Biofilm Production Ability of Streptococcus dysgalactiae Subsp. equisimilis: Associations with Host Species, Lancefield Group, Source, Clonal Complex, and Virulence-Associated Genes

We assessed the biofilm production ability (BPA) of noninvasive Streptococcus dysgalactiae subsp. equisimilis (SDSE) in humans and companion animals and determined the relationship between bacterial populations with BPA and other host and microbiological features. Sixty-four isolates from companion animals and humans were collected along with host information. We measured BPA using crystal violet staining, in addition to emm typing, multilocus sequence typing, antimicrobial resistance (AMR) phenotyping/genotyping, and virulence -associated gene (VAG) detecting (prtF1-prtF2-lmb-cbp-sicG-srtp1-srtp2-brpA). Differences in the BPA of SDSE from different hosts and sources and different Lancefield groups were assessed. We analyzed the associations between populations with and without BPA (strong, moderate, weak, and no biofilm producers) and emm types, sequence types/clonal complexes (CCs), AMR phenotypes/genotypes, and VAG types. Seventeen, twenty-four, and twelve isolates were strong, moderate, and weak biofilm producers, respectively; eleven showed no BPA. There was a difference in the distribution of populations with BPA between human and animal origins and between isolates of groups G and C. We found an association between populations with BPA and the eye and ear source (vs. the pus and skin source). A relationship was observed between the populations with BPA and CC127 (vs. CC17). We observed no association between the populations with BPA and AMR phenotype/genotype. There was an association between the distribution of populations with BPA and srtpl expression. Our observations suggest potential associations between populations with BPA and the host species, Lancefield group, source, CC, and VAG type.