Isolation,Identification and Pathogenicity Analysis of Streptococcus suis Type 2

• 作者: Fangkun WANG Fanliang MENG Hongyu WANG Jinyuan GU Sidang LIU Tao PENG Yan LI Zhaohu LIU Zicheng MA
• 来源期刊: 农业生物技术:英文版
• 学科: 农学
• 关键词: STREPTOCOCCUS SUIS TYPE 2 ISOLATION and IDENTIFICATION Growth curve Drug sensitivity test PATHOGENICITY LD 50 determination
• 年，卷（期）: 2019,（4）
• 页码范围: 64-68
• 页数: 5页
• 分类号: S85

摘要

[Objectives]This study aimed to investigate the pathogenicity,growth characteristics and drug resistance of Streptococcus suis type 2.[Methods]Bacterial isolation and identification,biochemical experiments,determination of growth curve and correlation curve between OD 600 values and viable counts,drug susceptibility tests,pathogenicity analysis,and histopathological observations were carried out.[Results]The Streptococcus strain isolated from infected pigs was identified as Streptococcus suis type 2,which was named TA01 strain.TA01 strain reached the growth peak at 6-8 h post-incubation,and viable counts gradually declined after 8 h of incubation.The correlation equation between OD 600 values and viable counts is y=24.659 x-1.076 1,R^2=0.996 7.TA01 strain was sensitive to penicillin,erythromycin,florfenicol and oxacillin,and resistant to ciprofloxacin,polymyxin B and clindamycin.According to the results of pathogenicity analysis,all the mice in 3.6×10^9 cfu/mouse group died within 48,and these dead mice exhibited acute pyaemia septica.Based on the Reed-Muench formula,it was calculated that LD 50 of TA01 strain was 1.137×10^8 cfu/mouse.Pathological examination showed obvious blue-stained bacteria clusters,accompanied by neutrophil infiltration.[Conclusions]TA01 strain was a virulent strain of Streptococcus suis type 2.Compared with Streptococcus strains which were isolated and reported in China,TA01 strain exhibited strong virulence and rapid proliferation.