Evaluation of several methods of detecting salmonellae in groups of chickens.

Chickens exposed experimentally to Salmonella agona, S. blockley, S. enteritidis, S. infantis, and S. typhimurium were tested serologically by microagglutination and microantiglobulin procedures and culturally by cloacal swabs and environmental samples. Chicks infected at one day old yielded the highest level of positive cloacal swab cultures, whereas exposure of older birds gave maximal serologic titers. Recovery of salmonella from environmental samples is dependent on a number of factors, including excretion rate by the population and survival rate of salmonellae in the environment. Serologic titers persisted after salmonellae could no longer be isolated from cloacal swabs or environmental samples. The possibility of false-positive serologic reactions was explored in two groups of chickens, one exposed to other Enterobacteriaceae, and one composed of eight specific-pathogen-free flocks. Occasional serologic microantiglobulin titers were observed only in the latter group. Extensive culturing of the environment from these flocks had negative results.