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大口黑鲈(Micropterus salmoides)是我国重要的淡水养殖经济鱼类品种,目前包括细菌性疾病在内的诸多因素影响了其养殖业的健康发展。维氏气单胞菌是引起淡水鱼败血症和溃疡综合征的重要病原菌。从患病大口黑鲈肝脏组织中分离到1株病原菌,通过形态学观察、生理生化特性分析、16S rRNA序列和特定毒力基因分析对其进行鉴定,并通过人工回归感染试验和药敏试验分析其致病性和耐药性。结果表明该菌为致病性维氏气单胞菌(Aeromonas veronii),含有aer、act、lip、fla、gcaT和OMPA I等毒力基因;药敏试验显示其对头孢曲松、氯霉素、氟苯尼考、强力霉素、四环素、多粘菌素、复方新诺明、左氟沙星等8种抗生素高度敏感,对新霉素、恩诺沙星、庆大霉素、链霉素、阿齐霉素、环丙沙星等6种抗生素中度敏感,对其他8种抗生素具有一定耐药性;人工回归感染实验表明该菌具有较高的致病性,对大口黑鲈的半致死浓度为1.4×106 CFU/mL。维氏气单胞菌是水产养殖中的条件性致病菌,研究结果揭示了该菌株的部分生物学特性,有利于丰富维氏气单胞菌属的基础数据,同时也为鲈鱼养殖过程中的病害防控提供了一定的参考依据。 相似文献
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Although Escherichia coli is widely distributed in the marine environment, only a small percentage are pathogenic to humans. Nonetheless, the widespread occurrence of waterborne infections of E. coli origin in humans has become one of the major health problems worldwide. To date, several types of enterovirulent E. coli have been recognized as the aetiologic agents of various gastrointestinal infections in humans. The most commonly encountered are those belonging to the enterotoxigenic (ETEC), enteroinvasive (EIEC), enterohaemorrhagic (EHEC) and enteropathogenic (EPEC) subtypes. In order to better determine the health risks that are associated with exposure to some of these specific subtypes, we have developed a very sensitive multiplex PCR system for the rapid detection and typing of ETEC, EHEC and possibly EPEC strains of E. coli in the aquatic environment. The target genes chosen for this investigation included: the PHO-A housekeeping gene (present in all E. coli); the LT1, LT2 and ST1 genes of ETEC; the VT1 and VT2 verotoxin, and EAE virulence genes of EHEC and EPEC, respectively. Six pairs of oligonucleotide primers were designed to simultaneously amplify internal fragments of these genes by multiplex PCR to generate PCR products that could be analysed and confirmed with relative ease by gel electrophoresis and HincII enzyme digestion. The results showed that the six sets of PCR primers were highly specific for their target genes and produced specific amplimers of the expected size from several control strains of E. coli – ATCC 35401 (LT1+/ST1+); SA53 (LT2+/VT2+); and O157 (VT1+/VT2+/EAE+). The detection sensitivity of the multiplex PCR system for the six target genes in an E. coli cell mixture was optimized and enhanced by preincubating serially diluted cells in Luria-Bertani broth for 6 h prior to PCR analysis. The results obtained indicated a detection sensitivity of 10° CFU (of each strain) per 100 μl reaction. Multiplex PCR analysis of seawater samples collected from four sewage-polluted sites in Hong Kong indicated the presence in all four samples of E. coli bacteria that were positive for LT1, ST1, VT1 and EAE virulence genes. Overall, the data indicated that the multiplex PCR system described in this study is a potentially very useful and powerful method for routine monitoring and risk assessment of water quality. 相似文献
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Chemotactic motility is involved in the virulence of many pathogenic bacteria. In order to understand the role of chemotactic motility of Vibrio harveyi in cellular processes and virulence, mini-Tn10/Kan transposon-induced mutants with deficient chemotactic motility were constructed, screened, and identified. Sequence analysis revealed that the 465-bp fragment (GenBank accession number HM630274) flanking the transposon insertion site in mutant TS-CM1 had the highest identity (96.9%) with a hypothetical protein gene of V. harveyi ATCC BAA-1116 and the second-highest identity (91.8%) with the pgk gene of V. parahaemolyticus RIMD 2210633. In another mutant, TS-CM2, 356 bp of transposon-flanking sequence (GenBank accession number HM630275) also showed the highest identity (94.6%) with a hypothetical protein gene of V. harveyi ATCC BAA-1116 and the second-highest identity (92.4%) with the flaB gene of V. alginolyticus HY9901. Studies on virulence-related biological characteristics such as growth,motility, adhesion, and infectivity of themutants showed that disruption of either the flagellin gene or energymetabolism gene led to subsequent loss of chemotactic motility and changes in growth, motility, adhesion, and virulence of the pathogenic V. harveyi. Hence, the flagellin gene and crucial energy metabolism gene played an important role in the chemotacticmotility of V. harveyi. 相似文献
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近年来细菌性疾病因病原菌种类繁多、覆盖区域广而影响了其养殖业的健康发展,造成较大的经济损失。从体表具有黑斑、肢体残损症状的罗氏沼虾(Macrobrachium rosenbergii)肝胰腺组织中分离得到1株病原菌,通过形态学观察、生理生化特性鉴定、16S rRNA序列和特定毒力基因检测鉴定,以及人工回归感染试验和药敏试验分析其致病性和耐药性。结果表明,该菌为豚鼠气单胞菌(Aeromonas caviae),含有aer、lip、gcat、ser和OMPA I等毒力基因;药敏试验显示其对头孢曲松、氯霉素等7种抗生素高度敏感,对恩诺沙星、阿米卡星及复方新诺明3种抗生素中度敏感,对四环素、环丙沙星等10种抗生素具有耐药性;人工回归感染实验表明该菌具有较高的致病性,对罗氏沼虾的半致死浓度为6.54×105 CFU/mL。豚鼠气单胞菌作为水产养殖中的条件性致病菌,研究结果揭示了该菌株的部分生物学特性,有利于丰富豚鼠气单胞菌属的基础数据,同时也为罗氏沼虾养殖过程中的病害防控提供了一定参考依据。 相似文献
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副溶血弧菌(Vibrio parahaemolyticus)是一种嗜盐性革兰氏阴性菌, 广泛分布于海洋环境中, 能够引起肠胃炎、伤口感染以及败血症, 是人类重要的病原菌之一。宿主体内被认为是一种低铁环境, 能够激发致细菌的毒力。副溶血弧菌能够分泌弧菌素或利用外源铁载体来获取铁。在低铁条件下, 编码双组份调控系统的基因簇VPA0148-VPA0149转录上调, 使含铁肠杆菌素受体PeuA转录出有活性的蛋白。VPA0148编码产物为一个响应调节因子, 具有一个磷酸基团接收结构域和一个DNA结合结构域。本研究发现, VPA0148的缺失增强了菌株的生物膜形成能力和对斑马鱼的致死能力, 同时能够促进菌株在低铁环境中的生长, 并增强菌株的群集运动。研究结果表明含铁肠杆菌素受体调节蛋白VPA0148对副溶血弧菌致病力具有调控作用, 增进了对铁调节副溶血弧菌毒力机制的认识。 相似文献
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鱼源无乳链球菌致病机理研究进展 总被引：2，自引：0，他引：2
从无乳链球菌的感染与传播途径,引起的病理学变化,致病机制,毒力因子和理化因子的影响等5个方面对鱼源无乳链球菌的致病机理作一综述。 相似文献
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白斑综合征病毒对脊尾白虾的致病性研究 总被引：1，自引：0，他引：1
2010年、2011年江苏沿海多数地方海水养殖中发生了脊尾白虾大规模死亡的现象,本课题通过对患暴发性流行病的脊尾白虾(Exopalaemon carinicauda)进行病毒分子生物学检测,发现病虾体内白斑综合征病毒(White Spot Syndrome Virus,简称WSSV)检测普遍呈阳性;应用发病虾组织制备的病毒粗提液,进行了人工感染实验,实验表明该病毒对脊尾白虾具有较强的致病性,可引起68.5%的死亡率。电镜结果表明,发病虾与感染病虾鳃及肝胰脏等组织器官都发生了相同的细胞病理变化,主要表现为细胞核内染色质边聚、线粒体肿胀、内嵴消失等一系列细胞病理变化,在其细胞核与细胞质中发现了具有单层囊膜结构的对虾白斑综合征病毒粒子,病毒粒子大小约为(130~170)nm×(305~405)nm,核衣壳呈子弹形,一端较细另一端较粗,完整病毒粒子由核心、衣壳和囊膜构成,分子生物学实验表明该病毒为WSSV。实验结果符合柯赫氏法则,可以初步推断WSSV感染脊尾白虾并与引发的大规模死亡有着直接关系。 相似文献
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宁波沿海陆源排污口细菌结构多样性和铁代谢相关的毒力基因的研究 总被引：1，自引：1，他引：0
应用多重PCR技术对肠杆菌铁代谢相关毒力基因fhuA、irp2、sltA和sodB进行同步检测, 研究宁波沿海陆源排污口人畜共患致病菌群落结构在人类活动影响下的分布差异及对环境因子变化的响应趋势。通过16S rRNA 基因的PCR扩增和限制性片段长度多态性(restriction fragment length polymorphism, RFLP)分析技术, 研究了东海重要陆源排污口的细菌群落多样性; 建立肠杆菌铁载体外膜受体蛋白fhuA、铁调节蛋白irp2、类志贺样毒素sltA、含铁超氧物歧化酶sodB基因多重PCR体系, 并用该体系检测铁代谢相关毒力基因在陆源排污口的分布情况。2011年3、5、8、10月份, 在宁波沿海陆源排污口中共分离纯化1000余株、98种细菌, 16S rRNA 基因序列分析表明, 它们分属于4个门5个纲13个科21个属, 其中?-变形杆菌纲(67株, 68.4%)和芽孢杆菌纲(16株, 16.3%)分别为变形菌门、厚壁菌门中主要纲。98株细菌中, fhuA+irp2+sodB+基因型检出率为35.71%; fhuA+irp2+ sltA+的基因型检出率为25.27%; irp2的基因型检出率为13.19%; fhuA基因型检出率为12.09%; fhuA+ irp2+
基因型检出率为9.89%; sltA+sodB+基因型检出率为8.79%; fhuA+irp2+sodB+sltA+基因型检出率为8.79%。 相似文献
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用RAPD技术对养殖环境溶藻弧菌遗传多样性的研究 总被引：5，自引：1，他引：5
利用RAPD技术对不同宿主，不同环境分离的8个溶藻弧菌Vibrio alginolyticus株系进行了遗传多样性分析，8个引物共获得了46条多态性条带，将8个株系分为3个类群，不同宿主（石斑鱼Einephelus fario和凡纳对虾Penaeus vannamei)，不同环境及药物处理前后的株系之间有很高的遗传多样性，使用药物后，溶藻弧菌株系遗传多样性和基因型发生了明显的变化，而同一环境和同一时间分离的菌株之间有较高的同源性。从患病石斑鱼上分离到的致病朱与非致病株有极高的相似性，但有一个约2kb的条带的差异，该差异条带可能与溶藻弧菌的致病性相关。 相似文献