PDF(Pubmed)
Abstract：
UNASSIGNED: Motile Aeromonas septicemia (MAS) is a burden for striped catfish (Pangasius hypophthalmus) farmers in Vietnam. MAS can be caused by several species of Aeromonas but Aeromonas hydrophila is seen as the leading cause of MAS in aquaculture, but recent reports suggest that A. dhakensis is also causing MAS.
UNASSIGNED: Here we investigated the bacterial etiology of MAS and compared the genomic features of A. hydrophila and A. dhakensis. We collected 86 isolates from diseased striped catfish fingerlings over 5 years from eight provinces in Vietnam. Species identification was done using PCR, MALDI-TOF and whole genome sequence (WGS). The MICs of commonly used antimicrobials was established. Thirty presumed A. hydrophila isolates were sequenced for species confirmation and genomic comparison. A phylogenetic analysis was conducted using publicly available sequences and sequences from this study.
UNASSIGNED: A total of 25/30 isolates were A. dhakensis sequence type (ST) 656 and 5/30 isolates were A. hydrophila ST 251. Our isolates and all publicly available A. hydrophila isolates from Vietnam belonged to ST 251 and differed with <200 single nucleotide polymorphisms (SNP). Similarly, all A. dhakensis isolates from Vietnam belonged to ST 656 and differed with <100 SNPs. The tet(A) gene was found in 1/5 A. hydrophila and 19/25 A. dhakensis. All A. hydrophila had an MIC ≤2 mg/L while 19/25 A. dhakensis had MIC ≥8 mg/L for oxytetracycline. The floR gene was only found in A. dhakensis (14/25) which showed a MIC ≥8 mg/L for florfenicol. Key virulence genes, i.e., aerA/act, ahh1 and hlyA were present in all genomes, while ast was only present in A. dhakensis.
UNASSIGNED: This study confirms previous findings where A. dhakensis was the dominating pathogen causing MAS and that the importance of A. hydrophila has likely been overestimated. The differences in antimicrobial susceptibility between the two species could indicate a need for targeted antimicrobial treatment plans. The lipopolysaccharide regions and outer membrane proteins did not significantly differ in their immunogenic potentials, but it remains to be determined with in vivo experiments whether there is a difference in the efficacy of available vaccines against A. hydrophila and A. dhakensis.
UNASSIGNED: Here we investigated the bacterial etiology of MAS and compared the genomic features of A. hydrophila and A. dhakensis. We collected 86 isolates from diseased striped catfish fingerlings over 5 years from eight provinces in Vietnam. Species identification was done using PCR, MALDI-TOF and whole genome sequence (WGS). The MICs of commonly used antimicrobials was established. Thirty presumed A. hydrophila isolates were sequenced for species confirmation and genomic comparison. A phylogenetic analysis was conducted using publicly available sequences and sequences from this study.
UNASSIGNED: A total of 25/30 isolates were A. dhakensis sequence type (ST) 656 and 5/30 isolates were A. hydrophila ST 251. Our isolates and all publicly available A. hydrophila isolates from Vietnam belonged to ST 251 and differed with <200 single nucleotide polymorphisms (SNP). Similarly, all A. dhakensis isolates from Vietnam belonged to ST 656 and differed with <100 SNPs. The tet(A) gene was found in 1/5 A. hydrophila and 19/25 A. dhakensis. All A. hydrophila had an MIC ≤2 mg/L while 19/25 A. dhakensis had MIC ≥8 mg/L for oxytetracycline. The floR gene was only found in A. dhakensis (14/25) which showed a MIC ≥8 mg/L for florfenicol. Key virulence genes, i.e., aerA/act, ahh1 and hlyA were present in all genomes, while ast was only present in A. dhakensis.
UNASSIGNED: This study confirms previous findings where A. dhakensis was the dominating pathogen causing MAS and that the importance of A. hydrophila has likely been overestimated. The differences in antimicrobial susceptibility between the two species could indicate a need for targeted antimicrobial treatment plans. The lipopolysaccharide regions and outer membrane proteins did not significantly differ in their immunogenic potentials, but it remains to be determined with in vivo experiments whether there is a difference in the efficacy of available vaccines against A. hydrophila and A. dhakensis.
摘要：
■活动气单胞菌败血症（MAS）是越南条纹cat鱼（Pangasiushypothromus）农民的负担。MAS可以由几种气单胞菌引起，但嗜水气单胞菌被视为水产养殖中MAS的主要原因，但是最近的报道表明，达克也引起了MAS。
■在这里，我们研究了MAS的细菌病因学，并比较了嗜水菌和达克氏杆菌的基因组特征。我们在5年内从越南八个省的患病条纹cat鱼种中收集了86种分离物。物种鉴定是用PCR进行的，MALDI-TOF和全基因组序列(WGS)。建立了常用抗微生物剂的MIC。对30个推测的嗜水嗜水气单胞菌分离株进行了测序，以进行物种确认和基因组比较。使用公开可用的序列和来自本研究的序列进行系统发育分析。
■总共有25/30个分离株是达克A.dhakensis序列型（ST）656，而5/30个分离株是嗜水A.ST251。我们的分离株和所有来自越南的公开可用的嗜水气单胞菌分离株属于ST251，并且具有<200个单核苷酸多态性（SNP）。同样，来自越南的所有达克氏芽孢杆菌分离株都属于ST656，差异<100个SNP。tet(A)基因发现于1/5嗜水气单胞菌和19/25达克单胞菌。所有亲水A.对土霉素的MIC≤2mg/L，而19/25A.dhakensis的MIC≥8mg/L。floR基因仅在达克氏酵母（14/25）中发现，氟苯尼考的MIC≥8mg/L。关键毒力基因,即，aerA/act,ahh1和hlyA存在于所有基因组中，而AST只存在于达克A.
■这项研究证实了先前的发现，即达克氏杆菌是导致MAS的主要病原体，并且可能高估了嗜水虫的重要性。两个物种之间的抗微生物敏感性的差异可能表明需要有针对性的抗微生物治疗计划。脂多糖区域和外膜蛋白的免疫原性潜力没有显着差异，但是，是否有可用的疫苗对嗜水气单胞菌和达克曲霉的效力存在差异，尚待体内实验确定。
■在这里，我们研究了MAS的细菌病因学，并比较了嗜水菌和达克氏杆菌的基因组特征。我们在5年内从越南八个省的患病条纹cat鱼种中收集了86种分离物。物种鉴定是用PCR进行的，MALDI-TOF和全基因组序列(WGS)。建立了常用抗微生物剂的MIC。对30个推测的嗜水嗜水气单胞菌分离株进行了测序，以进行物种确认和基因组比较。使用公开可用的序列和来自本研究的序列进行系统发育分析。
■总共有25/30个分离株是达克A.dhakensis序列型（ST）656，而5/30个分离株是嗜水A.ST251。我们的分离株和所有来自越南的公开可用的嗜水气单胞菌分离株属于ST251，并且具有<200个单核苷酸多态性（SNP）。同样，来自越南的所有达克氏芽孢杆菌分离株都属于ST656，差异<100个SNP。tet(A)基因发现于1/5嗜水气单胞菌和19/25达克单胞菌。所有亲水A.对土霉素的MIC≤2mg/L，而19/25A.dhakensis的MIC≥8mg/L。floR基因仅在达克氏酵母（14/25）中发现，氟苯尼考的MIC≥8mg/L。关键毒力基因,即，aerA/act,ahh1和hlyA存在于所有基因组中，而AST只存在于达克A.
■这项研究证实了先前的发现，即达克氏杆菌是导致MAS的主要病原体，并且可能高估了嗜水虫的重要性。两个物种之间的抗微生物敏感性的差异可能表明需要有针对性的抗微生物治疗计划。脂多糖区域和外膜蛋白的免疫原性潜力没有显着差异，但是，是否有可用的疫苗对嗜水气单胞菌和达克曲霉的效力存在差异，尚待体内实验确定。
