Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: February 21, 2003
Publication Date: April 20, 2003
Citation: BROCKMEIER, S.L., REGISTER, K.B. A BORDETELLA BRONCHISEPTICA DNT MUTANT PREDISPOSES PIGS TO INFECTION WITH TOXIGENIC PASTEURELLA MULTOCIDA. 103rd GENERAL MEETING OF THE AMERICAN SOCIETY FOR MICROBIOLOGY. 2003. Abstract p. 675, #Z-001. Technical Abstract: Both Bordetella bronchiseptica and toxigenic strains of Pasteurella multocida cause atrophic rhinitis in pigs. Infection with toxigenic strains of P. multocida results in a more severe and chronic form of the disease and is referred to as progressive atrophic rhinitis, while infection with B. bronchiseptica alone is referred to as nonprogressive atrophic rhinitis. Infection with B. bronchiseptica has been shown to predispose pigs to infection with P. multocida, and coinfection with these agents is often found in cases of progressive atrophic rhinitis. Previous work showed that a dermonecrotic toxin (DNT) mutant of B. bronchiseptica did not cause the turbinate atrophy characteristic of nonprogressive atrophic rhinitis, despite colonizing the respiratory tract well. The experiment described here was designed to determine whether a DNT mutant of B. bronchiseptica was still capable of predisposing pigs to infection with P. multocida and progressive atrophic rhinitis. Three groups of 6 caesarian-derived, colostrum-deprived pigs were challenged intranasally with wild type B. bronchiseptica, an isogenic DNT mutant of B. bronchiseptica, or PBS. All pigs were then challenged intranasally with a toxigenic strain of P. multocida 4 days later. Pigs were euthanized 4 weeks after challenge with P. multocida, examined for pathology and sampled for colonization with P. multocida. P. multocida was not detected in the respiratory tissues of pigs inoculated with PBS followed by P. multocida, and no turbinate atrophy was present in these pigs. P. multocida was isolated in similar numbers from the respiratory tract of pigs initially inoculated with either wild type B. bronchiseptica or the DNT mutant of B. bronchiseptica. Moderate to severe turbinate atrophy of a similar magnitude was also seen in pigs of both groups which received B. bronchiseptica prior to P. multocida. Thus, although the DNT of B. bronchiseptica is responsible for much of the pathology seen with infections of this organism alone, infection with non-DNT producing strains can still predispose to secondary respiratory infections with P. multocida.