Adhesion ofTypeA Pasteurella multocida toRabbit Pharyngeal Cells andItsPossible RoleinRabbit Respiratory Tract Infections

Pasteurella multocida serotype A was foundinassociation withthemucosal epithelium ofthenasopharynges ofrabbits withrespiratory tract infections. The bacteria specifically attached tosquamous epithelial cells ofthepharyngeal mucosa bothinvivoandinvitro andtosome tissue culture cell lines suchas HeLa.Allstrains withserotype A capsules were adhesive. Withtheexception of one serotype D strain, strains withcapsular serotypes B,D,andE were atleast 10-fold lessadhesive. Bacterial adhesiveness was muchreduced after pronase digestion, heat treatment, andhomogenization, butremoval ofthehyaluronic acid capsule increased adhesion. Electron microscopy revealed thatfimbriae were produced byan adhesive pasteurella strain, butnotbytwononadherent strains. Theattachment oftheformer strain topharyngeal andHeLacells was inhibited by N-acetyl-D-glucosamine. Together, these findings suggest thatthis aminosugar may bea componentofthereceptor on bothanimal cell surfaces andthatthe fimbriae may betheadhesins. Itisproposed that bacterial attachment hasarole in colonization andinfection ofrabbit upperrespiratory mucosae.