美洲鳗鲡及其养殖水体分离耐药菌的多样性和耐药性分析

为了更有针对性地防控水产动物细菌性病害的发生和流行,本实验对美洲鳗鲡及其养殖水体耐药细菌的种属特征及耐药情况开展了相关研究。首先采集美洲鳗鲡不同部位(表皮、鳃、肠道)及其养殖水体的样品,经5种抗菌药物平板筛选耐药菌株,然后采用K-B纸片扩散法检测细菌对抗菌药物的耐药性,同时测定耐药菌株的16S rDNA序列,进而分析耐药菌的种属分布和多重耐药性。结果显示,经耐药平板筛选分离纯化得到108株细菌,分别属于气单胞菌属、柠檬酸杆菌属、不动杆菌属等20个属;其中,93.5%的菌株对3种(含)以上的抗菌药物具有耐药性,86.1%的菌株对3类(含)以上的药物具有抗性。对阿莫西林的耐药率高达90.7%,对四环素、利福平以及磺胺类和酰胺醇类药物类的耐药率为60%~80%,对头孢噻肟、新霉素以及喹诺酮类的耐药性弱(低于20%)。美洲鳗鲡肠道(0.40)、表皮(0.41)、鳃部(0.42)及水样(0.47)菌群的多重耐药指数显示各生态样品耐药程度较为严重,尤以水样为最。各菌属中,柠檬酸杆菌属(0.58)和克雷伯菌属(0.61)的多重耐药指数最高,而不动杆菌属(0.21)则相对较低。美洲鳗鲡及养殖水体普遍存在多重耐药菌株,对此应引起足够的重视;水产动物及养殖环境耐药细菌对某些水产用药如诺氟沙星、新霉素等耐药率低,可将其做为水产动物细菌性疾病治疗的首选药物。

Diversity and antimicrobial susceptibility of drug-resistant bacteria isolated from Anguilla rostrata and the farming water

To provide information for controlling bacterial disease of aquatic animals,this study reveals the diversity and resistance of the drug-resistant bacteria around Anguilla rostrata and the farming ponds.Drug-resistant bacteria in the samples from intestine,epidermis,gill of A.rostrata and the pond water were screened by five antimicrobials.Their antibiotic resistance was determined by the Kirby-Bauer disc diffusion method and taxonomic status was identified by phylogenetic analysis of 16S rDNA sequences.The results showed that 108 resistant strains were isolated and classified into 20 genera,such as Aeromonas,Citrobacter,and Acinetobacter.The percentage of multiple resistance to three or more varieties of antibiotics was 93.5%,while the rate judged by three or more classes of antibiotics was 86.1%.The frequency of resistance to amoxicillin(90.7%)was high,and so with tetracycline,rifampicin,sulfonamides,and amphenicols(60%-80%).On the contrary,resistance to cefotaxime,neomycin and quinolones(less than 20%)was unfrequent.The multiple antibiotic resistance(MAR)indexes of isolates from intestine,epidermis,gill,and water were 0.40,0.41,0.42 and 0.47 respectively,which showed the high risk of MAR in every ecological sample,especially in the water sample.Among genera,MAR indexes of Citrobacter(0.58)and Klebsiella(0.61)were high,while that of Acinetobacter(0.21)was low relatively.Multi-drug resistant bacteria turned out to be ubiquitous in A.rostrata and the farming water,to which enough attention should be paid.Resistant bacteria from A.rostrata and water environments were mostly sensitive to some fishery drugs such as norfloxacin and neomycin.So they could be preferential drugs to treat the bacterial disease in aquaculture.