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Background: The clindamycin-resistant erythromycin-susceptible (CRES) phenotype is rare in Streptococcus agalactiae (group B streptococci). We aimed to determine the molecular characteristics of CRES S. agalactiae using whole genome sequencing (WGS). Methods: Sixty-six S. agalactiae isolates obtained from blood (N = 26), cerebrospinal fluid (N = 10), urine (N = 17), and vaginal discharge (N = 13) between 2010 and 2017 in Korea were subjected to WGS. Based on the WGS data, we analyzed antimicrobial resistance (AMR) determinants, sequence types (STs), capsular polysaccharide (CPS) genotypes, and virulence gene profiles, and constructed a phylogenetic tree. We included the clindamycin-susceptible erythromycin-resistant (CSER) phenotype for comparison. Results: We identified seven CRES S. agalactiae isolates from urine (N = 5) and vaginal discharge (N = 2) collected between 2010 and 2011. All CRES isolates harbored AMR determinants of lnu(B), lsa(E), and aac(6')-aph(2''), revealed ST19 and CPS genotype III, and had a virulence gene profile of rib-lmb-cylE. Phylogenetic tree analysis revealed that all CRES isolates belonged to the same cluster, suggesting a clonal distribution. In contrast, seven CSER isolates showed a diverse distribution and clustered separately from the CRES isolates. Conclusions: CRES isolates collected between 2010 and 2011 showed a unique cluster with ST19 and CPS genotype III in Korea. This is the first report on WGS-based characteristics of S. agalactiae in Korea.

This study evaluated cell invasion ability (CIA) of Streptococcus canis isolates and clarified the relationship between high-frequency CIA and microbiological features. Of the companion animal-origin isolates (n = 117) in 2017, 40 isolates were randomly selected with the host information, and two human blood-origin isolates were included. We measured the CIA using human colon carcinoma epithelium and the hemolytic activity (HA) using sheep blood, along with S. canis M-like protein (SCM) allele typing, sequence type (ST) determination, and antimicrobial resistance (AMR) phenotyping/genotyping. CIA measurements revealed that 19 isolates were high-frequency and 24 isolates were low-frequency. The HA assessment revealed that 24 isolates were categorized as high-level and 19 isolates were low-level. There was no difference in the high/low-level HA between the high-frequency/low-frequency CIA populations. There was a significant difference in the high/low-frequency CIA between SCM group I/II populations. There was also significantly higher CIA in the SCM allele type 10/type 11 than in others. We found a significant association between high-frequency CIA and ST21/ST41 populations. There was no difference in the high/low-frequency CIA between the presence and absence of AMR phenotype/genotype. Our observations suggest a relationship between high-frequency CIA and its microbiological characteristics (SCM allele type 10/type 11 or ST21/ST41).

Background: Few studies have investigated the invasiveness of Streptococcus pyogenes based on whole-genome sequencing (WGS). Using WGS, we determined the genomic features associated with invasiveness of S. pyogenes strains in Korea.Methods: Forty-five S. pyogenes strains from 1997, 2006, and 2017, including common emm types, were selected from the repository at Gyeongsang National University Hospital in Korea. In addition, 48 S. pyogenes strains were randomly selected depending on their invasiveness between 1997 and 2017 to evaluate the genetic evolution and the associations between invasiveness and genetic profiles. Using WGS datasets, we conducted virulence-associated DNA sequence determination, emm genotyping, multi-locus sequence typing (MLST), and superantigen gene profiling.Results: In total, 87 strains were included in this study. There were no significant differences in the genomic features throughout the study periods. Four genes, csn1, ispE, nisK, and citC, were detected only in invasive strains. There was a significant association between invasiveness and emm cluster type A-C3, including, emm1.0, emm1.18, emm1.3, and emm1.76 (P < 0.05). The predominant emm1 lineage belonged to ST28. There were no associations between invasiveness and superantigen gene profiles.Conclusions: This is the first study using WGS datasets of S. pyogenes strains collected between 1997 and 2017 in Korea. Streptococcal invasiveness is associated with the presence of csn1, ispE, nisK, and citC. The emm1 lineage and ST28 clone are explicitly associated with invasiveness, whereas genomic features remained stable over the 20-year period.

We report the draft genome sequence of Pasteurella canis strain PA42, which was isolated from the blood of a diseased dog in Japan in 2021. The 2.151-Mbp genome has a G+C content of 36.6%. Sequences unmapped to the reference genome sequence of NCTC 11621 T (GenBank accession number UGTV00000000.1 ) were characterized.