Pathogenic Characterization And Treatment Of S. Suis Isolated From Pigs In Hebei Province, China

S. suis of pigs was caused by serological groups C and D ( S. suis ) in China. Strains of S. suis are divided into 35 serotypes according to their polysaccharide capsular antigens. Serotype 2 spread in many countries. In 1991, this germ was identified on pigs in Guangdong province, China. Recently, there are a number of pigs were infected in China. The economic loss to the swine industry from S. suis infection is huge. S. suis cause high mortality. The bacterium leads to arthrositis of weaning piglets, meningitis, septicaemia and bronchitis. The pig can also be asymptomatic carrier of S. suis, the site of colonization with S. suis being mainly in the tonsils. Carrier rate is up to 76 percent. Serotypes of S. suis were detected by molecular biological technique, which is an advanced method for molecular epidemiological investigation of the disease. S. suis immunization is usually failure for vaccine serotype is not matching with pathogenic bacteria. For this reason, we have to isolate S. suis from pigs in the farm, and select typical serotype to make effective vaccine to control this disease.In autumn of 2005, we found two cases and isolated 3 strains of S. suis at 2 district in Hebei province. The pathogenic character of the bacteria was identified. Colonies of the bacteria are small, grayish or transparent, and slightly mucoid. The strains produced narrow zones ofα-hemolysis andβ-hemolysis. Biochemical characteristics of the strains are same. They are sensitive to temperature and can not grow in agar medium. The strains are able to grow in anaerobic or aerobic condition, however, they are unable to grow in high concentration NaCl solution. Presumptive identification based on the following biochemical tests (Voges-Proskauer negativity, hydrolysis of esculin positivity, amylum positivity, arginine positivity, hydrolysis of salicin positivity, sucrose positivity, lactose positivity, hydrolysis of sorbitol negativity, hydrolysis of mannitol negativity) can be successful for all capsular types of S. suis. PCR results showed that 3 strains are2 serotype of S. suis. The results of animal experiment indicated that 3 strains were low pathogenicity to rats, however, the rats died 12~15 days postinfection. The strains isolated from Hebei province were pathogenic S. suis. The bacterium susceptibility test was performed using 23 antibiotics. The results indicated that SS2-1 and SS2-2 strains were resistant to a lot of antibiotics, however, they were sensitive to piperacillin, erythromycin and furadantin. SS2-3 strain was sensitive to piperacillin, cefoperazone, complex sulfonamide, rifampicine, erythromycin, cefuroxime, tobramycine, oxacillin, ampicillin, ceftazidime, however, was not sensitive to other antibiotics. SS2-1 and SS2-2 strains were not sensitive to amikacin,Oxacillin,ceftazidime,ampicillin etc. Multivalent inactivated vaccine generated from the strains isolated from sick pigs. This vaccine is safety and high protective efficacy.