Analysis of the type II-A CRISPR-Cas system in Streptococcus canis isolated from diseased companion animals and one human patient in Japan.

We determined the whole genome sequence (WGS) of Streptococcus canis strain TA4 harboring the M-like protein gene (scm), which was isolated from a human patient presenting with bacteremia. The potential of type II-A CRISPR array-based typing was explored and the genetic lineage between spacer genogroups and scm prevalence/polymorphisms in the isolates from 19 diseased companion animals and the human patient was elucidated. The CRISPRFinder/CRISPRCasFinder detected the type II-A locus with the same repeat sequences in TA4 and another WGS of Sc isolated from a cow with mastitis. An optimized PCR-based amplification method was used to sequence the region covering the locus around the leader and terminal repeat sequences. From the 20 isolates sequenced, 16 strains (including TA4) were identified with the CRISPR array. We comparatively analyzed the homologous spacer sequences and performed grouping based on the successive common ancestral spacer types. These 16 isolates were grouped into five genogroups (A to E) with scm being absent in genogroup A. We found a relationship between the genogroups C/E and allele type 1 of the deduced M-like protein. These preliminary findings suggest the possibility of CRISPR array-based typing and genetic lineage between the spacer genogroups and scm prevalence/polymorphisms in the isolates.