Characterization of envelope proteins from Pasteurella haemolytica and Pasteurella multocida

A method was devised for the reproducible isolation of envelopes from Pasteurella haemolytica serotype A2. It was also possible to prepare envelopes from other serotypes of P. haemolytica and Pasteurella multocida using this methodology. Examination of these preparations by SDS-PAGE showed major differences between strains of P. haemolytica and strains of P. multocida which allowed the clear distinction of isolates of these species. Amongst the P. haemolytica serotypes it was possible to distinguish envelope preparations made from A biotype and T biotype organisms easily, but it was not possible to identify individual serotypes from each other. Envelope profiles were sufficiently different between the individual P. multocida serotypes examined to allow each to be identified by its polypeptide profile. Experiments using radiolabelling, antibody absorption, and susceptibility to protease digestion, together with heat modifiability and detergent solubility characteristics indicated that 13 of the envelope proteins were probably surface-located. A high molecular mass immunogenic envelope protein was shown, by immunoblotting, to be present in all strains of P. haemolytica and P. multocida examined.     

Transformation of Pasteurella novicida

Deoxyribonucleic acid from a streptomycin-resistant mutant of Pasteurella novicida transformed portions of P. novicida streptomycin-sensitive populations to streptomycin-resistant. Similarly, mutants auxotrophic for tryptophan or purine biosynthesis were also transformed to nutritional independence.     

Morphology of Pasteurella multocida bacteriophages

Twenty-one tailed phages with icosahedral heads belong to the Myoviridae, Siphoviridae, and Podoviridae families and to four morphological types. Type AU, with 10 phages, has a contractile tail and is morphologically identical with coliphage P2. Lysates contain contracted tail sheaths assembled end-to-end and abnormal structures with long tails and multiple tail sheaths. Types C-2 and 32, with one and three phages, respectively, have long, noncontractile tails. Type 22 includes seven phages, has a short tail, and resembles coliphage T7. Our results agree with previous biological data and suggest that types AU, C-2, 32, and 22 correspond to four different phage species.     

Selective media for Pasteurella pneumotropica

Bacteria from the subcutaneous abscesses which appeared in a laboratory colony of DS mouse since October of 1977 were identified as Pasteurella pneumotropica by various biological examinations. The abscess formation was limited to multiparous female mice over 100 day-age, but virgin females were free from the disease. The MIC of various antibacterial substances showed that potassium tellurite, kanamycin and bacitracin were effective to isolate the organism selectively from various infection sites harboring many other species of bacteria. A novel NKBT medium was prepared by adding these antibacterial substances to the heart infusion agar (HIA) supplemented by 10% Fildes digested blood. A fluid culture medium, TGN broth was prepared for multiplication of the organism by adding 10% Fildes digested blood and potassium tellurite to GN broth. To isolate the organism from the pharyngo-larynx a direct application of mucus wiped off the infection site onto the culture medium was sufficient, but pre-multiplication in the TGN broth was required for isolation of the organism from gut contents before inoculation onto the NKBT medium. The pre-cultivation in the TGN broth vastly improved the recovery of the organism especially from feces. Thereby we could easily detect the latent infection of this bacterium without sacrificing animals.     

R-Plasmids in Pasteurella multocida.

Multiple drug-resistant strains of Pasteurella multocida were associated with a high incidence of fatal pneumonia in feedlot cattle. A representative strain, CAH160, resistant to tetracycline (Tc), streptomycin (Sm), and sulfonamide (Su) was studied. The minimal inhibitory concentration (MIC) of Tc was 32 μg/ml while Sm had an MIC of 256 μg/ml. Plasmid DNA was isolated from CAH160 by cesium chloride-ethidium bromide centrifugation. Agarose gel electrophoresis showed that at least three distinct species of plasmid DNA were present. DNA isolated from CAH160 was used to transform Escherichia coli K12 strain C600 r_k^?m_k^?. Transformants resistant to Tc; to Sm, Su; and to Tc, Sm, Su were obtained. Contour length measurements of plasmid DNA isolated from transformant cells showed that Tc resistance was associated with a 3-Mdal plasmid (pSR10), while Sm, Su resistance resided on a 2.7-Mdal molecule (pSR11). More than 20% of the transformants were resistant to Tc, Sm, Su and contained both plasmid species. In E. coli the MIC of Tc was 256 μg/ml and that of Sm was 64 μg/ml. The buoyant density of pSR10 was 1.699 g/cm³, while the density of pSR11 was 1.709 g/cm³.