Table 1.
Pig No. | Inoculum | Necropsy day post-inoculation | Gross pathology1 | Histology | FISH4 | ||
Histopathology2 | Spiral-shaped bacteria3 | 1 | 2 | ||||
1 | Br1622 | 7 | - | + | - | + | - |
2 | Br1622 | 9 | - | (+) | + | - | - |
3 | Br1622 | 11 | + | + | ++ | + | - |
4 | Br1622 | 15 | ++ | + | ++, s | + | - |
5 | Br1622 | 16 | ++ | (+) | -, s | + | - |
6 | Br1622 | 17 | + | + | ++ | + | - |
7 | Br1622 | 21 | + | (+) | ++ | - | - |
8 | Br1622 | 23 | ++ | + | - | - | - |
9 | P43/6/78 | 7 | + | (+) | + | - | - |
10 | P43/6/78 | 9 | - | (+) | - | + | - |
11 | P43/6/78 | 11 | + | (+) | + | - | - |
12 | P43/6/78 | 15 | ++ | (+) | ++ | - | - |
13 | P43/6/78 | 16 | ++ | (+) | ++ | + | - |
14 | P43/6/78 | 17 | + | + | + | - | - |
15 | P43/6/78 | 21 | + | (+) | ++ | + | - |
16 | P43/6/78 | 23 | ++ | (+) | - | - | - |
17 | control | 7 | - | (+) | - | - | - |
18 | control | 15 | + | + | - | + | - |
19 | control | 17 | - | (+) | ++ | + | - |
20 | control | 23 | + | + | - | - | - |
21 | control | 9 | + | (+) | - | - | - |
22 | control | 11 | - | (+) | - | - | - |
23 | control | 21 | + | (+) | ++ | + | - |
1Gross findings in caecum and/or colon. - = normal; + = mucosa slightly hyperaemic; ++ = mucosa hyperaemic and slightly oedematous.
2(+) = diffuse lymphocytic and plasmacytic infiltration in lamina propria, and multifocal accumulation of phagocytic macrophages beneath the epithelial cells of the caecum and/or colon; + = in addition, occasional microabscesses in crypts and/or mild exocytosis of neutrophils.
3Spiral-shaped bacteria in caecum and/or colon in silver-stained sections. - = none; + = very rare or irregularly observed in crypts and/or near tips of villi; ++ = invading through epithelial lining into lamina propria and/or abundantly in crypts; s = Br1622 reisolated from necropsy samples.
4Fluorescent in situ hybridisation. Positive (+) and negative (-) results with probes designed for 1 = domain bacteria and genus Leptospira, and 2 = genus Brachyspira, species B. pilosicoli and strain Br1622.