erm (T)-Mediated Macrolide-Lincosamide Resistance in Streptococcus suis

Macrolide and lincosamide resistance due to the presence of erm (T) have posed a challenge for the treatment of Gram-positive pathogens. Because of the low detection rate of erm (T) gene among the S. suis population due to the fitness cost of the erm (T)-carrying plasmid and ICE, the presence of erm (T) in S. suis and its potential transmission to other Gram-positive pathogens will be of important significance.

XRE Family Transcriptional Regulator XtrSs Modulates Streptococcus Suis Fitness of Hydrogen Peroxide Stress

Streptococcus suis is an important emerging zoonosis that causes economic losses in the pig industry and severe threats to public health. Transcriptional regulators play essential roles in bacterial adaptation to host environments. In this study, we identified a novel XRE family transcriptional regulator in S. suis CZ130302, XtrSs, involved in the bacterial fitness to hydrogen peroxide stress. Based on electrophoretic mobility shift and β-galactosidase activity assays, we found that XtrSs autoregulated its own transcription and repressed the expression of its downstream gene psePs, a surface protein with unknown function in S. suis, by binding to a palindromic sequence from the promoter region. Furthermore, we proved that the deletion of the psePs gene attenuated bacterial antioxidant response. Phylogenetic analysis revealed that XtrSs and PsePs naturally co-existed as a combination in most S. suis genomes. Collectively, we demonstrated the binding characteristics of XtrSs in S. suis and provided a new insight that XtrSs played a critical role in modulating psePs to the hydrogen peroxide resistance of S. suis.

Genomic Characterization of Streptococcus suis Serotype 24 Clonal Complex 221/234 From Human Patients

Streptococcus suis is a zoonotic pathogen that causes invasive infections in humans and pigs. Although S. suis serotype 2 is prevalent among patient and swine infections, other serotypes are occasionally detected in humans. Of these, serotype 24 clonal complex (CC) 221/234 are recognized as emerging clones of human infection. Genomic exploration of three S. suis serotype 24 CC221/234 strains revealed antimicrobial resistance genes, pathotyping, virulence-associated gene (VAG) profiles, minimum core genome (MCG) typing, and comparison of the genomes. Based on these analyzes, all three serotype 24 strains were MCG7-3 and should be classified in the intermediate/weakly virulent (I/WV) group. All selected serotype 24 strains were susceptible to several antibiotics including β-lactam, fluoroquinolone, and chloramphenicol. Resistance to tetracycline, macrolide, and clindamycin was observed and attributed to the genes tet(O) and erm(B). Genomic comparison revealed the strains S12X, LSS66, LS0L, LS0E, 92–4,172, and IMT40201 that had phylogenetic affinity with serotype 24 CC221/234. Analysis of 80 virulence-associated genes (VAG) showed that all three serotype 24 strains lacked 24 genes consisting of adhesin P, epf, hyl, ihk, irr, mrp, nadR, neuB, NisK/R, ofs, permease (SSU0835), rgg, revS, salK/R, sao, sly, spyM3_0908, srtBCD, srtF, srtG, SSU05_0473, virA, virB4, and virD4. Eleven specific sequences were identified in the 3 serotype 24 genomes that differed from the genomes of the representative strains of epidemic (E; SC84), highly virulent (HV; P1/7), I/WV (89–1,591), and avirulent (T15 and 05HAS68).

Research Progress on the pathogenic mechanism of Streptococcus suis 2

Streptococcus suis (S.suis) is an important zoonotic pathogen that can cause many diseases in pigs, such as sepsis, arthritis, endocarditis, and meningitis, of which meningitis is the most serious. There are 35 serotypes, and serotype two is the most virulent. At the same time, Streptococcus suis serotype 2(SS2) can also infect humans, causing severe public health problems. Although SS2 has attracted significant attention worldwide, the research on its pathogenesis is still limited. The adhesion of pathogenic bacteria to the surface of host cells or tissues and its subsequent invasion and diffusion are the critical steps of pathogenic bacteria. Moreover, the interaction between pathogen and host is involved in these processes. Therefore, to study the pathogenic mechanism of pathogenic bacteria is to study the interaction between pathogenic bacteria and host. This paper described several common virulence factors, such as CPS, SLY, MRP, EF, SAO, Srt, FBPS, SadP, and Eno. Under the actions of virulence factors, SS2 adheres and colonizes to the mucosal and epithelial surface of host cells. Then SS2 invades into deeper tissues and bloodstream. If SS2 in the blood does not cause fatal sepsis, It can go to the third stage. The third stage is to cross the BBB and access the CNS and ultimately causes meningitis. During pathogenesis, SS2 interacts with multiple host cells, such as neutrophils, macrophages, epithelial cells, and microvascular endothelial cells to evade the innate or adaptive immunity of the host.

Predicción molecular de serotipos de Streptococcus suis aislados de granjas porcinas en México

Infections caused by Streptococcus suis (S. suis) pose a problem for the pig industry worldwide. Pigs often carry multiple serotypes of S. suis in the upper respiratory tract, where S. suis is frequently isolated from. The clinical diagnosis of the infection is presumptive and is generally based on clinical signs, the age of the animal and macroscopic lesions. In the laboratory, identification of S. suis is performed biochemically, and then, serotyping is performed with antisera to determine the serotype, but these tests can be inconclusive. To date, there are few studies that have documented the presence and diversity of S. suis serotypes in Mexico. In the present study, it was characterized S. suis strains from Mexican pig farms using molecular approaches; samples were first processed by PCR of the gdh gene to detect S. suis. Positive samples were then subjected to a two-step multiplex PCR (cps PCR) to detect and characterize each strain; the first step consisted of a grouping PCR and the second step consisted of a typing PCR. The serotypes detected in the pig farming areas of Mexico included 1/2, 2, 3, 5, 7, 8, 9, 17, and 23. These findings are important for the characterization of serotypes present in Mexico and for outbreak prevention.