Isolation,Identification and Pathogenicity Analysis of a Strain of Streptococcus suis Causing Meningitis in Piglets
[Objective]The purpose of this experiment was to determine the pathogen in the tissue samples of pigs with suspected piglet meningitis caused by Stre ptococcus suis in a pig farm in Guangdong,and to determine its drug sensitivity and pathogenicity,so as to provide medication for pig farms and explore the mechanism of meningitis caused by this pathgen.[Method]Bacterial isolation and culture,morphological observation,biochemical testing,and molecular identification were performed on the samples of piglets suspected to have meningitis caused by Streptococcus suis.Drug sensitivity testing,virulence gene testing,mouse infection testing,and histopathological diagnosis were also conducted.[Result]The isolate from the piglet brain tissue showed hemolysis on the blood plate.Gram staining microscopy showed that bacteria were stained purple,with a circular shape and some arranged in a chain shape.Biochemical characteristics showed that the isolate could ferment raffinose,lactose,inulin and esculin,but could not ferment sorbitol,mannitol,arabinose,melezitose and D-ribose.The hippurate reduction test was negative,which were consistent with Streptococcus suis,and was determined to be Streptococcus suis after sequencing analysis.The serotype identification results showed that the isolate was Streptococcus suis type 9,named GDS209.The results of drug sensitivity test showed that GDS209 was resistant to 10 antibacterials such as cefalotin(pioneer Ⅰ),cefalexin(pioneer Ⅳ)and ampicillin/sulbactam,and was sensitive to ticarcillin/clavulanic acid,florfenicol and amoxicillin.The detection results of virulence genes showed that GDS209 carried gdh,gapdh,fbps,orf2,srtA and ccpA virulence genes,but did not carry mrp,sly,luxS and epf virulence genes.The mouse infection test showed that the LD50 of GDS209 was 1 × 109 CFU.Histopathological observation showed that GDS209 could cause congestion and inflammation in Kunming mice's heart,liver,spleen,lung and brain to varying degrees.[Conclusion]In this study,a strain of Streptococcus suis serotype 9 was isolated,which was resistant to commonly used antimicrobials in most pig farms and sensitive to ticarcillin/clavulanic acid,florfenicol and amoxicillin.The results of this study could provide some reference for the clinical diagnosis and drug treatment of Streptococcus suis serotype 9.
piglet meningitisStreptococcus suisisolation and identificationdrug resistancepathogenicity
国家科技期刊平台
NSTL
万方数据
维普
