| 280 tissue samples of swine were obtained in 235 pig farms in QinHuangdao,TangShan and so on ,where locate in the east of HeBei province .Out of which, 48 strains streptococcsis(Strep.Suis) were isolated and tested through Lancefield serum group ,combined clinical case dada and epidemiologic investigation. The results showed that swine Strep.Suis were mainly caused by such groups of streptococcsis as groups D (47.9%),group C(38.5%).In addition,swine Strep.suis was firstly reported in the east of Hebei province,according to the epidemic rule,serum group distribution and destruction.ln fact,swine of 35-140 days were infected and demonstrated the septiccmic type and meningitis type .The bacteria could be tested in the cold season in the east of HeBei province,owning 83.2% of the whole morbidity.Tested rate and isolated rate were 68.6%(192/280),40.6% respectively in the clinical practice.12 typical strains out of 48 were test through biochemical identification,The results indicated that D group was mainly occurred by a-hematocytolysis,meanwhile,C group,p-hernatocytolysis.furthermore,strep.suis was more adapted to growing in the GMTB,containing 2% FBS.pathogenicity experiment was show that mouse,rabbit and swine were easly infected by tested-strain.Drug-sensitivity experiment was reconfirmed the above resit. MLD of isolating strains of CL7 and LN2 were 5×108CFU and 1 ×l08CFU.Tested bacteria was more sensitive to these drugs,such as Cefazolin,Ciprofloxacin,Enrofloxacin,Penicillin and Amoxicillin, the sensitivity ratio are 100%, 100%, 91.7%, 91.7%, 83.3%, and resistant to Streptomycin and Gentamicin.To prepare an inactivated combined vaccine,the strains of LN2 and CL2 with high virulence and good immunity were selected form 48 isolated strains of C serum group and D serum group respectively. Immunity test indicated that it's protection rate was 100%,which had been confirmed in the mouse.On the other hand,protection value of AGP was 98.5%.Which demonstrated the vaccine was safe and effective. |
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