黄河鲤嗜水气单胞菌的分离、毒力及用药分析

Isolation,Virulence,Resistance and Medication of Aeromonas hydrophila from Common Carp Cyprinus carpio

自发病黄河鲤4种组织中分离致病菌,结合形态学和16SrDNA序列分析,发现分离到的细菌属气单胞菌属。回归感染试验发现,患病鱼体出现鳃盖等多处组织出血且伴随肠炎等症状,表明引起黄河鲤发病的致病菌为嗜水气单胞菌,命名为HNAh01。半致死密度测定发现,嗜水气单胞菌HNAh01的半致死密度为1.38×10~7 cfu/mL。药敏结果表明,该致病性嗜水气单胞菌是典型的多重耐药嗜水气单胞菌,但对恩诺沙星极为敏感。因此,选择恩诺沙星对分离菌株进行体外药效学和用药分析试验。药效学试验表明,恩诺沙星对嗜水气单胞菌HNAh01的最小抑菌质量浓度为1.56ng/mL,最小杀菌质量浓度为3.12ng/mL,防耐药突变质量浓度为12.5ng/mL,耐药选择窗的范围为1.56~12.5ng/mL。用药分析结果显示,黄河鲤口服剂量为10mg/kg时对嗜水气单胞菌HNAh01的相对保护率达83%。本文研究为嗜水气单胞菌的防治提供了理论基础与实践依据。

A pathogenic bacterial strain was isolated from four tissues of common carp Cyprinus carpio suffering from hemorrhagic septicemia.Combined with the morphological characteristics and the 16S rDNA sequence analysis showed that the identified isolate belongs to Aeromonas hydrophila,named HNAh01.Recurrent infection showed that the LD（50） was 1.38×10~7 cfu/mL after artificial infect healthy common carp with hemorrhages at the base of pectoral and pelvic fins.The drug sensitivity test revealed that HNAh01 was a typical multi-drug resistant A.hydrophila.However,the pathogen was extremely sensitive to enrofloxacin and the minimum inhibitory concentration（MIC）was 1.56 ng/mL,the minimum bactericidal concentration（MBC）was 3.12 ng/mL,mutant prevention concentration（MPC）was 12.5 ng/mL,and drug selection window（MSW）in the range of 1.56—12.5 ng/mL.Medication showed that oncedaily dose of 10 mg/kg for 6 d the relative protection ratio（RPS）was amounted to 83% .The methods described in this study also can be used for developing dose guidelines for other anti-bacterial drugs for the prevention and treatment of A.hydrophila.