背景:猪链球菌(S.suis)是重要的猪和人类病原体。最近的一项研究报道了第一个能够感染鱼类的猪链球菌,命名为猪链球菌菌株3112。该细菌是从蛇皮古拉米(Trichopoduspectoralis)中分离出来的,一种原产于东南亚的重要经济鱼类,以前证明它可以感染并导致鱼类的致命链球菌病。
结果:在这项研究中,我们展示了猪链球菌3112的完整基因组。分子序列分析表明,它属于血清型6,序列型2340。系统发育分析表明,该细菌与健康猪猪链球菌分离株聚集在一起,暗示细菌的最终猪(与人类相反)起源。两个氟喹诺酮耐药基因存在于细菌基因组中,即patA和patB。我们的结果表明,这两个基因都在我们的细菌中表达,这种细菌对诺氟沙星有抗药性,但仍然对其他氟喹诺酮类药物敏感,包括环丙沙星,恩诺沙星,和司帕沙星.此外,该细菌对β-内酰胺敏感,四环素,磺酰胺,和氨基糖苷.
结论:这项研究报告并描述了猪链球菌3112的完整基因组,这是已知感染鱼类的第一个猪链球菌分离株,并提供了对细菌分离的进一步见解,特别是关于它的耐药性。这些结果将有助于进一步研究猪链球菌的比较基因组学和致病特征,以及针对这种新发现的鱼类病原体的控制策略的发展。
BACKGROUND: Streptococcus suis (S. suis) is an important swine and human pathogen. A recent study reported the first isolate of S. suis capable of infecting fish, designated as S. suis strain 3112. The bacterium was isolated from snakeskin gourami (Trichopodus pectoralis), an economically important fish species native to Southeast Asia, and it was previously shown that it can infect and cause lethal streptococcosis in the fish.
RESULTS: In this study, we present the complete genome of S. suis 3112. Molecular sequence analysis revealed that it belongs to serotype 6, sequence type 2340. Phylogenetic analysis showed that the bacterium clustered with healthy-pig S. suis isolates, suggestive of an ultimate swine (as opposed to human) origin of the bacterium. Two fluoroquinolone resistance genes are present in the bacterial genome, namely patA and patB. Our results showed that both genes are expressed in our bacterium, and the bacterium is resistant to norfloxacin, but is still sensitive to other fluoroquinolones, including ciprofloxacin, enrofloxacin, and sparfloxacin. Additionally, the bacterium is sensitive to β-lactams, tetracyclines, sulphonamides, and an aminoglycoside.
CONCLUSIONS: This study reports and describes the complete genome of S. suis 3112, the first isolate of S. suis known to infect fish, and provides further insights into the bacterial isolate, particularly regarding its drug resistance profile. These results will facilitate further investigations of the comparative genomics and pathogenic characteristics of S. suis, as well as the development of control strategies against this newly-identified fish pathogen.