摘要

兰斯菲尔德C组停乳链球菌代表了一种致病因子，导致全球许多养殖鱼类的高死亡率。尽管具有致病性，但与该病原体有关的流行病学知识有限。在本研究中，使用脉冲场凝胶电泳（PFGE）对来自台湾（n = 67）和日本（n = 12）的患病水生动物的79株停滞不动的分离株进行了表征。还研究了分离毒力因子的分布和抗菌药物敏感性。具有SmaI和ApaI消化的PFGE分别显示19种和20种不同的脉型，反映了来自不同来源的分离物之间的遗传多样性。所有检测的菌株都含有毒力相关基因sagA，NAPlr和α-烯醇化酶，而76/79（96.2％）和77/79（97.5％）分别含有spegg和sof。最常见的四环素和大环内酯抗性基因的PCR分析表明，分离物携带tet（M）（14/79,17.7％），tet（S）（12/79,15.2％），erm（B）（5/79， 6.3％）和mef（A）和msr（D）（3/79，3.8％）。含有一种或多种抗性基因的分离物通过纸片扩散法表现出对药物的抗性。总之，我们的数据表明，台湾和日本的停乳链球菌分离株表现出与其宿主物种和地理起源相关的不同的基因组谱，含有多个推定的毒力因子，并且一些被发现对四环素和红霉素有抗性。

Lancefield group C Streptococcus dysgalactiae represents an etiological agent causing high mortality in many farmed fish species worldwide. Despite its pathogenic importance, limited epidemiological knowledge related to this pathogen is available. In the present study, 79 S.dysgalactiae isolates from diseased aquatic animals in Taiwan (n = 67) and Japan (n = 12) were characterized using pulsed-field gel electrophoresis (PFGE). The distribution of isolate virulence factors and antimicrobial susceptibility were also investigated. PFGE with SmaI and ApaI digestions displayed 19 and 20 different pulsotypes respectively, reflecting a genetic diversity among isolates from different sources. All examined strains harbored the virulence-associated genes sagA, NAPlr, and α-enolase, whereas 76/79 (96.2%) and 77/79 (97.5%) harbored spegg and sof, respectively. PCR analysis of the most commontetracycline and macrolide resistance genes demonstrated that isolates carried tet(M) (14/79, 17.7%), tet(S) (12/79, 15.2%), erm(B) (5/79, 6.3%), and mef(A) and msr(D) (3/79, 3.8%). Isolates harboring one or more resistance genes showed resistance to drugs by the disk diffusion method. Together, our data indicates that S. dysgalactiae isolates in Taiwan and Japan exhibit distinct genomic profiles associated with their host species and geographical origins, harbor multiple putative virulence factors, and some are found resistant to tetracycline and erythromycin.

https://www.sciencedirect.com/science/article/abs/pii/S0044848617302727