Department of Food Safety & Infection Biology, Norwegian School of Veterinary Science, Oslo, Norway.
Microb Drug Resist. 2012 Apr;18(2):207-14. doi: 10.1089/mdr.2011.0142. Epub 2012 Jan 27.
Flavobacterium psychrophilum is the causative agent of the recognized diseases 'bacterial coldwater disease' and 'rainbow trout fry syndrome' and is found in many farmed freshwater and marine fish species. In Norway, the bacterium has mainly been isolated from Atlantic salmon (Salmo salar L.) and brown trout (Salmo trutta L.). In the present study, 26 isolates from Norwegian farmed salmonids were examined. All isolates were tested for susceptibility towards various antibacterial drugs by the disk diffusion method, and minimum inhibitory concentration values for oxolinic acid and flumequine were established for selected isolates. All isolates from rainbow trout displayed reduced susceptibility towards quinolones, while brown trout and Atlantic salmon isolates were susceptible. The quinolone resistance determining regions (QRDRs) of the gyrA, gyrB, parC, and parE genes were sequenced. Sequence analysis of the QRDR of gyrA in quinolone resistant isolates revealed a threonine:arginine amino acid substitution at position 82 in all 16 isolates from Norwegian rainbow trout and a single reference strain isolated from rainbow trout in Sweden. No evidence for plasmid-mediated quinolone resistance was found in any of the isolates. Pulsed-field gel electrophoresis and phylogenetic analysis of parC and gyrB sequences indicate a clonal relationship between rainbow trout isolates.
嗜冷杆菌是公认的“细菌性冷水病”和“虹鳟鱼苗综合征”的病原体，存在于许多淡水和海水养殖鱼类物种中。在挪威，这种细菌主要从大西洋鲑（Salmo salar L.）和褐鳟（Salmo trutta L.）中分离出来。在本研究中，对来自挪威养殖鲑鱼的 26 个分离株进行了检查。所有分离株均通过纸片扩散法检测对各种抗菌药物的敏感性，并为选定的分离株建立了氧氟沙星和氟甲喹的最小抑菌浓度值。所有来自虹鳟的分离株对喹诺酮类药物的敏感性降低，而褐鳟和大西洋鲑的分离株则敏感。对 gyrA、gyrB、parC 和 parE 基因的喹诺酮耐药决定区（QRDR）进行了测序。对来自挪威虹鳟的 16 个喹诺酮耐药分离株的 gyrA 的 QRDR 进行序列分析，发现所有分离株在第 82 位都有苏氨酸：精氨酸氨基酸取代，而来自瑞典虹鳟的一个参考菌株也是如此。在任何分离株中均未发现质粒介导的喹诺酮耐药证据。parC 和 gyrB 序列的脉冲场凝胶电泳和系统发育分析表明，虹鳟分离株之间存在克隆关系。
