TOXIN-PRODUCING PASTEURELLAE IN A CATTLE HERD

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