Zhang Chunping, Zhang Zhongqiu, Song Li, Fan Xuezheng, Wen Fang, Xu Shixin, Ning Yibao
National Antimicrobial Resistance Monitoring Laboratory in Bacteria of Animal Origin, Department of Inspection Technology Research, China Institute of Veterinary Drug Control, Beijing 100081, China.
China Animal Disease Control Center, Beijing 100125, China.
Biomed Res Int. 2015;2015:284303. doi: 10.1155/2015/284303. Epub 2015 May 3.
Streptococcus suis serotype 2 is an important zoonotic pathogen. Antimicrobial resistance phenotypes and genotypic characterizations of S. suis 2 from carrier sows and diseased pigs remain largely unknown. In this study, 96 swine S. suis type 2, 62 from healthy sows and 34 from diseased pigs, were analyzed. High frequency of tetracycline resistance was observed, followed by sulfonamides. The lowest resistance of S. suis 2 for β-lactams supports their use as the primary antibiotics to treat the infection of serotype 2. In contrast, 35 of 37 S. suis 2 with MLSB phenotypes were isolated from healthy sows, mostly encoded by the ermB and/or the mefA genes. Significantly lower frequency of mrp+/epf+/sly+ was observed among serotype 2 from healthy sows compared to those from diseased pigs. Furthermore, isolates from diseased pigs showed more homogeneously genetic patterns, with most of them clustered in pulsotypes A and E. The data indicate the genetic complexity of S. suis 2 between herds and a close linkage among isolates from healthy sows and diseased pigs. Moreover, many factors, such as extensive use of tetracycline or diffusion of Tn916 with tetM, might have favored for the pathogenicity and widespread dissemination of S. suis serotype 2.
猪链球菌2型是一种重要的人畜共患病原体。来自携带母猪和患病猪的猪链球菌2型的抗菌药物耐药表型和基因型特征在很大程度上仍不清楚。在本研究中，分析了96株猪源猪链球菌2型，其中62株来自健康母猪，34株来自患病猪。观察到四环素耐药的频率很高，其次是磺胺类药物。猪链球菌2型对β-内酰胺类药物的耐药性最低，这支持将其作为治疗2型感染的主要抗生素。相比之下，37株具有大环内酯-林可酰胺-链阳菌素B（MLSB）表型的猪链球菌2型中有35株从健康母猪中分离得到，大多由ermB和/或mefA基因编码。与患病猪的2型菌株相比，健康母猪的2型菌株中mrp+/epf+/sly+的频率显著更低。此外，患病猪的分离株显示出更均匀的遗传模式，其中大多数聚集在脉冲型A和E中。数据表明猪链球菌2型在不同猪群间的遗传复杂性以及健康母猪和患病猪分离株之间的紧密联系。此外，许多因素，如四环素的广泛使用或携带tetM的Tn916的扩散，可能有利于猪链球菌2型的致病性和广泛传播。
