一株猪链球菌的分离鉴定及其生物学特性研究

Isolation, Identification and Biological Characterization of a Streptococcus suis Strain

为了确定扬州市某猪场发病猪的病原,对该猪场送检的病猪心脏进行了细菌分离与培养。通过16S rDNA测序和gdh基因PCR扩增,确定细菌种类;用血清型特异性引物进行PCR扩增,确定分离菌株的血清型;通过生长曲线测定、小鼠感染试验和药敏试验对分离菌株的生物学特性进行研究。结果表明,分离菌株为猪链球菌2型;分离菌株的生长情况与猪链球菌2型SC19菌株相似,但最高OD 595值略低于SC19菌株;分离菌株对小鼠具有高致病性;分离菌株主要对青霉素类和头孢类药物敏感。这说明猪链球菌2型很可能是该猪场发病猪的病原,该猪场对猪链球菌感染的防控应优先选用青霉素类和头孢类药物。

To detect the pathogen of diseased pigs from a pig farm in Yangzhou,bacterial isolation and culture were conducted on the heart sample of a diseased pig.The bacterial species were determined by 16S rDNA sequencing and PCR amplification of gdh gene.The serotype of the isolated strain was determined by PCR amplification using the serotype-specific primers.The biological characteristics of the isolated strain were explored by growth curve analysis,experimental infection of mice and antimicrobial susceptibility testing.The results showed that the isolated strain belonged to Streptococcus suis serotype 2.The isolated strain exhibited similar growth kinetics compared to S.suis 2 strain SC19,except that the maximum OD 595 value was lower than that of strain SC19.The isolated strain also displayed high pathogenicity in a mouse infection model.Moreover,the isolated strain was sensitive to penicillins and cephalosporins.Collectively,the results suggested that S.suis 2 was likely to be the pathogen of the diseased pigs from the pig farm,and that penicillins and cephalosporins should be the preferred drugs for the prevention and control of S.suis infections.