犬源奇异变形杆菌的分离鉴定及生物学特性分析

Isolation identification and biological characteristics of Proteus mirabilis of canine

为了对吉林省长春地区致犬腹泻的奇异变形杆菌进行流行病学调查及药物敏感性检测,试验采用传统细菌鉴定方法及16S rRNA系统发育学分析方法,对2015—2017年间送检的62份疑似患细菌性肠炎犬的腹泻物进行奇异变形杆菌的分离鉴定及遗传进化分析,并对分离菌进行药物敏感性试验及小鼠致病性试验。结果表明:从送检病料中共分离获得12株奇异变形杆菌(分离率为19.35%),革兰氏染色为阴性,理化特性鉴定与奇异变形杆菌的生理特性基本一致;分离菌经16S rRNA基因扩增获得大小的为1 600 bp条带,所测序列与奇异变形杆菌的核苷酸序列同源性在98%以上,12株分离株处于3个独立分株;其中分离菌对兽医临床常用药物整体耐药水平较高,仅有部分菌株对环丙沙星、恩诺沙星、头孢曲松敏感;分离菌CC15031对小鼠的半数致死量(LD_(50))为2.8×10~6 cfu/mL,具有较强的致病性。说明分离得到的奇异变形杆菌具有较强的耐药性和不同程度的致病性,应引起重视。

In order to investigate the epidemiology and drug sensitivity of Proteus mirabilis causing diarrhea from dogs in Changchun,Jilin Province,62 dogs with diarrhea suspected of having bacterial enteritis from 2015 to 2017 were isolated and identified by traditional bacterial identification method and 16 S rRNA gene phylogenetic analysis method,and the genetic evolution of Proteus mirabilis was analyzed.At the same time,drug sensitivity test and pathogenicity test of mice were carried out.The results showed that twelve strains of Proteus mirabilis(19.35%)were isolated from the samples,and Gram staining was negative.The physical and chemical characteristics of the isolates were basically the same as those of Proteus mirabilis.After 16 S rRNA gene amplification,the bands about 1600 bp in size were obtained.The homology between the sequencing results and the nucleotide sequence of Proteus mirabilis was more than 98%,and 12 isolates were in three independent branches.Isolated bacteria showed a high overall drug resistance to veterinary commonly used drugs,while only some strains were sensitive to ciprofloxacin,enrofloxacin and ceftriaxone.CC15031 strain had a strong pathogenicity with a half lethal dose of 2.8×10~6 cfu/mL in mice.It is pointed out that the isolated Proteus mirabilis in this study have strong drug resistance and different degrees of pathogenicity,which should be paid attention to.