TONSILLAR SWABS CAN BE USED IN A PCR ASSAY FOR THE DETECTION OF VIRULENT STREPTOCOCCUS SUIS SEROTYPE 2 STRAINS IN WEANED PIGLETS

摘要

Streptococcus suis infections lead to high mortality rates and an increased use of antibacterial drugs in weaned pigs. Post-mortem investigations showed that Streptococcus suis type 2 and type 9 are the most prevalent serotypes found in clinical casesin the Netherlands. Virulent S. suis type 2 strains are characterised by a 136 kDa muramidase-released-protein and a 110 kDa extracellulair factor (MRP~+EF~+). Recently, a PCR assay detecting EF~+ strains in tonsillar specimens collected at the slaughterhouse has been described. This PCR is specific (82.2%) and very sensitive (No false negatives, n=99). The test has been validated by comparing the results of the PCR assay with an extensive bacteriological examination on the same tonsils. An agreement beyond chance (kappa) of 0.776 has been found. So far, the PCR assay was carried out on tonsillar tissues of pigs. However, for routine detection of carriers, tonsillar swab specimens would be preferable.