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PubMed2005

Streptococcus pyogenes collagen type I-binding Cpa surface protein. Expression profile, binding characteristics, biological functions, and potential clinical impact.

The Streptococcus pyogenes collagen type I-binding protein Cpa (collagen-binding protein of group A streptococci) expressed by 28 serotypes of group A streptococci has been extensively characterized at the gene and protein levels. Evidence for three distinct families of cpa genes was found, all of which shared a common sequence encoding a 60-amino acid domain that accounted for selective binding to type I collagen. Surface plasmon resonance-based affinity measurements and functional studies indicated that the expression of Cpa was consistent with an attachment role for bacteria to tissue containing collagen type I. A cpa mutant displayed a significantly decreased internalization rate when incubated with HEp-2 cells but had no effect on the host cell viability. By utilizing serum from patients with a positive titer for streptolysin/DNase antibody, an increased anti-Cpa antibody titer was noted for patients with a clinical history of arthritis or osteomyelitis. Taken together, these results suggest Cpa may be a relevant matrix adhesin contributing to the pathogenesis of S. pyogenes infection of bones and joints.

Amino Acid Sequence↗
PubMed1998

Streptococcus pyogenes serotype M1 encodes multiple pathways for entry into human epithelial cells.

The ability of a serotype M1 strain of Streptococcus pyogenes to efficiently invade A549 human lung epithelial cells was previously shown to be dependent on bacterial exposure to human or bovine serum proteins or synthetic peptides containing the sequence RGD. In this study, stimulation by invasion agonists was determined to be dependent on expression of the streptococcal cell surface protein, M1. Fetal bovine serum (FBS), fibronectin (Fn), the extracellular matrix protein laminin (Lm), and RGD-containing peptides were tested for their abilities to promote epithelial cell invasion and adherence by isogenic M1(+) and M1(-) strains of S. pyogenes. In the absence of an agonist, invasion and adherence were comparable for the two bacterial strains. FBS, Fn, and Lm stimulated invasion of the M1(+) strain as much as 70-fold but failed to significantly affect invasion by the M1(-) mutant. Adherence of the wild-type strain was stimulated by these same agonists. Epithelial cell adherence by the M1(-) strain, however, was unaffected by the presence of Fn or Lm. Several RGD-containing peptides were found to promote invasion independently of M1 expression. Binding of 125I-Fn was reduced 88% by the M1(-) mutation and Fn was found to bind purified M1 protein, suggesting that Fn mediates invasion by direct binding to M1. To determine if host integrins might be involved in internalization of streptococci, several anti-integrin monoclonal antibodies (MAbs) were tested for their abilities to inhibit invasion. Antibody directed against integrin beta1 inhibited FBS-, Fn-, and Lm-mediated invasion but did not abrogate RGD-peptide-stimulated invasion. MAb directed against the epithelial cell Fn receptor, integrin alpha5beta1, inhibited Fn and FBS-mediated invasion but did not specifically inhibit Lm-mediated invasion. These results indicate that S. pyogenes has evolved multiple mechanisms for invasion of eukaryotic cells, at least two of which involve interactions between M1 protein, host integrins, and integrin ligands.

Antigens, Bacterial↗
PubMed1998

Biological strategies expressed by different Streptococcus pyogenes strains: an explanation of the epidemiology.

The numerous reports in the last ten years on the serious diseases caused by Streptococcus pyogenes indicate the continued significance of this pathogen. Furthermore, clinical studies and modern techniques have yielded new information on S. pyogenes and its pathogenic mechanisms. Although much still remains to be discovered about the biology of S. pyogenes, two different strategies--the 'epidemic' and the 'endemic' strategy--can be seen in the interaction of different S. pyogenes strains with the human host. The challenges posed by these two groups of bacteria are also outlined.

Disease Outbreaks↗
PubMed2005

SpeB-Spi: a novel protease-inhibitor pair from Streptococcus pyogenes.

This study presents evidence for a novel protease-protease inhibitor couple, SpeB-Spi, in the human pathogen Streptococcus pyogenes. The gene for the inhibitor Spi is located directly downstream of the gene for the streptococcal cysteine protease SpeB. Spi is 37% identical and 70% similar to the sequence of the SpeB propeptide, suggesting that Spi and the SpeB propeptide might bind to SpeB in an analogous manner. Secondary structure predictions and molecular modelling suggested that Spi would adopt a structure similar to the SpeB propeptide. The spi gene was co-transcribed with speB on the 1.7 knt and 2.2 knt transcripts previously identified for speB. The Spi protein was purified by SpeB-affinity chromatography from the S. pyogenes cytoplasm. Recombinant Spi was produced and purified, and shown to bind to SpeB and to inhibit its protease activity. Although a similar genetic arrangement of protease and inhibitor is present in staphylococci, this is the first example of an inhibitor molecule that is a structural homologue of the cognate propeptide, and which is genetically linked to the protease gene. Thus, this represents a novel system whereby bacteria may control the intracellular activity of their proteases.

Amino Acid Sequence↗
PubMedDate not supplied

Spontaneous gangrenous myositis induced by Streptococcus pyogenes: case report and review of the literature.

A 54-year-old man presented with gangrenous myositis caused by Streptococcus pyogenes. A review of the literature disclosed 10 similar cases. Their presenting manifestations were spontaneously occurring, localized, excruciating pain; mottling suggestive of ischemic changes; and signs of sepsis. The duration of illness ranged from two to six days, and the outcome was uniformly fatal. This rare but distinct entity resembles clostridial myonecrosis except that it lasts slightly longer and does not involve gaseous crepitus. A definitive diagnosis of myonecrosi scan be established by surgical exploration; early, radical debridement plus penicillin therapy should be undertaken after diagnosis in an attempt to alter the usual devastating outcome.

Gangrene↗
PubMed2001

Identification of conditionally expressed genes in Streptococcus pyogenes using RNA fingerprinting.

RNA fingerprinting using arbitrarily primed reverse transcription-polymerase chain reaction was employed on isolated RNA from Streptococcus pyogenes bacteria in order to identify genes that were regulated in response to environmental changes. When S. pyogenes was cultured under glucose-rich growth conditions a number of transcriptionally up-regulated products were identified, cloned and sequenced. Using the Streptococcal Genome Sequencing Project database and similarity searches against the GenBank database the corresponding genes encoding enzyme IIB and IIC component of a putative phosphotransferase system were identified. Thus, we show that RNA fingerprinting could be a useful tool to identify unknown genes in S. pyogenes that are expressed under certain environmental conditions.

Blotting, Western↗
PubMed1996

[An outbreak of Streptococcus pyogenes infections in institutions for the mentally retarded in Greater Copenhagen 1995].

The largest reported outbreak of infections due to Streptococcus pyogenes, M-type 18, in recent years is described. Ninety persons at institutions for mentally retarded (73% residents) had infections due to the epidemic strain. Pharyngitis and scarlatina were the most common infections. Six patients died, five having a streptococcal toxic shock syndrome. During the outbreak an intensive surveillance was carried out together with improved infection control measures and prompt culturing of residents and employees before antimicrobial treatment. The primary outbreak was confined but a secondary outbreak could not be prevented. This was probably due to difficulties in implementing proper isolation precautions in this setting.

Adult↗
PubMed1999

Protective immune response against Streptococcus pyogenes in mice after intranasal vaccination with the fibronectin-binding protein SfbI.

Despite the significant impact on human health of Streptococcus pyogenes, an efficacious vaccine has not yet been developed. Here, the potential as a vaccine candidate of a major streptococcal adhesin, the fibronectin-binding protein SfbI, was evaluated. Intranasal immunization of mice with either SfbI alone or coupled to cholera toxin B subunit (CTB) triggered efficient SfbI-specific humoral (mainly IgG) and lung mucosal (14% of total IgA) responses. CTB-immunized control mice were not protected against challenge with S. pyogenes (90%-100% lethality), whereas SfbI-vaccinated animals showed 80% and 90% protection against homologous and heterologous challenge, respectively. Multiple areas of consolidation with diffused cellular infiltrates (macrophages and neutrophils) were observed in lungs from control mice; the histologic structure was preserved in SfbI-vaccinated animals, which occasionally presented focal infiltrates confined to the perivascular, peribronchial, and subpleural areas. These results suggest that SfbI is a promising candidate for inclusion in acellular vaccines against S. pyogenes.

Adhesins, Bacterial↗
PubMed1986

Nucleotide sequence of the type A streptococcal exotoxin (erythrogenic toxin) gene from Streptococcus pyogenes bacteriophage T12.

The gene specifying type A streptococcal exotoxin (speA), also known as erythrogenic toxin, was cloned from the Streptococcus pyogenes bacteriophage T12 genome and analyzed by nucleotide sequencing. The speA gene consists of 753 base pairs and codes for a 29,244-molecular-weight protein. The speA gene product contains a putative 30-amino acid signal peptide, resulting in a molecular weight of 25,787 for the secreted protein. A possible promoter and ribosome-binding site are present in the region upstream from the speA gene, and a transcriptional terminator is located 69 bases downstream from the translational termination codon. The amino acid sequence of the carboxy-terminal portion of the type A streptococcal exotoxin exhibits extensive homology with the carboxy terminus of Staphylococcus aureus enterotoxins B and C1.

Amino Acid Sequence↗
PubMed2000

Purification and biochemical characterization of a basic superantigen (SPEX/SMEZ3) from Streptococcus pyogenes.

A potent basic superantigen (designated streptococcal pyrogenic exotoxin X, SPEX/SMEZ3) was purified to homogeneity from culture supernatants of a Streptococcus pyogenes scarlatina strain of type 12 (genotype speA(-), speC(-)) and characterized. Sequence alignments revealed SPEX to be an allele of the streptococcal mitogens type Z (SMEZ). The N-terminal amino acid sequence of SPEX was found with LEVDNNSLLR to be identical to the recently described acidic superantigen SMEZ. Although SPEX/SMEZ genes were present in all of the streptococcal strains tested, a toxin production could only be detected in a small number of strains. The produced toxin concentration in the culture supernatants of positive strains differed between 0 and 20 ng ml(-1). The purified SPEX stimulated human T-lymphocytes with Vbeta8 specificity at extremely low concentrations (lower than 100 pg ml(-1)).

Amino Acid Sequence↗
PubMed1997

Streptococcus pyogenes bacteraemia: a 27-year study in a London teaching hospital.

The clinical and epidemiological features of 120 episodes of Streptococcus pyogenes bacteraemia in St. Thomas' Hospital between 1970 and 1997 were analysed. One-third of episodes were nosocomial. M1 was the most common serotype, and 29% of strains were non-typable. There was a variety of presenting features, but nearly half of the patients had cellulitis, 15% were shocked, and 6% had necrotic infections. There was no focus of infection in 13%. 54% of patients had an underlying disease, and 23% of infections were associated with a medical procedure or device. The mortality rate was 19%, and was associated with shock, coma, no focus of infection, and underlying disease. Since 1989, the annual incidence has more than doubled, and M1 strains and necrotic infections have increased, but the mortality rate and the proportion of patients presenting with shock have decreased, and the increase in cases involved many different M-types.

Bacteremia↗
PubMed2003

Antimicrobial susceptibility patterns and genomic diversity in strains of Streptococcus pyogenes isolated in 1978-1997 in different Brazilian cities.

Penicillin has been the antimicrobial of choice for the treatment of Streptococcus pyogenes infections for almost six decades. Although penicillin-resistant isolates have not been described to date, clinical failures have been reported after treatment with beta-lactams. In this study, we analysed the antimicrobial susceptibility and genetic diversity of S. pyogenes isolates obtained from healthy carriers or patients in different cities in the south and south east of Brazil. The MICs were determined for penicillin and seven other antimicrobials. Penicillin tolerance was also investigated. Genetic diversity was analysed by PFGE after SmaI fragmentation of the genomic DNA. All 211 isolates tested were susceptible to penicillin (MIC 0.0025-0.02 mg l(-1)). Four isolates were moderately penicillin-tolerant (MBC/MIC = 16 mg l(-1)). Most of the other drugs tested were very active against the strains examined, except for tetracycline, to which 50 % of strains were resistant. We also found extensive genetic diversity, in that 60 different patterns were recognized in the 96 strains studied. Indeed, we found no correlation between tetracycline resistance and clonality. Despite this diversity, some PFGE patterns persisted for up to 18 years and specific clone types were spread over different geographical locations

Anti-Bacterial Agents↗
PubMed2002

Acquisition of regulators of complement activation by Streptococcus pyogenes serotype M1.

Opsonization of bacteria by complement proteins is an important component of the immune response. The pathogenic bacterium Streptococcus pyogenes has evolved multiple mechanisms for the evasion of complement-mediated opsonization. One mechanism involves the binding of human regulators of complement activation such as factor H (FH) and FH-like protein 1 (FHL-1). Acquisition of these regulatory proteins can limit deposition of the opsonin C3b on bacteria, thus decreasing the pathogen's susceptibility to phagocytosis. Binding of complement regulatory proteins by S. pyogenes has previously been attributed to the streptococcal M and M-like proteins. Here, we report that the S. pyogenes cell surface protein Fba can mediate binding of FH and FHL-1. We constructed mutant derivatives of S. pyogenes that lack Fba, M1 protein, or both proteins and assayed the strains for FH binding, susceptibility to phagocytosis, and C3 deposition. Fba expression was found to be sufficient for binding of purified FH as well as for binding of FH and FHL-1 from human plasma. Plasma adsorption experiments also revealed that M1(+) Fba(+) streptococci preferentially bind FHL-1, whereas M1(-) Fba(+) streptococci have similar affinities for FH and FHL-1. Fba was found to contribute to the survival of streptococci incubated with human blood and to inhibit C3 deposition on bacterial cells. Streptococci harvested from log-phase cultures readily bound FH, but binding was greatly reduced for bacteria obtained from stationary-phase cultures. Bacteria cultured in the presence of the protease inhibitor E64 maintained FH binding activity in stationary phase, suggesting that Fba is removed from the cell surface via proteolysis. Western analyses confirmed that E64 stabilizes cell surface expression of Fba. These data indicate that Fba is an antiopsonic, antiphagocytic protein that may be regulated by cell surface proteolysis.

Adhesins, Bacterial↗
PubMed2003

Identification of the domains of the fibronectin-binding protein I of Streptococcus pyogenes responsible for adjuvanticity.

Intranasal administration of antigens coupled to full-length fibronectin-binding protein I (SfbI) of Streptococcus pyogenes results in the elicitation of improved humoral and cellular immune responses, at both systemic and mucosal levels. We want to evaluate if SfbI also exhibits adjuvant properties when co-administered with the antigen, as well as identify the minimal domain responsible for its adjuvanticity. To achieve this aim, mice were immunized by the intranasal route with the model antigen beta-galactosidase (beta-gal) co-administered with recombinant proteins spanning different portions of the SfbI protein. The obtained results demonstrated that the adjuvant properties of SfbI were maintained intact when admixed to the model antigen. Similar kinetics and absolute titers of beta-gal-specific IgG antibodies as well as a dominant IgG(1) isotype response pattern were observed using SfbI derivatives spanning either the aromatic and proline-rich (H10) or the fibronectin-binding (H12) domains, respectively. The use of all tested derivatives also stimulated the elicitation of efficient beta-gal-specific IgA responses in lung lavages (23-25% of the total IgA). The obtained results suggest that different sub-domains of the SfbI protein can be used as adjuvants for the development of mucosal vaccines.

Adhesins, Bacterial↗
PubMed2005

MsmR, a specific positive regulator of the Streptococcus pyogenes FCT pathogenicity region and cytolysin-mediated translocation system genes.

As a prerequisite for colonization or causing local infections, Streptococcus pyogenes (group A streptococci, GAS) need to specifically adhere to eukaryotic cell surfaces. Predominantly responsible adhesin genes are contained in a genotype-specific pattern within the FCT region of the GAS genome. In this study, MsmR, belonging to AraC/XylS type transcriptional regulators, was identified in the FCT region as a positive regulator of the major fibronectin-binding adhesin protein F2 in a serotype M49 strain. Compared with the wild-type strain, the msmR mutant showed reduced binding to immobilized fibronectin and decreased adherence to and internalization into human pharyngeal epithelial cells. These results suggested that altered levels of fibronectin-binding proteins in the mutant affect eukaryotic cell attachment and internalization. Complete transcriptome and reporter fusion assay data revealed that MsmR positively regulates FCT region genes including Nra and cytolysin-mediated translocation system genes. Consistent with the genetic data, the mutant showed attenuated streptolysin O activity and eukaryotic cell cytotoxity. Direct binding of recombinant MsmR to nga, nra/cpa and prtF2 promoter regions was confirmed by EMSA assays. As prior analysis demonstrated the Nra regulator negatively affects gene expression from the FCT region, MsmR and Nra appear to adversely control crucial virulence factor expression in GAS and thus contribute to a fine-tuned balance between local destructive process and metastatic spreading of the bacteria.

Bacterial Adhesion↗
PubMed1996

Different alleles of the fcrA/mrp gene of Streptococcus pyogenes encode M-related proteins exhibiting an identical immunoglobulin-binding pattern.

The majority of group A streptococci (GAS, Streptococcus pyogenes) express immunoglobulin (Ig)-binding proteins. The genes encoding these proteins belong either to the emm or the emm-related (fcrA/mrp and enn) gene family and are located in close proximity on the GAS genome, where they form part of the vir regulon. In the present study analysis of sequence data of the 5' terminal portions of the fcrA/mrp genes from GAS isolates representing 37 different M serotypes led to a classification of six different types. Thus, although fcrA/mrp genes exhibit an allelic polymorphism, they do not display the high degree of N-terminal sequence diversity found among emm genes. The nucleotide sequences of the fcrA/mrp genes from 3 GAS isolates, belonging to serotypes M8, M9, and M13 and representing newly characterized fcrA/mrp gene types, are reported. Analysis of the Ig-binding properties of recombinant FcrA/Mrp8, 9, and 13 proteins, demonstrated a similar Ig-binding profile being reactive with human IgG subclasses 1, 2, and 4. This pattern is identical to that previously described for other recombinant fcrA/mrp4, 49, 64/14 and 76 gene products, indicating that this property is not affected by the N-terminal variability. Evidence for recombination between an fcrA/mrp and an mga gene was observed in an M-type 33 strain isolate providing further support for the concept of gene rearrangement contributing to the diversity of vir regulon gene products.

Amino Acid Sequence↗
PubMed1992

[Infections by Streptococcus pyogenes: new aspects of diagnosis, epidemiology, clinical practice, and therapy].

Essential procedures for the cultural and serological laboratory diagnosis of Streptococcus pyogenes are described. A reliable and rapid species identification is achieved by serologic or biochemical tests. Direct antigen detection tests from throat swabs have broadened the diagnostic possibilities; however, they are often not satisfactory in terms of sensitivity. Typing of strains (either by classic serologic techniques or by molecular methods) is of high value for the study of clinical and therapeutic questions. In recent years, the epidemiology of the prevalent group A streptococcal strains has changed in Europe as well as in the U.S.: an increase of those M protein serotypes that are associated with higher virulence is being recognized. There is good evidence that the unexpected resurgence of rheumatic fever in the U.S. and the emerging number of life-threatening invasive and toxic manifestations of disease (including the toxic shock syndrome) in the U.S. and in Europe are related to the changing epidemiology. The existence of strains with rheumatogenic and nephritogenic potency has been established, but genetic host factors are a prerequisite for the sequelae as well. Although, based on experimental data, there are a lot of hypotheses concerning the nonsuppurative sequelae and the toxic shock syndrome, the exact pathogenesis of these diseases remains to be clarified. A thorough knowledge of the various clinical manifestations of group A streptococcal infections is necessary in order to apply the therapeutic and preventive measures in a rational and sophisticated manner. For most infections penicillins are considered the drug of choice, although no final conclusions regarding optimal dosages or the reasons for treatment failures can be made.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗