Isolation, detection, and antibiotic sensitivity determination of Ornithobacterium rhinotracheale in commercial chicken farms with respiratory signs in Mazandaran province

Ornithobacterium rhinotracheale (ORT) is an economically important bacterial pathogen of poultry worldwide. The Aim of the present study was conducted to isolation, detection and determination of antibiotic sensitivity of ORT isolates in commercial poultry flocks with respiratory signs in Mazandaran province, northern Iran. Tracheal swab samples were taken from 60 different flocks, after cultivation on a selective medium, suspected colonies were subjected to biochemical and molecular identification of ORT. Then, confirmed isolates were aimed to antibiotic resistance assay. A total of 13 isolates, including seven isolates from broiler flocks (19.44%) and six isolates from broiler breeder flocks (33.33%) were obtained. All ORT isolates that were positive by culture were also detected to be positive by the PCR. The most resistance rates among all ORT isolates were obtained for ampicillin, erythromycin, ceftriaxone, and penicillin (100%). The majority of ORT isolates were susceptible to furazolidone. According to the results, the isolates showed different antibiotic resistance profiles, and most of the strains proved multiresistant. This can indicate the circulation of various multidrug resistant strains among poultry farms in northern Iran.