Interactions between Bordetella bronchiseptica and toxigenic Pasteurella multocida in atrophic rhinitis of pigs |
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Authors: | N Chanter T Magyar J M Rutter |
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Institution: | Agricultural and Food Research Council, Institute for Animal Health, Compton, Berkshire. |
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Abstract: | Three strains of Bordetella bronchiseptica were compared for their ability to assist colonisation of the nasal cavity of gnotobiotic pigs by toxigenic Pasteurella multocida. Toxigenic P multocida (counted in nasal washings) colonised the cavity in large numbers in pigs previously infected with a cytotoxic phase I strain of B bronchiseptica (B58), whereas it colonised only in small numbers in those previously infected with B65, a phenotypic phase III variant of B58. Toxigenic P multocida colonised pigs infected with a non-cytotoxic phase I strain of B bronchiseptica (PV6) in fewer numbers than were seen in pigs infected with the cytotoxic phase I strain but in greater numbers than in pigs infected with the phase III strain. The turbinates of pigs infected with the cytotoxic phase I strain of B bronchiseptica and toxigenic P multocida were most severely affected and those in pigs infected with the non-cytotoxic phase I strain and toxigenic P multocida were moderately reduced in size. The turbinates of pigs infected with the phase III strain and toxigenic P multocida were slightly reduced in size except for one piglet whose turbinates were severely affected. Pigs infected with the non-cytotoxic phase I strain of B bronchiseptica alone showed no signs of atrophy and their turbinates were used to calculate reductions (per cent) in those infected with P multocida. The reduction (per cent) in size of turbinates and total numbers of P multocida isolated from the nasal washings of each pig were linearly related.(ABSTRACT TRUNCATED AT 250 WORDS) |
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