-
Microbiology Spectrum Oct 2018Bacteria belonging to the genus are the first inhabitants of the oral cavity, which can be acquired right after birth and thus play an important role in the assembly of... (Review)
Review
Bacteria belonging to the genus are the first inhabitants of the oral cavity, which can be acquired right after birth and thus play an important role in the assembly of the oral microbiota. In this article, we discuss the different oral environments inhabited by streptococci and the species that occupy each niche. Special attention is given to the taxonomy of , because this genus is now divided into eight distinct groups, and oral species are found in six of them. Oral streptococci produce an arsenal of adhesive molecules that allow them to efficiently colonize different tissues in the mouth. Also, they have a remarkable ability to metabolize carbohydrates via fermentation, thereby generating acids as byproducts. Excessive acidification of the oral environment by aciduric species such as is directly associated with the development of dental caries. However, less acid-tolerant species such as and produce large amounts of alkali, displaying an important role in the acid-base physiology of the oral cavity. Another important characteristic of certain oral streptococci is their ability to generate hydrogen peroxide that can inhibit the growth of . Thus, oral streptococci can also be beneficial to the host by producing molecules that are inhibitory to pathogenic species. Lastly, commensal and pathogenic streptococci residing in the oral cavity can eventually gain access to the bloodstream and cause systemic infections such as infective endocarditis.
Topics: Carbohydrate Metabolism; Dental Caries; Endocarditis; Fermentation; Humans; Hydrogen Peroxide; Metagenomics; Microbiota; Mouth; Phylogeny; Streptococcus; Streptococcus gordonii; Streptococcus mutans; Streptococcus salivarius
PubMed: 30338752
DOI: 10.1128/microbiolspec.GPP3-0042-2018 -
European Journal of Clinical... Dec 2020The Mitis group of streptococci includes an important human pathogen, Streptococcus pneumoniae (pneumococcus) and about 20 other related species with much lower... (Review)
Review
The Mitis group of streptococci includes an important human pathogen, Streptococcus pneumoniae (pneumococcus) and about 20 other related species with much lower pathogenicity. In clinical practice, some representatives of these species, especially Streptococcus pseudopneumoniae and Streptococcus mitis, are sometimes mistaken for S. pneumoniae based on the results of classical microbiological methods, such as optochin susceptibility and bile solubility. Several various molecular approaches that address the issue of correct identification of pneumococci and other Mitis streptococci have been proposed and are discussed in this review, including PCR- and gene sequencing-based tests as well as new developments in the genomic field that represents an important advance in our understanding of relationships within the Mitis group.
Topics: Automation; Humans; Multilocus Sequence Typing; Phenotype; Polymerase Chain Reaction; Streptococcus mitis; Streptococcus pneumoniae; Whole Genome Sequencing
PubMed: 32710352
DOI: 10.1007/s10096-020-03991-9 -
Microbiology Spectrum Jul 2019is the best characterized species among the lactococci, and among the most consumed food-fermenting bacteria worldwide. Thanks to their importance in industrialized... (Review)
Review
is the best characterized species among the lactococci, and among the most consumed food-fermenting bacteria worldwide. Thanks to their importance in industrialized food production, lactococci are among the lead bacteria understood for fundamental metabolic pathways that dictate growth and survival properties. Interestingly, lactococci belong to the Streptococcaceae family, which includes food, commensal and virulent species. As basic metabolic pathways (e.g., respiration, metal homeostasis, nucleotide metabolism) are now understood to underlie virulence, processes elucidated in lactococci could be important for understanding pathogen fitness and synergy between bacteria. This chapter highlights major findings in lactococci and related bacteria, and covers five themes: distinguishing features of lactococci, metabolic capacities including the less known respiration metabolism in Streptococcaceae, factors and pathways modulating stress response and fitness, interbacterial dialogue metabolites, and novel applications in health and biotechnology.
Topics: Bacterial Proteins; Fermentation; Lactococcus lactis; Metabolic Networks and Pathways
PubMed: 31298208
DOI: 10.1128/microbiolspec.GPP3-0035-2018 -
Nature May 2022Gasdermins (GSDMs) are a family of pore-forming effectors that permeabilize the cell membrane during the cell death program pyroptosis. GSDMs are activated by...
Gasdermins (GSDMs) are a family of pore-forming effectors that permeabilize the cell membrane during the cell death program pyroptosis. GSDMs are activated by proteolytic removal of autoinhibitory carboxy-terminal domains, typically by caspase regulators. However, no activator is known for one member of this family, GSDMA. Here we show that the major human pathogen group A Streptococcus (GAS) secretes a protease virulence factor, SpeB, that induces GSDMA-dependent pyroptosis. SpeB cleavage of GSDMA releases an active amino-terminal fragment that can insert into membranes to form lytic pores. GSDMA is primarily expressed in the skin, and keratinocytes infected with SpeB-expressing GAS die of GSDMA-dependent pyroptosis. Mice have three homologues of human GSDMA, and triple-knockout mice are more susceptible to invasive infection by a pandemic hypervirulent M1T1 clone of GAS. These results indicate that GSDMA is critical in the immune defence against invasive skin infections by GAS. Furthermore, they show that GSDMs can act independently of host regulators as direct sensors of exogenous proteases. As SpeB is essential for tissue invasion and survival within skin cells, these results suggest that GSDMA can act akin to a guard protein that directly detects concerning virulence activities of microorganisms that present a severe infectious threat.
Topics: Animals; Caspases; Keratinocytes; Mice; Pore Forming Cytotoxic Proteins; Pyroptosis; Streptococcus pyogenes; Virulence; Virulence Factors
PubMed: 35545676
DOI: 10.1038/s41586-022-04717-x -
Proceedings of the National Academy of... Jun 2023M family proteins are critical virulence determinants of Streptococci. subsp. (SEZ) are Group C streptococci that cause meningitis in animals and humans. SzM, the M...
M family proteins are critical virulence determinants of Streptococci. subsp. (SEZ) are Group C streptococci that cause meningitis in animals and humans. SzM, the M protein of SEZ, has been linked to SEZ brain invasion. Here, we demonstrate that SzM is important in SEZ disruption of the blood-brain barrier (BBB). SEZ release SzM-bound membrane vesicles (MVs), and endocytosis of these vesicles by human brain endothelial microvascular cells (hBMECs) results in SzM-dependent cytotoxicity. Furthermore, administration of SzM-bound MVs disrupted the murine BBB. A CRISPR screen revealed that SzM cytotoxicity in hBMECs depends on PTEN-related activation of autophagic cell death. Pharmacologic inhibition of PTEN activity prevented SEZ disruption of the murine BBB and delayed mortality. Our data show that MV delivery of SzM to host cells plays a key role in SEZ pathogenicity and suggests that MV delivery of streptococcal M family proteins is likely a common streptococcal virulence mechanism.
Topics: Humans; Animals; Mice; Blood-Brain Barrier; Autophagic Cell Death; Antigens, Bacterial; Streptococcus; Streptococcus equi; Endothelial Cells; Streptococcal Infections
PubMed: 37276410
DOI: 10.1073/pnas.2219435120 -
Current Issues in Molecular Biology 2019The genus comprises a wide variety of pathogenic and commensal gram-positive bacteria, many of which the pathogenic species cause severe, invasive infections that... (Review)
Review
The genus comprises a wide variety of pathogenic and commensal gram-positive bacteria, many of which the pathogenic species cause severe, invasive infections that account for a high burden of morbidity and mortality. Here, we reviewed the evolution of representative virulence factors, capsule in , M protein in (GAS), biofilm in (GBS) and some oral , as well as the effect caused by evolution, antibiotic resistance and vaccine escape. Thanks to the rapid development of whole genome sequence (WGS) data, the impact of genetic recombination to the evolution has been proved. As to adaptive evolution caused by antibiotics, vaccine and so on, continuous surveillance is an essential to monitor evolution of causing disease. This knowledge is invaluable to the development of preventative and control strategies against this important pathogen.
Topics: Anti-Bacterial Agents; Antigens, Bacterial; Bacterial Outer Membrane Proteins; Biofilms; Carrier Proteins; Drug Resistance, Bacterial; Evolution, Molecular; Gene Expression Regulation, Bacterial; Host-Pathogen Interactions; Humans; Recombination, Genetic; Signal Transduction; Streptococcal Infections; Streptococcal Vaccines; Streptococcus agalactiae; Streptococcus pneumoniae; Streptococcus pyogenes; Virulence; Virulence Factors
PubMed: 31166180
DOI: 10.21775/cimb.032.561 -
Revista Chilena de Infectologia :... Jun 2015Granulicatella spp. is a bacteria of the oral cavity, belonging to the nutritionally variant group streptococci, and has been identified in 5% of all bacterial...
Granulicatella spp. is a bacteria of the oral cavity, belonging to the nutritionally variant group streptococci, and has been identified in 5% of all bacterial endocarditis. It's an important etiologic species in endocarditis, particularly in the setting of negative blood cultures. Granulicatella is a non-mobile, non- spore forming organism that is both catalase and oxidase negative. The treatment for Granulicatella, is the same for Enterococcus according to the American and European guidelines, however resistance to this treatment has been reported.
Topics: Streptococcus
PubMed: 26230446
DOI: 10.4067/S0716-10182015000400017 -
Scandinavian Journal of Immunology Sep 2015Streptococcal bacteria are a versatile group of gram-positive bacteria capable of infecting several host organisms, including humans and fish. Streptococcal species are... (Review)
Review
Streptococcal bacteria are a versatile group of gram-positive bacteria capable of infecting several host organisms, including humans and fish. Streptococcal species are common colonizers of the human respiratory and gastrointestinal tract, but they also cause some of the most common life-threatening, invasive infections in humans and aquaculture. With its unique characteristics and efficient tools for genetic and imaging applications, the zebrafish (Danio rerio) has emerged as a powerful vertebrate model for infectious diseases. Several zebrafish models introduced so far have shown that zebrafish are suitable models for both zoonotic and human-specific infections. Recently, several zebrafish models mimicking human streptococcal infections have also been developed. These models show great potential in providing novel information about the pathogenic mechanisms and host responses associated with human streptococcal infections. Here, we review the zebrafish infection models for the most relevant streptococcal species: the human-specific Streptococcus pneumoniae and Streptococcus pyogenes, and the zoonotic Streptococcus iniae and Streptococcus agalactiae. The recent success and the future potential of these models for the study of host-pathogen interactions in streptococcal infections are also discussed.
Topics: Animals; Disease Models, Animal; Humans; Streptococcal Infections; Streptococcus; Streptococcus agalactiae; Streptococcus pneumoniae; Streptococcus pyogenes; Zebrafish
PubMed: 26095827
DOI: 10.1111/sji.12320 -
Journal of Bacteriology Nov 2022Oral commensal streptococci are primary colonizers of the oral cavity. These streptococci produce many adhesins, metabolites, and antimicrobials that modulate microbial... (Review)
Review
Oral commensal streptococci are primary colonizers of the oral cavity. These streptococci produce many adhesins, metabolites, and antimicrobials that modulate microbial succession and diversity within the oral cavity. Often, oral commensal streptococci antagonize cariogenic and periodontal pathogens such as Streptococcus mutans and Porphyromonas gingivalis, respectively. Mechanisms of antagonism are varied and range from the generation of hydrogen peroxide, competitive metabolite scavenging, the generation of reactive nitrogen intermediates, and bacteriocin production. Furthermore, several oral commensal streptococci have been shown to alter the host immune response at steady state and in response to oral pathogens. Collectively, these features highlight the remarkable ability of oral commensal streptococci to regulate the structure and function of the oral microbiome. In this review, we discuss mechanisms used by oral commensal streptococci to interact with diverse oral pathogens, both physically and through the production of antimicrobials. Finally, we conclude by exploring the critical roles of oral commensal streptococci in modulating the host immune response and maintaining health and homeostasis.
Topics: Streptococcus; Streptococcus mutans; Mouth; Symbiosis; Porphyromonas gingivalis; Biofilms
PubMed: 36286512
DOI: 10.1128/jb.00257-22 -
Frontiers in Cellular and Infection... 2024Streptococci are primary colonizers of the oral cavity where they are ubiquitously present and an integral part of the commensal oral biofilm microflora. The role oral... (Review)
Review
Streptococci are primary colonizers of the oral cavity where they are ubiquitously present and an integral part of the commensal oral biofilm microflora. The role oral streptococci play in the interaction with the host is ambivalent. On the one hand, they function as gatekeepers of homeostasis and are a prerequisite for the maintenance of oral health - they shape the oral microbiota, modulate the immune system to enable bacterial survival, and antagonize pathogenic species. On the other hand, also recognized pathogens, such as oral and , which trigger the onset of dental caries belong to the genus . In the context of periodontitis, oral streptococci as excellent initial biofilm formers have an accessory function, enabling late biofilm colonizers to inhabit gingival pockets and cause disease. The pathogenic potential of oral streptococci fully unfolds when their dissemination into the bloodstream occurs; streptococcal infection can cause extra-oral diseases, such as infective endocarditis and hemorrhagic stroke. In this review, the taxonomic diversity of oral streptococci, their role and prevalence in the oral cavity and their contribution to oral health and disease will be discussed, focusing on the virulence factors these species employ for interactions at the host interface.
Topics: Humans; Dental Caries; Streptococcus; Streptococcus mutans; Streptococcus sobrinus; Mouth; Biofilms
PubMed: 38456080
DOI: 10.3389/fcimb.2024.1357631