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1.
A Streptococcus species biochemically and serologically identical to the rainbow trout pathogenic Streptococcus species was isolated from the internal organs of the fish specific leech, Batracobdelloides tricarinata. These leeches were obtained from Roodeplaat Dam, near Pretoria, in which rainbow trout do not occur. This is the first isolation of this bacterium from an environmental source not related to rainbow trout and it is proposed that this leech is a possible reservoir of the rainbow trout pathogenic Streptococcus sp. in South Africa.  相似文献   

2.
The indirect fluorescent antibody technique has been used successfully for the rapid serological identification of the Streptococcus sp. responsible for streptococcosis of rainbow trout. This technique has been used to identify the Streptococcus sp. in pure cultures and smears made from experimentally infected and diseased fish.  相似文献   

3.
New selective and differential media were devised for the isolation and identification of Streptococcus suis type 2. The selective medium (NNCC) agar) was Todd-Hewitt broth containing 1.5% Bactoagar and 5% defibrinated sheep blood with addition of sodium azide (50 micrograms/ml), nalidixic acid (25 micrograms/ml), colistin (12.5 micrograms/ml) and crystal violet (2 micrograms/ml). The differential medium consisted of heart infusion agar and antiserum specific only for S. suis type 2. In a total of 291 pigs tested by a combination of these media, S. suis type 2 was isolated and confirmed from 40 of them (13.7%).  相似文献   

4.
A comparative pharmacokinetic study was conducted in rainbow trout (Salmo gairdneri) and African catfish (Clarias gariepinus) following intravenous (i.v.) and intramuscular (i.m.) administration of oxytetracycline (OTC) at a dose rate of 60 mg/kg body weight. Trout and catfish were kept in aerated tap water in tanks at constant temperatures of 12 degrees C and 25 degrees C, respectively. The two- and three-compartment open models adequately described plasma drug disposition in African catfish and rainbow trout respectively, following i.v. OTC administration. Compared to catfish (COP = 86 +/- 10 micrograms/ml) an eightfold higher extrapolated zero time concentration was obtained in trout (COP = 753 +/- 290 micrograms/ml). A significant difference was observed with respect to the relatively large apparent distribution volumes (Vd(area] after i.v. OTC administration (trout, mean value: 2.1 l/kg; catfish, mean value: 1.3 l/kg). The mean final elimination half-lives of both fish species were greater than previously reported in mammals (trout, 89.5 h; catfish, 80.3 h). A mean maximum plasma concentration (Cmax = 56.9 micrograms/ml) was obtained in trout at 4 h after i.m. administration of OTC. In catfish a lower Cmax of 43.4 micrograms/ml was determined at about 7 h. No significant difference was observed with respect to bioavailability following i.m. administration of OTC (trout, 85%; catfish, 86%).  相似文献   

5.
Selective medium for isolation of Haemophilus somnus from cattle and sheep   总被引：6，自引：0，他引：6  
Incorporation of vancomycin (5 micrograms/ml), neomycin (5 micrograms/ml), sodium azide (50 micrograms/ml), nystatin (100 iu/ml) and cyclohexamide (100 micrograms/ml) into 5 per cent horse blood agar results in a selective medium for the primary isolation of Haemophilus somnus from cattle and sheep. Addition of thiamine monophosphate (1 microgram/ml) to the medium enhanced growth of this bacterium. Gram-positive bacteria did not grow on the medium and colonies of many Gram-negative bacteria were eliminated or reduced in numbers and size. Colonies of H somnus were larger on the selective medium than on sheep blood agar but retained typical morphology. Recovery of 18 laboratory strains was 73 to 166 per cent (mean 112) on selective medium compared to sheep blood agar. H somnus was isolated from the vagina of a total of 136 (28.6 per cent) of 476 cows surveyed, 79 (16.6 per cent) on sheep blood agar and 129 (27.1 per cent) on selective medium. The selective agents and thiamine were stable indefinitely as a freeze dried mixture while prepared plates were stable for two weeks.  相似文献   

6.
Chlorinated dioxins, as typified by the most potent isomer, TCDD, are immunosuppressive in mammalian species and can enhance the susceptibility to a number of diseases. In recent years chlorinated dioxins have been detected in fish in many freshwater and marine habitats. Thus far, the effects of these chemicals on the immune responses of fish have not been examined. We studied the influence of TCDD on the defense mechanisms of rainbow trout. Yearling trout were injected intraperitoneally with the vehicle, 0.1, 1.0 or 10 micrograms/kg of TCDD. Interactions with the humoral immune response to sheep red blood cells (SRBC) were assessed by the Jerne plaque assay using head kidney and spleen leukocytes. Serum antibody was measured by complement-mediated lysis of SRBC in a chromium release assay. Effects of TCDD on the cellular immune responses were evaluated by the response of thymic and splenic lymphocytes to Con A and PWM. In addition, the phagocytic activity of peritoneal macrophages was examined in vitro. Trout which received 0.1 or 1.0 micrograms/kg TCDD remained clinically normal, and defense mechanisms were unaltered in these fish. Trout which received 10 micrograms/kg of TCDD became hypophagic and exhibited fin necrosis, ascites and suppression of hematopoiesis. In this treatment group, Con A-induced blastogenesis of thymic and splenic lymphocytes was not significantly changed, however, suppression of the PWM-induced response of splenic lymphocytes occurred. No statistically significant alterations occurred in humoral immune responses, and phagocytic activity of peritoneal macrophages was not decreased. The dose-response curve for various biologic effects of TCDD in the rainbow trout appears different from that in sensitive mouse strains. The 30-day, single-dose, parenteral LD50 for TCDD in the C57BL mouse is 100 micrograms/kg, and TCDD suppresses both cell-mediated and humoral immune responses at 1-2 micrograms/kg in this mouse strain. In the rainbow trout, however, immunosuppression was evident only at doses of TCDD approaching the 80-day, single-dose, parenteral LD50 of 20 micrograms/kg.  相似文献   

7.
Propolis is a substance produced by honeybees. It is inhibitory to some bacteria species, mainly Gram-positive bacteria, but less inhibitory to Listeria monocytogenes (L.m) than to the other Gram-positive bacteria tested. In order to obtain selective growth of L.m. from contaminated samples, the effect of propolis in plating media and broths on various strains of bacteria was examined. Table I shows the effect of increasing concentrations of propolis in tryptose-agar (TA). L.m. tolerated higher concentrations of propolis than Streptococcus viridans and Staphylococcus aureus. L.m. grew well in tryptosebroth (TB) that contained 0.15 mg propolis pr. ml medium, while Streptococcus viridans and Streptococcus agalactiae were completely inhibited as seen in Table II. Table III shows that when serum was added to the agar, the inhibitory effect was reduced. It can also be seen that Gram-negative bacteria grew quite well on media that contained 0.19 mg propolis pr. ml. To reduce the growth of Gram-negative bacteria, nalidixic acid was added to the medium. Table IV illustrates growth of various species of bacteria in tryptosephosphatebroth (TFB) with or without propolis and nalidixic acid. Most of the strains tested were inhibited, but Pseudomonas aeruginosa and to some extent faecal streptococci were able to grow in the medium that contained the selective substances. As a conclusion it seems that propolis may be a valuable additive to a medium for the selective isolation of L.m.  相似文献   

8.
Since 1975, the rainbow trout strain BORN (Germany) has been bred in brackish water from a coastal form imported from Denmark. Accompanying phenotypic monitoring of the adapted BORN trout until now revealed that this selection strain manifested a generally elevated resistance towards high stress and pathogenic challenge including lower susceptibility towards Aeromonas salmonicida infections in comparison to other trout strains in local aqua farms. We focus on the elucidation of both, genetic background and immunological basis for the increased survivorship to infections. A first comparison of gene expression profiles in liver tissue of healthy rainbow trout from the local selection strain BORN and imported trout using a GRASP 16K cDNA microarray revealed six differentially expressed genes evoking pathogen and wounding responses, LEAP2A (encoding for liver-expressed antimicrobial peptide), SERPINA1 (alpha-1 antitrypsin), FTH1 (middle subunit of ferritin), FGL2 (fibroleukin), CLEC4E (macrophage-inducible C-type lectin), and SERPINF2 (alpha-2 antiplasmin). Since the latter gene is not described in salmonid species so far, our first aim was to characterize the respective sequence in rainbow trout. Two trout SERPINF2 genes were identified, which share only 48% identical amino acid residues and a characteristic SERPIN domain. Second, we aimed to analyse the expression of those genes after temperature challenge (8 °C and 23 °C). Only FTH1 was upregulated in BORN and import trout after increase of temperature, while SERPINA1 and FGL2 were only elevated in import trout. Third, the expression of all named genes was analyzed after pathogen challenge with A. salmonicida subsp. salmonicida. As a main finding, we detected a comparably faster regeneration of LEAP2A mRNA abundance in BORN trout following bacterial infection. Ingenuity Pathways Analysis suggested a functional interplay among the mentioned factors and the pro-inflammatory cytokine TNF, whose stronger expression was validated in liver of BORN trout. This data indicate that the examined genes contribute to an improved first barrier against invading pathogens in BORN trout.  相似文献   

9.
Infectious diseases represent a limiting factor for the further development of Italian aquaculture. The recent introduction and spreading of new pathogens, along with the global climatic change, has contributed to a considerable decrease in trout production. Emerging pathologies in rainbow trout culture include viral diseases, e.g. infectious haematopoietic necrosis (IHN), bacterial diseases, such as lactococcosis and visceral flavobacteriosis, and parasitical diseases, e.g. proliferative kidney disease (PKD). Higher mortality rates in trout fry and fingerlings are generally induced by visceral flavobacteriosis and IHN, while the main losses in large trout during the warm season are due to lactococcosis and PKD. Mariculture has at present a better sanitary status compared to trout culture, but a rapid dissemination of pathogens, including zoonosis agents, is envisaged also for seabass and seabream. Emerging pathologies in sea bass include VNN, pseudotuberculosis, streptococcosis and tuberculosis. Seabream is much more resistant and is mainly affected by novel Vibrio infections and enteromyxidiosis. A good sanitary management of fish farms is essential for avoiding or limiting losses caused by emerging pathologies. Transmission of zoonosis agents to man, through the consumption of cultured fish, is very remote in Italy. On the contrary, transmission of Streptococcus iniae, Vibrio vulnificus and Mycobacterium marinum by means of improper manipulation of infected fish, could represent a potential hazard for fish farmers and fish processors, as well as for people preparing fish meals.  相似文献   

10.
Abstract

Two sizes of fingerling Snake River cutthroat trout Oncorhynchus clarkii behnkei and Colorado River rainbow trout O. mykiss were raised at hatcheries testing negative for Myxobolus cerebralis and stocked into the Dolores and Cache la Poudre rivers from 1999 to 2001. Populations were resampled over a 2-year period to determine which species and size combination had the highest growth and survival rates. Fish were tested for M. cerebralis via polymerase chain reaction and pepsin?trypsin digest analyses. Growth and survival rates between the species and size groups were not significantly different in either river. In the Dolores River, annual survival for both species and sizes of fish combined ranged from 0.063 to 0.12. In the Cache la Poudre River, survival for both sizes of rainbow trout was 0.004; survival for cutthroat trout ranged from 0.182 to 0.53. Larger fish had higher growth rates than smaller fish, and cutthroat trout had higher rates than similar sizes of rainbow trout. In both rivers, a higher percentage of the rainbow trout sample was infected than in the cutthroat trout sample. Rainbow trout also had a higher mean number of spores per head than cutthroat trout, and small rainbow trout had higher spore counts than large rainbow trout. Survival rates for cutthroat trout in the Cache la Poudre River were the highest of any of the groups, suggesting a difference that is biologically significant. Raising fingerlings to sizes greater than 100 mm can improve poststocking survival. If rainbow trout are stocked into contaminated waters, raising fingerlings to a larger size does not appear to improve growth or survival rates. Stocking rainbow trout in the spring could maximize growth rates but will expose fish to greater triactinomyxon densities, resulting in higher intensities of infection.  相似文献   

11.
Excessive mortalities were experienced in the bigger rainbow trout (Salmo gairdneri) at an efficiently managed trout farm. All tests for known toxins in the feed and water proved to be negative. A faecal Streptococcus which belongs to the Lancefield group D but which could not be identified as belonging to any of the recognized species within this group, was isolated from the spleens, livers and kidneys of affected fish. Pathogenicity studies with this organism proved it to be highly fatal to trout but not to Mozambique bream (Sarotherodon mossambicus), banded bream (Tilapia sparrmenii), carp (Cyprinus carpio) or largemouth bass (Micropterus salmoides). The isolation and biochemical characteristics of the organism are described. The symptoms, gross- and histopathology of this disease are described and discussed. The disease resembles a haemorrhagic septicaemia and appears to be associated with intensification and conditions of stress.  相似文献   

12.
Five media were evaluated to determine their selectivity for Bifidobacterium sp. in hen and rabbit caecal samples. The colonies arising on the plates inoculated with the caecal samples were Gram stained and screened for the presence of fructose-6-phosphate phosphoketolase activity. Rogosa agar modified by the addition of cysteine-hydrochloride (0.05% w/v), Beeren's agar (with 5 ml/l of propionic acid as a selective agent), BS 2 agar (containing per one litre sodium propionate 15 g, lithium chloride 3 g, paromomycin sulphate 50 mg, neomycin sulphate 200 mg), and Wilkins-Chalgren agar (MW) modified by the addition of acetic acid (1 ml/l) and mupirocin (100 mg/l) were selective for Bifidobacterium sp. from rabbit caecal samples. In contrast, only MW medium was suitable for the isolation and enumeration of bifidobacteria in hen caecal samples. In conclusion, the results suggest that MW agar showed the greatest selectivity. A further advantage of this medium is its case of preparation. Therefore this agar could contribute to the study of the effects of the ingestion both probiotics and prebiotics. Finally, it could be noted that the bifidobacteria selective media should be chosen in respect of the animal species origin of the sample tested.  相似文献   

13.
The minimal inhibitory concentrations (MIC) of sulfonamides were determined against Bordetella bronchiseptica (n = 10), Pasteurella multocida (n = 10), Haemophilus pleuropneumoniae (n = 20), and Streptococcus suis (n = 10) strains isolated from pigs with atrophic rhinitis, pneumonia, or meningitis. Sulfonamides tested in an agar dilution method were sulfachloropyridazine, sulfadiazine, sulfadimethoxine, sulfamethazine, sulfadoxine, sulfisoxazole, sulfamerazine, sulfamethoxazole, sulfamethoxypyridazine, sulfanilamide, sulfatroxazole, and sulfisomidine. Results indicated that monotherapy of S suis infections with sulfonamides should not be encouraged because the MIC50 of all sulfonamides investigated was greater than 32 micrograms/ml. The MIC50 of the sulfonamides against B bronchiseptica ranged from 0.5 to 8 micrograms/ml, against P multocida from 2 to 32 micrograms/ml, and against H pleuropneumoniae from 8 to 64 micrograms/ml. The MIC50 of sulfachloropyridazine, sulfadiazine, sulfadimethoxine, sulfamerazine, and sulfamethoxazole for the gram-negative bacteria did not exceed 16 micrograms/ml. Among these compounds, sulfamethoxazole had the highest activity. The frequently prescribed sulfamethazine had an overall low antimicrobial activity.  相似文献   

14.
Five media were evaluated to determine their selectivity for Bifidobacterium sp. in hen and rabbit caecal samples. The colonies arising on the plates inoculated with the caecal samples were Gram stained and screened for the presence of fructose-6-phosphate phosphoketolase activity. Rogosa agar modified by the addition of cysteine-hydrochloride (0.05 % w/v), Beeren’s agar (with 5 ml/l of propionic acid as a selective agent), BS 2 agar (containing per one litre sodium propionate 15 g, lithium chloride 3 g, paromomycin sulphate 50 mg, neomycin sulphate 200 mg), and Wilkins-Chalgren agar (MW) modified by the addition of acetic acid (1 ml/l) and mupirocin (100 mg/l) were selective for Bifidobacterium sp. from rabbit caecal samples. In contrast, only MW medium was suitable for the isolation and enumeration of bifidobacteria in hen caecal samples. In conclusion, the results suggest that MW agar showed the greatest selectivity. A further advantage of this medium is its ease of preparation. Therefore this agar could contribute to the study of the effects of the ingestion both probiotics and prebiotics. Finally, it could be noted that the bifidobacteria selective media should be chosen in respect of the animal species origin of the sample tested.  相似文献   

15.
猪链球菌病的研究进展   总被引：1，自引：0，他引：1  
猪链球菌病是由多种致病性链球菌感染引起的一种人畜共患病,该病不仅危害养猪业的健康发展,还可引起人类发病甚至死亡。主要对猪链球菌病在病原、发病特点、致病因子、致病机理等方面的研究进展作一介绍,以期为有效诊断和防治该病提供参考。  相似文献   

16.
试验选取10尾贵州都匀养殖场的虹鳟(1562±32)g和10尾市场出售的挪威大西洋鲑(1856±45 g),采集其背部肌肉,分别进行质构特性及营养成分分析。结果表明:质构特性上,虹鳟肌肉的失水率显著低于大西洋鲑(P<0.05),剪切力显著高于大西洋鲑(P<0.05);常规成分中,虹鳟肌肉的粗脂肪含量显著低于大西洋鲑(P<0.05),二者的粗蛋白含量无显著差异(P>0.05);脂肪酸组成上,虹鳟肌肉的n-6多不饱和脂肪酸含量显著低于大西洋鲑(P<0.05),但基于脂肪酸组成获得的饱和度(S/P)、动脉粥样硬化指数(AI)、凝血指数(TI)和降胆固醇/致高血脂比率(HH)等指标无显著性差异(P>0.05);氨基酸组成方面,虹鳟肌肉内的人体必需氨基酸比例显著低于大西洋鲑(P<0.05),鲜味氨基酸含量显著高于大西洋鲑(P<0.05)。结果表明,养殖虹鳟在肉质质构上相比大西洋鲑较“干硬”,且虹鳟肌肉多不饱和脂肪酸和必需氨基酸含量均低于大西洋鲑。  相似文献   

17.
From early April into mid-June 1977, sequential groups of juvenile rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta) were each exposed for 10 days to the parasite Myxobolus cerebralis by immersion in a stream inhabited by infected wild trout. Following incubation in a M. cerebralis-free facility, trout were subsequently killed, and heads and gill arches were examined by routine histologic methods. A grading scale to quantify lesion severity was developed and applied. Percentage infected, lesion severity scores, effects of water temperature and flow rates on percentage infected and lesion severity scores, and resulting pathology were determined for each species at each exposure period. The percentage of rainbow trout infected with M. cerebralis was significantly higher than the percentage of brown trout infected for each exposure period. The percentages of rainbow trout infected in exposure periods later in the calendar year were significantly higher than those in earlier periods. The percentages of brown trout infected were not significantly different among exposure periods. Overall average lesion severity scores were significantly higher in rainbow than in brown trout. Lesion severity scores in rainbow trout increased over time (a positive correlation with exposure period). Lesion severity scores were not significantly different for brown trout among exposure periods. A significant correlation existed between water temperature and percentage of rainbow trout infected; a significant correlation also existed between water temperature and lesion severity scores in rainbow trout. Similar correlations did not exist for percentage of brown trout infected or accompanying lesion severity scores. In rainbow trout, ventral calvarium was the most common site of M. cerebralis replication, followed by gill arches. In brown trout, lesions were virtually confined to gill arches. Early lesions consisted of foci of cartilage necrosis with small numbers of M. cerebralis developmental stages. More advanced lesions consisted of multifocal areas of cartilage necrosis with numerous M. cerebralis developmental stages and/or mature myxospores bordered and/or infiltrated by mono- and multinuclear leukocytes. Lesions in brown trout were smaller and had fewer associated leukocytes and M. cerebralis developmental stages and/or mature myxospores. Higher infection rates, lesion severity scores, and differences in lesion location in rainbow versus brown trout explain in part why numbers of rainbow but not brown trout have fallen in western rivers inhabited with M. cerebralis-infected trout.  相似文献   

18.
Abstract

Laboratory exposures to the infectious stages (triactinomyxons) of Myxobolus cerebralis demonstrated a range of susceptibility to whirling disease among four species of inland salmonids. Replicate groups of each species were exposed to two concentrations of triactinomyxons, a low dose (100–200 per fish) and a high dose (1,000–2,000 per fish). Exposed fish were evaluated for clinical signs, for severity of microscopic lesions at 35 d, 2 and 5 months, and for spore concentrations in the head cartilage at 5 months. A standard strain of rainbow trout Oncorhynchus mykiss matched for age served as a susceptible species control. Rainbow trout, westslope cutthroat trout O. clarki lewisi, Yellowstone cutthroat trout O. clarki bouvieri, and bull trout Salvelinus confluentus were susceptible to M. cerebralis infections. Clinical signs, including radical swimming (“whirling”) and black tails, were observed at 7 weeks postexposure among rainbow and cutthroat trout challenged at 3 weeks of age. Clinical signs were rare among bull trout exposed at an age of 4 weeks and absent among rainbow and cutthroat trout exposed at 3 months posthatch. Most rainbow, cutthroat, and bull trout were found to be infected when examined at 5 months postexposure. The most severe microscopic lesions among infected fish at 5 months postexposure were found among rainbow trout. Cutthroat trout had less severe lesions, bull trout had mild infections, and no evidence of infection was found among Arctic grayling Thymallus arcticus. Mean spore concentrations among infected fish correlated with the severity of microscopic lesion scores. Rainbow trout had mean concentrations of spores in head cartilage reaching 106, whereas more resistant species such as bull trout had 104 spores; no spores were found among Arctic grayling at 5 months postexposure.  相似文献   

19.
A study was undertaken to compare the virulence and serum killing resistance properties of Atlantic salmon and rainbow trout Yersinia ruckeri isolates. Five isolates, covering heat-stable O-antigen O1, O2 and O5 serotypes, were tested for virulence towards fry and juveniles of both species by experimental bath challenge. The sensitivity of 15 diverse isolates to non-immune salmon and rainbow trout serum was also examined. All five isolates caused significant mortality in salmon fry. Serotype O1 isolate 06059 caused the highest mortality in salmon (74% and 70% in fry and juveniles, respectively). Isolate 06041, a typical ERM-causing serotype O1 UK rainbow trout strain, caused mortalities in both rainbow trout and salmon. None of the salmon isolates caused any mortalities in 150–250 g rainbow trout, and only serotype O2 isolate 06060 caused any significant mortality (10%) in rainbow trout fry. Disease progression and severity was affected by water temperature. Mortality in salmon caused by the isolates 06059 and 05094 was much higher at 16 °C (74% and 33%, respectively) than at 12 °C (30 and 4% respectively). Virulent rainbow trout isolates were generally resistant to sera from both species, whereas salmon isolates varied in their serum sensitivity. Convalescent serum from salmon and rainbow trout that had been infected by serotype O1 isolates mediated effective classical pathway complement killing of serotype O1 and O5 isolates that were resistant to normal sera. Overall, strains recovered from infected salmon possess a wider range of phenotypic properties (relative virulence, O serotype and possession of serum-resistance factors), compared to ERM-causing rainbow trout isolates.  相似文献   

20.
Antibody production in rainbow trout to extracellular antigens was investigated. The following antigen preparations and immunisation regimes were used: native extracellular products (ECP) in Freund's complete adjuvant (FCA), intraperitoneally (i.p.) with and without booster; formalinized ECP in FCA, i.p. with and without booster; washed, formalinized A. salmonicida cells in FCA, i.p., with booster; native ECP in saline, i.m., four weekly injections at two different doses, 45 micrograms and 6 micrograms each injection (after the protocol of Shieh, 1985). Using crossed normal rainbow trout serum, i.p., single injection (after the protocol of Sakai, 1985). Using crossed immunoelectrophoresis all antisera contained precipitating antibodies to three to five ECP components except that from fish immunised i.m. with 6 micrograms protein where antibodies were undetectable. In no case were specific antibodies to ECP protease or haemolysin detected. In a rabbit immunised with formalinized ECP in FCA under a similar regime to the rainbow trout, antibodies to at least 15 ECP components, including protease and haemolysin, were detected. The assumption of a specific immune response to the protease, at least in respect of antibody production, in recent reports of protection afforded by vaccines composed of either crude ECP or partially purified protease (Shieh, 1985) or partially purified protease inactivated by normal serum (Sakai, 1985) is not supported by the present findings.  相似文献   

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