南方大口鲶烂尾病病原菌的分离鉴定及药敏试验

Isolation, identification and drug sensitivity test of pathogenic bacteria from Silurus meridionalis infected with tail-rotted disease

【目的】查明广西南宁邕江上游网箱养殖南方大口鲶烂尾病病原及其对药物的敏感性,为该病的有效防治提供参考。【方法】以常规方法进行病原菌分离与纯化,通过API 20E细菌鉴定系统和16S r RNA基因PCR扩增进行病原菌鉴定,并以K-B纸片扩散法进行药敏试验。【结果】从患病南方大口鲶病料中分离获得1株优势菌株（DKN01）,经鉴定为阪崎克罗诺杆菌（Cronobacter sakazakii）,与阪崎克罗诺杆菌标准菌株NBRC 102416和ATCC 29544的亲缘关系最近,同源性均达99.5%。菌株DKN01对南方大口鲶的致死率为70.0%～95.0%,对复达欣、菌必治、舒普深、多粘菌素B、左氟沙星、先锋必、特治星、盐酸沙拉沙星等8种药物高度敏感,对青霉素G、复方新诺明、新生霉素、多西环素、氟苯尼考、磺胺间甲氧嘧啶、磺胺对甲氧嘧啶等7种药物则不敏感。【结论】引起广西南宁邕江上游网箱养殖南方大口鲶烂尾病的病原菌为阪崎克罗诺杆菌,生产中可选用复达欣、菌必治、舒普深、多粘菌素B、左氟沙星、先锋必、特治星和盐酸沙拉沙星等药物进行防治。

[Objective]In order to provided reference for effective prevention and control of tail-rot disease, the present experiment was conducted to investigate pathogen of tail-rot disease on Silurus meridionalis cultured with net cages in upstream of Yongjiang River in Nanning, Guangxi and drug sensitivity of pathogen. [Method]The pathogen was isolated and purified from diseased S. meridionalis by using conventional methods, then the pathogen was identified based on API 20E bacteria identification system and PCR amplification of 16S rRNA gene. Moreover, the K-B paper diffusion method was used to test drug sensitivity of pathogen. [Resuh]The results showed that a dominant strain （DKN01） was isolated from diseased S. meridionalis, which was identified as Cronobaeter sakazakii. And it had the closest genetic relationship relatives with two standard strains of C. sakazakii viz., NBRC 102416 and ATCC 29544, sharing homology of 99.5%. Furthermore, the fatality rate of S. meddionalis Chen was 70.0%-95.0%, and strain DKN01 was highly sensitive to 8 kinds of drugs viz., fortum, rocephin, sulperazone, polymyxin B, levofloxacin, cefobid, tazocin, sarafloxacin hydrochloride, however, it was insensitive to 7 kinds of drugs viz., penicillin G, selectrin, novobiocin, doxycycline, lqorfenicol, sulfamonomethoxine, sulfametoxydiazine. [Conclusion]The tail-rot disease of S. meridionalis cultured with net cages was caused by pathogenic C. sakazakii in upstream of Yongjiang River pathogen in Nanning, Guangxi. Beside, the fortum, rocephin, sulperazone, polymyxin B, levofloxacin, cefobid, tazocin, sarafloxacin and hydrochloride can be used for controlling tail-rot disease of S. meridionalis.