Emergence of a Streptococcus dysgalactiae subspecies equisimilis stG62647-lineage associated with severe clinical manifestations

Abstract

Increasing incidence rates of invasive Streptococcus dysgalactiae subspecies equisimilis (SDSE) infections have been reported worldwide, but the evolutionary mechanisms underlying this development remain elusive. Through prospective surveillance of invasive SDSE infections in western Norway, we observed the emergence of a novel and virulent SDSE genotype, stG62647. This emm-type, rarely encountered as a cause of invasive disease during 1999–2012, emerged in 2013 as the predominant SDSE-genotype. The stG62647-infections were associated with an aggressive clinical course, including the occurrence of streptococcal toxic shock syndrome, necrotizing soft-tissue infections and endocarditis. All the invasive stG62647-isolates were subjected to whole genome sequencing, attempting to explore the genetic events underpinning its epidemicity. Although 10% of the genomes was unique for stG62647-genotype, notably 18 out of 19 isolates contained a disrupted streptococcal invasive locus (sil) due to the insertion of a transposase, IS1548, into the silB-gene. We postulate that the virulence of stG6267-isolates could be partly attributable to the abrogation of the attenuating control normally exerted by this regulon, although experimental verification was not performed. To the best of our knowledge, this is the first study employing large scale whole genome sequencing to illuminate the genetic landscape of epidemic lineages in SDSE.

Risk Factors and Predictors of Mortality in Streptococcal Necrotizing Soft-tissue Infections: A Multicenter Prospective Study

“…Even though several other emm types where identified, the fact that >70% of the isolates belonged to only 3 emm types add to the evidence that some emm types have a particular ability to cause severe infections [ 11 , 28 , 29 ]. In SD, stG62747 was the predominant emm type, in accordance with a previous report from our region [ 30 ]. The virulence gene profiles of GAS largely reflected the emm type distribution, with a high proportion with speA and speG consistent with the predominance of emm1 and emm3 types.…”

Exploring the arthritogenicity of Streptococcus dysgalactiae subspecies equisimilis

“…Similar conclusions have been drawn in studies on tissue tropism in Staphylococcus aureus [ 24 ]. Our findings are further corroborated by the diverse clinical manifestations produced by virtually identical isolates in clonal outbreaks of S. pyogenes and SDSE disease [ 25 , 26 ]. However, exploring bacterial pathogens only at the DNA-level, precludes the consideration of transcriptional and translational regulatory events, and further studies are warranted to encompass these aspects.…”

“…The assemblies were assessed using Quast [ 35 ], and RAST was used for annotation [ 36 ]. emm -type and MLST-profiles were identified as previously outlined [ 26 ], and novel MLST alleles and profiles were submitted to pubMLST ( www.pubMLST.org ). SNP based phylogenetic analysis was performed [ 37 ], using Streptococcus dysgalactiae subspecies equisimilis ATCC 12394 (GenBank accession number CP002215) as a reference-genome.…”

Singularities of Pyogenic Streptococcal Biofilms – From Formation to Health Implication

“…The increased expression of coding genes was observed in strong biofilm-producing strains ( Genteluci et al, 2015 ). Oppegaard et al (2017) showed that genetic alterations in the pilus-region (also known as the FCT-region – Fibronectin and Collagen binding, and T-antigen) were associated with bacteria’s propensity to adhere to different surfaces, which could also be related to the expression of a wide range of adhesins putatively encoded in this region, including proteins predicted to adhere to collagen and fibronectin. Interestingly, although they are genomic closely related, the presence of fibrillary-like structures was not observed in SDSD strains.…”