Virulence of capsulated and noncapsulated isolates of Pasteurella multocida and their adherence to porcine respiratory tract cells and mucus.

The virulence and the adherence to porcine respiratory tract cells and mucus of three toxigenic, capsular type D Pasteurella multocida isolates and their noncapsulated variants were evaluated in the present study. Loss of capsule by P. multocida, verified by transmission electron microscopy after polycationic ferritin labeling, was associated with a massive reduction in virulence of the organisms in mice.

Enhanced adherence of Pasteurella multocida to porcine tracheal rings preinfected with Bordetella bronchiseptica.

Adherence of 25 isolates of Pasteurella multocida to porcine tracheal rings was evaluated. Results indicated that adherence was not related to the isolate's origin, capsular or somatic types, dermonecrotoxin production or hemagglutination activity. The effect of a preinfection with Bordetella bronchiseptica on the colonization by P.

Adherence of Bordetella bronchiseptica 276 to porcine trachea maintained in organ culture.

Two organ culture models have been adapted for porcine tracheae in order to study colonization by Bordetella bronchiseptica. Rings or segments excised from tracheae of newborn piglets were incubated overnight at 37 degrees C in a nutrient medium under 5% CO2-95% air conditions. Tracheal segments were infected with B bronchiseptica 276, and after different incubation times, bacterial counts were done.