TABLE 3.
Recovery of STEC O157 bacteria and detection of A/E O157+ bacteria in samples obtained from weaned calves 4 days after inoculation with STEC O157:H7 strain 86-24
| Type of result | No. of samples positive/no. tested (% positive) fora:
|
P value for DEX vs nontreatedb | ||
|---|---|---|---|---|
| All calves | DEX-treated calves | Nontreated Calves | ||
| Recovery of bacteria from: | ||||
| Feces | 40/54 (74) | 24/25 (96) | 16/29 (55) | <0.01 |
| Distal colon | 24/51 (47) | 15/21 (71) | 9/30 (30) | <0.01 |
| Cecum | 19/51 (37) | 14/21 (67) | 5/30 (17) | <0.01 |
| Ileum | 7/48 (15) | 6/21 (29) | 1/27 (4) | 0.04 |
| Gall bladder | 4/26 (15) | 4/11 (36) | 0/15 (0) | 0.02 |
| Detection of A/E O157+ bacteria in: | ||||
| Any site | 38/55 (69) | 23/25 (92) | 15/30 (50) | <0.001 |
| Distal colon | 22/55 (40) | 18/25 (72) | 4/30 (13) | <0.01 |
| Cecum | 12/55 (22) | 11/25 (44) | 1/30 (3) | <0.01 |
| Ileum | 5/55 (9) | 5/25 (20) | 0/30 (0) | 0.02 |
| Gall bladder | 6/46 (13) | 6/25 (24) | 0/21 (0) | 0.02 |
| Ileocecal tissue | 28/45 (62) | 16/24 (67) | 12/21 (57) | 0.55 |
| Rectoanal junction | 15/18 (83) | 11/12 (92) | 4/6 (67) | 0.25 |
a
Number of samples from which STEC O157 bacteria were recovered or samples in which A/E O157+ bacteria were detected by histology and immunohistochemistry.
b
Two-sided P values by Fisher's exact test.