摘要
从患病家兔肝、肺、脑和心血中分离到1株链状革兰阳性球菌P110323,以1×106 CFU/mL菌液灌胃感染健康家兔后,表现出站立不稳、四肢划动、惊厥和呼吸障碍等症状,感染96h后,死亡率为60%。解剖见肺淤血、出血;肝、脾和肾肿大,坏死;大脑肿胀,脑膜充血,脑回肿胀扁平,脑沟变浅。分离菌在BHI平板上形成湿润、边缘整齐的灰白色菌落;在5%的脱纤维羊血平板上形成透明的β溶血环;V-P试验、水解精氨酸与马脲酸等为阳性;水解七叶苷和利用甘露醇、山梨醇和乳糖产酸为阴性。16SrDNA系统发育分析显示分离菌与Streptococcus difficilis和Streptococcus agalactiae聚在一簇。gyrB基因系统发育分析表明分离菌属于无乳链球菌(S.agalactiae),结合细菌形态特点和生理生化特性鉴定该病原菌为无乳链球菌(S.agalactiae),多重PCR方法确定该菌荚膜多糖类型为Ia型。
A pathogenic bacterium （P110323） was isolated from the liver,lung,cerebrum and heart blood of the diseased rabbit. Artificial infection of rabbits with Pl10323 proved that it was the pathogen of the disease,disease signs and a mortality rate of 60% were noted after 96 h postinocu-lation with 106 CFU/mL bacterium. The clinical symptoms of infected rabbits included incoordina-tion,lateral prostration,paddling and convulsions with acute respiratory distress syndrome. Nec-ropsy revealed degeneration and necrotic changes in many organs, especially, serious lesions oc-curred in the liver and kidney. Hemorrhage and swelling of the lung and spleen were considerable; The surfece of gyri was swollen and flattened with the shallow cerebullar sulci,hyperemia of me-ninges was obvious. The isolated bacterium was a Gram-positive cocci which possessed β-hemolyt-ic activity on agar media with 5% sterile sheep＇s blood and had moistening and gray colonies in BHI. Arginine, hippuric acid and V-P test were positive; esculin, sorbitol, lactose and mannitol were negative. Phylogenetic analysis showed that it was hardly differentiated between S. difficilis and S. agalactiae on the basis of 16S rRNA, however, the phylogenetic tree constructed by compa-ring gyrB sequences of the separated strain showed that Pl10323 belonged to S. agalactiae. Ac-cording to the morphological, biochemical characteristics and phylogenetic analysis, the isolated strain was identified as S. agalactiae. The direct identification of the capsular type by multiplex PCR method indicated that Pl10323 was S. agalactiae Ia.
出处
《中国兽医学报》
CAS
CSCD
北大核心
2013年第8期1247-1252,共6页
Chinese Journal of Veterinary Science
基金
四川省科技支撑计划资助项目(09CZ1719)
教育部<长江学者和创新团队发展计划>创新团队资助项目(IRTO848)
