Establishment and competitive exclusion of Yersinia enterocolitica in the gut of monoxenic and holoxenic chicks.

Newly hatched chicks subcutaneously injected with or orally exposed to Yersinia enterocolitica were colonized in the gastrointestinal tract by this bacteria. Colonization did not take place when chicks were exposed to less than 10(8) colony-forming units. In monoxenic chicks, major colonization was detected in the crop, ceca, and cloaca; fewer numbers colonized other regions of the gastrointestinal tract, and there was little evidence of bacteremia. None of the chicks exhibited clinical signs, although colonization was demonstrated throughout the gastrointestinal tract over the 28-day test period. Prior colonization by native gut microflora prevented subsequent colonization by Y. enterocolitica in holoxenic chicks.