Population structure, genetic diversity and pathotypes of Streptococcus suis isolated during the last 13 years from diseased pigs in Switzerland

Abstract

Streptococcus (S.) suis is a globally important swine pathogen, which comprises certain zoonotic serotypes. In this study, a detailed characterization of 88 porcine S. suis isolates was performed by analyzing capsular (cps) types, multilocus sequence typing (MLST) and investigation of the minimum core genome (MCG). In order to focus on the virulence potential of presumable invasive disease-associated S. suis isolates, virulence-associated gene profiles were assessed followed by screening a chosen subset of S. suis strains with a molecular pathotyping tool. Results showed a high genetic variability within this strain collection. In total, seventeen cps types were identified with a predominance of cps type 9 (15.9%) and 6 (14.8%). MLST revealed 48 sequence types (STs) including 41 novel ones. The population structure of S. suis was heterogenous and isolates belonged to eight different clonal complexes (CCs) including CC28 (9.1%), CC1109 (8%), CC13/149 (6.8%), CC1237 (5.7%), CC1 (3.4%), CC17 (3.4%), CC87 (2.3%), and CC1112 (1.1%), whereas a significant portion of isolates (60.2%) could not be assigned to any described CCs. Virulence-associated markers, namely extracellular protein factor (epf), muramidase-released protein (mrp), and suilysin (sly), showed a link with STs rather than with cps types. With this study an expanded knowledge about the population structure and the genetic diversity of S. suis could be achieved, which helps to contribute to an optimal public health surveillance system by promoting a focus on strains with an increased virulence and zoonotic potential.

Comparative virulence and antimicrobial resistance distribution of Streptococcus suis isolates obtained from the United States

“…4 This set contained 1690 unique profiles. Using previously reported stringency criteria, a clonal complex (CC) was defined as a group of STs comprised of at least six identical alleles and containing at least three STs (Single Locus Variant (SLV) clustering) ( Wang et al, 2015 ; Scherrer et al, 2020 ). STs that did not fall into any group were classified as singlets and STs that grouped with only one other ST were classified as doublets.…”

Mini Review: Clinical Routine Microbiology in the Era of Automation and Digital Health

“…We can today apply NGS to study the core and/or whole genome (Genomics; Figure 1) to infer any kind of molecular typing from MLST to vaccine antigens (Peŕez-Losada et al, 2018;Muzzi et al, 2019;Leo et al, 2020) and even study clonal relationships by investigating single nucleotide polymorphisms (SNPs) or genomic recombination events (Didelot and Wilson, 2015;Donner et al, 2020;Olearo et al, 2020;Pham et al, 2020;Scherrer et al, 2020).…”

Streptococcal autolysin promotes dysfunction of swine tracheal epithelium by interacting with vimentin

“…Streptococcus suis is a Gram-positive opportunistic bacterium that asymptomatically colonizes in the upper respiratory tract and is divided into 29 different serotypes based on capsular polysaccharide antigens [ 1 , 2 ]. S .…”

“…Streptococcus suis is a Gram-positive opportunistic bacterium that asymptomatically colonizes in the upper respiratory tract and is divided into 29 different serotypes based on capsular polysaccharide antigens [1,2]. S. suis serotype 2 (SS2) is the serotype with the highest clinical isolation rate and is regarded as one of the most virulent in pigs and humans [3,4].…”