Comparative genome analysis of Streptococcus suis serotype 5 strains from humans and pigs revealed pathogenic potential of virulent, antimicrobial resistance, and genetic relationship

Current prevalence and therapeutic strategies for porcine Streptococcus suis in China

Porcine Streptococcus suis is a zoonotic bacterial pathogen that poses serious threats to both human and animal health. S. suis is ubiquitously transmitted from the swine industry to the environments and human communities. However, the ambiguous epidemiological patterns and the escalating risk of antimicrobial resistance render S. suis infections a considerable challenge. Here, we review the current prevalence of S. suis infection worldwide, including identified bacterial strains, routes of infection, and transformation of resistance genes. This comprehensive overview of the prevalent patterns in S. suis offers detailed insights into therapeutic approaches for porcine infections and alternative strategies to address emerging resistant strains, highlighting potential multitarget prevention and treatment options to combat S. suis infection.

First WGS Characterization of Streptococcus suis Isolated From a Case of Human Meningitis in Southern Italy

This study is the first report in Italy on the molecular characterization by whole-genome sequencing (WGS) analysis of a Streptococcus suis strain isolated from a human case of meningitis in Italy. The characterized S. suis strain was classified as a serotype 2 (SS2), multilocus sequence typing (MLST) sequence type ST1. The strain exhibited the presence of several virulence genes and resistance to penicillin, tetracycline and macrolide-lincosamide-streptogramin. Finally, we found a frameshift mutation in the gene mrp determining the translation of two truncated forms of the corresponding muramidase-release protein. These results highlight the importance of complete genomic data to understand the pathogenesis and epidemiology of this bacterium, capable to pose serious risks to human health.

Genetic diversity and antimicrobial susceptibility of Streptococcus suis from diseased Swiss pigs collected between 2019 - 2022

Streptococcus suis is an important pathogen causing severe disease in pigs and humans, giving rise to economic losses in the pig production industry. Out of 65 S. suis isolates collected from diseased pigs in Switzerland between 2019 and 2022, 57 isolates were thoroughly examined by phenotypic and whole genome sequence (WGS) based characterization. The isolates' genomes were sequenced allowing for a comprehensive analysis of their distribution in terms of serovar, sequence type (ST), clonal complex (CC), and classical virulence markers. Antimicrobial resistance (AMR) genes were screened, and phenotypic susceptibility to eight classes of antimicrobial agents was examined. Serovar 6, devoid of any resistance genes, was found to be most prevalent, followed by serovars 1, 3, 1/2, and 9. Thirty STs were identified, with ST1104 being the most prevalent. Serovar 2 and serovar 1/2 were associated with CC1, potentially containing the most virulent variants. Based on single nucleotide polymorphism (SNP) analyses, fifteen isolates belonged to one of seven putative transmission clusters each consisting of two or three isolates. High phenotypic AMR rates were detected for tetracyclines (80%) and macrolides (35%) and associated with the resistance genes tet(O) and erm(B), respectively. In contrast, susceptibility to β-lactam antibiotics and phenicols was high. Determination of phenotypic AMR profiling, including the minimum inhibitory concentrations (MICs) of the tested antimicrobial agents, sets a baseline for future studies. The study provides valuable insights into the genetic diversity and antimicrobial susceptibility of Swiss S. suis isolates, facilitating the identification of emerging clones relevant to public health concerns.