Studies of the Transmission Routes of Ornithobacterium rhinotracheale and Immunoprophylaxis to Prevent Infection in Young Meat Turkeys

The importance and prevention of the horizontal as well as the vertical transmission of Ornithobacterium rhinotracheale were investigated. In our first experiment we observed that specific-pathogen-free broiler chickens that were placed in hatching incubators at a commercial turkey hatchery during hatch showed respiratory tract lesions at postmortem examination that were positive for O. rhinotracheale by bacteriology and immunohistology. It appeared that vertical transmission occurred and that horizontal transmission of O. rhinotracheale is possible. In a second experiment, the turkeys derived from vaccinated parents showed significantly fewer respiratory tract lesions at postmortem examination at 16 days of age than the birds derived from nonvaccinated parents. In a third experiment, all vaccinated young birds, regardless of the vaccination state of their parents, showed significantly fewer respiratory tract lesions at 6 wk of age. We concluded that vaccination of the breeders reduces vertical transmission and that vaccination of the progeny is needed to resist challenge at 6 wk of age.

Prevalence of antibodies against Ornithobacterium rhinotracheale in broilers and breeders in Southern Brazil

In this investigation, we determined the prevalence of the Ornithobacerium rhinotracheale (ORT) infection in broilers and broiler breeders in southern Brazil. We also correlated the presence of antibodies in broilers with performance. Sera from 1550 broilers from 50 flocks were collected during the slaughter time in nine companies with federal veterinary inspection of the state of Rio Grande do Sul. Sera from 480 meat-type breeders of 40 flocks from 14 companies in southern Brazil were also analyzed by enzyme-linked immunosorbent assay, and the prevalence of antibodies was determined. The prevalence of ORT antibodies in broiler flocks was 63.83%, but in each individual flock only 6.52% of the birds were positive. The prevalence in broiler breeder flocks was 100.00%, and in each individual flock 94.62% of the birds were positive. There was a positive correlation between the presence of antibodies to ORT and decreased body weight in broilers. There was no significant correlation between presence of antibodies to ORT and age, lineage, efficiency index, feed conversion, and mortality. There was a positive correlation between the presence of respiratory signs and antibodies to ORT, although the reverse correlation was not significant. These results confirm that ORT is present and widespread in broilers and broiler breeders in southern Brazil.

In vitro susceptibility of Ornithobacterium rhinotracheale to several antimicrobial drugs

As part of the basic characterization of Ornithobacterium rhinotracheale, the minimal inhibitory concentrations of 10 antimicrobial drugs were determined for reference strains and Mexican isolates by a broth microdilution method. For optimal growth of the organisms, a supplemented brain-heart infusion broth was used. The susceptibility of O. rhinotracheale to amoxicillin, enrofloxacin, and oxytetracycline was variable. However, consistent higher minimal inhibitory concentrations values were obtained for gentamicin, fosfomycin, trimethoprim, sulfamethazine, sulfamerazine, sulfaquinoxaline, and sulfachloropyridazine. Obtained results among Mexican isolates indicate a marked antimicrobial drug resistance trend.