Isolation,Identification,Pathogenicity Detection And Screening Antibacterial Drugs Of Streptococcus Equi Subspecies Equi

Xinjiang Yili River Valley has been the source of strangles.In recent years it was found that there was continue to appear to the body with systemic multiple abscess is characterized on horses,in Zhaosu county and Fuyun county.In order to identify this suspected strangles whether it is related to a strain that causes strangles.The homology analysis the isolates of Streptococcus equi subspecies equi and detecting the pathogenicity of the strain,screening sensitive drugs and guiding the clinical drug.1.Isolation and identification of Streptococcus equi subspecies equi.In this study,a total of 35samples collected from Zhaoxu county race A and B.After normal THB enrichment,the bacteria were purified by 5%sheep blood culture,and identified by transmission electron microscopy,biochemical test and PCR.The fneB gene of the isolates was cloned and sequenced.The results showed that two isolates of Streptococcus equi subspecies equi were identified and collected from 35 samples,and the nucleotide homology between the two isolates was 98.6%and the amino acid homology was 96.2%.2.Streptococcus equi subspecies equi pathogenicity in mice.The growth curves of the isolates were determined.After grouping the kunming mice and intraperitoneal injecting Streptococcus equi subspecies equi bacterium solution under the same conditions?every groups have different concentration?,the LD₅₀0 of two isolates were calculated by modified Karber's method,on the basis,the animal disease models were established.And making pathological sections of mice viscus tissue.This experiment successfully established the animal disease model of Streptococcus equi subspecies equi infection.The N20 strain LD₅₀was 5.8*10⁶ CFU/mL,and the N25 strain LD₅₀0 was 2.25*10⁶ CFU/mL.Pathological section can be seen,two isolates of mice liver and kidney damage the most serious.3.Screening antibacterial drugs of Streptococcus equi subspecies equi.The in vitro antibacterial test of two isolates was carried out by using Tori,Coptis chinensis Franch,Lonicera japonica,Forsythia suspensa,Dendranthema indicum,Taraxacum mongolicum and 11 kinds of western medicine.Analysising of the antibacterial effect of these drugs.The results showed that the antibacterial effect of Coptis chinensis Franch,Forsythia suspensa and Dendranthema indicum on the two isolates was significant,and was difference from control group?P<0.05?.Other drugs and prescription antibacterial effect is poor.The N20 strain was sensitive to 10 selected western medicines except tetracycline.The N25 strain is sensitive to the seven drugs of Spectinomycin,Clarithromycin,clindamycin,tetracycline,minocycline,Compound ulfamethoxazole,Furazolidone and is resistant to penicillin G and vancomycin.In this study,two strains of Streptococcus equi subspecies equi were successfully isolated from the cases of systemic multiple abscess.Streptococcus equi subspecies equi is the main pathogenic bacteria in this cases.Two strains of isolates had strong pathogenicity to mice,and the pathogenicity of N25 was stronger than N20.Chinese medicine Coptis chinensis had the best antibacterial effect.The best effect of spectinomycin,clarithromycin,clindamycin,tetracycline,minocycline,cotrimoxazole and nitrofurantoin in western medicine.