Bibliografische Informationen der Deutschen - TiHo Bibliothek elib ...

7 SUMMARY 155
Salmonella. Both experiments were repeated identically except that a higher infective
dose (1 x 10 9 CFU/animal) was administered to ducks being 15 days old or older.
There was a significantly higher frequency of detection and of the amounts of
Salmonella isolated in younger ducks infected on the 5 th and 8 th day of life than in
both of the oldest groups infected on day of life 22 and 43. The group infected on day
15 was normally positioned in between the others. This was the case regardless of
whether the infection was caused by S. Enteritidis or S. Typhimurium.
After infection with S. Enteritidis the maximum frequency of detection was mostly
reached in all organs on the 5 th day p.i. After that time, there was a continuous
decrease in salmonella infections, so that no S. Enteritidis, at all, could be isolated
from liver and spleen 28 days p.i. At that time this strain was only detected in very
few samples from the caecum.
Infection with S. Typhimurium reached its maximum 5 days p.i. within the caecum
and 7 days p.i. within liver and spleen. This strain was also isolated 28 days after
infection, primarily in organs from younger animals.
S. Enteritidis could be isolated with a maximum rate of 70 % from liver and 50 % from
spleen. For S. Typhimurium the maximum rate was 90 % from liver and 70 % from
spleen. These differences were confirmed by bacterial count, which was nearly twice
as high for S. Typhimurium as for S. Enteritidis. When summarizing all results, both
Salmonella strains were found most frequently within the caecum, whereas the rate
of isolation was significantly lower from liver and, once more, the isolation rate from
spleen was significantly lower than that from liver. At the same time, S. Enteritidis
was isolated from caecum, liver and spleen significantly less frequently than
S. Typhimurium which may indicate that S. Typhimurium invades extra-intestinal
organs more intensely and is thus more pathogenic for the duck than S. Enteritidis.