Edwardsiella ictaluri bacteraemia elicits shedding of Aeromonas hydrophila complex in latently infected channel catfish, Ictalurus punctatus (Rafinesque)     

K E Nusbaum  & E E Morrison 《Journal of fish diseases》2002,25(6):343-350

Edwardsiella ictaluri is a primary bacterial pathogen of channel catfish, Ictalurus punctatus, and the causative agent of enteric septicaemia of catfish . Edwardsiella ictaluri is known to gain entry to the host by infection of the nares, gastrointestinal tract, and gills, and to disseminate to organs via an as yet uncharacterized acute bacteraemia. In this study, fluorescent microscopy showed E. ictaluri on the gill within 5 min of immersion challenge and E. ictaluri could also be isolated from the circulation within 5 min. When removed to clean water, catfish cleared circulating bacteria within 15 min and the blood remained free of E. ictaluri until its reappearance at the 12 h post-infection sampling. However, Aeromonas hydrophila , the aetiological agent of motile aeromonad septicaemia, appeared within the circulation 7 h post-challenge with E. ictaluri and was detected in all fish at 12 h post-infection. Only 20% of fish carried A. hydrophila in the trunk kidney that could be detected by plate culture on Rimler–Shotts agar; however, 100% of challenged and stress-control fish were A. hydrophila complex positive at 24 h post-challenge. These results suggest that although the catfish is capable of clearing its circulation of E. ictaluri , superinfection with latent A. hydrophila may enhance clinical signs of edwardsiellosis. This is the first report of a bacterial superinfection appearing in fish.  相似文献   

Multiplex nested-polymerase chain reaction for the simultaneous detection of Aeromonas hydrophila, Edwardsiella tarda, Photobacterium damselae and Streptococcus iniae, four important fish pathogens in subtropical Asia     

Chin-I Chang  Chia-Che Wu  Ta Chih Cheng  Jyh-Ming Tsai  & King-Jung Lin 《Aquaculture Research》2009,40(10):1182-1190

A multiplex nested-polymerase chain reaction (PCR)-based (m-nested PCR) method was developed for simultaneous detection of four important freshwater/marine fish pathogens in subtropical Asia, including Aeromonas hydrophila, Edwardsiella tarda, Photobacterium damselae and Streptococcus iniae . The specificity of the oligonucleotide primers used for PCR detection was confirmed to generate specific amplicons for the corresponding pathogens. Moreover, non-specific amplicons were observed when the primers were tested using pure DNA extracted from 31 related bacterial strains belonging to 23 species or tissue homogenates of infected tilapia. This m-nested PCR approach could detect 19 colony forming unit (CFU) for A. hydrophila , 62 CFU for E. tarda , 280 CFU for P. damselae subsp. piscicida and 179 CFU for S. iniae in infected tilapia kidney homogenates, consistent with the results derived from bacteriological methods. The assay described in this paper is a sensitive and effective method for simultaneous detection of multiple fish pathogens.  相似文献   

斑点叉尾鮰肠败血症PCR诊断方法的建立     

梁万文  陈明  余晓丽  李莉萍  雷爱莹  陈汉忠  徐增辉  甘西  黄维义 《大连水产学院学报》2007,22(4):264-269

为了建立快速、敏感的聚合酶链式反应(PCR)诊断斑点叉尾鮰Ictalurus punctatus的肠败血症技术,作者根据NCBI公布的鮰爱德华氏细菌序列,设计了一对特异性诊断引物CM3/CM4,对鮰爱德华氏细菌特异基因片段进行PCR扩增试验,PCR反应条件的优化以及不同检测材料的比较,同时测试了该方法的特异性和敏感性,并对广西4个市县临床样品进行了检测.结果表明:用该引物可以扩增到与预计大小相符的276 bp鮰爱德华氏菌特异性片段;PCR反应与Ⅰ型荧光假单胞菌、点状产气单胞菌点状亚种、鳗弧菌、温和气单胞菌、肠型点状产气单胞菌、柱状黄杆菌、嗜水气单胞菌、河弧菌、迟缓爱德华氏菌及海豚链球菌无交叉反应;用该PCR法可以检测出病鱼脑、肝、肾及脾中的病原菌,检测的最低细菌数为12个,且病鱼内脏组织、菌落及菌液均可直接用于该PCR扩增;临床菌株检测结果与基于菌株16S rRNA基因序列系统进化分析和生化鉴定结果一致.因此,本试验中所建立的PCR检测方法在斑点叉尾鮰肠败血症的诊断和防治方面具有较好的应用前景.  相似文献   

鱼类致病性迟钝爱德华氏菌中多药抗性质粒pEIB202的消除     

郑浚源  许黎黎  王启要  肖婧凡 《安徽农业科学》2011,39(29):17944-17948

[目的]考察迟钝爱德华氏菌（Edwardsiella tarda）EIB202中大质粒pEIB202在其致病过程中的作用,将质粒pEIB202消除,为开发抗迟钝爱德华氏菌病的安全减毒的活疫苗打下良好基础。[方法]采用同源重组技术以sacB为反向筛选标记消除质粒。[结果]对质粒pEIB202进行序列分析,发现该质粒编码多种抗性基因及部分VI型分泌系统（T4SS）组分,暗示该质粒可能与E.tarda的多重耐药性及致病力相关;质粒消除菌株EIB202Δp丧失氯霉素及四环素抗性,在生长、毒力、胞外蛋白分泌等方面与野生株无显著差异。[结论]PEIB202质粒是造成EIB202多重耐药性的主要原因,在其致病过程中可能并不起直接作用。  相似文献   

Effects of dietary supplementation of a purified nucleotide mixture on immune function and disease and stress resistance in channel catfish,Ictalurus punctatus     

Thomas L Welker  Chhorn Lim  Mediha Yildirim‐Aksoy  Phillip H Klesius 《Aquaculture Research》2011,42(12):1878-1889

Juvenile channel catfish (14.4 g average initial weight) were fed diets supplemented with a purified nucleotide mixture for 8 weeks. The mixture consisted of five nucleotides supplied on an equal basis as disodium salts at combined concentrations of 0 (control), 0.1%, 0.3%, 0.9% or 2.7% of diet. Addition of nucleotides to diet produced a dose‐dependent reduction in survival of channel catfish to Edwardsiella ictaluri. Although the reasons are unclear, the high levels of nucleotides supplemented in this study may have contributed to the decrease in disease resistance, and this decrease appeared to be unrelated to the innate immune (unaffected) and specific antibody (enhanced) responses. Stress resistance increased with a corresponding amelioration of the immunosuppressive effects of the stress response on non‐specific immunity (lysozyme and bactericidal activity) as nucleotides increased in diet. Use of exogenous nucleotides as a prophylactic treatment before culture‐related stress exposure may prove beneficial by decreasing the immunosuppressive effects of stress but not in prevention of ESC.  相似文献   

Detection of tetracycline-resistance determinants by multiplex polymerase chain reaction in Edwardsiella tarda isolated from fish farms in Korea     

Lyu Jin Jun  Joon Bum Jeong  Min-Do Huh  Joon-Ki Chung  Dong-lim Choi  Chang-Hoon Lee  Hyun Do Jeong   《Aquaculture (Amsterdam, Netherlands)》2004,240(1-4):89-100

To determine and discriminate the types of tetracycline (Tc)-resistance determinants (tet), we developed a multiplex polymerase chain reaction (PCR). With minimized numbers of primers derived from the variable and conserved regions of six different types of tet genes, tet(A)–(E) and (G), the multiplex PCR was sensitive and specific enough to discriminate the various types of tet genes, even multiple tet genes in an individual resistant isolate, by the different sizes of the resulting PCR products. Each of 20 Tc-resistant Edwardsiella tarda (Ed. tarda) isolates from diseased fish from aquatic farms in Korea carrying either one or two tet genes of types (A), (D), (B), or (G) gave PCR products of the appropriate lengths. Among the four types of tet genes found in Ed. tarda, two types, tet(A) and (D), were always present on mobile plasmids, and the other two types, tet(B) and (G), were located on the nonmobile nucleic acids. This is the first time that either of these two genes, type (B) or (G), have been found in Ed. tarda isolates. The two most common types of Tc-resistance determinant were, tet(A) and (D), occurring in 55% and 45% of total Tc-resistant Ed. tarda isolates, respectively.  相似文献   

A comparative study of Edwardsiella ictaluri parent (EILO) and E. ictaluri rifampicin-mutant (RE-33) isolates using lipopolysaccharides,outer membrane proteins,fatty acids,Biolog, API 20E and genomic analyses     

Arias CR  Shoemaker CA  Evans JJ  Klesius PH 《Journal of fish diseases》2003,26(7):415-421

The biological properties of Edwardsiella ictaluri RE-33 rifampicin-mutant and its parent strain EILO were analysed. RE-33 is an avirulent isolate used as a modified live vaccine against enteric septicaemia of catfish. Electrophoretic analysis of lipopolysaccharide (LPS) patterns showed high homology between both isolates. Further characterization of LPS by immunoblotting revealed the main differences in LPS composition. The RE-33 isolate lacks the high molecular weight bands of LPS (HMW-LPS). Outer membrane protein analysis also showed some immunological differences between RE-33 and the EILO parent strain. Only two fingerprinting techniques, fatty acid composition analysis and Biolog phenotypic profiles, were able to discriminate between both isolates.  相似文献   

Identification of Edwardsiella ictaluri from diseased freshwater catfish, Pangasius hypophthalmus (Sauvage), cultured in the Mekong Delta, Vietnam   总被引：1，自引：0，他引：1  

M Crumlish  T T Dung  J F Turnbull  N T N Ngoc  H W Ferguson 《Journal of fish diseases》2002,25(12):733-736

  相似文献   

Effect of temperature and salinity on virulence of Edwardsiella tarda to Japanese flounder, Paralichthys olivaceus (Temminck et Schlegel)     

Dahai Zheng  Kangsen Mai  Shuqing Liu  Limin Cao  Zhiguo Liufu  Wei Xu  Beiping Tan  & Wenbing Zhang 《Aquaculture Research》2004,35(5):494-500

Experiments were designed to determine the effects of temperature and salinity on the virulence of Edwardsiella tarda to Japanese flounder, Paralichthys olivaceus. In the temperature experiment, a two‐factor design was conducted to evaluate the effects of both pathogen incubation temperature and fish cultivation temperature on pathogen virulence. E. tarda was incubated at 15, 20, 25 and 30±1°C, and the fish (mean weight: 10 g) were reared at 15, 20 and 25±1°C respectively. The fish reared at different temperatures were infected with the E. tarda incubated at different temperatures. The results of a 4‐day LD₅₀ test showed that temperature significantly affected the virulence of E. tarda (P<0.01) and the interaction between the two factors was also significant (P<0.01). For fish reared at 15°C the virulence of E. tarda was the highest at 25°C of pathogen incubation, followed by 20, 15 and 30°C. When the fish rearing temperature was raised to 20 and 25°C, the virulence of E. tarda incubated at all temperatures increased. Isolation testing demonstrated results similar to those of LD₅₀. The higher rearing temperature increased the proliferation rate of the pathogen in fish. In the salinity experiment, the incubation salinity of E. tarda was at 0, 10, 20 and 30 g L^?1, respectively, and the fish with mean weight of 50 g were cultured in natural seawater of 30 g L^?1. The results of one‐way anova in 4‐day LD₅₀ test showed that incubation salinity significantly affected virulence. Virulence was lower when the salinity of the incubation medium was at 0 and 30 g L^?1, higher at 10 and 20 g L^?1. The results of isolation test were in accordance with those of LD₅₀. At 20 g L^?1E. tarda had a faster proliferation rate than that at 10 g L^?1.  相似文献   

嗜水气单胞菌与迟顿爱德华氏菌二联外膜蛋白的表达及其初步免疫原性   总被引：1，自引：0，他引：1  

王玉  冯建军  郭松林  林鹏 《华中农业大学学报》2015,34(1):96-102

在构建鳗鲡病原性嗜水气单胞菌与爱德华氏菌二联外膜蛋白重组表达载体的基础上,采用不同的诱导剂(IPTG)浓度、诱导温度、诱导时间和诱导时菌液浓度对重组表达载体的表达条件进行探讨。结果表明,不同诱导剂(IPTG)浓度、诱导温度、诱导时间和诱导时菌液浓度对该载体的表达无明显影响。在菌液浓度D600nm=0.8时,采用0.25mmol/L的IPTG经16℃诱导培养过夜后表达。表达产物采用KTApurifier-100蛋白质纯化仪,结合His标签柱亲和层析后获得分子质量87.1ku的高纯度蛋白。蛋白经透析复性后免疫鳗鲡以初步研究其免疫原性。结果表明,免疫后第28天,重组蛋白不同剂量注射组的鳗鲡血清中抗体效价均显著高于PBS注射对照组,初步表明该重组表达蛋白具有良好的免疫原性。  相似文献