| χ7274 | 1.4 ± 1.5* | 0.3 ± 0.5* | 2.00 ± 1.4* | 0.2 ± 0.4* | 0.70 ± 0.1* | 1.94 ± 0.6 | <1.3* | <1.3* |
a
Asterisks indicate values significantly lower (P < 0.001) than those observed for wild-type strain χ7122.
b
Lesion scoring values: 0 to 4 for air sacs, 0 to 2 for heart, and 0 to 2 for liver.
c
Bacterial counts are presented as the mean log10 CFU per gram (per milliliter for blood) ± standard deviation for 10 birds from each infected group. Counts in organs were made 48 h postinfection.