猪源绿脓杆菌的分离鉴定及16S rRNA基因同源性分析

从解剖病变为心包炎、纤维素性肺炎、肺脓肿的病死仔猪体内分离到1株细菌,通过形态特征观察、生化试验,将分离菌株初步鉴定为绿脓杆菌。动物致病性试验结果显示,分离菌株对小鼠具有很强的致病性。药敏试验结果显示,分离菌株对氧氟沙星、恩诺沙星高度敏感,对头孢噻肟、庆大霉素中度敏感,对青霉素、氟苯尼考、氨苄西林、阿莫西林、强力霉素、卡那霉素等耐药。将分离菌株的16S rRNA基因序列与Gen Bank中发表的绿脓杆菌序列进行Blast比对,结果表明,分离菌株与绿脓杆菌不同菌株的同源性高达99%以上,进一步确定分离菌株为绿脓杆菌。基于16S rRNA基因序列,使用MEGA 5.05软件,构建系统进化树,结果表明,分离菌株与病人痰液和腹泻婴儿分离菌株的同源性最高,与未加工水果分离菌株同源性最低。

Isolation,Identification and Antimicrobial Susceptibility Test of Pseudomonas aeruginosa from the Infected Piglet and Phylogenetic Analysis of 16S Ribosomal DNA Sequences

A bacterial strain was isolated from the dead piglet with pericarditis,fibrinous pneumonia and lung abscess lesions.The isolate has been identified as Pseudomonas aeruginosa through the obervation of morphological characteristics and biochemical test.Animal pathogenicity test showed that the Pseudomonas aeruginosa isolate is highly pathogenic to mice.Drug sensitive test indicated that the isolate was highly sensitive to ofloxacin and enrofloxacin,intermediate sensitive to cefotaxime and gentamicin,and resistant to penicillin,florfenicol,amoxicillin,ampicillin,doxycycline,kanamycin,and so on.Homologous relationship was searched bween 16S rRNA gene sequence of the isolate and that of organisms published in GenBank by blast-sequence alignment.The results indicated that the homology reached more than 99％ beween the isolate and other strains of Pseudomonas aeruginosa registered in GenBank,furtherly confirming that the isolate belongs to Pseudomonas aeruginosa.Phylogenetic tree was constructed using MEGA 5.05on basis of 16S Ribosomal DNA Sequences of the isolate and those of eight Pseudomonas aeruginosa isolates from different sourcs in GenBank,revealing that the isolate has the highest homology with the Pseudomonas aeruginosa isolates from sputum and infant diarrhea,and the lowest one with that from unprocessed fruit.