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Francisella sp. is an emergent bacterial pathogen that causes acute to chronic disease in warm and cold water cultured and wild fish species. During the past 3 years, the bacterium has been detected in tilapia, Oreochromis niloticus , cultured in Costa Rica. Infected fish presented non-specific clinical signs, such as erratic swimming, anorexia, anaemia, exophthalmia and high mortality. Upon macroscopic and microscopic examination, several internal organs (mainly spleen and kidney) were enlarged and contained white nodules. Histological examination revealed the presence of multifocal granulomatous lesions, with the presence of numerous small, pleomorphic, cocco-bacilli. The bacteria were isolated from infected tilapia on selective media and grown on several media with and without antibiotics. Specific PCR primers to the Francisella genus were used to confirm the preliminary diagnoses. In comparison with several bacterial 16S rRNA sequences, our isolate was found to share 99% identity with other Fransicella spp. isolated from fish, and more than 97% identity to the human pathogen Francisella tularensis . Koch's postulates were fulfilled after experimental intraperitoneal and gill exposure challenges. 相似文献
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A. S. Overton F. J. Margraf C. A. Weedon L. H. Pieper & E. B. May 《Fisheries Management and Ecology》2003,10(5):301-308
Several species of bacteria have been isolated from diseased striped bass, Morone saxatilis (Walbaum), in Chesapeake Bay. Mycobacteria species are of particular interest because of their association with chronic lesions in both fish and humans. The resulting disease in fish may be characterised by emaciation, inflammation of the skin, exophthalmia (pop‐eye), ascites (dropsy), open lesions, and ulceration. The prevalence of mycobacterial infection in 217 striped bass in the Maryland portion of Chesapeake Bay was determined to provide evidence of decreased overall condition of fish affected by these bacteria. The density of the granulomas was higher in the spleen and head kidney than either the heart or liver, and appeared to be most closely associated with the presence of an external lesion. Thirty‐eight per cent of the fish showed some sign of an external lesion. Granulomas appeared in at least one organ in 53% of the fish sampled regardless of the presence or absence of an external skin lesion. Condition factor was significantly higher for striped bass without external lesions (0.96) than those with lesions (0.82). Striped bass with no internal granulomas and no external lesion had the highest condition factor (0.99) and fish with granulomas and external lesions the lowest (0.81). Slopes of the regression loge weight (g) and loge length (mm) for striped bass with external lesions was significantly higher than those fish without external lesions and had a lower r2. The results suggest that striped bass that are infected with mycobacteria have decreased overall health. 相似文献
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Vilar P Faílde LD Bermúdez R Vigliano F Riaza A Silva R Santos Y Quiroga MI 《Journal of fish diseases》2012,35(6):437-445
This study describes morphopathologic changes in naturally infected farmed Senegalese sole affected by tenacibaculosis caused by Tenacibaculum maritimum. Macroscopic observation, in addition to light microscopy and scanning electron microscopy, was used to study the lesions. Main lesions were characterized by complete loss of epidermis and dermis, as well as extensive necrosis of muscle layers. Mild-to-moderate inflammatory response with the presence of macrophages was noted around hyaline degenerated muscle cells. Gram-negative filamentous bacteria could be detected only at the dermis. Under scanning electron microscopy, filamentous bacteria located over the scales without epithelium could be observed. These findings together with the isolation and PCR detection of the bacteria in kidney and skin tissues suggest that once the bacteria reach the dermis, probably through eroded epidermis, they are able to proliferate and produce enzymes that are responsible for the damage in the underlying tissues. 相似文献
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Abstract. Deep necrotic ulcers in Atlantic menhaden, Brevoortia tyrannus (Latrobe), were consistently associated with the presence of oomycete fungi. These organisms were found in over 95% of all lesions both early and late. More than one species of fungus appears to be involved, indicating that these organisms are secondary to some other stressor. However, all characteristically elicit an atypical intense granulomatous inflammatory response and do not behave pathologically as typical oomycetes. Our observation that these fungi appear to be the only organisms consistently present in the earliest stages of the disease indicates that some non-infectious stressor may be responsible for initiating the lesions and subsequently allowing the fungi to induce this atypical response. 相似文献
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Three cases of pyogranulomatous cephalic osteochrondritis of intensively reared rainbow trout, Oncorhynchus mykiss (Walbaum), and Atlantic salmon, Salmo salar L., in Canada and Chile, respectively, were examined for histopathological and bacteriological changes, and by using immunohistochemistry. Bilateral exophthalmia and intraocular haemorrhage were the most common gross lesions seen in the Ontario fish. Histologically, the major pathological changes seen in all cases involved the developing bone and cartilage of the head region, including the eye. Necrosis and pyogranulomatous inflammation of the scleral cartilage (necrotic scleritis) were the major ocular changes. Similarly, lysis of cephalic cartilage and immature bone, accompanied by pyogranulomatous inflammation, usually progressing to fibrosis, were the most common lesions associated with the cranial changes in both the rainbow trout and Atlantic salmon. Routine histological staining, including special stains, failed to reveal the presence of pathogens associated with these lesions. However, immunohistochemical staining of representative sections from all cases with rabbit anti- Flexibacter psychrophilus serum (ATCC 49510) demonstrated significant numbers of antigenically related bacteria within the leading edge of some of the scleral and cephalic osteochondritic lesions. Axenic cultures of Flexibacter psychrophilus were recovered from the eye lesions of the rainbow trout, but it was not possible to reproduce ocular lesions experimentally. However, mortality was produced following intramuscular injection of rainbow trout with bacteria. 相似文献
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The occurrence of Mycobacterium spp. in freshwater and marine ornamental fish was studied in Italy from June 2002 to May 2005. Two surveys were carried out, one of aquarium fish sent to the Laboratory for diagnosis, and the other of prevalence of infection by mycobacteria in ornamental fish imported into Italy. Bacterial isolation was carried out from the spleen, kidney and liver, and the isolates were subsequently identified by biochemical tests. In the first survey, 387 fish were examined and Mycobacterium spp. were isolated from 181 (46.8%) fish. In the second survey 127 batches of ornamental fish from different countries were examined. Mycobacterium spp. were isolated from 38 (29.9%) batches. The following species were found: M. fortuitum, M. peregrinum, M. chelonae, M. abscessus, M. marinum, M. gordonae, M. nonchromogenicum and M. interjectum. There was a high prevalence of infection independent of the presence of macroscopic lesions. Mycobacterium fortuitum and M. chelonae were more prevalent than M. marinum in the samples examined. 相似文献
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The udders of 100 heifers were examined for clinical changes during parturition. Of each quarter colostral samples were taken and analyzed bacteriologically. 35 heifers (13.5% of the quarters) showed clinical changes of the quarters and/or of colostral samples. 14 of these animals (4.75% of the quarters) suffered from cellulitis-like mastitis. 13 (5.25% of the quarters) had acute catarrhalic mastitis and eight heifers (3.5% of the quarters) showed acute galactophoritis. In all milk samples of animals with pathological changes of the udder or of colostrum the causing bacteria could be identified. Besides the group of 35 heifers with clinical lesions udder-pathogenic bacteria were found in samples of 24 apparently healthy animals (20.5% of the quarters) during parturition. However, these animals failed to show clinical signs of inflammation at least until the end of this study (10 days post partum). Isolated bacteria included facultative and obligate pathogenic species, 70% of which were gram-positive cocci (i.e. Streptococcus [Sc.] uberis, Sc. dysgalactiae, Sc. agalactiae, Staphylococcus aureus and other staphylococci) versus 30% of gram-negative bacteria (i.e. Escherichia [E.] coli, Klebsiella and other coliform species. In-vitro-susceptibility tests showed best effectiveness of Penicillin against Sc., Cloxacillin against staphylococci and Gentamycin and Polymyxin B against coliform bacteria. Possible pathways, leading to bacterial infection of first lactating heifers during parturition, are discussed. Pathways of infection seem to be of lesser importance for the development of apparent, sometimes severe mastitis with coliform bacteria.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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H. W. FERGUSON V. E. OSTLAND D. D. MacPHEE J. S. LUMSDEN P. J. BYRNE D. J. SPEARE 《Journal of fish diseases》1995,18(1):49-57
Abstract A skin disease of intensively reared salmonids in Ontario hatcheries, known to the farmers as'no-mucus skin disease', is reported for the first time. It was characterized by erosive and ulcerative lesions found mainly on the flanks of fingerlings, which resulted in exposure of the tips of the scales. Associated with these lesions were colonies of bacteria seen in the SEM to be clustered round the mucous cell pores and under-running the margins of epithelial cells. The cause of this condition is unknown, although the response of fish to formalin treatment, and the presence of bacilli seen in skin scrapings and in the SEM, suggest that bacteria are responsible. 相似文献
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A Elkesh K P L Kantham A P Shinn M Crumlish R H Richards 《Journal of fish diseases》2013,36(2):141-149
Marine cultured meagre, Argyrosomus regius Asso, in central and western Greece were affected by an outbreak of systemic granulomatous disease subsequently demonstrated to be nocardiosis. The fish were originally imported as juveniles from hatcheries in France and Italy and on‐grown in Greece, the latter also providing broodstock for a small number of local Greek hatcheries for the production of second‐generation juveniles. The disease in cage reared fish had been present throughout the year, particularly in the 1+ and 2+ year old fish with a low to variable morbidity and 1–4% total mortality. Multiple lesions were visible externally on the skin of affected fish, with severe ulcerations and necrosis. Internally, multifocal yellowish‐white nodules, 0.1–0.5 cm in diameter, were visible on the surface of several internal organs. Histopathology revealed systemic granulomatous inflammation. Fite‐Faraco staining clearly demonstrated the presence of Nocardia‐like organisms which were Gram‐positive, long, rod to beaded filamentous bacteria. Nocardia genus‐specific 16s RNA primers NG1 and NG2 were used to generate a 600 bp fragment recovered from affected tissue, confirming the diagnosis of Nocardia spp. To our knowledge, this is the first report of nocardiosis in meagre. 相似文献
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Gross, histological and scanning electron microscopic appearance of dorsal fin rot in farmed Atlantic salmon, Salmo salar L., parr 总被引：1，自引：0，他引：1
The gross, histological and scanning electron microscopic appearance of dorsal fin rot in farmed Atlantic salmon parr, Salmo salar L. is described. The lesions were grouped into seven categories: (1) peripheral erosion and ray splitting; (2) peripheral erosion with some nodularity; (3) severe nodularity with differing degrees of tissue loss; (4) extensive to total loss of the dorsal fin; (5) smooth thickening of the dorsal fin; (6) haemorrhagic dorsal fin lesions; and (7) healed dorsal fin rot lesions. The main sign of injury was clefts extending through the epithelium. These injuries were consistent with bites from other parr. During healing from such wounds, damaged cells sloughed from the surface, and there was swelling and hyperplasia in the remaining cells. The majority of the thickening in the fins was the result of epithelial hyperplasia with a variable cellular inflammatory response. The distal epithelium of fins with severe fin rot (i.e. nodular and eroded) was rough, irregular and swollen with superficial nodular extensions. Wounds in all stages of repair were more numerous in such areas. Fin rays were frequently observed protruding from the abnormal epithelium at the distal edge of the fin. With the exception of the isolation of Aeromonas salmonicida from a small number of cases, no significant bacterial involvement was detected. Under scanning electron microscopy, bacteria were only detected on the exposed fin rays and not in association with the abnormal epithelium. In the majority of cases, the dorsal fin was either the only fin damaged or the most severely damaged. It is suggested that the hyperplastic response to numerous bite wounds is responsible for the accumulation of abnormal epithelium typical of dorsal fin rot in farmed Atlantic salmon parr. 相似文献
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Abstract. Histologic differences were observed in channel catfish, Ictalurus punctatus (Rafinesque), with naturally occurring cutaneous (bacteria isolated only from lesions of skin and superficial muscle) and systemic Aeromonas hydrophila infections. Systemic infections were characterized by diffuse necrosis in several internal organs and the presence of melanin-containing macrophages in the blood. Fish with only cutaneous infections had several types of concealed lesions including increased amounts of lipofuscin and haemosiderin in the liver and spleen; however, most visceral organs were not necrotic. The average condition factor of fish with cutaneous infections was lower than for fish with systemic infections. Early histologic lesions in channel catfish experimentally infected by immersion in a suspension of A. hydrophila were similar to lesions observed in naturally occurring systemic infections and to lesions previously reported in channel catfish injected intraperitoneally with A. hydrophila . In experimentally infected fish, all lesions healed in fish that did not die, and prolonged infections limited to skin and muscle did not occur. 相似文献
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Twenty-three smooth dogfish, Mustelus canis L., and 20 spiny dogfish, Squalus acanthias (Mitchill), were examined for the presence of diseases. Sharks were collected from the north-western Atlantic between April and September 2000. Major organs were sampled for histopathology and bacterial cultures were taken from kidneys. Macroscopic lesions were infrequent and included intestinal cestodiasis and gastric and dermal erosions. Microscopic lesions were common in both shark species. Mustelus canis had numerous degenerative lesions involving the pancreatic ducts, seminiferous tubules and coronary vessels. The most frequent lesions in S. acanthias were parasitic and included pancreatic nematodiasis and biliary myxosporeosis. Additionally, both species had focal meningitis, encephalitis, dermatitis, gastritis, enteritis and glomerulomesangial thickening. Microscopic parasites included intestinal coccidiosis, unclassified gastric and testicular protozoa, skeletal muscle and renal tubular myxosporeans, a branchial trichodinid ciliate, olfactory and branchial trematodes, gastrointestinal cestodes and larval nematodes. Shewanella putrefaciens , Photobacterium sp., Vibrio sp., Pseudomonas sp. and Alteromonas sp. were isolated from kidneys of nine sharks. The role of the above lesions in the natural mortality and morbidity of the two shark species is unknown. The finding that apparently healthy sharks can harbour potentially debilitating lesions warrants the inclusion of histopathological studies in the management and conservation of sharks. 相似文献
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Macroscopic and histopathological changes in cultured turbot, Scophthalmus maximus (L.), in Spain caused by infection with Edwardsiella tarda are described. Eye tumefaction, inflammation, haemorrhages, ascites and the presence of a purulent fluid were the main macroscopic lesions observed. Histopathological lesions were found in the kidney, spleen and liver. In the kidney and spleen these were characterized by a severe apostematous inflammatory reaction, with a large number of abscesses. The liver was affected to a lesser degree and only some phagocytes loaded with bacteria were observed. Ultrastructural observations indicated that macrophages were the main cell type implicated in the inflammatory response. Most of the bacteria observed within the phagocyte cytoplasm showed no degenerative changes and some were dividing. Degenerative changes observed in macrophages indicate their failure in preventing the infection. 相似文献
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Lymphocystis disease is a prevalent, non-fatal disease that affects many teleost fish and is caused by the DNA virus lymphocystis disease virus (LCDV). Lymphocystis-like lesions have been observed in yellow perch, Perca flavescens (Mitchell), in lakes in northern Alberta, Canada. In an effort to confirm the identity of the virus causing these lesions, DNA was extracted from these lesions and PCR with genotype generic LCDV primers specific to the major capsid protein (MCP) gene was performed. A 1357-base pair nucleotide sequence corresponding to a peptide length of 452 amino acids of the MCP gene was sequenced, confirming the lesions as being lymphocystis disease lesions. Phylogenetic analysis of the generated amino acid sequence revealed the perch LCDV isolate to be a distinct and novel genotype. From the obtained sequence, a real-time PCR identification method was developed using fluorgenic LUX primers. The identification method was used to detect the presence/absence of LCDV in yellow perch from two lakes, one where lymphocystis disease was observed to occur and the other where the disease had not been observed. All samples of fin, spleen and liver tested negative for LCDV in the lake where lymphocystis disease had not been observed. The second lake had a 2.6% incidence of LCD, and virus was detected in tissue samples from all individuals tested regardless of whether they were expressing the disease or not. However, estimated viral copy number in spleen and liver of symptomatic perch was four orders of magnitude higher than that in asymptomatic perch. 相似文献
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Abstract. Lesions present on sea mullet, Mugil cephalus L., during the first 3 weeks of red spot disease outbreaks are described. Necrotizing dermatitis is a severe, locally extensive, granulomatous lesion associated with invasion of dermis and underlying skeletal muscle by numerous, non-septate, fungal hyphae 12–18 μm in diameter. Erythematous dermatitis is a mild to severe, focal, chronic active dermatitis without fungal involvement. Lesions intermediate between these two forms, with small to moderate numbers of fungal hyphae in dermis and skeletal muscle also occur. Findings indicate that erythematous dermatitis lesions and intermediate-type lesions subsequently resolve, while necrotizing dermatitis lesions consistently develop into dermal ulcers, with associated severe necrotizing granulomatous myositis. Generally, dermal ulcers occur significantly more often on posterior and dorsal areas of the body surface than on anterior and ventral areas. Lesions heal by combinations of epidermal and dermal repair, fibroplasia, destruction of fungi, removal of necrotic skeletal muscle and regeneration of myofibres. Atrophy of exocrine pancreas occurs in both diseased and clinically normal fish, but is generally more severe in diseased fish. The possible roles of suspected disease determinants, including falls in dissolved oxygen concentrations to sub-lethal levels prior to red spot disease outbreaks, are discussed. 相似文献
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Enumeration of protein mineralizing and ammonifying bacterial populations in water and sediment samples of six fish-farming ponds (polyculture, monoculture and traditional systems) over a period of two and a half years revealed significant differences between the culture systems with maximal and lowest counts in the monoculture and traditional systems respectively. This distribution pattern was related to the degree of organic loading in the system. Both groups of bacteria were most numerous during winter but were greatly reduced in number during the summer. The factors responsible for their spatial and seasonal distributions are discussed. 相似文献
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The bacterial pathogen Flavobacterium psychrophilum was successfully identified from formalin-fixed, wax-embedded tissue blocks of infected rainbow trout heart and spleen tissues, using a polymerase chain reaction (PCR)-based assay. Filamentous bacteria were observed in haematoxylin and eosin and Giemsa-stained sections but no bacteria were recovered from the diseased fish using standard bacteriology isolation techniques. All infected fish had histopathological evidence of myocarditis or rainbow trout fry syndrome. Immunohistochemistry was attempted using three different anti-F. psychrophilum sera but the results were inconclusive, and an alternative molecular approach was therefore attempted. This paper describes the use of a PCR-based assay to help identify bacteria present in formalin-fixed, wax-embedded tissue samples. This is the first time that this technique has been used for the detection of fish bacteria from diagnostic samples. 相似文献