Isolation and characterization of Ornithobacterium rhinotracheale in the commercial turkey, quail flocks and domestic pigeons by bacteriological and molecular methods

Abstract

Ornithobacterium rhinotracheale (ORT) is a respiratory pathogen which has been isolated throughout the world from numerous bird species. The present study was designed to isolate and characterize the ORT from domestic turkeys, quails and pigeons. For this purpose, 250 samples from each bird species (turkey, quail and pigeon) with or without respiratory signs were tested by taking of tracheal swabs. In addition, respiratory tissue samples (tracheal and lung), from 250 slaughtered turkeys, 50 slaughtered quails and 100 dead pigeons were also subjected to culture for ORT as tracheal swabs. Respiratory tissues were also tested for bacterial DNA by using polymerase chain reaction (PCR). In general, 30 isolates including 4 isolates from turkeys, 3 isolates from quails and 23 isolates from pigeons were identified as ORT by bacteriological method and then confirmed by PCR. Bacterial DNA was detected in 20%, 50% and 35% of respiratory tissues in turkeys, quails and pigeons respectively. Five ORT isolates from pigeon and all four isolates from turkey showed smaller colony size, while other isolates had larger colonies when cultured in blood agar. Fifty percent of the isolates with larger colony but none of the isolates with small colony size could agglutinate red blood cells (RBCs). All of the isolates were sensitive to danofloxacin and chloramphenicol while more than 90% of pigeon isolates were resistant to ampicillin. All of turkey and quail and 30% of pigeon isolates were resistant to tetracycline. Our ORT isolates showed high identity (98%- 100%) in sequence of 16S rRNA gene to related data in GeneBank.