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The Biology of Streptococcus and Streptococcal Infection

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A special issue of Pathogens (ISSN 2076-0817). This special issue belongs to the section "Bacterial Pathogens".

Deadline for manuscript submissions: closed (15 August 2023) | Viewed by 12487

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Special Issue Editor

Prof. Dr. James Leigh

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Guest Editor

School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Nottingham, Leicestershire, UK
Interests: streptococci; epidemiology; sequence variation; bacterial population

Special Issue Information

Dear Colleagues,

Streptococci are significant pathogens in humans, animals, and fish. Some show a high degree of host and disease specificity whilst others can cause a wide array of different pathologies in distinct hosts. Many streptococcal species, commonly considered pathogens, also co-exist in an asymptomatic carriage state with their host; while others, originally considered benign commensals, have now been associated with diseases such as endocarditis and colon cancer.

The investigation into the biology of streptococcus has a history of discovery across the wider fields of biology; it was research on streptococci which led to the discovery that DNA was the molecule of heredity and, in more recent years, led to the discovery of the CRISPR/Cas system. The investigation of streptococcal diseases offers the opportunity to investigate the fundamental processes of infection in an unprecedented array of host-pathogen combinations. For most of us, this will be specifically focused on understanding distinct individual processes, such as transmission, colonization, the avoidance of/resistance to host defenses, or the induction of pathology. For many years this has involved the investigation of individual genes and products in model systems, but the blossoming fields of genomics and bioinformatics now provide the opportunity to decipher this complex interplay at more holistic levels of the genome and/or population.

Prof. Dr. James Leigh
Guest Editor

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Keywords

pathogenesis
virulence
innate immunity
epidemiology
genomics

Published Papers (6 papers)

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Research

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18 pages, 3850 KiB

Open AccessArticle

Study of the Role of Lipoprotein Maturation Enzymes in the Pathogenesis of the Infection Caused by the Streptococcus suis Serotype 2 Sequence Type 25 North American Prototype Strain

by Servane Payen, David Roy, Masatoshi Okura, Mariela Segura and Marcelo Gottschalk

Pathogens 2023, 12(11), 1325; https://doi.org/10.3390/pathogens12111325 - 7 Nov 2023

Viewed by 1010

Abstract

Streptococcus suis serotype 2 is an important swine bacterial pathogen causing sudden death, septic shock, and meningitis. However, serotype 2 strains are phenotypically and genotypically heterogeneous and composed of a multitude of sequence types (STs) whose distributions greatly vary worldwide. It has been previously shown that the lipoprotein (LPP) maturation enzymes diacylglyceryl transferase (Lgt) and signal peptidase (Lsp) significantly modulate the inflammatory host response and play a differential role in virulence depending on the genetic background of the strain. Differently from Eurasian ST1/ST7 strains, the capsular polysaccharide of a North American S. suis serotype 2 ST25 representative strain only partially masks sub-capsular domains and bacterial wall components. Thus, our hypothesis is that since LPPs would be more surface exposed in ST25 strains than in their ST1 or ST7 counterparts, the maturation enzymes would play a more important role in the pathogenesis of the infection caused by the North American strain. Using isogenic Δlgt and Δlsp mutants derived from the wild-type ST25 strain, our studies suggest that these enzymes do not seem to play a role in the interaction between S. suis and epithelial and endothelial cells, regardless of the genetics background of the strain used. However, a role in the formation of biofilms (also independently of the STs) has been demonstrated. Moreover, the involvement of LPP dendritic cell activation in vitro seems to be somehow more pronounced with the ST25 strain. Finally, the Lgt enzyme seems to play a more important role in the virulence of the ST25 strain. Although some differences between STs could be observed, our original hypothesis that LPPs would be significantly more important in ST25 strains due to a better bacterial surface exposition could not be confirmed. Full article

(This article belongs to the Special Issue The Biology of Streptococcus and Streptococcal Infection)

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19 pages, 2241 KiB

Open AccessEditor’s ChoiceArticle

Interactions of Mycoplasma hyopneumoniae and/or Mycoplasma hyorhinis with Streptococcus suis Serotype 2 Using In Vitro Co-Infection Models with Swine Cells

by Héloïse Pageaut, Sonia Lacouture, Mélanie Lehoux, Corinne Marois-Créhan, Mariela Segura and Marcelo Gottschalk

Pathogens 2023, 12(7), 866; https://doi.org/10.3390/pathogens12070866 - 22 Jun 2023

Cited by 1 | Viewed by 1757

Abstract

Bacterial and/or viral co-infections are very common in swine production and cause severe economic losses. Mycoplasma hyopneumoniae, Mycoplasma hyorhinis and Streptococcus suis are pathogenic bacteria that may be found simultaneously in the respiratory tracts of pigs. In the present study, the interactions of S. suis with epithelial and phagocytic cells in the presence or absence of a pre-infection with M. hyopneumoniae and/or M. hyorhinis were studied. Results showed relatively limited interactions between these pathogens. A previous infection with one or both mycoplasmas did not influence the adhesion or invasion properties of S. suis in epithelial cells or its resistance to phagocytosis (including intracellular survival) by macrophages and dendritic cells. The most important effect observed during the co-infection was a clear increment in toxicity for the cells. An increase in the relative expression of the pro-inflammatory cytokines IL-6 and CXCL8 was also observed; however, this was the consequence of an additive effect due to the presence of different pathogens rather than a synergic effect. It may be hypothesized that if one or both mycoplasmas are present along with S. suis in the lower respiratory tract at the same time, then increased damage to epithelial cells and phagocytes, as well as an increased release of pro-inflammatory cytokines, may eventually enhance the invasive properties of S. suis. However, more studies should be carried out to confirm this hypothesis. Full article

(This article belongs to the Special Issue The Biology of Streptococcus and Streptococcal Infection)

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16 pages, 2696 KiB

Open AccessArticle

Molecular Mimicry Mapping in Streptococcus pneumoniae: Cues for Autoimmune Disorders and Implications for Immune Defense Activation

by Mutaib M. Mashraqi, Ahmad Alzamami, Norah A. Alturki, Saleh Alshamrani, Mousa M. Alshahrani, Hassan H. Almasoudi and Zarrin Basharat

Pathogens 2023, 12(7), 857; https://doi.org/10.3390/pathogens12070857 - 21 Jun 2023

Cited by 2 | Viewed by 1558

Abstract

Streptococcus pneumoniae contributes to a range of infections, including meningitis, pneumonia, otitis media, and sepsis. Infections by this bacterium have been associated with the phenomenon of molecular mimicry, which, in turn, may contribute to the induction of autoimmunity. In this study, we utilized a bioinformatics approach to investigate the potential for S. pneumoniae to incite autoimmunity via molecular mimicry. We identified 13 S. pneumoniae proteins that have significant sequence similarity to human proteins, with 11 of them linked to autoimmune disorders such as psoriasis, rheumatoid arthritis, and diabetes. Using in silico tools, we predicted the sequence as well as the structural homology among these proteins. Database mining was conducted to establish links between these proteins and autoimmune disorders. The antigenic, non-allergenic, and immunogenic sequence mimics were employed to design and validate an immune response via vaccine construct design. Mimic-based vaccine construct can prove effective for immunization against the S. pneumoniae infections. Immune response simulation and binding affinity was assessed through the docking of construct C8 to human leukocyte antigen (HLA) molecules and TLR4 receptor, with promising results. Additionally, these mimics were mapped as conserved regions on their respective proteins, suggesting their functional importance in S. pneumoniae pathogenesis. This study highlights the potential for S. pneumoniae to trigger autoimmunity via molecular mimicry and the possibility of vaccine design using these mimics for triggering defense response. Full article

(This article belongs to the Special Issue The Biology of Streptococcus and Streptococcal Infection)

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20 pages, 3741 KiB

Open AccessArticle

Epidemiological and Clinical Features of Streptococcus dysgalactiae ssp. equisimilis stG62647 and Other emm Types in Germany

by Andreas Itzek, Victoria Weißbach, David Meintrup, Beate Rieß, Mark van der Linden and Stefan Borgmann

Pathogens 2023, 12(4), 589; https://doi.org/10.3390/pathogens12040589 - 13 Apr 2023

Cited by 2 | Viewed by 1723

Abstract

(1) Background: Streptococcus dysgalactiae subspecies equisimilis (SDSE) is an important β-hemolytic pathogen historically described as mainly affecting animals. Studies epidemiologically assessing the pathogenicity in the human population in Germany are rare. (2) Methods: the present study combines national surveillance data from 2010 to 2022 with a single-center clinical study conducted from 2016 to 2022, focusing on emm type, Lancefield antigen, antimicrobial resistance, patient characteristics, disease severity, and clinical infection markers. (3) Results: The nationwide reported invasive SDSE infections suggest an increasing infection burden for the German population. One particular emm type, stG62647, increased over the study period, being the dominant type in both study cohorts, suggesting a mutation-driven outbreak of a virulent clone. The patient data show that men were more affected than women, although in the single-center cohort, this trend was reversed for patients with stG62647 SDSE. Men affected by stG62647 developed predominantly fascial infections, whereas women suffering from superficial and fascial non-stG62647 SDSE infections were significantly younger than other patients. Increasing age was a general risk factor for invasive SDSE infections. (4) Conclusions: further studies are needed to further elucidate the raised questions regarding outbreak origin, underlying molecular mechanisms as well as sex-dependent pathogen adaptation. Full article

(This article belongs to the Special Issue The Biology of Streptococcus and Streptococcal Infection)

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15 pages, 2789 KiB

Open AccessArticle

Enhanced Vulnerability of Diabetic Mice to Hypervirulent Streptococcus agalactiae ST-17 Infection

by Jéssica da Conceição Mendonça, João Matheus Sobral Pena, Noemi dos Santos Macêdo, Dayane de Souza Rodrigues, Dayane Alvarinho de Oliveira, Brady L. Spencer, Eduardo José Lopes-Torres, Lindsey R. Burcham, Kelly S. Doran and Prescilla Emy Nagao

Pathogens 2023, 12(4), 580; https://doi.org/10.3390/pathogens12040580 - 11 Apr 2023

Viewed by 1659

Abstract

Streptococcus agalactiae (Group B Streptococcus, GBS) is the leading cause of neonatal sepsis and meningitis but has been recently isolated from non-pregnant adults with underlying medical conditions like diabetes. Despite diabetes being a key risk factor for invasive disease, the pathological consequences during GBS infection remain poorly characterized. Here, we demonstrate the pathogenicity of the GBS90356-ST17 and COH1-ST17 strains in streptozotocin-induced diabetic mice. We show that GBS can spread through the bloodstream and colonize several tissues, presenting a higher bacterial count in diabetic-infected mice when compared to non-diabetic-infected mice. Histological sections of the lungs showed inflammatory cell infiltration, collapsed septa, and red blood cell extravasation in the diabetic-infected group. A significant increase in collagen deposition and elastic fibers were also observed in the lungs. Moreover, the diabetic group presented red blood cells that adhered to the valve wall and disorganized cardiac muscle fibers. An increased expression of KC protein, IL-1β, genes encoding immune cell markers, and ROS (reactive oxygen species) production was observed in diabetic-infected mice, suggesting GBS promotes high levels of inflammation when compared to non-diabetic animals. Our data indicate that efforts to reverse the epidemic of diabetes could considerably reduce the incidence of invasive infection, morbidity and mortality due to GBS. Full article

(This article belongs to the Special Issue The Biology of Streptococcus and Streptococcal Infection)

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Review

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20 pages, 1420 KiB

Open AccessReview

Role of Metabolic Adaptation of Streptococcus suis to Host Niches in Bacterial Fitness and Virulence

by Muriel Dresen, Peter Valentin-Weigand and Yenehiwot Berhanu Weldearegay

Pathogens 2023, 12(4), 541; https://doi.org/10.3390/pathogens12040541 - 31 Mar 2023

Cited by 4 | Viewed by 4154

Abstract

Streptococcus suis, both a common colonizer of the porcine upper respiratory tract and an invasive pig pathogen, successfully adapts to different host environments encountered during infection. Whereas the initial infection mainly occurs via the respiratory tract, in a second step, the pathogen can breach the epithelial barrier and disseminate within the whole body. Thereby, the pathogen reaches other organs such as the heart, the joints, or the brain. In this review, we focus on the role of S. suis metabolism for adaptation to these different in vivo host niches to encounter changes in nutrient availability, host defense mechanisms and competing microbiota. Furthermore, we highlight the close link between S. suis metabolism and virulence. Mutants deficient in metabolic regulators often show an attenuation in infection experiments possibly due to downregulation of virulence factors, reduced resistance to nutritive or oxidative stress and to phagocytic activity. Finally, metabolic pathways as potential targets for new therapeutic strategies are discussed. As antimicrobial resistance in S. suis isolates has increased over the last years, the development of new antibiotics is of utmost importance to successfully fight infections in the future. Full article

(This article belongs to the Special Issue The Biology of Streptococcus and Streptococcal Infection)

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