COMPARATIVE PATHOLOGY OF AND PATHOGENIC MECHANISMS IN BOVINE BACTERIAL PNEUMONIA

摘要

In North American cattle, Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, Arcanobacterium pyogenes, and Mycoplasma bovis are isolated from severe bacterial pneumonia frequently seen in dairy calves (enzootic pneumonia) and in feedlotcattle (shipping fever) in what is known as the Bovine Respiratory Disease (BRD) Complex. All of these bacteria are ubiquitous in the cattle population as commensals in the nasopharynx, and following stress or viral infection, each can proliferate and be inhaled into the lungs. Each has its own cadre of known virulence factors such as adhesins, toxins, and enzymes that enhance their ability to colonize, cause tissue destruction, and incite an intense inflammatory response. The purpose of this talk is to review the virulence factors, pathogenesis, and lesions associated with these various bacteria.