Ornithobacterium rhinotracheale Infection in Poultry: an Updated Review

Ornithobacterium rhinotracheale is a Gram-negative bacterium of the rRNA superfamily V within the Cytophaga-Flavobacterium-Bacteroides phylum, which has become an emerging pathogen in the poultry industry. The purpose of this work is to review the current literature on O. rhinotracheale infection in domestic poultry. Despite the difficulties to identify the bacteria using biochemical tests, the polymerase chain reaction (PCR) technique has been successfully used to identify suspected isolates. Moreover, pulsed-field gel electrophoresis (PFGE) has allowed the genetic typing of O. rhinotracheale . Recent investigations carried out in the United States and Argentina described the unusual and extensive β-hemolytic activity of field strains isolated from affected chickens and turkeys. According to the latest serological studies, the causing agent has eighteen serotypes (A to R) and serotype A is the most prevalent among chicken and turkey strains. Gross findings typically found in broiler chickens are unilateral pneumonia, pleuritis, and abdominal airsacculitis with foamy, white yogurt-like exudate, which cause increased condemnation rates at slaughter, whereas those found in turkeys include tracheitis, pneumonia or bronchopneumonia, thoracic and/or abdominal airsacculitis, pericarditis, and peritonitis. Despite the worldwide efforts to control O. rhinotracheale infection, the present situation shows several problems not only because antibiotic treatments appear to be less effective due to the resistance acquired in the poultry industry but also because the vaccines developed so far show variable results in commercial poultry.