Genetic analysis reveals the genetic diversity and zoonotic potential of Streptococcus dysgalactiae isolates from sheep.

Streptococcus dysgalactiae (S. dysgalactiae ) is a common pathogen of humans and various animals. However, the phylogenetic position of animal S. dysgalactiae isolates and their zoonotic potential remain unclear. Most molecular epidemiological studies explicate beta-hemolytic streptococci according to their MLST and M protein gene (emm) types. Although human S. dysgalactiae isolates are relatively well characterized, the data concerning animal isolates are scarce. Here, we report the molecular characteristics and antimicrobial resistance of S. dysgalactiae strains recovered from sheep and their genetic relationship with isolates from other animal hosts and humans. Overall, 11 PFGE pulsotypes, five MLST sequence types (STs), and two emm types were distinguished, with ST248 and stL1376 being the most prevalent, indicating genetic diversity among tested 17 ovine isolates. Some isolates exhibited resistance to doxycycline (59%), erythromycin (6%), ciprofloxacin (6%), and trimethoprim/sulfamethoxazole (6%), harboring various resistance determinants. Phylogenetic analysis showed that studied ovine isolates grouped together with human S. dysgalactiae isolates from the cases of zoonotic infections. Moreover, some ovine isolates shared identical STs and emm gene sequences with human non-invasive and invasive S. dysgalactiae strains. These findings suggest a possible link between human and ovine isolates and indicate the zoonotic potential of this pathogen.