[Toxin-producing pasteurellas in a cattle herd]

Besides other agents, indole-negative Pasteurellae, producing dermonecrotic Pasteurella toxin, were isolated from the noses of calves in a herd with enzootic bronchopneumonia. In some blood sera, antitoxin was detected. According to their biochemical activities, isolated strains were classified as P. multocida ssp. septica (ornithine-negative), P. avium (biovar 2), and P. canis (biovar 2). However, in DNA-DNA hybridisation tests there was much coincidence with P. multocida. In experimental calves, pneumonic lesions were produced with one of the isolates as well as with the dermonecrotic toxin. Therefore, indole negative toxinogenic Pasteurellae are considered pneumonia causing agents. They should be taken into account in bacteriological diagnostic and for production of herd specific bacterins.