黃鰭鯛海豚鏈球菌的分離·鑒定及藥敏試驗

王漢清 黃郁蔥 林潮峰

摘要 [目的]鑒定引起黃鰭鯛眼球充血、肝腎腫大等病征的病原菌。[方法] 從發病黃鰭鯛肝腎組織中分離致病菌，并結合致病菌的形態特征、培養特性、生理生化特征及16S RNA基因測序進行鑒定，測定分離菌株的半數致死量（LD50）；通過藥敏試驗篩選對分離菌株敏感的抗生素。[結果]經鑒定分離菌株為海豚鏈球菌（Streptococcus iniae）。回歸試驗結果證實該分離菌株是引起此次黃鰭鯛發病的病原菌，其對黃鰭鯛的LD50為5.0×103 CFU/g。藥敏試驗結果表明，該分離菌株對頭孢噻吩、頭孢呋辛、頭孢他啶和頭孢曲松等抗菌藥物有較高的敏感性。 [結論]研究結果可為黃鰭鯛海豚鏈球菌病的防治提供理論依據。

關鍵詞 黃鰭鯛；海豚鏈球菌；分離；鑒定

中圖分類號 S917.1 文獻標識碼 A 文章編號 0517-6611（2018）21-0100-03

Abstract [Objective] To identify the pathogen that caused bloodstream congestion， hepatorenal enlargement and other symptoms in Sparus latus. [Method] The pathogen was isolated from the liver and kidney tissues of diseased S. latus. Combined with its morphological characteristics， culture characteristics， physiological and biochemical characteristics and 16S RNA gene sequencing results，the pathogen was identified. LD50 of the isolated strain was determined and the sensitive antibiotics were screened out by drug sensitivity test. [Result] The isolated strain was identified as Streptococcus iniae. The results of the regression test proved that the isolated strain was the pathogen that caused the disease of S. latus. Its LD50 to S.latus was 1.84×104 CFU/g. The results of drug sensitivity test showed that the isolated strain was highly sensitive to cefthiaxone， cefuroxime， ceftazidime， ceftriaxone， etc..[Conclusion] The research could provide theoretical basis for the prevention and control of S. suis.

Key words Sparus latus；Streptococcus iniae；Isolation；Identification

黃鰭鯛（Sparus latus）又名闊黑鯛，隸屬鱸亞目（Pencoidei）鯛科（Sparidae）鯛屬（Sparus），為淺海近岸底棲魚類，是我國海水養殖的重要品種之一，廣泛分布于我國臺灣、廣東沿海、福建、浙江，俗稱黃腳立、黃墻、赤翅等[1-3]。2017年湛江部分黃鰭鯛養殖區域暴發了以眼球充血突出、鰓蓋內緣出血、剖檢出現肝腎腫大及腹腔積液等癥狀為主要病征的疫情，傳染速度快，死亡率較高，給養殖戶造成了巨大的經濟損失。筆者對此病的病原菌開展了分離與培養，利用生化鑒定及16S RNA基因測序進行比對，測定分離菌株的LD50，通過藥敏試驗篩選敏感抗生素，旨在為黃鰭鯛的病害防治提供一定的理論依據。

1 材料與方法

1.1 病料及試驗魚

病料采自湛江某養殖網箱發病黃鰭鯛；……