碩士 / 國立屏東科技大學 / 獸醫學系 / 94 / During May 2003 to 2005, epizootic Nocardia spp. Infection in pond cultured fish, three striped tigerfish Terapon jarbua, spotted butterfish Scatophagus argus, red snapper Lutjanus erythropterus, long dorsal fin pompano Trachinotus blochii, japanese sea bass Lateolabrax japonicus, grey mullet Mugil cephalus, stripted bass Morone sasatilis, common slipmouth Leiognathus equulus, largemouth bass Micropterus salmoides, grouper Epinephelus malabaricus occurred in Taiwan causing a cumulative mortality of 1.2-15％. The clinical signs of infection are erosion and ulcer in the skin. Histopathological examinations of affected tissues revealed typical granuloma with marked central necrosis. The pathogenicity experiments were tested by intraperitoneal injection ( IP ) in juvenile three striped tigerfish ( 50-70g ). Fish were received 0.5mL of 1.8x108 CFU/mL and 1.8x107 CFU/mL of bacterial suspension for IP showed 100％ mortality after 37 days, respectively. In the gross finding, the lesions were severe peritoneal granulomas in IP group. The IP group showed nodules in the heart, liver, spleen, kidney and gill were similar to those naturally infected fish were seen. Pure cultures of bacteria were reisolated from the kidney and spleen. There were no death terminated during the entire trials in control group, without showed clinical signs and significant lesion. The growth character, morphological and biochemical properties of 27 isolates, Nocardia spp. isolated from seawater fish were similar to those of reference strain Nocardia seriolae BCRC13745. Neomycin, doxycycline were the most active antimicrobial agents against the isolates tested followed by streptomycin and oxytetracycline. The 16S rDNA sequence for 596 bp PCR amplicon and heat shock protein ( HSP ) gene for 439 bp PCR amplicon from 27 isolates was determined. Those sequences showed 99.9-100％ identity with N. seriolae ( GenBank accession number AF380937 and GenBank accession number AY756533 ). The results demonstrated that all PCR amplicon for HSP gene of N. seriolae ( 27 isolates and reference strain BCRC13745 ) exhibited one NarⅠrecognition site, producing two DNA fragments of 280 and 159 bp. Specific-specific sequence of 16S rDNA of N. seriolae were amplified by PCR using the NG1 and NS1 primer. A 432 bp amplicom was observed in 27 isolates. The technique is conceived to enable the rapid identification of the species Nocardia in fish. Altogether the results constitute the first confirmation that N. seriolae can cause disease outbreaks several pond marine cultured fish. The results of this study reveal N. seriolae is the major pathogen in nocardia infection of fish in Taiwan. This is the first report of a confirmed infection of N. seriolae in three striped tigerfish, spotted butterfish, red snapper, long dorsal fin pompano, grey mullet, common slipmouth, grouper aquaculture.
| Identifer | oai:union.ndltd.org:TW/094NPUST541006 |
| Date | January 2006 |
| Creators | Shi-De Chen, 陳旭德 |
| Contributors | Shih-Chu Chen, 陳石柱 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 86 |
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