RESUMEN
Ornithobacterium rhinotracheale [ORT] has been identified as one of the emerging respiratory bacterial pathogens in turkey and chicken flocks. Diagnosis of ORT infection has been faced some difficulties in isolation and identification of the bacterium based on the biochemical properties. A reliable identification method that can be used in routine laboratory investigations is of importance. The Purpose of this study was diagnosis of ORT using polymerase chain reaction [PCR] in comparison with culture. The PCR was optimized using the primer combination OR16S-F1 and OR16S-R1, positive control of ORT bacteria, and 7 other bacteria such as Haemophilus paragallinarum and Pasteurella multocida as negative control. All samples were prepared for DNA extraction by use of phenol- chloroform method. Sixty pooled tracheal and infraorbital sinus samples from 30 broiler flocks slaughtered at an abattoir in Gazvin province were examined for presence of ORTusing culture and PCR assay. Afragment of 784-bp was amplified in 5 positive known ORTsamples, but not in other 7 bacteria as negative controls. 19 out of 60 primary samples including 11 homogenized tracheal samples and 8 infraorbital sinus swabs, and also all 17 suspected and purified colonies identified microbiologically as ORTwere positive in PCR assay. One out of 41 negative primary samples in PCR test became positive through the culture. Then the propagated bacterium was confirmed in PCR. Fifteen out of 30 flocks [50%] were positive in PCR test and only one of them was negative in culture. Upon the results the PCR method of this study can be used as a reliable and rapid identification of ORT in samples suspected to ORT infection. However, it is better to use a combination of the PCR and culture in order to maximize the diagnosis of ORT infections