A molecular approach to the characterization and intra-species differentiation of porcine Pasteurella multocida strains associated with pneumonia and progressive atrophic rhinitis

摘要

Pasteurella multocida (PM) is a heterogeneous species that can induce progressive atrophic rhinitis (PAR), septicemia, or pneumonia in pigs. Considerable variation has been observed among field isolates with respect to colony morphology, antigenic specificity, and pathogenicity. Although five distinct capsular serogroups (A, B, D, E, and F) have been recognized, serotype A and D are the only two serogroups that had been recognized among all of the porcine PM strains. Toxigenic strains associated withPAR could be either serotype A or D. Yet they usually produce a 145-kD toxin, which is encoded by the toxA gene. This toxin can induce osteolysis in nasal turbinate bones and cause atrophic rhinitis. Non-toxigenic PM strains will not induce PAR. But some porcine PM strains still could induce pneumonia. It is known that prior infection of pigs with other bacteria such as Bordetella bronchiseptica or Mycoplasma hyopneumoniae will predispose pigs to a secondary infection of P multocida.