Pathogens

Editorial

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8 pages, 237 KiB

Open AccessEditorial

Streptococcus suis Research: Progress and Challenges

by Mariela Segura

Pathogens 2020, 9(9), 707; https://doi.org/10.3390/pathogens9090707 - 27 Aug 2020

Cited by 35 | Viewed by 6921

Abstract

Streptococcus suis is considered among the top bacterial pathogens leading to important economic losses to the swine industry, with the incidence of disease increasing as the prophylactic use of antimicrobial is being vanished worldwide. S. suis is also a zoonotic agent afflicting people [...] Read more.

Streptococcus suis is considered among the top bacterial pathogens leading to important economic losses to the swine industry, with the incidence of disease increasing as the prophylactic use of antimicrobial is being vanished worldwide. S. suis is also a zoonotic agent afflicting people in close contact with infected pigs or pork meat. Besides, in some Asian countries, it is considered a major public health concern for the general population as well. Antimicrobial resistance is one of the most important global health challenges, and in the absence of preventive measures (such as effective vaccines), S. suis remains a risk for increased antimicrobial resistance and transmission of resistance genes to other bacteria beyond the host animal species. The studies in this Special Issue have evidenced the importance of swine population demographics and management on disease control, progress in molecular tools to better understand the epidemiology of S. suis infections in swine and humans, and the mechanisms involved in different aspects of the immuno-pathogenesis of the disease. The importance of reducing the prophylactic use of antimicrobials in livestock productions and the development of alternative control measures, including vaccination, are herein discussed. Full article

(This article belongs to the Special Issue Update on Streptococcus suis Research and Prevention in the Era of Antibiotic Restriction - 4th International Workshop on Streptococcus suis)

Research

Jump to: Editorial, Review, Other

15 pages, 2841 KiB

Open AccessArticle

Streptococcus suis Uptakes Carbohydrate Source from Host Glycoproteins by N-glycans Degradation System for Optimal Survival and Full Virulence during Infection

by Jiale Ma, Ze Zhang, Zihao Pan, Qiankun Bai, Xiaojun Zhong, Yinchu Zhu, Yue Zhang, Zongfu Wu, Guangjin Liu and Huochun Yao

Pathogens 2020, 9(5), 387; https://doi.org/10.3390/pathogens9050387 - 18 May 2020

Cited by 4 | Viewed by 2927

Abstract

Infection with the epidemic virulent strain of Streptococcus suis serotype 2 (SS2) can cause septicemia in swine and humans, leading to pneumonia, meningitis and even cytokine storm of Streptococcal toxic shock-like syndrome. Despite some progress concerning the contribution of bacterial adhesion, biofilm, toxicity [...] Read more.

Infection with the epidemic virulent strain of Streptococcus suis serotype 2 (SS2) can cause septicemia in swine and humans, leading to pneumonia, meningitis and even cytokine storm of Streptococcal toxic shock-like syndrome. Despite some progress concerning the contribution of bacterial adhesion, biofilm, toxicity and stress response to the SS2 systemic infection, the precise mechanism underlying bacterial survival and growth within the host bloodstream remains elusive. Here, we reported the SS2 virulent strains with a more than 20 kb endoSS-related insertion region that showed significantly higher proliferative ability in swine serum than low-virulent strains. Further study identified a complete N-glycans degradation system encoded within this insertion region, and found that both GH92 and EndoSS contribute to bacterial virulence, but that only DndoSS was required for optimal growth of SS2 in host serum. The supplement of hydrolyzed high-mannose-containing glycoprotein by GH92 and EndoSS could completely restore the growth deficiency of endoSS deletion mutant in swine serum. EndoSS only hydrolyzed a part of the model glycoprotein RNase B with high-mannose N-linked glycoforms into a low molecular weight form, and the solo activity of GH92 could not show any changes comparing with the blank control in SDS-PAGE gel. However, complete hydrolyzation was observed under the co-incubation of EndoSS and GH92, suggesting GH92 may degrade the high-mannose arms of N-glycans to generate a substrate for EndoSS. In summary, these findings provide compelling evidences that EndoSS-related N-glycans degradation system may enable SS2 to adapt to host serum-specific availability of carbon sources from glycoforms, and be required for optimal colonization and full virulence during systemic infection. Full article

(This article belongs to the Special Issue Update on Streptococcus suis Research and Prevention in the Era of Antibiotic Restriction - 4th International Workshop on Streptococcus suis)

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16 pages, 5132 KiB

Open AccessArticle

Examining the Effect of Host Recruitment Rates on the Transmission of Streptococcus suis in Nursery Swine Populations

by Elissa Giang, Benjamin M. Hetman, Jan M. Sargeant, Zvonimir Poljak and Amy L. Greer

Pathogens 2020, 9(3), 174; https://doi.org/10.3390/pathogens9030174 - 01 Mar 2020

Cited by 6 | Viewed by 3836

Abstract

Streptococcus suis is a swine pathogen that is capable of causing severe outbreaks of disease in the nursery. Demographic parameters such as host recruitment rates can have profound effects on the transmission dynamics of infectious diseases and, thus, are critically important in high-turnover [...] Read more.

Streptococcus suis is a swine pathogen that is capable of causing severe outbreaks of disease in the nursery. Demographic parameters such as host recruitment rates can have profound effects on the transmission dynamics of infectious diseases and, thus, are critically important in high-turnover populations such as farmed swine. However, knowledge concerning the implications that such parameters have on S. suis disease control remains unknown. A stochastic mathematical model incorporating sub-clinically infected pigs was developed to capture the effects of changes in host recruitment rate on disease incidence. Compared to our base model scenario, our results show that monthly introduction of pigs into the nursery (instead of weekly introduction) reduced cumulative cases of S. suis by up to 59%, while increasing disease-removal rates alone averted up to 64% of cases. Sensitivity analysis demonstrated that the course of infection in sub-clinically infected pigs was highly influential and generated significant variability in the model outcomes. Our model findings suggest that modifications to host recruitment rates could be leveraged as a tool for S. suis disease control, however improving our understanding of additional factors that influence the risk of transmission would improve the precision of the model estimates. Full article

(This article belongs to the Special Issue Update on Streptococcus suis Research and Prevention in the Era of Antibiotic Restriction - 4th International Workshop on Streptococcus suis)

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20 pages, 3561 KiB

Open AccessEditor’s ChoiceArticle

Recognition of Lipoproteins by Toll-like Receptor 2 and DNA by the AIM2 Inflammasome Is Responsible for Production of Interleukin-1β by Virulent Suilysin-Negative Streptococcus suis Serotype 2

by Agustina Lavagna, Jean-Philippe Auger, Stephen E. Giradin, Nicolas Gisch, Mariela Segura and Marcelo Gottschalk

Pathogens 2020, 9(2), 147; https://doi.org/10.3390/pathogens9020147 - 21 Feb 2020

Cited by 10 | Viewed by 3056

Abstract

Streptococcus suis serotype 2 is an important porcine bacterial pathogen and zoonotic agent causing sudden death, septic shock and meningitis. These pathologies are the consequence of an exacerbated inflammatory response composed of various mediators including interleukin (IL)-1β. Elevated levels of the toxin suilysin [...] Read more.

Streptococcus suis serotype 2 is an important porcine bacterial pathogen and zoonotic agent causing sudden death, septic shock and meningitis. These pathologies are the consequence of an exacerbated inflammatory response composed of various mediators including interleukin (IL)-1β. Elevated levels of the toxin suilysin (SLY) were demonstrated to play a key role in S. suis-induced IL-1β production. However, 95% of serotype 2 strains isolated from diseased pigs in North America, many of which are virulent, do not produce SLY. In this study, we demonstrated that SLY-negative S. suis induces elevated levels of IL-1β in systemic organs, with dendritic cells contributing to this production. SLY-negative S. suis-induced IL-1β production requires MyD88 and TLR2 following recognition of lipoproteins. However, the higher internalization rate of the SLY-negative strain results in intracellularly located DNA being recognized by the AIM2 inflammasome, which promotes IL-1β production. Finally, the role of IL-1 in host survival during the S. suis systemic infection is beneficial and conserved, regardless of SLY production, via modulation of the inflammation required to control bacterial burden. In conclusion, this study demonstrates that SLY is not required for S. suis-induced IL-1β production. Full article

(This article belongs to the Special Issue Update on Streptococcus suis Research and Prevention in the Era of Antibiotic Restriction - 4th International Workshop on Streptococcus suis)

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8 pages, 779 KiB

Open AccessArticle

Genotypic Comparison between Streptococcus suis Isolated from Pigs and Humans in Thailand

by Anusak Kerdsin, Dan Takeuchi, Aniroot Nuangmek, Yukihiro Akeda, Marcelo Gottschalk and Kazunori Oishi

Pathogens 2020, 9(1), 50; https://doi.org/10.3390/pathogens9010050 - 09 Jan 2020

Cited by 30 | Viewed by 4130

Abstract

Streptococcus suis is a zoonotic pathogen of economic significance to the swine industry. The number of infected cases is increasing in humans worldwide. In this study, we determined the prevalence and diversity of S. suis carriage in slaughterhouse pigs in Phayao province, Thailand, [...] Read more.

Streptococcus suis is a zoonotic pathogen of economic significance to the swine industry. The number of infected cases is increasing in humans worldwide. In this study, we determined the prevalence and diversity of S. suis carriage in slaughterhouse pigs in Phayao province, Thailand, where an outbreak occurred in 2007. The overall S. suis carriage rate was 35.2% among slaughterhouse pigs. The prevalence rates of serotypes 2 and 14 (the major serotypes infected in humans) were 6.7% and 2.6%, respectively. In both serotypes, 70.4% of isolates of serotypes 2 and 14 revealed sequence types and pulsotypes identical to human isolates in Thailand. It is suggested that pathogenic strains of S. suis are a risk factor for occupational exposure to pigs or the consumption of raw pork products. Food safety, hygiene, and health education should be encouraged to reduce the risk group. Full article

(This article belongs to the Special Issue Update on Streptococcus suis Research and Prevention in the Era of Antibiotic Restriction - 4th International Workshop on Streptococcus suis)

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13 pages, 954 KiB

Open AccessArticle

A Case-Control Study to Investigate the Serotypes of S. suis Isolates by Multiplex PCR in Nursery Pigs in Ontario, Canada

by Leann C. Denich, Abdolvahab Farzan, Robert Friendship, Emily Arndt, Marcelo Gottschalk and Zvonimir Poljak

Pathogens 2020, 9(1), 44; https://doi.org/10.3390/pathogens9010044 - 05 Jan 2020

Cited by 11 | Viewed by 2661

Abstract

Streptococcus suis naturally inhabits the tonsils and nasal cavities of pigs. Some strains can cause systemic infection, leading to a wide range of diseases. A case-control study was conducted to (i) examine serotypes isolated from systemic sites (blood/meninges/spleen) in cases, (ii) determine whether [...] Read more.

Streptococcus suis naturally inhabits the tonsils and nasal cavities of pigs. Some strains can cause systemic infection, leading to a wide range of diseases. A case-control study was conducted to (i) examine serotypes isolated from systemic sites (blood/meninges/spleen) in cases, (ii) determine whether serotypes in systemic sites were found in upper respiratory sites (tonsil/nasal cavity) of the same cases, and (iii) determine the serotypes in upper respiratory sites of case and farm and pen- matched controls. In total, 606 samples from 128 pigs were cultured for S. suis. The isolates were examined for presence of gdh and recN genes by polymerase chain reaction (PCR) and were identified as S. suis if both genes were present. The S. suis isolates were then serotyped using a two step-multiplex PCR. Serotypes 9 (n = 9), (2,1/2) (n = 7) and untypable isolates (n = 7) were most commonly found in systemic sites. Detection of serotypes 9 (p = 0.03) in upper respiratory sites were positively associated with their detection in systemic sites of cases, while a trend was seen with serotype (2,1/2) (p = 0.07). Last, no association between serotypes recovered from upper respiratory sites of cases and controls could be detected. Untypable isolates were detected in high frequency, which warrants further investigation. This study confirms that a variety of serotypes can be found in commercial swine production and shows a difference in serotypes recovered from systemic sites in pigs with clinical signs of S. suis infections. Full article

(This article belongs to the Special Issue Update on Streptococcus suis Research and Prevention in the Era of Antibiotic Restriction - 4th International Workshop on Streptococcus suis)

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17 pages, 1925 KiB

Open AccessEditor’s ChoiceArticle

Analysis of Porcine Pro- and Anti-Inflammatory Cytokine Induction by S. suis In Vivo and In Vitro

by Florian S. Hohnstein, Marita Meurer, Nicole de Buhr, Maren von Köckritz-Blickwede, Christoph G. Baums, Gottfried Alber and Nicole Schütze

Pathogens 2020, 9(1), 40; https://doi.org/10.3390/pathogens9010040 - 03 Jan 2020

Cited by 14 | Viewed by 4368

Abstract

Weaning piglets are susceptible to the invasive Streptococcus (S.) suis infection, which can result in septicemia. The aim of this study was to investigate the cytokine profile induced upon S. suis infection of blood, to determine the cellular sources of those cytokines, and [...] Read more.

Weaning piglets are susceptible to the invasive Streptococcus (S.) suis infection, which can result in septicemia. The aim of this study was to investigate the cytokine profile induced upon S. suis infection of blood, to determine the cellular sources of those cytokines, and to study the potential effects of the induced cytokines on bacterial killing. We measured TNF-α, IL-6, IFN-γ, IL-17A and IL-10 after an experimental intravenous infection with S. suis serotype 2 in vivo, and analyzed whole blood, peripheral blood mononuclear cells (PBMC) and separated leukocytes to identify the cytokine-producing cell type(s). In addition, we used a reconstituted whole blood assay to investigate the effect of TNF-α on bacterial killing in the presence of different S. suis-specific IgG levels. An increase in IL-6 and IL-10, but not in IFN-γ or IL-17A, was observed in two of three piglets with pronounced bacteremia 16 to 20 h after infection, but not in piglets with controlled bacteremia. Our results confirmed previous findings that S. suis induces TNF-α and IL-6 and could demonstrate that TNF-α is produced by monocytes in vitro. We further found that IL-10 induction resulted in reduced secretion of TNF-α and IL-6. Rapid induction of TNF-α was, however, not crucial for in vitro bacterial killing, not even in the absence of specific IgG. Full article

(This article belongs to the Special Issue Update on Streptococcus suis Research and Prevention in the Era of Antibiotic Restriction - 4th International Workshop on Streptococcus suis)

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19 pages, 2039 KiB

Open AccessEditor’s ChoiceArticle

Membrane Binding, Cellular Cholesterol Content and Resealing Capacity Contribute to Epithelial Cell Damage Induced by Suilysin of Streptococcus suis

by Désirée Vötsch, Maren Willenborg, Walter M.R. Oelemann, Graham Brogden and Peter Valentin-Weigand

Pathogens 2020, 9(1), 33; https://doi.org/10.3390/pathogens9010033 - 30 Dec 2019

Cited by 7 | Viewed by 2744

Abstract

Streptococcus (S.) suis is a major cause of economic losses in the pig industry worldwide and is an emerging zoonotic pathogen. One important virulence-associated factor is suilysin (SLY), a toxin that belongs to the family of cholesterol-dependent pore-forming cytolysins (CDC). However, [...] Read more.

Streptococcus (S.) suis is a major cause of economic losses in the pig industry worldwide and is an emerging zoonotic pathogen. One important virulence-associated factor is suilysin (SLY), a toxin that belongs to the family of cholesterol-dependent pore-forming cytolysins (CDC). However, the precise role of SLY in host–pathogen interactions is still unclear. Here, we investigated the susceptibility of different respiratory epithelial cells to SLY, including immortalized cell lines (HEp-2 and NPTr cells), which are frequently used in in vitro studies on S. suis virulence mechanisms, as well as primary porcine respiratory cells, which represent the first line of barrier during S. suis infections. SLY-induced cell damage was determined by measuring the release of lactate dehydrogenase after infection with a virulent S. suis serotype 2 strain, its isogenic SLY-deficient mutant strain, or treatment with the recombinant protein. HEp-2 cells were most susceptible, whereas primary epithelial cells were hardly affected by the toxin. This prompted us to study possible explanations for these differences. We first investigated the binding capacity of SLY using flow cytometry analysis. Since binding and pore-formation of CDC is dependent on the membrane composition, we also determined the cellular cholesterol content of the different cell types using TLC and HPLC. Finally, we examined the ability of those cells to reseal SLY-induced pores using flow cytometry analysis. Our results indicated that the amount of membrane-bound SLY, the cholesterol content of the cells, as well as their resealing capacity all affect the susceptibility of the different cells regarding the effects of SLY. These findings underline the differences of in vitro pathogenicity models and may further help to dissect the biological role of SLY during S. suis infections. Full article

(This article belongs to the Special Issue Update on Streptococcus suis Research and Prevention in the Era of Antibiotic Restriction - 4th International Workshop on Streptococcus suis)

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15 pages, 2505 KiB

Open AccessArticle

Streptococcus suis in Brazil: Genotypic, Virulence, and Resistance Profiling of Strains Isolated from Pigs between 2001 and 2016

by Carlos E. C. Matajira, Luisa Z. Moreno, Andre P. Poor, Vasco T. M. Gomes, Andressa C. Dalmutt, Beatriz M. Parra, Carolina H. de Oliveira, Mikaela R. F. Barbosa, Maria Inês Z. Sato, Franco F. Calderaro and Andrea M. Moreno

Pathogens 2020, 9(1), 31; https://doi.org/10.3390/pathogens9010031 - 28 Dec 2019

Cited by 16 | Viewed by 3028

Abstract

Streptococcus suis remains an important challenge for the worldwide swine industry. Considering that Brazil is a major pork producer and exporter, proper monitoring of the pathogen and resistance rates are required. We present here the characterization of Brazilian S. suis strains isolated over [...] Read more.

Streptococcus suis remains an important challenge for the worldwide swine industry. Considering that Brazil is a major pork producer and exporter, proper monitoring of the pathogen and resistance rates are required. We present here the characterization of Brazilian S. suis strains isolated over a 15 year period by pulsed-field gel electrophoresis (PFGE) typing, capsular, virulence, and antimicrobial resistance profiling. Serotype prevalence revealed a predominance of serotype 2/½ followed by 3, 7, 1/14, 6, 8, 18, 28, and 27; the latter had not yet been reported in Brazil. Resistance profiling enabled the differentiation of nine profiles presenting resistance to three and up to eight antimicrobial classes. Even though an association between the most resistant strains and isolation year starting from 2009 was observed, a high frequency of multidrug-resistant strains isolated from 2001 to 2003 was also detected. This suggests that despite the isolation period, S. suis strains already presented high resistance selection pressure. A slight association of serotype 2/½ with some virulence profiles and PFGE pulsotypes was also identified. Nevertheless, no clonal dispersion or persistency of clones over the analyzed years and herds was detected. Full article

(This article belongs to the Special Issue Update on Streptococcus suis Research and Prevention in the Era of Antibiotic Restriction - 4th International Workshop on Streptococcus suis)

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23 pages, 5544 KiB

Open AccessEditor’s ChoiceArticle

Chromosomal Conjugative and Mobilizable Elements in Streptococcus suis: Major Actors in the Spreading of Antimicrobial Resistance and Bacteriocin Synthesis Genes

by Virginie Libante, Yves Nombre, Charles Coluzzi, Johan Staub, Gérard Guédon, Marcelo Gottschalk, Sarah Teatero, Nahuel Fittipaldi, Nathalie Leblond-Bourget and Sophie Payot

Pathogens 2020, 9(1), 22; https://doi.org/10.3390/pathogens9010022 - 25 Dec 2019

Cited by 26 | Viewed by 4599

Abstract

Streptococcus suis is a zoonotic pathogen suspected to be a reservoir of antimicrobial resistance (AMR) genes. The genomes of 214 strains of 27 serotypes were screened for AMR genes and chromosomal Mobile Genetic Elements (MGEs), in particular Integrative Conjugative Elements (ICEs) and Integrative [...] Read more.

Streptococcus suis is a zoonotic pathogen suspected to be a reservoir of antimicrobial resistance (AMR) genes. The genomes of 214 strains of 27 serotypes were screened for AMR genes and chromosomal Mobile Genetic Elements (MGEs), in particular Integrative Conjugative Elements (ICEs) and Integrative Mobilizable Elements (IMEs). The functionality of two ICEs that host IMEs carrying AMR genes was investigated by excision tests and conjugation experiments. In silico search revealed 416 ICE-related and 457 IME-related elements. These MGEs exhibit an impressive diversity and plasticity with tandem accretions, integration of ICEs or IMEs inside ICEs and recombination between the elements. All of the detected 393 AMR genes are carried by MGEs. As previously described, ICEs are major vehicles of AMR genes in S. suis. Tn5252-related ICEs also appear to carry bacteriocin clusters. Furthermore, whereas the association of IME-AMR genes has never been described in S. suis, we found that most AMR genes are actually carried by IMEs. The autonomous transfer of an ICE to another bacterial species (Streptococcus thermophilus)—leading to the cis-mobilization of an IME carrying tet(O)—was obtained. These results show that besides ICEs, IMEs likely play a major role in the dissemination of AMR genes in S. suis. Full article

(This article belongs to the Special Issue Update on Streptococcus suis Research and Prevention in the Era of Antibiotic Restriction - 4th International Workshop on Streptococcus suis)

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12 pages, 1474 KiB

Open AccessArticle

Bactericidal Effect of Clove Oil against Multidrug-Resistant Streptococcus suis Isolated from Human Patients and Slaughtered Pigs

by Kanruethai Wongsawan, Wasana Chaisri, Sahatchai Tangtrongsup and Raktham Mektrirat

Pathogens 2020, 9(1), 14; https://doi.org/10.3390/pathogens9010014 - 21 Dec 2019

Cited by 26 | Viewed by 7207

Abstract

Streptococcus suis is a zoonotic pathogen that is currently considered an emerging multidrug-resistant (MDR). Increasing antibiotic resistance can lead to the unsuccessful treatment of S. suis infection. Recently, many investigations of medicinal plants were conducted for the treatment of infection as a result [...] Read more.

Streptococcus suis is a zoonotic pathogen that is currently considered an emerging multidrug-resistant (MDR). Increasing antibiotic resistance can lead to the unsuccessful treatment of S. suis infection. Recently, many investigations of medicinal plants were conducted for the treatment of infection as a result of the increase of antibiotic-resistant bacteria. The aims of this study were to determine the chemical composition of essential oil from Syzygium aromaticum (L.) Merr. & L.M. Perry and the antibacterial activities of clove oil on MDR S. suis. Using gas chromatography coupled to a mass spectrometer, eugenol (97.76%) was found to be the major active ingredient of clove oil. In vitro antibacterial activities of clove oil against MDR S. suis were evaluated. Using the agar disc diffusion test, the clove oil showed a maximum zone of inhibition at 15% (v/v) oil concentration. In a broth microdilution method, the minimum bactericidal concentration of clove oil against all MDR S. suis isolates was 0.1% (v/v). A time-kill analysis was performed, and the killing kinetics of clove oil showed that MDR S. suis was completely reduced after 15 min of exposure to clove oil. In addition, clove oil exhibited a strong antibacterial activity at all pH values applied following incubation of MDR S. suis in pH-adjusted media with clove oil. Moreover, scanning electron microscopy revealed the nonviable S. suis isolates clearly showed atypical form and cell membrane lysis after incubation with clove oil. This study confirms the efficacy of clove oil as a natural antimicrobial against MDR S. suis and suggests the possibility of employing it as a promising alternative product for control of infectious diseases caused by S. suis in animal and human patients. Full article

(This article belongs to the Special Issue Update on Streptococcus suis Research and Prevention in the Era of Antibiotic Restriction - 4th International Workshop on Streptococcus suis)

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9 pages, 1863 KiB

Open AccessArticle

The Impact of SsPI-1 Deletion on Streptococcus suis Virulence

by Yan Zhao, Gang Li, Xin-Yue Yao, Shu-Guang Lu, Jing Wang, Xiao-Dong Shen and Ming Li

Pathogens 2019, 8(4), 287; https://doi.org/10.3390/pathogens8040287 - 06 Dec 2019

Cited by 3 | Viewed by 2563

Abstract

(1) Background: Streptococcus suis is an important zoonotic pathogen that infects pigs and can occasionally cause life-threatening systemic infections in humans. Two large-scale outbreaks of streptococcal toxic shock-like syndrome in China suggest that the pathogenicity of S. suis has been changing in recent [...] Read more.

(1) Background: Streptococcus suis is an important zoonotic pathogen that infects pigs and can occasionally cause life-threatening systemic infections in humans. Two large-scale outbreaks of streptococcal toxic shock-like syndrome in China suggest that the pathogenicity of S. suis has been changing in recent years. Genetic analysis revealed the presence of a chromosomal pathogenicity island (PAI) designated SsPI-1 in Chinese epidemic S. suis strains. The purpose of this study is to define the role of SsPI-1 in the virulence of S. suis. (2) Methods: A SsPI-1 deletion mutant was compared to the wild-type strain regarding the ability to attach to epithelial cells, to cause host disease and mortality, and to stimulate host immune response in experimental infection of piglets. (3) Results: Deletion of SsPI-1 significantly reduces adherence of S. suis to epithelial cells and abolishes the lethality of the wild-type strain in piglets. The SsPI-1 mutant causes no significant pathological lesions and exhibits an impaired ability to induce proinflammatory cytokine production. (4) Conclusions: Deletion of the SsPI-1 PAI attenuates the virulence of this pathogen. We conclude that SsPI-1 is a critical contributor to the evolution of virulence in epidemic S. suis. Full article

(This article belongs to the Special Issue Update on Streptococcus suis Research and Prevention in the Era of Antibiotic Restriction - 4th International Workshop on Streptococcus suis)

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23 pages, 36962 KiB

Open AccessArticle

From Stable to Lab—Investigating Key Factors for Sudden Deaths Caused by Streptococcus suis

by Isabel Hennig-Pauka, Rabea Imker, Leonie Mayer, Michael Brügmann, Christiane Werckenthin, Heike Weber, Andrea Menrath and Nicole de Buhr

Pathogens 2019, 8(4), 249; https://doi.org/10.3390/pathogens8040249 - 20 Nov 2019

Cited by 9 | Viewed by 4071

Abstract

Swine stocks are endemically infected with the major porcine pathogen Streptococcus (S.) suis. The factors governing the transition from colonizing S. suis residing in the tonsils and the exacerbation of disease have not yet been elucidated. We analyzed the sudden [...] Read more.

Swine stocks are endemically infected with the major porcine pathogen Streptococcus (S.) suis. The factors governing the transition from colonizing S. suis residing in the tonsils and the exacerbation of disease have not yet been elucidated. We analyzed the sudden death of fattening pigs kept under extensive husbandry conditions in a zoo. The animals died suddenly of septic shock and showed disseminated intravascular coagulopathy. Genotypic and phenotypic characterizations of the isolated S. suis strains, a tonsillar isolate and an invasive cps type 2 strain, were conducted. Isolated S. suis from dead pigs belonged to cps type 2 strain ST28, whereas one tonsillar S. suis isolate harvested from a healthy animal belonged to ST1173. Neither S. suis growth, induction of neutrophil extracellular traps, nor survival in blood could explain the sudden deaths. Reconstituted blood assays with serum samples from pigs of different age groups from the zoo stock suggested varying protection of individuals against pathogenic cps type 2 strains especially in younger pigs. These findings highlight the benefit of further characterization of the causative strains in each case by sequence typing before autologous vaccine candidate selection. Full article

(This article belongs to the Special Issue Update on Streptococcus suis Research and Prevention in the Era of Antibiotic Restriction - 4th International Workshop on Streptococcus suis)

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17 pages, 2478 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Genomic Epidemiology of Streptococcus suis Sequence Type 7 Sporadic Infections in the Guangxi Zhuang Autonomous Region of China

by Mingliu Wang, Pengcheng Du, Jianping Wang, Ruiting Lan, Jun Huang, Ming Luo, Yan Jiang, Jun Zeng, Yi Quan, Zhaohui Shi and Han Zheng

Pathogens 2019, 8(4), 187; https://doi.org/10.3390/pathogens8040187 - 12 Oct 2019

Cited by 16 | Viewed by 3582

Abstract

Streptococcus suis is an important zoonotic pathogen. Serotype 2 and sequence type (ST) 1 are the most frequently reported strains in both infected humans and pigs. ST7 is only endemic to China, and it was responsible for outbreaks in 1998 and 2005 in [...] Read more.

Streptococcus suis is an important zoonotic pathogen. Serotype 2 and sequence type (ST) 1 are the most frequently reported strains in both infected humans and pigs. ST7 is only endemic to China, and it was responsible for outbreaks in 1998 and 2005 in China. In the present study, 38 sporadic ST7 S. suis strains, which mostly caused sepsis, were collected from patients in the Guangxi Zhuang Autonomous Region (GX) between 2007 and 2018. Of 38 sporadic ST7 strains, serotype 14 was the most frequent (27 strains, 71.1%), followed by serotype 2 (11 strains, 28.9%). The phylogenetic structure of the ST7 population, including epidemic and sporadic ST7 strains, was constructed using mutational single-nucleotide polymorphisms (SNPs). High diversity within the ST7 population was revealed and divided into five lineages. Only one sporadic ST7 strain, GX14, from a Streptococcal toxic-shock-like syndrome (STSLS) patient was clustered into the same lineage as the epidemic strains. GX14 and the epidemic strains diverged in 1974. The sporadic ST7 strains of GX were mainly clustered into lineage 5, which emerged in 1980. Comparing to genome of epidemic strain, the major differences in genome of sporadic ST7 strains of GX was the absence of 89 kb pathogenicity island (PAI) specific to epidemic strain and insertion of 128 kb ICE_phage tandem MGE or ICE portion of the MGE. These mobile elements play a significant role in the horizontal transfer of antibiotic resistance genes in sporadic ST7 strains. Our results enhanced the understanding of the evolution of the ST7 strains and their ability to cause life-threatening infections in humans. Full article

(This article belongs to the Special Issue Update on Streptococcus suis Research and Prevention in the Era of Antibiotic Restriction - 4th International Workshop on Streptococcus suis)

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20 pages, 3950 KiB

Open AccessArticle

Characterization and Protective Activity of Monoclonal Antibodies Directed against Streptococcus suis Serotype 2 Capsular Polysaccharide Obtained Using a Glycoconjugate

by Guillaume Goyette-Desjardins, Sonia Lacouture, Jean-Philippe Auger, René Roy, Marcelo Gottschalk and Mariela Segura

Pathogens 2019, 8(3), 139; https://doi.org/10.3390/pathogens8030139 - 07 Sep 2019

Cited by 10 | Viewed by 4291

Abstract

Streptococcus suis serotype 2 is an encapsulated bacterium and an important swine pathogen. Opsonizing antibody responses targeting capsular polysaccharides (CPSs) are protective against extracellular pathogens. To elucidate the protective activity of monoclonal antibodies (mAbs) directed against S. suis serotype 2 CPS, mice were [...] Read more.

Streptococcus suis serotype 2 is an encapsulated bacterium and an important swine pathogen. Opsonizing antibody responses targeting capsular polysaccharides (CPSs) are protective against extracellular pathogens. To elucidate the protective activity of monoclonal antibodies (mAbs) directed against S. suis serotype 2 CPS, mice were immunized with a serotype 2 CPS-glycoconjugate and three hybridomas were isolated; of which, two were murine IgMs and the other a murine IgG1. Whereas the IgMs (mAbs 9E7 and 13C8) showed different reactivity levels with S. suis serotypes 1, 1/2, 2 and 14, the IgG1 (mAb 16H11) was shown to be serotype 2-specific. All mAbs targeted the sialylated chain of the CPSs. Using an opsonophagocytosis assay, the IgMs were opsonizing towards the S. suis serotypes to which they cross-react, while the IgG1 failed to induce bacterial elimination. In a model of mouse passive immunization followed by a lethal challenge with S. suis serotype 2, the IgG1 and IgM cross-reacting only with serotype 14 (mAb 13C8) failed to protect, while the IgM cross-reacting with serotypes 1, 1/2, and 14 (mAb 9E7) was shown to be protective by limiting bacteremia. These new mAbs show promise as new S. suis diagnostic tools, as well as potential for therapeutic applications. Full article

(This article belongs to the Special Issue Update on Streptococcus suis Research and Prevention in the Era of Antibiotic Restriction - 4th International Workshop on Streptococcus suis)

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Review

Jump to: Editorial, Research, Other

10 pages, 1173 KiB

Open AccessReview

Tools for Molecular Epidemiology of Streptococcus suis

by Rujirat Hatrongjit, Nahuel Fittipaldi, Marcelo Gottschalk and Anusak Kerdsin

Pathogens 2020, 9(2), 81; https://doi.org/10.3390/pathogens9020081 - 27 Jan 2020

Cited by 22 | Viewed by 4509

Abstract

Diseases caused by Streptococcus suis are a significant economic and welfare concern in pigs as well as in humans. Several molecular methods have been applied to investigate S. suis strain diversity and identify phylogenetic groups. Multilocus sequence typing (MLST), commonly used to differentiate [...] Read more.

Diseases caused by Streptococcus suis are a significant economic and welfare concern in pigs as well as in humans. Several molecular methods have been applied to investigate S. suis strain diversity and identify phylogenetic groups. Multilocus sequence typing (MLST), commonly used to differentiate between S. suis strains, has been instrumental in identifying that the species is genetically highly diverse. Recent advances in whole-genome analysis have resulted in schemes permitting the classification of S. suis populations as pathogenic or non-pathogenic, or disease-associated or non-disease associated. Here, we review these and other molecular approaches that can be used for surveillance, outbreak tracking, preventative health management, effective treatment and control, as well as vaccine development, including PCR based-assays that are easy to apply in modest diagnostic settings and which allow for the rapid screening of a large number of isolates at relatively low cost, granting the identification of several major clonal complexes of the S. suis population. Full article

(This article belongs to the Special Issue Update on Streptococcus suis Research and Prevention in the Era of Antibiotic Restriction - 4th International Workshop on Streptococcus suis)

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39 pages, 1846 KiB

Open AccessConference Report

Update on Streptococcus suis Research and Prevention in the Era of Antimicrobial Restriction: 4th International Workshop on S. suis

by Mariela Segura, Virginia Aragon, Susan L. Brockmeier, Connie Gebhart, Astrid de Greeff, Anusak Kerdsin, Mark A O’Dea, Masatoshi Okura, Mariette Saléry, Constance Schultsz, Peter Valentin-Weigand, Lucy A. Weinert, Jerry M. Wells and Marcelo Gottschalk

Pathogens 2020, 9(5), 374; https://doi.org/10.3390/pathogens9050374 - 14 May 2020

Cited by 69 | Viewed by 8405

Abstract

Streptococcus suis is a swine pathogen and a zoonotic agent afflicting people in close contact with infected pigs or pork meat. Sporadic cases of human infections have been reported worldwide. In addition, S. suis outbreaks emerged in Asia, making this bacterium a primary [...] Read more.

Streptococcus suis is a swine pathogen and a zoonotic agent afflicting people in close contact with infected pigs or pork meat. Sporadic cases of human infections have been reported worldwide. In addition, S. suis outbreaks emerged in Asia, making this bacterium a primary health concern in this part of the globe. In pigs, S. suis disease results in decreased performance and increased mortality, which have a significant economic impact on swine production worldwide. Facing the new regulations in preventive use of antimicrobials in livestock and lack of effective vaccines, control of S. suis infections is worrisome. Increasing and sharing of knowledge on this pathogen is of utmost importance. As such, the pathogenesis and epidemiology of the infection, antimicrobial resistance, progress on diagnosis, prevention, and control were among the topics discussed during the 4th International Workshop on Streptococcus suis (held in Montreal, Canada, June 2019). This review gathers together recent findings on this important pathogen from lectures performed by lead researchers from several countries including Australia, Canada, France, Germany, Japan, Spain, Thailand, The Netherlands, UK, and USA. Finally, policies and recommendations for the manufacture, quality control, and use of inactivated autogenous vaccines are addressed to advance this important field in veterinary medicine. Full article

(This article belongs to the Special Issue Update on Streptococcus suis Research and Prevention in the Era of Antibiotic Restriction - 4th International Workshop on Streptococcus suis)

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Update on Streptococcus suis Research and Prevention in the Era of Antibiotic Restriction - 4th International Workshop on Streptococcus suis

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