斑马鱼迟缓爱德华氏菌的鉴定、致病性及药物敏感性

Identification,pathogenicity and drug sensitivity of Edwardsiella tarda from Danio rerio

从患病斑马鱼(Danio rerio)肝脏组织分离到菌株Z1,通过对该菌株形态特征、生理生化特性、ATB系统鉴定和16S rRNA、DNA促旋酶B亚单位蛋白(gyrB)基因测序等综合分析,鉴定Z1菌株为迟缓爱德华氏菌(Edwardsiella tarda)。Z1菌株对健康斑马鱼和透明四带无须鲃(Puntius tetrazona)人工感染试验发现,感染发病症状与自然发病症状一致,再分离菌株的特性与Z1菌株相同,并再次感染成功,证实迟缓爱德华氏菌为斑马鱼病原菌。药敏试验发现Z1菌株对呋喃妥因等11种药物敏感,对苯唑西林等6种药物耐受。15种中草药对Z1菌株的体外抑菌试验结果发现,五倍子、石榴皮的抑菌作用明显,最小抑菌质量浓度(MIC)和最小杀菌质量浓度(MBC)均≤6.25 mg/mL;艾叶等有一定抑菌作用,MIC和MBC均在25～200 mg/mL;而野菊花等抑菌作用不明显,MBC>200 mg/mL。

The dominant bacterial strain,designated as Zl,was isolated from hepatopancreas of diseased Danio rerio. The biochemical and physiological characteristics of the isolated strain was studied by using conventional method, such as ATB Expression System （ID32 STREP）, 16S rRNA and gyrB gene sequence. The results confirmed that the strain Z1 was Edwardsiella tarda. The challenge tests were carried out by artificially infecting D. rerio and Puntius tetrazona with the pure culture of the isolated strain. The symptoms of the artificially infected fish were similar to those infected naturally and the characters of the re-isolated strains were the same as the initially isolated strain. Antibiotic sensitivity test showed that among 17 antibiotics tested 11 were sensitive and 6 were resistant. The antibacterial activity of 15 Chinese herbs to pathogenic E. tarda （Z1） was determined in vitro by two fold dilution method. The results showed that Galla chinensis and Pericarpium granati were found to have signifi- cant inhibition on the bacterium with both minimal inhibitory concentration （MIC） and minimal bactericidal concentration （MBC） less than 6.25 mg/mL; Artemisiae argyi, Catsia tora, Prunus mume Sieb. et Zucc. , Pulsatilla chinensis , Coptis chinensis Franch. ,Rheum palmatum L. , Scutellariae baicalensis Georgi showed some extent inhibition on the bacterium with MIC and MBC of 25-200 mg/mL, but Chrysanthemum indicum L. , Lonicera japonica ,Astragalus membranaceus （Fisch.） Bge, Gl ycyrrhiza glabra, SophoraeJTavescentis and Phellodendri chinense Scheeid had no inhibition on the bacterium with MBC of more than 200 mg/mL.