Study on serotypes of Streptococcus suis isolated from pigs in Tien Giang

Abstract

The aim of this study was to detect the presence of Streptococcus suis serotypes from the pigs raising in Tien Giang province. A total of 270 pig swab samples were collected for testing the presence of S. suis and identifying S. suis serotypes. Specific antisera for S. suis capsular antigens (Statens Serum Institute, Denmark) was used to determine the serotypes of the isolated strains. A total of 206 S. suis isolated strains were genotyped using PCR assays for detecting four virulent genes, such as: the suilysin (sly gene), the muramidase-released protein (mrp gene), subtilisin serin protease (sspA gene) and S. suis secreted nuclease (ssnA gene). The studied result showed that S. suis was detected from 21.48% of pigs in the farms without clinical signs, 85.19% of pigs in the farms with clinical signs. 28 different serotypes were identified. Serotypes S. suis 1, 1/2, 2, 3, 5, 7, 8, 9, 11, 14, 16, 21, 23, 30, 31 and 5/21 were only isolated from the pig samples in the farms with clinical signs. The four virulent genes were found, especially in the S. suis serotypes 1/2, 2 and 31 carried 2 to 4 virulent genes. Single variability was used for analyzing the risk factors relating to S.suis in pigs. The analysed result indicated that there were 3 related risk factors, including the large size s farms raising the post-weaning piglets (OR = 11; P < 0.05); disinfection of the weaning piglet houses (OR = 0.13; P < 0.05) and using fresh swine manure for the farm crops (OR = 9.75; P < 0.05).