In vitro cytotoxicity of an Alcaligenes faecalis and its relationship in in vivo tracheal pathologic changes in turkeys.

Two isolates of Alcaligenes faecalis from turkeys with respiratory disease were indistinguishable physically, biochemically, and for specific agglutinating antibodies. The isolates differed in in vitro cytotoxicity for turkey tracheal organ cultures and in ability to induce clinical rhinotracheitis in poults. The isolate designated NCDp induced in vitro cytotoxic changes in turkey tracheal organ cultures. Additionally, poults inoculated with NCDp developed severe clinical signs of rhinotracheitis, flaccid (collapsing) trachea, bacterial colonization of the cilia, and degeneration and loss of the columnar epithelium from the anterior one third to one half of the trachea. The isolate designated NCDm induced little or no cytotoxic changes in turkey tracheal organ culture. Isolate NCDm caused mild clinical signs of rhinotracheitis and colonized the trachea of inoculated poults, but it caused no other observable changes. A correlation seems to exist between in vitro cytotoxicity and in vivo pathogenicity for these isolates of A. faecalis.