Alcaligenes fecalis infected tracheal epithelium: An ultrastructural study

Abstract

Alcaligenes fecalis is a gram negative bacterium previously thought to be nonpathogenic for humans and animals. The organism is commonly isolated in the gastrointestinal tract. In 1978 it was proven that A. fecalis was the etiologic agent of turkey coryza, an upper respiratory disease of young poults.The infectivity of A. fecalis in the upper respiratory tract suggests that the bacterium has altered its tissue tropism and developed a mechanism of adherence enabling colonization of the tracheal epithelium in spite of the muco-ciliary clearing mechanisms of the trachea. The purpose of this work was to examine the adherence of A. fecalis to the tracheal epithelium and to characterize the host cell response to infection.One day old poults were infected intranasally with either 108 colony forming units of A. fecalis, Wampler, or, as a control, 0.5 ml of sterile brain heart infusion broth. For TEM, the cranial portion of the trachea was cut into 2 mm2 sections, fixed in 2.5% glutaraldehyde, post-fixed in 1% OsO4, dehydrated in ethanol, and embedded in Epon-Araldite. Thin sections were stained with uranyl acetate and Sato's lead. For SEM, tracheal sections were fixed in glutaraldehyde, dehydrated in ethanol, critical point dried, and coated with 250 Å of gold-palladium.