Isolation, identification and antibiotic sensitivity determination of Ornithobacterium rhinotracheale in slaughtering broiler chicken flocks of Guilan province

Ornithobacterium rhinotracheale (ORT)، a species of bacteria، is known to be associated with respiratory disease، growth retardation، mortality and decreased egg production. The aim of the present study was to determine seroprevalence of the infection and to identify the microorganism by bacteriological and molecular methods. In this study، 460 serum samples and also 290 tracheal swabs were collected from 29 broiler chicken flocks in slaughter houses. Serological results showed that 24 out of 460 (5. 12%) serum samples related to 5 flocks were positive for ORT by ELISA test. ORT was isolated from tracheal swabs of 3 flocks (1. 03% out of 290 tracheal swabs) by culture and confirmed as ORT by specific primers in PCR method. Statistically، there was no significant difference between the rate of isolation and ORT serum titers (P>0. 05). Antibiotic sensitivity test using standard disk diffusion technique was performed with 13 antibiotics. All the isolates were resistant (100%) to erythromycin، tetracycline، oxytetracyclin، enrofloxacin، ciprofloxacin، flumequin، lincospectin، furazolidon، and 100% of them were found to be susceptible to ceftriaxon and tiamulin، but 2 isolates (66. 7%) were moderately sensitive to tylosin and amoxicillin and sensitive to florfenicol. This study is the first report of the prevalence of ORT، bacterial isolation and molecular method in broiler chickens after broiler breeder vaccination in Guilan province.