Genomic comparison of two Streptococcus suis serotype 1 strains recovered from porcine and human disease cases

Abstract

Streptococcus suis is a zoonotic pathogen that causes invasive infections in humans and pigs. Although S. suis serotype 2 strains are most prevalent worldwide, other serotypes are also occasionally detected. Herein, we investigated the genomes of two S. suis serotype 1 strains belonging to the clonal complex 1, which were recovered from a human patient and an asymptomatic pig, respectively. The genomes differed in pathotype, virulence-associated gene (VAG) profile, minimum core genome (MCG) typing, and antimicrobial resistance gene content. The porcine serotype 1 strain was sequence type (ST) 237 and MCG1, whereas the human serotype 1 strain was ST105 and MCG ungroupable. Both strains were susceptible to several antibiotics consisting of β-lactams, fluoroquinolones, and chloramphenicol. Resistance to tetracycline, macrolides, and clindamycin was observed, which was attributed to the genes tet(O) and erm(B). Analysis of 99 VAG revealed Hhly3, NisK, NisR, salK/salR, srtG, virB4, and virD4 were absent in both serotype 1. However, the porcine strain lacked sadP (Streptococcal adhesin P), whereas the human strain harbored sadP1. Phylogenetic analysis revealed that human S. suis ST105 strains from Vietnam were genetically the closest to the human serotype 1 strain, whereas porcine S. suis ST11 strains from China and Thailand were genetically the closest to the porcine strain.

Streptococcus suis serotype 4: a population with the potential pathogenicity in humans and pigs

“…Also, serotype Chz and 27 novel cps loci (NCLs) have been identified from non-typeable isolates based on differences in the cps gene cluster [ 8–13 ]. To date, 11 serotypes have been documented as capable of inducing human infections, consisting of serotypes 1, 2, 4, 5, 7, 9, 14, 16, 21, 24, and 31 [ 14 , 15 ].…”