-
Virulence Nov 2013
Topics: Bacterial Proteins; Gene Expression Regulation, Bacterial; Streptococcus pyogenes
PubMed: 24128432
DOI: 10.4161/viru.26767 -
Scientific Reports Apr 2021Group A Streptococcus (GAS) causes 700 million infections and accounts for half a million deaths per year. Biofilm formation has been implicated in both pharyngeal and...
Group A Streptococcus (GAS) causes 700 million infections and accounts for half a million deaths per year. Biofilm formation has been implicated in both pharyngeal and dermal GAS infections. In vitro, plate-based assays have shown that several GAS M-types form biofilms, and multiple GAS virulence factors have been linked to biofilm formation. Although the contributions of these plate-based studies have been valuable, most have failed to mimic the host environment, with many studies utilising abiotic surfaces. GAS is a human specific pathogen, and colonisation and subsequent biofilm formation is likely facilitated by distinct interactions with host tissue surfaces. As such, a host cell-GAS model has been optimised to support and grow GAS biofilms of a variety of GAS M-types. Improvements and adjustments to the crystal violet biofilm biomass assay have also been tailored to reproducibly detect delicate GAS biofilms. We propose 72 h as an optimal growth period for yielding detectable biofilm biomass. GAS biofilms formed are robust and durable, and can be reproducibly assessed via staining/washing intensive assays such as crystal violet with the aid of methanol fixation prior to staining. Lastly, SEM imaging of GAS biofilms formed by this model revealed GAS cocci chains arranged into three-dimensional aggregated structures with EPS matrix material. Taken together, we outline an efficacious GAS biofilm pharyngeal cell model that can support long-term GAS biofilm formation, with biofilms formed closely resembling those seen in vivo.
Topics: Biofilms; Calibration; Cell Culture Techniques; Cells, Cultured; Humans; Microbiological Techniques; Models, Biological; Pharynx; Streptococcal Infections; Streptococcus pyogenes; Virulence Factors
PubMed: 33859234
DOI: 10.1038/s41598-021-87377-7 -
Journal of the Chinese Medical... May 2016The group A streptococcus (GAS) M protein, encoded by the emm gene, acts as a major virulence factor. Emm-typing is the GAS gold standard molecular typing and is based...
BACKGROUND
The group A streptococcus (GAS) M protein, encoded by the emm gene, acts as a major virulence factor. Emm-typing is the GAS gold standard molecular typing and is based on the DNA sequence of the nucleotides of the emm gene. The aim of the present study was to isolate GAS from patients and to detect the emm types of the isolates using emm typing.
METHODS
A total of 1000 throat samples were collected from patients with pharyngitis referred to Aboozar Children's Hospital in Ahvaz, Iran. We performed antimicrobial susceptibility testing on all isolates using the Kirby-Bauer disk diffusion method. Additionally, amplification of the emm gene was performed using polymerase chain reaction using the standard primers and described protocol.
RESULTS
From all throat samples screened, 25 isolates (2.5%) were identified as GAS. Antibiotic susceptibility testing revealed that all the GAS isolates were susceptible to penicillin and erythromycin, but 44% showed resistance to vancomycin. Based on polymerase chain reaction for the emm gene, the obtained emm types were: emm-3, observed in 20 isolates (80%); emm-1 observed in four isolates (16%); and emm-75 observed in one isolate (4%).
CONCLUSION
The result of the present study showed that penicillin and erythromycin are still the most effective antibiotics against the organism. The emm typing revealed that emm type-3 was detected in most of the isolates from patients with purulent pharyngitis. On the basis of the findings of this study, we may conclude that emm typing provides new insights on the genetic diversity of the M proteins, and is of demonstrable value for molecular studies of GAS.
Topics: Adolescent; Antigens, Bacterial; Bacterial Outer Membrane Proteins; Carrier Proteins; Child; Child, Preschool; Female; Humans; Male; Microbial Sensitivity Tests; Pharyngitis; Streptococcus pyogenes
PubMed: 26874680
DOI: 10.1016/j.jcma.2016.01.002 -
Emerging Infectious Diseases 1999The aim of this study was to determine whether the high levels of erythromycin resistance in Streptococcus pyogenes found in Spain are due to the introduction and spread... (Review)
Review
The aim of this study was to determine whether the high levels of erythromycin resistance in Streptococcus pyogenes found in Spain are due to the introduction and spread of one or more clones. Phenotypic and genotypic techniques were used to characterize all erythromycin-resistant S. pyogenes (ErR) isolated in Gipuzkoa, Spain, in the last 10 years and 128 ErR isolated in Vitoria and Madrid during 1996. Of 437 ErR, 97% had the M phenotype; all 283 of the strains studied had the mefA determinant of resistance. After biotyping, T serotyping, emm typing, and genotyping, four major clones were detected. Clones B (biotype I, type T4, emm4, pulsed-field gel electrophoresis [PFGE] II) and D (biotype V, type T8.25, emm75, PFGE IV) comprised 78.8% of all ErR. The resistance of S. pyogenes to erythromycin was mainly due to an efflux mechanism of resistance (M phenotype); few clones were responsible for it.
Topics: Anti-Bacterial Agents; Bacterial Typing Techniques; Drug Resistance, Microbial; Electrophoresis, Gel, Pulsed-Field; Erythromycin; Spain; Streptococcus pyogenes
PubMed: 10221875
DOI: 10.3201/eid0502.990207 -
Infection, Genetics and Evolution :... Jul 2009Streptococcus pyogenes, also referred to as beta-hemolytic group A streptococci, are strictly human pathogens with a global distribution and high prevalence of... (Review)
Review
Streptococcus pyogenes, also referred to as beta-hemolytic group A streptococci, are strictly human pathogens with a global distribution and high prevalence of infection. The organisms are characterized by high levels of genetic recombination, extensive strain diversity, and a narrow habitat. This review highlights many key features of the population genetics and molecular epidemiology of this biologically diverse bacterial species, with special emphasis on ecological subdivisions and tissue-specific infections, strain diversity and population dynamics in communities, selection pressures arising from the specific host immune response and antibiotic exposure, and within-host selection during the course of invasive disease.
Topics: Anti-Bacterial Agents; Drug Resistance, Bacterial; Ecology; Evolution, Molecular; Genetics, Population; Humans; Molecular Epidemiology; Phylogeny; Selection, Genetic; Streptococcal Infections; Streptococcus pyogenes
PubMed: 19460325
DOI: 10.1016/j.meegid.2009.03.002 -
Future Microbiology Oct 2010Streptococcus pyogenes is an important cause of human morbidity and mortality worldwide. A wealth of genomic information related to this pathogen has facilitated... (Review)
Review
Streptococcus pyogenes is an important cause of human morbidity and mortality worldwide. A wealth of genomic information related to this pathogen has facilitated exploration of the proteome, particularly in response to environmental conditions thought to mimic various aspects of pathogenesis. Proteomic approaches are also used to identify immunoreactive proteins for vaccine development and to identify proteins that may induce autoimmunity. These studies have revealed new mechanisms involved in regulating the S. pyogenes proteome, which has opened up new avenues in the study of S. pyogenes pathogenesis. This article describes the methods used, and progress being made towards characterizing the S. pyogenes proteome, including studies seeking to identify potential vaccine candidates.
Topics: Bacterial Proteins; Humans; Proteome; Streptococcal Vaccines; Streptococcus pyogenes; Virulence Factors
PubMed: 21073313
DOI: 10.2217/fmb.10.116 -
Journal of Bacteriology Dec 2008The 1,815,783-bp genome of a serotype M49 strain of Streptococcus pyogenes (group A streptococcus [GAS]), strain NZ131, has been determined. This GAS strain (FCT type 3;...
The 1,815,783-bp genome of a serotype M49 strain of Streptococcus pyogenes (group A streptococcus [GAS]), strain NZ131, has been determined. This GAS strain (FCT type 3; emm pattern E), originally isolated from a case of acute post-streptococcal glomerulonephritis, is unusually competent for electrotransformation and has been used extensively as a model organism for both basic genetic and pathogenesis investigations. As with the previously sequenced S. pyogenes genomes, three unique prophages are a major source of genetic diversity. Two clustered regularly interspaced short palindromic repeat (CRISPR) regions were present in the genome, providing genetic information on previous prophage encounters. A unique cluster of genes was found in the pathogenicity island-like emm region that included a novel Nudix hydrolase, and, further, this cluster appears to be specific for serotype M49 and M82 strains. Nudix hydrolases eliminate potentially hazardous materials or prevent the unbalanced accumulation of normal metabolites; in bacteria, these enzymes may play a role in host cell invasion. Since M49 S. pyogenes strains have been known to be associated with skin infections, the Nudix hydrolase and its associated genes may have a role in facilitating survival in an environment that is more variable and unpredictable than the uniform warmth and moisture of the throat. The genome of NZ131 continues to shed light upon the evolutionary history of this human pathogen. Apparent horizontal transfer of genetic material has led to the existence of highly variable virulence-associated regions that are marked by multiple rearrangements and genetic diversification while other regions, even those associated with virulence, vary little between genomes. The genome regions that encode surface gene products that will interact with host targets or aid in immune avoidance are the ones that display the most sequence diversity. Thus, while natural selection favors stability in much of the genome, it favors diversity in these regions.
Topics: Bacterial Proteins; Chromosomes, Bacterial; DNA Transposable Elements; Gene Expression Profiling; Genetic Variation; Genome, Bacterial; Multigene Family; Prophages; Pyrophosphatases; Streptococcus pyogenes; Virulence; Nudix Hydrolases
PubMed: 18820018
DOI: 10.1128/JB.00672-08 -
Current Protocols in Microbiology Oct 2013Streptococcus pyogenes is a Gram-positive bacterium that strictly infects humans. It is the causative agent of a broad spectrum of diseases accounting for millions of...
Streptococcus pyogenes is a Gram-positive bacterium that strictly infects humans. It is the causative agent of a broad spectrum of diseases accounting for millions of infections and at least 517,000 deaths each year worldwide. It is a nutritionally fastidious organism that ferments sugars to produce lactic acid and has strict requirements for growth. To aid in the study of this organism, this unit describes the growth and maintenance of S. pyogenes.
Topics: Bacteriological Techniques; Preservation, Biological; Streptococcus pyogenes
PubMed: 24510893
DOI: 10.1002/9780471729259.mc09d02s30 -
Infection and Immunity Jan 2014A bacterium's ability to acquire nutrients from its host during infection is an essential component of pathogenesis. For the Gram-positive pathogen Streptococcus...
A bacterium's ability to acquire nutrients from its host during infection is an essential component of pathogenesis. For the Gram-positive pathogen Streptococcus pyogenes, catabolism of the amino acid arginine via the arginine deiminase (ADI) pathway supplements energy production and provides protection against acid stress in vitro. Its expression is enhanced in murine models of infection, suggesting an important role in vivo. To gain insight into the function of the ADI pathway in pathogenesis, the virulence of mutants defective in each of its enzymes was examined. Mutants unable to use arginine (ΔArcA) or citrulline (ΔArcB) were attenuated for carriage in a murine model of asymptomatic mucosal colonization. However, in a murine model of inflammatory infection of cutaneous tissue, the ΔArcA mutant was attenuated but the ΔArcB mutant was hyperattenuated, revealing an unexpected tissue-specific role for citrulline metabolism in pathogenesis. When mice defective for the arginine-dependent production of nitric oxide (iNOS(-/-)) were infected with the ΔArcA mutant, cutaneous virulence was rescued, demonstrating that the ability of S. pyogenes to utilize arginine was dispensable in the absence of nitric oxide-mediated innate immunity. This work demonstrates the importance of arginine and citrulline catabolism and suggests a novel mechanism of virulence by which S. pyogenes uses its metabolism to modulate innate immunity through depletion of an essential host nutrient.
Topics: Animals; Arginine; Citrulline; Disease Models, Animal; Gene Expression Regulation, Bacterial; Hydrolases; Immunity, Innate; Macrophages; Mice; Nitric Oxide Synthase Type II; Streptococcus pyogenes; Virulence
PubMed: 24144727
DOI: 10.1128/IAI.00916-13 -
Emerging Infectious Diseases Oct 2008The resurgence of severe invasive group A streptococcal infections in the 1980s is a typical example of the reemergence of an infectious disease. We found that this... (Review)
Review
The resurgence of severe invasive group A streptococcal infections in the 1980s is a typical example of the reemergence of an infectious disease. We found that this resurgence is a consequence of the diversification of particular strains of the bacteria. Among these strains is a highly virulent subclone of serotype M1T1 that has exhibited unusual epidemiologic features and virulence, unlike all other streptococcal strains. This clonal strain, commonly isolated from both noninvasive and invasive infection cases, is most frequently associated with severe invasive diseases. Because of its unusual prevalence, global spread, and increased virulence, we investigated the unique features that likely confer its unusual properties. In doing so, we found that the increased virulence of this clonal strain can be attributed to its diversification through phage mobilization and its ability to sense and adapt to different host environments; accordingly, the fittest members of this diverse bacterial community are selected to survive and invade host tissue.
Topics: Genes, Bacterial; Humans; Molecular Epidemiology; Serotyping; Streptococcal Infections; Streptococcus Phages; Streptococcus pyogenes; Virulence
PubMed: 18826812
DOI: 10.3201/eid1410.071660