| On the basis of promoting the development of Plateau Characteristic Industries in the past,combined with poverty alleviation,Tibet Autonomous Region has listed Tibet pig industry as one of the seven key industries with plateau characteristics,which plays a key role in improving the quality and efficiency of Tibet's agriculture and animal husbandry,and increasing the income of farmers and herdsmen.Streptococcus suis has always been an important disease that seriously endangers the pig industry,but at present,the report of this disease in our region is only in the isolation,identification and epidemiological investigation of bacteria,and the epidemic serotypes of this pathogen in our region,the virulence genes and drug resistance genes carried by it have not been reported.In order to understand the prevalence of Streptococcus suis in Tibetan Pig Population and the biological characteristics of the pathogen,1679 Tibetan pig serum samples were detected by enzyme-linked immunosorbent assay(ELISA),and 327 Tibetan pig disease samples(lungs and tonsils)were isolated and identified by PCR The capsule serum typing,virulence gene detection,drug resistance gene detection,drug resistance analysis and pathological experimental observation were carried out.This study is divided into three parts:1.902 sera from 1679 Tibetan pigs were positive for Streptococcus suis antibody,the total positive rate was 53.72%.Among them,the positive rates of Lhasa,Nyingchi,Shigatse,Shannan and Changdu were51.84%,61.92%,55.23%,19.23% and 48.90% respectively,among which Nyingchi had the highest antibody positive rate,Shannan had the lowest antibody positive rate,and Tibetan boar and Tibetan sow had51.58% and 55.93% respectively.Statistical analysis with SPSS 13.0software showed that there was no significant difference in the detection rate of Streptococcus suis antibody between regions and genders(P?0.05).2.17 strains of Streptococcus suis from Tibet were isolated from 327 samples by bacterial isolation and culture,biochemical identification,PCR detection and sequence analysis.The isolation rate was 5.2%.The homology of the gene sequence of the isolates with Streptococcus suis isolates from Nanjing,Huazhong and Hunan Agricultural University was over 98%.According to the differences of the capsular antigens,17 isolates were serotyped.The results showed that 5 strains were Streptococcus suis type 2,1 strain was Streptococcus suis type 7,7 strains were Streptococcus suis type 9 and 4 strains were Streptococcus suis type16.29.41%,5.88%,41.18% and 23.53% respectively.The above results showed that there were many serotypes of Streptococcus suis in Tibetan pigs,and the four serotypes of the isolated bacteria had strong pathogenicity.Therefore,targeted measures should be taken in the prevention and treatment at ordinary times.According to the primers of six virulence genes(GDH,FBPS,EPF,MRP,ORF2,SLY)of Streptococcus suis,the virulence genes of 17 strains of Streptococcus suis were amplified by PCR.The detection results were as follows: GDH detection rate was 100%,FBPS detection rate was 100%,EPF detection rate was 100%,EPF detection rate was 88.24%,MRP detection rate was70.59%,ORF2 detection rate was 64.71%,and SLY detection rate was70.59%.Nine genotypes were detected in the virulence gene test,among which GDH +EPF+SLY+FBPS+MRP+ORF2 + were the main genotypes.3.The drug resistance of 17 strains of Streptococcus suis isolated in Tibet was analyzed by selecting 30 kinds of antibiotics commonly used in clinic.Especially for amikacin,compound xinnuoming and polymyxin,the drug resistance were 88.24%,94.12% and 100%,respectively.The trend of resistance to oxacillin,gentamycin and neomycin was obvious.17 strains of Streptococcus suis macrolides resistant genes(erm A,erm B,ermC,erm TR,mef A,mef E,msr D)were amplified.The detection rates were 23.53%,41.18%,70.59%,52.94%,64.71%,35.29% and 41.18%,respectively.ermC was the highest. |
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