Molecular characterization and antimicrobial sensitivity of Ornithobacterium rhinotracheale strains isolated from poultry in Taiwan

• Main Authors: Shin-Ying Lin, 林欣穎
• Other Authors: 蔡向榮
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/02340708507988929063

碩士 === 臺灣大學 === 獸醫學研究所 === 95 === Ornithobacterium rhinotracheale (ORT), a poultry respiratory disease, is worldwidely distributed in commercial poultry industires as well as in wild birds. In Taiwan, ORT has been found in chickens, pigeons and turkeys. In this study, tracheal swabs were collected from different avain species from 2005 to 2006. The isolation rate were 20.7% (29/140), 12.1% (4/33), 2.8% (6/211), 1.2% (1/87) and 0% (0/435), from chickens, ostrichs, quails, pet and wild birds, and ducks respectively. Identification were done by API 20NE and the result showed that 52.6% (20/38) of the isolates belonged to biocode 0-2-2-0-0-0-4, and 39% (15/38) of them for biocode 0-0-2-0-0-0-4 and 7.9% (3/38) of them beloged to biocode 0-2-2-0-0-0-0. Rapid slide agglutination test were done by using standar serotype A antiserum and 84.2% (32/38) belonged to serotype A. More than 80% of the isolates were resistant to colistin, gentamicin, neomycin, lincomycin and sulfamethoxazol/trimethoprim, however, they were susceptible to amoxycillin, and ceftiofur based on the agar disc diffusion method. The isolated ORT strains of each species (chicken, pigeon, ostrich, quail, turkey and Asian Crested Goshawk) were further differentiated by molecular typing methods including 16S rRNA sequence, random amplified polymorphic DNA (RAPD), and single enzyme amplified fragment length polymorphism (SE-AFLP). In the results of 16S rRNA sequence, high genetic similarity (97-100%) were revealed except those of chicken-origin isolates from Yunlin county, pigeon-origin and turkey-origin isolates which were also divided into different clusters within the phylogenetic tree. In order to investigate the genetic polymorphysm among the ORT isolates, SE-AFLP and RAPD methods were conducted and analyzed with the ATCC 51464 strain. The results showed that the DNA patterns of chicken-origin quail-origin and partial turkey-origin isolates were different from those of ostrich-origin, pigeon-origin and Asian Crested Goshawk-origin isolates. Base on the feature that different-origin ORT isolates were separated by the SE-AFLP and RAPD methods, it is suggested that intraspecies differerce within species rhinotracheale or even other species than rhinotracheale may exist. Furthermore, to investigate the resistance to quinolones antibiotics of ORT, E-test were performed to exam the MIC values for the ORT isolates, 15.2% (14/92) of isolates were determined susceptible and 26.1% (24/92) were determined being resistant to enrofloxacin. Moreover, 30 ORT isolates including enrofloxacin-susceptible and enrofloxacin-resistant strains were selected randomly for further examination of the existence of gyrA gene fragment after the amplification by primers ORTgyrAF/R. By the results of sequencing and comparing with other previous studies, it is our speculation that the change of nucleic acid position 635 (C635T) play an important role in the quinolone resistance of ORT.