Application of in situ Hybridization for Streptococcus suis
Streptococcus suis is a gram-positive bacteria that is normally found in the swine respiratory tract. However, some of the strains can lead to systemic and neurological diseases such as meningitis. The strains normally found in the respiratory tract are considered commensal and need to be distinguished from the strains that are pathogenic. One way to identify the different strains is to do gene sequencing. Multi-locus sequencing was used to identify 7 housekeeping genes that were used to identify sequence types(ST). Two of the sequence types found were S. suis ST1 and ST28. ST1 is the most common isolate from the clinical cases and is accepted as pathogenic. While ST28 has suggested emergence as being pathogenic but is not universally accepted as pathogenic. In order to confirm that these sequence types are pathogenic, in situ hybridization with an RNA probe was performed to stain S. suis in the lesions of the affected tissue. The RNA probes were made with virulence-associated genes of the sequence types ST1 and ST28 in order to gain a positive signal indicating affected tissue.