Isolation And Identification Of Pathogenic Streptococcus Suis Of The Huanghe River Mouth Area And Detection Of Virulence Associated Factors By PCR Assay

Streptococcus suis is one of the primary diseases that threaten modern pig industry. Because of the great varity of streptothrix serum type and the complex structure of antigen, it presents different clinical symptom, such as septicemia, meningoencephalitis, endocarditis, pneumonitis, porodenia arthritis and so on. Now we are not very clear with occurrence regulation and the original characteristic of streptococcosis disease, and its infection and spread can not be effectively controlled simply by medicines. There occurred swine streptococcosis at different degree in large-scale piggery in Huanghe River Mouth Area from 2005 to 2009. In order to provide theoretical basis for immune protection of Swine Streptococcosis, we study it from pathogen, on the foundation of culture and identification of Streptococcus suis from Huanghe River Mouth Area, PCR method was established to detecte the virulence gen. Three experiments were carried out to obtain the study.1 Isolation and identification and investigation on serotypes and drug resistance of pathogenic Streptococcus suis of Huanghe River Mouth Area. Molecular epidemiology of Streptococcus suis isolates were primarily studied through morphology, gramstain, biochemical test, drug sensitivity test. Fifteen Streptococcus suis strains were isolated from infected pigs of different areas in Huanghe River Mouth Area, which morphology, dyeing, cultural characteristics and physicochemical properties are coincidence with Streptococcus suis. The drug sensitivity test indicated that Huanghe River isolates are only sensitive to ampicillin, amikacin, cefotaxime, cefazolin, and have produced drug resistance at different degree to other routine drug.2 Detection of virulence-associated factors of Streptococcus suis by duplex PCR assay. Design and synthesis two distinct primers based on the main virulence factors Sly and MRP of Streptococcus suis, establish a duplex PCR detection method by optimizing the condition and system, the method was used to analyse the experimental strains and control strains. With the identified 15 Streptococcus suis strains, the positive detection rates of Sly, MRP were 4/15 , 2/15 , there were no specific amplification products in negative control strains. The results demonstrated that duplex PCR was a highly specific and sensitive diagnostic tool for the detection of virulence-associated factors of Streptococcus suis.