Intestinal colonisation in the chicken by food-poisoning Salmonella serotypes; microbial characteristics associated with faecal excretion.
Following oral inoculation of newly-hatched or three-week-old chickens, Salmonella organisms persisted longest in the caeca and they were also present for a shorter time in the crop. S. cholerae-suis, E. coli K12 and Saccharomyces cerevisiae did not colonise the alimentary tract when inoculated orally, but they persisted longer in the caeca than in other regions of the gut. This suggested that preferential localisation of Salmonella in the caeca may be the result of non-specific or host factors. This may include the slow rate of flow of contents through this organ which would allow greater microbial multiplication and persistence. Some Salmonella strains, particularly S. typhimurium, inoculated orally into three-week-old chickens were isolated in greater numbers from homogenates of the crop wall and, much less frequently, from the caecal wall, than from the luminal contents of these organs. None of the strains associated with the crop wall to the same extent as did lactobacilli. After oral inoculation of food-poisoning Salmonella serotypes the number of chickens excreting Salmonellae in their faeces gradually declined over a period of at least 4 weeks. In contrast, host adapted serotypes such as S. cholerae-suis and S. abortus-ovis were not excreted for longer than a few days. By testing mutants of S. typhimurium and S. infantis which were devoid of easily recognised characteristics it was concluded that neither flagellar (H) antigens, somatic (O) antigens, mannose-sensitive haemagglutinins nor the possession of the virulence-associated 85 kilobase plasmid of S. typhimurium, were essential for colonisation (persistent faecal excretion). However, a mutant of S. infantis which was created by nitroso-guanidine treatment still possessed flagellar and somatic antigens and haemagglutinins and yet did not colonise the alimentary tract, indicating that an unidentified microbial factor was essential for colonisation.
Barrow
P A
PA
Houghton Laboratory, AFRC Institute for Animal Health, Cambridgeshire, England.
Simpson
J M
JM
Lovell
M A
MA