In vitro study of Pasteurella multocida adhesion to trachea, lung and aorta of rabbits

In vitro experiments were undertaken to study the adhesion and colonization to tl tracheal mucosa, lung and aorta explants from freshly killed rabbits of two different strains of Pasteurella multocida. Serotype A:3 (capsulate d, fimbriae +, haemagglutination -, dermonecrotic toxin -) isolated from a rabbit with rhinitis, and serotype D:1 (non-capsulated, fimbriae +, haemagg lutination +, dermonecrotic toxin +) isolated from a dead rabbit with septi caemia, were used. When the explants were observed under the scanning elect ron microscope, the type D strain was highly adherent to trachea and aorta explants compared to the type A strain. Adhesion to lung explants was best achieved by the type A strain after 45 min incubation, but after 2 h incuba tion no significant difference was observed between the strains. Our data i ndicate that the presence of fimbriae and the absence of capsule seem to en hance the adherence of P. multocida type D strain to tracheal tissue. The c apsular material of P. multocida type A strain and the toxin of the type D strain seem to influence the adherence to lung tissue in rabbit, Adhesion o f strain D to aorta may indicate the expression of receptors on the endothe lium to that strain and may also explain the ability of certain strains to cause septicaemia. (C) 2000 Harcourt Publishers Ltd.