Submitter Withdrawn 20th Lancefield International Symposium on Streptococci and Streptococcal Diseases 2017

Novel genetic determinants of Streptococcus dysgalactiae subspecies equisimilis  (#43)

Alexander V Dmitriev 1 2 , Alexandra G Kireeva 1 2 , Artem M Kiselyov 3 , Olga V Kalinina 3 4
  1. Institute of Experimental Medicine, Saint-Petersburg, Russia
  2. Saint-Petersburg State University, Saint-Petersburg, Russia
  3. Almazov North-West Federal Medical Research Centre, Saint-Petersburg, Russia
  4. Saint-Petersburg State Technological Institute (Technical University), Saint-Petersburg, Russia

Streptococcus dysgalactiae subsp. equisimilis (SDSE) is currently recognized as causative agent of about 60% of group C and G streptococcal infections.

Goal of this study was the search of novel SDSE genetic determinants acquired from other bacterial species.

Four strains isolated from healthy children in Vietnam in 2013-2014 were selected and cultured in THY broth. Genomic DNA was isolated by phenol/chloroform extraction. Libraries were prepared using Nextera XT Kit and sequenced at Illumina MiSeq (USA) using MiSeq reagent Kit v3. The reads were edited using SPAdes and Genomics Workbench v8 (CLCBio, USA). The contigues were analyzed using BLAST software.

Numerous DNA fragments previously undescribed for SDSE were revealed. Most of them contained genes of migrating genetic elements such as S. pyogenes A25 and phi-m46.1 bacteriophage genes, S. agalactiae and E. faecalis transposon Tn916 genes, plasmid genes, S. pyogenes ICESp1108 element genes, etc. Integrase and recombinase genes involved in recombination similar to those of S. agalactiae, S. pyogenes, S. suis, S. pneumoniae, and genes involved in transcriptional regulation of streptococci (XRE, Cro/CI family genes, DNA-binding protein genes, etc.) were discovered. For the first time the tetS, tetT and lsaE, lnuB genes encoding resistance to tetracycline and lincosamides, respectively, were revealed in SDSE. Several genes of animal pathogens (S. suis, S. equi) were also found in SDSE.

Bioinformation analysis suggested an extensive genetic exchange between SDSE and other gram-positive cocci. Given that horizontal gene transfer is driving force of evolution, an emergence of novel highly virulent SDSE clones is expected.