Isolation and characterization of streptococcus suis from the tonsils of healthy pigs

Abstract

Streptococcus suis (S. suis) is a Gram-positive coccus that has been implicated as the cause of a wide range disease in swine including arthritis, meningitis, pneumonia , septicaemia , endocarditis , polyserositis, abortions and abscesses. Among 35 known serotypes, S. suis serotype 2 is known as zoonosis pathogen to cause meningitis in human with the first cases from Denmark in 1968 .Hearing loss is the most common symptom found in 60 % recovered meningitis patients infected with S. suis. There were over 700 meningitis human cases reported worldwide including over 200 cases reported from Viet Nam. This pathogen is directly transmitted from pig to human, pig is the natural host for S. suis with the tonsil is the main site of carriage. However in Viet Nam , where the pig population is high , the tonsil carriage rate in healthy pig is not known . The aim is to investigate S. suis serotype 2 carriage rate in healthy pigs slaughtered in the slaughterhouses to reduce the risk of people who contact daily with pigs as well as to investigate the potential virulence of these isolates . The randomly tonsils of healthy pigs are collected in Tien Giang Province and stored at - 20oC.The selective broths are prepared for culturing the mince of the tonsils after that using PCR with specific primer to amplify the cps2J fragment using the quick extracted DNA bacteria growing in selective broth media. Technique API 20 Strep and serotyping are used to identify S. suis serotpye 2 . All S. suis serotype 2 are characterized by MLST ( Multi Locus Serotype typing) and using PCR method to amplify the potential virulence , antimicrobial drug resistance genes. In this study , the percentage of S. suis serotype 2 which exist in tonsil of healthy pigs is 13 % and we successfully isolated 9 strains (4.5 % ) for characterization.