RESUMO
Ornithobacterium rhinotracheale is a bacterium that causes respiratory disease in birds and it has been isolated in countries with a large poultry production, including Mexico. The pathogenicity mechanisms of this bacterium have not been completely elucidated yet. The capacity of the bacterium to adhere to epithelial cells of chicken in vitro has been evidenced, and since this bacterium has been isolated from the lungs and air sacs of several avian species, the aim of this study was to determine if this bacterium can adhere to chicken lung cells. We used five O. rhinotracheale reference serovars (A-E) that were in contact with primary lung cells cultured from a 19-day-old chicken embryo. O. rhinotracheale adherence was evaluated through optical and transmission electron microscopies. The results revealed that O. rhinotracheale is capable of adhering to chicken embryo lung cells within 3â h of incubation with a diffuse adherence pattern. The adherence percentages of the chicken embryo lung cells were 51-96% according to the serovar of the bacterium. Relative adherence was from 4 to 8 bacteria per cell. Transmission electron microscope data revealed intracellular bacteria inside a vacuole in less than 3â h of incubation.
Assuntos
Aderência Bacteriana/fisiologia , Embrião de Galinha , Pulmão/citologia , Ornithobacterium/fisiologia , Animais , Células Cultivadas , Pulmão/embriologia , Organismos Livres de Patógenos EspecíficosRESUMO
The coinfection of Avibacterium paragallinarum and Ornithobacterium rhinotracheale in two outbreaks of infectious coryza from Peru is reported. The diagnosis was confirmed by bacteriologic isolation, PCR testing, and sequencing of the 16S rRNA gene. The susceptibility of the isolates to 12 antimicrobial agents was tested by a disk diffusion method. The isolates were susceptible to amoxicillin/clavulanic acid and florfenicol and were resistant to oxacillin and sulfamethoxazole/trimethoprim. The coinfection of Av. paragallinarum and O. rhinotracheale and the severity of clinical signs were evaluated by experimental infection of specific-pathogen-free chickens. The group inoculated with O. rhinotracheale alone presented minimal clinical signs in 3 of 10 chickens. However, the groups inoculated with both Av. paragallinarum and O. rhinotracheale induced the most-severe clinical signs compared with the group inoculated with Av. paragallinarum alone. In conclusion, coinfections with Av. paragallinarum and O. rhinotracheale may occur, and these outbreaks could be more severe than single infections. Hence, the prevention, control, and diagnosis of Av. paragallinarum with O. rhinotracheale are important in outbreaks of infectious coryza.