Strains isolated from clinically healthy pigs
S. suis is a normal inhabitant of the oral cavity of pigs. The biochemical
identification of isolates recovered from clinically healthy pigs (mainly
from tonsil samples) is difficult to achieve due to the presence of other
streptococci that are part of the normal oral microflora and that are
phenotypically similar to S. suis. For this reason, molecular biology
techniques have been developed during the last decade to allow the
detection and identification of S. suis strains, such as a PCR assay
targeting the specific house-keeping gene encoding for the glutamate
dehydrogenase (gdh).24 Although widely used, the gdh PCR test can