Wu Zuowei, Sippy Rachel, Sahin Orhan, Plummer Paul, Vidal Ana, Newell Diane, Zhang Qijing
Department of Veterinary Microbiology and Preventive Medicine, Iowa State University, Ames, Iowa, USA.
Department of Veterinary Microbiology and Preventive Medicine, Iowa State University, Ames, Iowa, USA
J Clin Microbiol. 2014 Jun;52(6):1853-61. doi: 10.1128/JCM.00355-14. Epub 2014 Mar 19.
Campylobacter infection is a leading cause of ovine abortion worldwide. Historically, genetically diverse Campylobacter fetus and Campylobacter jejuni strains have been implicated in such infections, but since 2003 a highly pathogenic, tetracycline-resistant C. jejuni clone (named SA) has become the predominant cause of sheep abortions in the United States. Whether clone SA was present in earlier U.S. abortion isolates (before 2000) and is associated with sheep abortions outside the United States are unknown. Here, we analyzed 54 C. jejuni isolates collected from U.S. sheep abortions at different time periods and compared them with 42 C. jejuni isolates associated with sheep abortion during 2002 to 2008 in Great Britain, using multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), and array-based comparative genomic hybridization (CGH). Although clone SA (ST-8) was present in the early U.S. isolates, it was not as tetracycline resistant (19% versus 100%) or predominant (66% versus 91%) as it was in the late U.S isolates. In contrast, C. jejuni isolates from Great Britain were genetically diverse, comprising 19 STs and lacking ST-8. PFGE and CGH analyses of representative strains further confirmed the population structure of the abortion isolates. Notably, the Great Britain isolates were essentially susceptible to most tested antibiotics, including tetracycline, while the late U.S. isolates were universally resistant to this antibiotic, which could be explained by the common use of tetracyclines for control of sheep abortions in the United States but not in Great Britain. These results suggest that the dominance of clone SA in sheep abortions is unique to the United States, and the use of tetracyclines may have facilitated selection of this highly pathogenic clone.
弯曲杆菌感染是全球绵羊流产的主要原因。从历史上看，基因多样的胎儿弯曲杆菌和空肠弯曲杆菌菌株与此类感染有关，但自2003年以来，一种高致病性、耐四环素的空肠弯曲杆菌克隆（命名为SA）已成为美国绵羊流产的主要原因。2000年之前的美国早期流产分离株中是否存在克隆SA以及它是否与美国以外地区的绵羊流产有关尚不清楚。在此，我们使用多位点序列分型（MLST）、脉冲场凝胶电泳（PFGE）和基于芯片的比较基因组杂交（CGH）分析了从美国不同时期绵羊流产中收集的54株空肠弯曲杆菌分离株，并将它们与2002年至2008年期间英国与绵羊流产相关的42株空肠弯曲杆菌分离株进行了比较。尽管克隆SA（ST-8）存在于美国早期分离株中，但其耐四环素性（19%对100%）或优势程度（66%对91%）不如美国后期分离株。相比之下，来自英国的空肠弯曲杆菌分离株基因多样，包括19个ST型且缺乏ST-8。对代表性菌株的PFGE和CGH分析进一步证实了流产分离株的群体结构。值得注意的是，英国分离株对包括四环素在内的大多数测试抗生素基本敏感，而美国后期分离株对这种抗生素普遍耐药，这可以通过美国但不是英国普遍使用四环素控制绵羊流产来解释。这些结果表明，克隆SA在绵羊流产中的优势在美国是独特的，四环素的使用可能促进了这种高致病性克隆的选择。
