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 respiratorydisease, growth retardation, mortality and decreased egg production. The aim of the present study was todetermine seroprevalence of the infection and to identify the microorganism by bacteriological and molecularmethods. In this study, 460 serum samples and also 290 tracheal swabs were collected from 29 broilerchicken flocks in slaughter houses. Serological results showed that 24 out of 460 (5.12%) serum samplesrelated 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 theisolates were resistant (100%) to erythromycin, tetracycline, oxytetracyclin, enrofloxacin, ciprofloxacin,flumequin, lincospectin, furazolidon, and 100% of them were found to be susceptible to ceftriaxon andtiamulin, but 2 isolates (66.7%) were moderately sensitive to tylosin and amoxicillin and sensitive toflorfenicol. This study is the first report of the prevalence of ORT, bacterial isolation and molecular methodin broiler chickens after broiler breeder vaccination in Guilan province.