| Streptococcus suis(S.suis)is the main pathogen of swine streptococcosis.This species contains pathogenic and symbiotic strains.Pathogenic strains can cause meningitis,arthritis,endocarditis,and multiple serous membranes.Inflammation and septicemia.Streptococcus suis is widely distributed globally,causing severe economic losses to the pig industry worldwide.At the same time,it is also an important zoonotic pathogenic bacteria,which poses a serious threat to human and animal public health safety.The prevention and control of the disease has attracted more and more attention.In this study,the virulence genotyping,multi-site sequence typing and tolerance of Streptococcus suis strains isolated from diseased materials(lungs)collected from apparently healthy pigs in slaughterhouses in some areas of Anhui from 2017 to 2018 The detection and analysis of medicinal properties are expected to provide scientific basis for the molecular epidemiological investigation and research of Streptococcus suis in some areas of Anhui,and to provide a certain reference for the prevention and treatment of Streptococcus suis in some areas of Anhui.The virulence genes of 39 strains of Streptococcus suis isolates epf,mrp,sly,fbps,orf2 and gadph were detected by PCR,and their carrying rates were 5.1%,71.8%,20.5%,28.2%,84.6%,94.9 %.sly-epf-mrp+ is the dominant virulence genotype,a total of 22 strains,accounting for 56.4%,followed by sly-epf-mrp-virulence genotype,a total of 9 strains,accounting for 23.0%.In addition,the carrying rate of mrp virulence genes of S.suis type 2 and 3 was significantly higher than the overall carrying rate of S.suis,with a carrying rate of 100.0%,and sly-epf-mrp+ was the dominant virulence genotype.Seven housekeeping genes(dpr,thr A,aro A,cpn60,gki,rec A and mut S)of 39 strains of Streptococcus suis were amplified by PCR,and the gene sequence after PCR product sequencing was compared with the allele information of MLST database.The results showed that a total of 17 different ST types were identified.Ten of these ST types(1245 to 1248,1250 to 1255)were newly discovered by our laboratory,and7 have been reported.Six of the eight identified serotypes contained multiple ST types,indicating the diversity of the distribution of S.suis and ST types.The distribution of ST type,serotype and virulence genotype in 39 strains of Streptococcus suis isolates has a certain relationship.ST28 is mainly serotype 2(8/9).All virulence genotypesare sly-epf-mrp+(9/9).ST117 is mainly serotype 3(6/7),and the main genotype of virulence is sly-epf-mrp+(6/7).ST308 is serotype 8(4/4),and most virulence genotypes are sly+epf-mrp+(3/4).Using START v 2.0 software,a UPG-MA evolutionary tree was constructed based on the tandem sequence of 7 housekeeping genes.The results showed that 39 strains of ST.phylogenetic tree of Streptococcus suis can be divided into two branches,among which ST54,ST87,ST92,ST308,ST737,ST1245,ST1247,ST1252 and ST1255 are branch 1,ST28,ST117,ST1246,ST1247,ST1248,ST1250,ST1251,ST1253,and ST1254 are branch 2.The newly discovered ST type has a far-reaching relationship with the reported ST type,which indicates that the genetic changes of ST type of Streptococcus suis epidemic in some areas of Anhui are obvious.18 kinds of commonly used antibacterial drugs were selected and the drug sensitivity test was conducted on 39 strains of Streptococcus suis isolates by K-B disc diffusion method.The results showed that the resistance rate to aminoglycoside,tetracycline,chloramphenicol and sulfonamide antibiotics was higher,among which streptomycin,neomycin,gentamicin,amikacin,kanamycin,strong The drug resistance rates of cyclamycin,tetracycline,florfenicol and co-trimoxazole were97.4%,84.6%,87.2%,82.1%,76.9%,94.9%,92.3%,94.9%,82.1%,and quinolones There is a certain resistance trend.Multi-drug resistance is relatively serious,7 strains are resistant to 3-7 drugs,accounting for 17.9%,23 strains are resistant to 8-11 drugs,accounting for 59%,and 7 strains are resistant to more than 11 drugs,accounting for17.9%.At present,penicillins and cephalosporins are still the first choice for clinical treatment of Streptococcus suis. |
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