首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 265 毫秒
1.
Abstract. Electrophoretic analysis of six types of tissue (serum, erythrocyte, liver, kidney, muscle and eye) and seven different isoenzymes (LDH, MDH, Est, ADH, IDH, α-GPDH and SOD) from both healthy grass carp, Ctenopharyngodon idellus Cuvier & Valenciennes, and carp affected by haemorrhagic disease was performed. It was found that: (1) Enzymes from diseased grass carp showed the most drastic changes within each tissue. The absolute activity of LDH in serum from the diseased fish increased to approximately twice that of the healthy fish; whereas the relative activity of A4 and A3B1, the main components of A sub-base in both serum and erythrocytes, was accelerated. (2) The isoenzymic changes in the control groups, diseased fish, artificially infected fish and healthy fish from diseased ponds indicated that biochemical changes occurred in the tissues before pathological change.  相似文献   

2.
Residue levels of the antibacterials enrofloxacin and ciprofloxacin were analysed in 15 commercially relevant animal by‐products (ABPs). Enrofloxacin was detected in all ABPs, and ciprofloxacin was detected in 11 of 15 ABP samples. Feed to muscle and skin carry –over of low background enro‐ and ciprofloxacin levels were assessed by applying a simple toxicokinetic model. The muscle and skin uptake and elimination rates were established in Atlantic salmon (Salmo salar L.) fed enrofloxacin enriched diets (100 μg kg?1 ‘low’ and 4000 μg kg?1 ‘high’) in triplicate for 41 days followed by a 90 days depuration period. The terminal half‐lives were 17 ± 0.4 and 18 ± 0.7 days, and uptake rates were 9.3 ± 3.3 and 11 ± 3.1 (day?1) for the ‘low’ and ‘high’ groups, respectively. Only fish fed high background levels had quantifiable levels of the metabolite ciprofloxacin with a formation of 0.25 ± 0.01% day?1. The toxicokinetic carry‐over model predicted muscle and skin steady state levels of 1.8 μg kg?1 when fed theoretically high enrofloxacin levels (158 μg kg?1), which is below the EU limit of 100 μg kg?1 for enrofloxacin in finfish food products. The antibacterial residue levels could however be detected in EU food surveillance programmes.  相似文献   

3.
Olive flounder is the most important species for the Northeast Asian fish farming industry. However, this species is substantially affected by multiple infectious agents, including Streptococcus parauberis. Evaluation of antibiotics before their application is critical to treat infections and prevent drug resistance. Therefore, in this study, the pharmacodynamics of amoxicillin (AMX) and other antimicrobials against the planktonic‐ and biofilm‐forming bacteria were assessed. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and Time–kill curve assay were analysed using micro‐dilution method. The minimum biofilm eradicating concentration (MBEC) was determined using the Calgary Biofilm device. The effects of temperature, pH, hardness and salinity were detected for both planktonic‐ and biofilm‐forming bacteria. The MIC of AMX ranged from 0.015 to 2 μg/ml, whereas that of cephalexin (CEP), enrofloxacin (ENR) and oxytetracycline (OTC) ranged from 0.125 to 256, 0.125 to >512 and 0.25 to >512 μg/ml respectively. No bacteria were resistant against AMX, while the percentage of resistance to CEP, OTC and ENR were 68.7%, 52.6% and 11.1% respectively. The IC50 of AMX, CEP, ENR and OTC was 0.03, 0.091, 0.015 and 0.213 μg/ml respectively. The MBEC of amoxicillin against S. parauberis ranged from 0.5 to 16 μg/ml. Higher rates of bacterial growth were obtained at 30°C, pH = 8 and salinity of 7.5–10 ppt. The hardness of the media suppressed the bacterial growth. In conclusion, AMX was found to be effective against both the planktonic and the biofilm forms of the prominent fish pathogen, S. parauberis.  相似文献   

4.
周帅  胡琳琳  房文红  周凯  于慧娟 《水产学报》2011,35(8):1182-1190
采用高效液相色谱法,研究盐度33条件下恩诺沙星口灌和肌肉注射给药(剂量10 mg/kg)后,恩诺沙星及其代谢物环丙沙星在拟穴青蟹体内的药代动力学和组织分布。血淋巴和组织中药代动力学参数采用基于统计矩原理的非房室模型进行计算。恩诺沙星口灌和肌肉注射拟穴青蟹给药后,血药达峰快,分别为0.5 h和1 min,达峰浓度分别为12.90和31.86 μg/mL,曲线下面积(AUC)分别为216.1和816.8 μg/(mL·h)。恩诺沙星在拟穴青蟹组织中分布较广,口灌给药下肌肉和肝胰腺AUC分别为445.9和817.6 μg/(g·h),肌肉注射给药下的AUC分别为554.7和2 573.7 μg/(g·h)。与其它水产动物相比,恩诺沙星在拟穴青蟹体内消除速度为中等水平,口灌和肌肉注射恩诺沙星后血药消除半衰期(t1/2z)分别为26.45和57.02 h,总体清除率(CLz)分别为0.054和0.012 L/(h·kg)。恩诺沙星在拟穴青蟹体内代谢生成环丙沙星的量较少,口灌给药下血淋巴、肌肉和肝胰腺的AUCCIP/AUCENR分别为6.66%、3.66%和4.78%,肌肉注射给药下,其相应值分别为4.16%、7.24%和1.48%,在拟穴青蟹体内起药效作用仍是以恩诺沙星为主。以Cmax/MIC、AUC0-24/MIC评价恩诺沙星在青蟹体内的药效作用,建议给拟穴青蟹以10 mg/kg剂量每隔24小时投喂一次恩诺沙星,对弧菌引起的细菌性疾病具有较好的防治效果。  相似文献   

5.
The present Present experiment was conducted for 75 days in triplicates groups in 18 aquaria of 50 L each to study the effect of Wolffia arrhiza and Spirulina platensis on growth and pigmentation of Botia dario. Six isonitrogenous diets were prepared with 350 g/kg crude protein (CP) level. Diet 1 (T1) was prepared without fortification of spirulina and wolffia. T2 diet was prepared with spirulina as supplement of carotenoids. Similarly, T3, T4, T5 and T6 diets were prepared by substituting 25, 50, 75 and 100 g/kg of CP from spirulina with wolffia, respectively. Significant differences (p < .05) in final mean weight, mean weight gain, body weight gain and specific growth rate were observed. 100 percent survivability was recorded in T4 and T5. Final carotenoids content (μg/g) in skin (166.39 ± 2.71) and muscle (10.67 ± 0.32) was recorded highest in T5 and in whole fish in T6 (13.03 ± 0.95 μg/g). Redness, yellowness and whiteness found to have no significant differences (p > .05). Thus, it can be concluded that diet containing 100 g/kg spirulina can be effective for better growth while diet containing 25 g/kg spirulina and 150 g/kg wolffia can be effective for higher survival and pigmentation in Botia dario.  相似文献   

6.
The present study was designed to explore the pharmacokinetics of enrofloxacin in Takifugu flavidus at different salinity levels (10‰, 20‰ and 30‰). The concentrations of enrofloxacin in plasma and tissues (kidney, liver and muscle) of T. flavidus after a single oral dose of 10 mg kg?1 were simultaneously determined using HPLC. The parameters of pharmacokinetics were calculated using non‐compartmental model based on statistic moment theory. The peak concentrations of enrofloxacin were higher and Tmax values in plasma, liver and muscle tissues of T. flavidus were lower at the salinity of 20‰ and 30‰ than that of 10‰, except the kidney tissue. These demonstrated the absorption of enrofloxacin was more quickly and more quantity at the high salinity. The elimination half‐life (t1/2z) of enrofloxacin in the plasma (45.22, 69.91 and 95.45 h) was increasing with the increase in salinity. And the t1/2z values of enrofloxacin in liver (76.44, 44.21 and 33.48 h) and kidney (212.16, 157.43 and 35.61 h) both decline with the increase in salinity, indicating the elimination of enrofloxacin was faster in liver and kidney but slower in plasma at the high salinity. The content of enrofloxacin in liver was increasing with the increase in salinity, suggesting that salinity affects tissue distribution and metabolism in T. flavidus. In addition, the AUC0–∞ data of enrofloxacin (kidney > plasma > liver > muscle) at different salinity levels were essentially consistent, and AUC0–∞ data of kidney were declined with the increase in salinity, supporting that the kidney was the main organ and the role of extent of kidney on excretion was different in different salinity levels.  相似文献   

7.
Y. Wang  M. Li  K. Filer  Y. Xue  Q. Ai  K. Mai 《Aquaculture Nutrition》2017,23(5):1113-1120
This trial was conducted to evaluate the effects of replacing dietary fish oil with Schizochytrium meal for Pacific white shrimp (Litopenaeus vannamei) larvae (initial body weight 4.21 ± 0.10 mg). Six test microdiets were formulated using Schizochytrium meal to replace 0 g/kg, 250 g/kg, 500 g/kg, 750 g/kg, 1000 g/kg or 1500 g/kg fish oil DHA. No significant differences were observed in survival, growth, final body length and activities of digestive enzyme among shrimp fed different diets (p > .05). No significant differences were observed in C20:5n‐3 (EPA) in muscle samples (p > .05). C18:3n‐3 and C20:4n‐6 in muscle increased as Schizochytrium meal replacement level increased (p < .05). No significant differences were observed in C22:6n‐3 (DHA) and n‐3 fatty acids among shrimp fed diets that algae meal replaced 0 g/kg ‐ 1000 g/kg of fish oil. Shrimp fed diet R150 had higher DHA content than other groups and had higher n‐3 fatty acids than that of shrimp fed diets R50, R75 and R100 (p < .05). C18:2n‐6, PUFA and n‐6 fatty acids in muscle increased, while n‐3/n‐6 ratio decreased with increasing algae meal replacement level from 0 g/kg to 1000 g/kg (p < .05). In conclusion, Schizochytrium meal could replace 1500 g/kg fish oil DHA in the microdiets without negatively affecting shrimp larvae survival, growth and activities of digestive enzyme.  相似文献   

8.
The phytoplanktivorous silver carp is an important biomanipulation fish to control cyanobacterial blooms and is also a food fish with the greatest production in China. The accumulation of the hepatotoxic microcystins (MCs) determined by LC-MS in various organs of silver carp was studied monthly in Lake Taihu dominated by toxic Microcystis aeruginosa. Average recoveries of spiked fish samples were 78% for MC-RR and 81% for MC-LR. The highest content of MCs was found in the intestine (97.48 μg g− 1 DW), followed by liver (6.84 μg g− 1 DW), kidney (4.88 μg g− 1 DW) and blood (1.54 μg g− 1 DW), and the annual mean MC content was in the order of intestine > liver > kidney > blood > muscle > spleen > gallbladder > gill. Silver carp could effectively ingest toxic Microcystis cells (up to 84.4% of total phytoplankton in gut contents), but showed fast growth (from 141 g to 1759 g in 1 year in mean weight). Silver carp accumulated less microcystins in liver than other animals in the same site or other fish from different water bodies at similar level of toxin ingestion. There was possible inhibition of the transportation of the most toxic MC-LR across the gutwall. Muscle of silver carp in Lake Taihu should not be consumed during period of dense Microcystis blooms while viscera were risky for consumption in more months.  相似文献   

9.
郑迪  王倩  王磊  施兆鸿  彭士明 《海洋渔业》2021,43(2):201-208
为研究肠道气泡堆积对银鲳(Pampus argenteus)组织抗氧化能力及溶菌酶活力的影响,采集了15尾肠道气泡堆积的银鲳为病鱼组,15尾健康银鲳为对照组,分别采集各组样品的肝脏、肾脏、肌肉和鳃组织,并对这4种组织的超氧化物歧化酶活力、过氧化氢酶活力、丙二醛含量、总抗氧化能力以及两种组织(鳃和肾脏)溶菌酶活力进行测定和比较。结果显示,相比对照组,病鱼组肝脏、鳃和肾脏的总抗氧化能力都有下降,其中肝脏和肾脏显著下降(P<0.05);而肌肉中总抗氧化能力病鱼组显著高于对照组(P<0.05)。对照组肝脏和肌肉的超氧化物歧化酶和过氧化氢酶活力显著高于病鱼组(P<0.05);丙二醛含量对照组肝脏和肌肉中显著低于病鱼组(P<0.05),但鳃和肾脏显著高于病鱼组(P<0.05);溶菌酶活力病鱼组鳃显著高于对照组(P<0.05),但肾脏与对照组间无显著性差异。结果表明,肠道气泡堆积对银鲳组织抗氧化能力及其溶菌酶活力影响较大,导致肝脏与肌肉中的超氧化物歧化酶、过氧化氢酶活力显著降低,鳃溶菌酶活力显著升高。  相似文献   

10.
A disease with white spots in internal organs of Nile tilapia occurred in Zhanjiang, southern China. Multiple, white nodules, 0.8–2.2 mm in diameter, were scattered throughout the liver, spleen and kidney of diseased fish. Signs of nodules reproduced after artificial infection with the isolated strain. Isolated bacteria were Gram‐negative, facultative anaerobic, motile, short rod‐shaped, with a length of 1.2–2.2 μm. Morphological and biochemical tests, as well as phylogenetic analysis, all strongly indicated that the isolate from tilapia is identical to Aeromonas schubertii (A. schubertii) which temporary named LF1708 strain. Antibiotic sensitivity assays showed the LF1708 is sensitive to 24 of 27 tested antibiotics. Pathogenicity test revealed that the isolate at the dose of 3.75 × 106 CFU/g killed 100% of experimental tilapia within 2 days and the dose of 1 × 107 CFU/g killed 100% of experimental zebrafish within 1 day. Histopathology of diseased tilapia infected with A. schubertii showed numerous necrotic lesions widely distributed in spleen, liver and kidney, and infiltration with a large number of bacteria. To our knowledge, this was the first report that associated A. schubertii with mortality in tilapia.  相似文献   

11.
The intensive production of farmed fish is at a global all‐time high, and the control of bacteria proliferation in fish farms requires the frequent use of antimicrobials. This practice raises important environmental concerns related to the emergence of antimicrobial‐resistant bacteria strains. Only a few antimicrobial drugs have been approved for use in aquaculture, one of which is florfenicol. This work studies the depletion and withdrawal period of florfenicol and its main metabolite, florfenicol amine, in pacu (Piaractus mesopotamicus), a neotropical characin widely farmed in the southern hemisphere. Juvenile pacu (average weight of 724 g) were stocked in a closed‐loop laboratory system with controlled water temperature (25.8°C), and were fed for 10 consecutive days with a diet containing an intended dose of 10 mg/florfenicol per kg bw. Muscle and skin tissues were collected at 1, 3, 6, 8, 10, 12 and 16 days post‐treatment, and florfenicol and florfenicol amine were quantified using a validated ultra‐high performance liquid chromatography‐tandem mass spectrometry (UPLC‐MS/MS) method. The limits of quantitation for florfenicol and florfenicol amine were 10 ng/g in muscle and 50 ng/g in skin. Considering a maximum residue limit of 1000 ng/g for the sum of florfenicol and florfenicol amine in muscle with skin in natural proportions a withdrawal period of 5 days (water temperature 25.8°C) or 129 degree days was calculated on the basis of the upper limit of the one‐sided 95% confidence interval for the 99th percentile derived from the residue depletion study.  相似文献   

12.
本研究比较了在20℃水温条件下恩诺沙星(Enrofloxacin)在3种主要养殖鲆鲽鱼[大菱鲆(Scophthalmus maximus)、牙鲆(Paralichthys olivaceus)和半滑舌鳎(Cynoglossus semilaevis)]体内的残留消除规律。选择体重为300–400 g 的健康2龄大菱鲆、牙鲆和半滑舌鳎,以10 mg/kg 的剂量连续3 d 通过灌胃的方式分别给予恩诺沙星后,于1、3、6、10、15、20、25、30、35、40 d 采集血浆、肝、鳃、肌肉和肾组织。利用高效液相色谱法检测血浆和各组织中的恩诺沙星浓度,拟合恩诺沙星在3种鲆鲽鱼体内的消除曲线,计算消除半衰期。结果显示,3种鲆鲽鱼的组织中,恩诺沙星在肾中残留浓度最高,其消除速度依次为牙鲆>大菱鲆>半滑舌鳎,其消除半衰期分别为3.75、6.54、7.37 d;恩诺沙星在大菱鲆、牙鲆和半滑舌鳎血浆中的消除比其代谢产物环丙沙星慢;综合比较恩诺沙星在3种鲆鲽鱼血浆和大多数组织中的消除规律,均呈现出牙鲆体内消除最快,大菱鲆次之,半滑舌鳎最慢的趋势。依据我国无公害水产品中恩诺沙星最高残留限量为50μg/kg 的标准,建议在20℃水温条件下使用恩诺沙星防治鲆鲽鱼细菌性疾病时的休药期为：大菱鲆44 d、牙鲆33 d、半滑舌鳎47 d 以上。  相似文献   

13.
A novel disease outbreak occurred among cultured loach, Misgurnus anguillicaudatus in China. The diseased fish displayed lethargy, loss of appetite, black discolouration, anasarca and ventral skin hyperaemia. Clinical signs were observed in most of the fish examined, which consisted of discoloured liver, swollen spleen and petechial haemorrhage in the intestine and peritoneal membranes. The causative agent was found to be two species of bacteria by experimental infection, identified as Shewanella sp. and Listonella sp. The result showed that these were likely to be Shewanella putrefaciens and Listonella anguillarum respectively. Bacterial identification consisted of physiological and biochemical tests as well as 16S rRNA sequence analysis. In addition, antibiotic susceptibility testing was performed, revealing that Shewanella putrefaciens and Listonella anguillarum were susceptible to enrofloxacin, ciprofloxacin, levofloxacin, pipemidicacid and norfloxacin. This is the first report of S. putrefaciens and L. anguillarum from cultured loach.  相似文献   

14.
The uptake and elimination profile of oxytetracycline (OTC) following a prolong bath treatment in gilthhead sea bream (Sparus aurata) were investigated in this study. The bath experiment was carried out using a OTC concentration of 50 μg/ml for 24 h at 17-18 °C water temperature. Plasma and muscle fish samples were analysed at 1, 3, 6 and 24 h during and at 1, 2, 3, 4 and 6 d following the bath. Detectable OTC levels were revealed only at the end of bath treatment (24 h) in examined tissues of gilthead sea bream, where drug concentration was measured to be as low as 0.096 and 0.047 μg/g or ml in muscle plus skin and plasma, respectively. The findings of the present study indicate that OTC bath treatment under this dosage schedule is unlikely to confront systemic bacterial infections.  相似文献   

15.
Rainbow trout Oncorhynchus mykiss were fed a ration medicated to provide enrofloxacin (Baytrilo®, Bayer) at 2.5, 5.0, or 10.0 mg drug per kg fish per d either 5 or 10 d. Tissue Concentrations of enrofloxacin were measured in liver, kidney, muscle, skin, and serum during the medication period, and thereafter for a total of 30 d. Highest tissue concentrations were observed in fish medicated with 5 mg enrofloxacin per kg fish per d for 10 d. Tissue concentrations of anitmicrobial activity were found to exceed minimum inhibitory concentrations of enrofloxacin for several isolates of Aeromonas salmonicida and Renibacterium salmoninarum . Lower than expected tissue concentrations were observed for the 10 mg per kg fish per d doses, perhaps due to a lack of acceptance of the medicated ration. The results support evaluation of a 5 mg per kg fish dose to treat bacterial infections of salmonids under field conditions.  相似文献   

16.
Aeromonas salmonicida subsp. masoucida (ASM) is classified as atypical A. salmonicida and brought huge economic damages to the local salmonid aquaculture in China. An ASM strain named AS‐C4 was used to investigate the colonization of ASM in Atlantic salmon (Salmo salar L.) by an immersion challenge with the control group (T0, no AS‐C4), group T1 (2.67 × 104 CFU/ml AS‐C4) and group T2 (2.67 × 107 CFU/ml AS‐C4). The numbers of AS‐C4 copies in different fish tissues (gill, intestine, skin, blood, muscle, spleen, liver and kidney) were determined at different time points post challenge using the quantitative real‐time PCR (qRT‐PCR). AS‐C4 were detected in the gill and intestine as early as 0 hr after the challenge both in T1 and T2 groups, suggesting that the gill and intestine were probably the portals of entry of AS‐C4 into salmon. Although AS‐C4 could not be detected in the skin until 24 hr after the challenge in T1 group, it could be detected in the skin as early as 0 hr after the challenge in T2 group, indicating that the skin may also be a portal of entry of AS‐C4 into salmon. AS‐C4 was immediately detected in the blood within 3 hr after it entered the host, suggesting that AS‐C4 successfully invaded the bloodstream of fish. After AS‐C4 colonized the host, it colonized the internal tissues, such as the spleen, liver, kidney and muscle. The results of this study will contribute to the understanding of the pathogenesis of the ASM strains and give a broader understanding of the infection route of ASM in it's host, providing more information for the development of new therapeutic strategies to protect against this pathogen in aquaculture.  相似文献   

17.
The research was aimed to assess the effect of dietary carvacrol (0.025% and 0.05%) on sea bass (Dicentrarchus labrax) growth, immune response and resistance to Listonella anguillarum. Fish (69.2 ± 0.22 g) were fed the experimental diets for 9 weeks. Dietary carvacrol did not negatively affect fish survival, growth performance, feed intake and feed conversion ratio (P > 0.05) nor carcass yield and viscerosomatic, hepatosomatic and mesenteric fat index (P > 0.05). Serum and head kidney leucocytes were collected after 1, 4 and 8 weeks of feeding. Carvacrol significantly reduced serum proteins, immunoglobulins and lysozyme activity (P < 0.01) and moderately increased phagocytosis and pinocytosis of head kidney macrophages. The release of reactive oxygen species by leucocytes was reduced in carvacrol‐fed fish, even if significantly (P < 0.05) only in those fed 0.05% carvacrol for 1 week. Dietary carvacrol did not significantly affect the aspecific immune response, although a potential antioxidant activity might be speculated. Moreover, feeding carvacrol provided an appreciable resistance to a challenge with L. anguillarum, when a bacterial dose lower than the Lethal Dose50 was used. Cumulative mortality in fish fed 0.025% carvacrol was significantly lower than that of untreated controls (75% Relative Per cent Survival).  相似文献   

18.
The present research was designed to investigate the growth promoting and immunostimulating properties of Moringa oleferia leaf meal (MLM) in grass carp. Juvenile grass carp (22.03 g ± 1.164) were fed with diets supplemented with 0, 50, 100 and 150 g/kg MLM for 48 days. At the end of feeding trial, skin mucus was used for analysis of lysozyme, protease, antiprotease and peroxidase activity. Head kidney was used for expression analysis of tumour necrosis factor‐alpha, interleukin‐8 and interferon‐γ. The obtained results showed that fish fed with 100 and 150 g/kg MLM had significant increase in weight gain and specific growth rate (p < .05). However, condition factor was not altered. The MLM (50 and 100 g/kg) inclusion resulted in higher mucus lysozyme and protease activity (p < .05), while peroxidase activity increased only in fish fed with 100 g/kg MLM and antiprotease activity was not altered. Expression of tnf‐α increased in a dose‐dependent manner, and significant (p < .05) increase was recorded in fish fed with 150 g/kg MLM. The expression of il‐8 and ifn‐γ increased in fish fed with 50 and 150 g/kg MLM; however, the increase was not significant (p > .05). In conclusion, supplementing juvenile grass carp feed with MLM up to 150 g/kg has growth promoting and immunostimulating effects.  相似文献   

19.
The aim of this study was to assess the effects of different dietary fibre concentrates (DFC: Mucilage = MG; pectin = PN or β‐glucan+mannan = βg+M), on biochemical parameters, stress and immune response and skin mucus of jundiá (Rhamdia quelen). The fish (7.16 ± 0.06 g) were fed with Control diet (0 g/kg of DFC); diet supplemented with 5 g/kg of commercial prebiotic (CP 5) or diets supplemented with 5 or 10 g/kg of MG; PN or βg+M. After 8 weeks of the feeding trials, biochemical parameters (cholesterol, glucose, albumin and total protein), cortisol, immunoglobulin IgM and mucoproteins of skin mucus were assessed. Results demonstrated that supplementation with PN increased cholesterol levels (p<.05). After application of the stressor, most fish, except those in the PN and 10 g/kg MG groups, showed significant increases (p<.05) in cholesterol, glucose and albumin levels. The jundiás showed no difference in cortisol levels after application of the stressor (p>.05). IgM levels were significantly high in fish supplemented with DFC (p<.05). However, the concentration of mucoproteins in skin mucus was not influenced in the different treatments (p>.05). The results showed that supplementation with DFC promoted beneficial effects on the metabolism of jundiá.  相似文献   

20.
Streptococcus iniae has emerged as an important fish pathogen over the past few decades causing high losses in aquaculture farms all over the world. At least 27 species of fish have been documented to be infected by S. iniae, including cultured and wild populations. In August and October 2013, a serious infectious disease characterized by body ulcer, internal organs haemorrhages and nodules showing on epicardium occurred on the Acipenser baerii farms in Ya'an country, China. Histological examination revealed a multisystemic, necrotising inflammatory response that was particularly marked in liver, kidney, heart and brain. Mass mortality (>40%) was observed in infected fish and two Gram‐positive cocci (Ab130920 and Ab131025) were obtained from kidneys and livers of diseased fish. Experimental infections with these two isolates resulted in marked symptoms in the sturgeons similar to those observed in natural outbreaks, and the LD50 values of the two isolates were 5.1 × 105 and 6.4 × 105 cfu per fish respectively. The two microorganisms were identified as S. iniae through physiological and biochemical tests, 16S rRNA and lctO gene sequence analysis. Both two isolates showed a similar antibiotic susceptibility, which were sensitive to ampicillin, amoxicillin, cefazolin, amikacin, deoxycycline, florfenicol, azithromycin, ciprofloxacin, vancomycin and resistant to streptomycin, gentamicin, kanamycin, norfloxacin and sinomin (SMZ/TMP). Multiplex PCR assay for virulence genes showed both isolates possessed six main virulence genes: simA, scpI, pdi, pgm, cpsD and sagA genes. These results indicated that S. iniae could act as a pathogen of farmed A. baerii. This is the first report of S. iniae infection associated with mass mortality in A. baerii.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号