猪源绿色气球菌的分离鉴定及16S rRNA基因序列测定与遗传进化分析

为研究引起广东部分地区猪场仔猪发生急性死亡的致病菌及其系统发育地位,本研究从广东英德、惠州龙门、翁源、汕头等地区猪场急性死亡病仔猪中分离到6株呈α溶血的细菌。通过细菌形态学观察、生化特性鉴定、药敏试验、致病性试验以及16S rRNA基因的序列分析,确定为猪源绿色气球菌,分别命名为HD、WY、ZQ、LM、YD和ST。动物感染试验表明：6株分离菌株均具有不同程度的致病性;药敏结果显示：6株分离株均对头孢曲松、头孢唑啉、恩诺沙星、阿莫西林高度敏感,对新生霉素、利福平、阿米卡星、庆大霉素、多粘菌素B中度敏感,对其他抗生素均耐药;同源性及遗传进化分析结果显示：6株分离株与12株国内外参考菌株核苷酸同源性在93%以上,其中与澳大利亚分离自犬的15MS株同源性最高,为98.1%,与广西分离自猪的GXBL-1株同源性最低,为83.6%;6株分离株与广东分离株和澳大利亚分离株亲缘关系最近,暗示进化不存在明显的地域相关性。本研究确定了广东部分地区引起规模化猪场仔猪发生急性死亡的病原菌,为该菌引起的疾病的防治提供了依据。

Isolation and Identification of Aerococcus viridans from Swine andPhylogenetic Analysis of 16S rRNA Gene Sequence

In order to investigate the pathogen of acute death occurred of piglets from pig farms in Guangdong province and the phylogenetic position, six strains of alpha hemolytic bacteria were isolated from sick pigletswith acute death in pig-rearing farm in Yingde, Longmen, Wongyuan, Shantou regions of Guangdong province. Morphological observation, biochemical identification, drug sensitive test, pathogenicity test and sequenceanalysis of 16S rRNA genes confirmed the six stains of alpha hemolytic bacteria as porcine green gas aureus, designated HD, WY, ZQ, LM, YD and ST, independently. Pathogenicity test showed that, the six isolates haddifferent degree of pathogenicity. The results of drug sensitive test indicated that, the six isolates were highly sensitive to ceftriaxone, cefazolin, enrofloxacin and amoxicillin, moderate sensitive to novobiocin, rifampin,amikacin gentamicin and polymyxin B, resistant to other antibiotics. Homologic and phylogenetic analyses indicated that, the six isolates shared identity above 93% with 12 reference strains at the nucleotide level, withthe highest identity 98.1% to strain 15MS from dog in Australia, and the lowest identity 83.6% to strain GXBL-1 from pig in Guangxi; The six isolates clustered with strains from Guangdong and Australia, suggesting thatevolution did not exist obvious regional correlation. This study confirmed the pathogenic bacteria causing acute death of piglets in large scale pig farm, and provided the basis for prevention and cure of disease caused by the bacteria.