An in vivo model for the study of Bordetella avium adherence to tracheal mucosa in turkeys.

An in vivo model was developed for studies characterizing the adherence of Bordetella avium to the tracheal mucosa of turkeys. Three-week-old turkeys were anesthetized, and the cervical part of the trachea was isolated after tracheostomy was done. A hemostat was applied craniad to the tracheostomy site to occlude the tracheal lumen. Isolated tracheal segments were filled with an aqueous bacterial inoculum for 1 minute, and then excess inoculum and the hemostat were removed. After 1 hour, a 1-cm section was excised from each tracheal segment, and adherent viable bacteria were quantified. Modifications of the procedure were evaluated to produce a model that was technically simple to do, economical, and reproducible. To examine the validity of the model, adherence of B avium was compared with that of Escherichia coli and Staphylococcus aureus. Adherence of B avium to tracheal mucosa was 17 times greater than that with E coli and 1,550 times greater than that with S aureus. Colonization of the tracheal mucosa by B avium was demonstrated in tracheal sections obtained 6 hours after filling with bacterial inoculum. Because the ciliary clearance mechanism of the tracheal segments remained functional, washing of the tracheal lumen had no effect on numbers of associated bacteria. An important advantage of this model over in vitro models is the excellent preservation of the tracheal mucosal surface.