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PubMed2004

Role of Streptococcus pyogenes two-component response regulators in the temporal control of Mga and the Mga-regulated virulence gene emm.

We examined the role of Streptococcus pyogenes two-component response regulators (SptR) in expression of Mga and the Mga-regulated gene emm. Both serotype M6 and serotype M1 mutants in 12 of the 13 identified sptR genes exhibited levels of emm transcripts and Mga protein comparable to those of the wild type during exponential and stationary phases of growth. Thus, temporal control of these virulence genes does not require Spt response regulators.

Antigens, Bacterial↗
PubMed1973

Effect of elevated atmospheric pressure on penicillin binding by Staphylococcus aureus and Streptococcus pyogenes.

A gas pressure of 68 atm, elicited by helium-oxygen gas mixtures, reduced the susceptibility to penicillin of Staphylococcus aureus but not of Streptococcus pyogenes. The elevated pressure also caused a reduction in the binding of (14)C-penicillin to S. aureus, but not to S. pyogenes. When these studies were extended to glycine incorporation, it was shown that, even without penicillin, pressurization reduced glycine incorporation into the cell wall of S. aureus. Incorporation into other cellular components was not altered by pressurization. Cells grown in a pressurized environment were slightly more susceptible than those grown at 1 atm to rapid change in osmotic pressure. In the presence of penicillin, glycine incorporation into the cell wall was reduced to the same low level at 68 atm and at 1 atm. These results suggest that pressurization renders S. aureus less susceptible to penicillin because it reduces the enzymatic activity of the binding component on the cell, a penicillin-sensitive transpeptidase.

Atmospheric Pressure↗
PubMed2000

Mitogenic factor (MF) is the major DNase of serotype M89 Streptococcus pyogenes.

To investigate the role of mitogenic factor (MF) in streptococcal pathogenesis, the structural gene (mf) encoding this protein was disrupted in a clinical isolate of Streptococcus pyogenes H293, to yield the isogenic mutant H363. Growth in enriched broth and on blood agar was unaffected by disruption of mf. Cell-free broth supernatants from H293 and H363 demonstrated identical promitogenic activities when co-incubated with human peripheral blood mononuclear cells, even when diluted 100000-fold, showing that MF is not a major streptococcal mitogen compared with other secreted superantigens. Disruption of mf resulted in complete loss of DNase B production and detectable DNase activity in H363 compared with the parent strain, confirming that the single gene mf, which is present in all group A streptococcal M serotypes studied, encodes DNase B. Despite loss of DNase activity, the virulence of S. pyogenes in a mouse model of necrotizing fasciitis and myositis was unaffected.

Animals↗
PubMed2006

Specificity of Streptococcus pyogenes NAD(+) glycohydrolase in cytolysin-mediated translocation.

The mechanism by which the cytolysin-mediated translocation (CMT) pathway of the Gram-positive pathogen Streptococcus pyogenes injects effector proteins into the cytosol of an infected host cell via the pore-forming protein streptolysin O is unknown. Key questions include whether the pathway can discriminate between different substrates for translocation, and whether the effector protein plays an active or passive role in the translocation process. Here we show that CMT can discriminate between a known effector of the pathway, the S. pyogenes NAD(+) glycohydrolase (SPN), and a second secreted protein, the mitogenic factor (MF), routing the former into the host cell cytosol and the latter into the extracellular milieu. Residues within the amino-terminal 190 residues of SPN were essential for discrimination, as deletions within this domain produced proteins that retained full enzymatic activity, but were completely uncoupled from the translocation pathway. The enzymatic domain itself played a pivotal role in the discrimination as deletions within this domain also produced translocation incompetent proteins and the conversion of MF to a translocation-competent form required fusion with both SPN domains in a contiguous orientation. These data establish that CMT is discriminatory, and that SPN is a multidomain protein that plays an active role in its translocation.

Amino Acid Sequence↗
PubMed1991

Expression of the fibronectin-binding components of Streptococcus pyogenes in Escherichia coli demonstrates that they are proteins.

The fibronectin-binding components (fbcs) of two clinical isolates and a culture collection strain of Streptococcus pyogenes have been analysed. Western immunoblotting of bacterial lysates which had been fractionated on polyacrylamide gels revealed trypsin-sensitive fibronectin-binding species. The genes specifying the fbcs were cloned from all three strains and expressed in Escherichia coli using a lambda EMBL3 vector. An fbc gene from the culture collection strain was subcloned and expressed in the E. coli expression vector pJLA601, and subjected to deletion analysis. The fibronectin-binding domain was thereby localized within a 40 kDa truncated peptide encoded by the 1000 bp C-terminal region of the gene. Southern hybridization experiments demonstrated that the analysed gene was present in the parental S. pyogenes chromosome, but not in the DNA of fbc expressing lambda clones obtained from the two clinical isolates. Further evidence for the existence of at least two different types of fbcs in group A streptococci was provided by Western blot analysis of recombinant phage lysates which revealed a complex series of fibronectin-binding species ranging from 120 to 200 kDa in size and showing strain-dependent variation in their patterns. As was the case with parental streptococcal strains all of the recombinant fbcs were protease-sensitive, and treatment with trypsin or pronase resulted in a total loss of fibronectin-binding activity. Competitive inhibition experiments indicated that lipoteichoic acid was not a significant fbc in the tested streptococcal strains.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗
PubMed1996

Genetic and phenotypic diversity among isolates of Streptococcus pyogenes from invasive infections.

To determine if recent cases of invasive group A streptococcal disease were caused by strains with a unique characteristic, 117 isolates Streptococcus pyogenes from patients with a variety of diseases, including necrotizing fasciitis and toxic shock syndrome, were analyzed. Significant genomic heterogeneity was observed among selected isolates, as determined using pulsed-field gel electrophoresis. The frequency of the bacteriophage-associated streptococcal erythrogenic toxin genes A and C (speA and speC) among the isolates was 44% (49/112) and 34% (38/112), respectively. Forty-three percent of speA-positive isolates produced streptococcal erythrogenic toxin (SPE) A in vitro. Seventy-six percent (85/112) of isolates produced SPE B in vitro, and in contrast to SPE A, little variation in the concentration of SPE B in broth culture supernatants was detected. The genetic and phenotypic heterogeneity observed among isolates from recent cases of severe infection does not support a clonal basis for the resurgence of invasive streptococcal infections.

Bacterial Proteins↗
PubMed1976

[The immunobiology of M-proteins of Streptococcus pyogenes. III. Immunization of rhesus monkeys (Macaca mulatta)].

Rhesus monkeys were used for the examination of immunogenicity of various preparations of M-antigens of Streptococcus pyogenes, types 1, 12, and 19. The antigens were applied in various dosages, but always with alumniumhydroxide as adjuvant. The challenge infection was provided by the homologous type, in some cases by an additional heterologous type. After intravenous infection all the animals fell ill, as the high dose of infective agents led to poisoning. The majority of immunized animals, however, did not show an increase of antistreptolysin titers with the type 1-infections - a sign of the absence of any reproduction of the injected streptococci in the animal organism. This behaviour was also observed in animals where no protective antibodies (bactericidal and long-chain antibodies) were verified before the infection. The electrocardiographic findings also indicate the protective effect of M-protein vaccines. In all control animals changes were seen which indicated an acute myocarditis. Normal electrocardiograms were obtained from the monkeys which had been immunized and afterwards infected. The administration of antigen every two weeks over a period of one year did not lead to the occurrence of any visible allergy in the skin test. The lymphocyte transformation test showed an increased rate of transformation in some immunized and infected animals, but this is not type-specific.

Animals↗
PubMed1996

Susceptibility of macrolide and beta-lactam antibiotics of Streptococcus pyogenes strains isolated over a four-year period in central Italy.

In vitro susceptibility to erythromycin, azithromycin, penicillin G, ceftriaxone and ceftibuten was investigated in 190 Streptococcus pyogenes strains isolated over a 4-year period (1991-1994) from patients attending a university hospital located in central Italy. The rate of susceptibility to macrolide antibiotics of the S. pyogenes strains showed a progressive decrease (from 90.3% in 1991 to 79.5% in 1994), while all strains were susceptible to the three beta-lactam antibiotics. Owing to the reduced prevalence of macrolide-susceptible S. pyogenes strains, in vitro susceptibility testing of streptococcal isolates appears to be always necessary before starting a macrolide-based chemotherapy. Concerning beta-lactams, ceftriaxone presented minimum inhibitory concentrations (MIC) always equal to or lower than those of penicillin G, while the oral long-acting cephalosporin, ceftibuten, had MICs higher than those of the other beta-lactams, although in the susceptible range. Results of in vitro susceptibility testing are discussed in relation to their implications for antimicrobial chemotherapy of S. pyogenes infections.

Anti-Bacterial Agents↗
PubMed1993

Virulence of two Streptococcus pyogenes strains (types M1 and M3) associated with toxic-shock-like syndrome depends on an intact mry-like gene.

The major virulence factor of Streptococcus pyogenes, the M protein, is positively regulated at the transcriptional level by mry in the M type 6 strain studied. We show here that in two S. pyogenes strains isolated from cases of toxic-shock-like syndrome, a type M1 strain and a type M3 strain, an mry-like gene is also required for resistance to phagocytosis.

Antigens, Bacterial↗
PubMed1999

SIgA- and IgG-coated Streptococcus pyogenes on the tonsillar surfaces during acute tonsillitis.

Bacterial swabs were collected from the tonsillar surfaces of eight patients with current acute tonsillitis, culture-positive for Streptococcus pyogenes. Using gold-labelled antiserum to S. pyogenes, these micro-organisms could be localized in the samples by transmission electron microscopy. S. pyogenes pathogens were further characterized with gold-labelled antiserum to human IgG and SIgA antibodies. Roughly 90% of the pathogens were found coated with IgG antibodies, irrespective of the duration of the disease, whereas the proportion of SIgA-coated pathogens increased with disease duration. Insufficient IgA coating of pathogens might well be a contributory cause of the induction of tonsillar infection, probably due to inadequate prevention of the attachment of the S. pyogenes bacteria to the tonsillar surface epithelium.

Acute Disease↗
PubMed2004

Multilocus sequence typing of Streptococcus pyogenes representing most known emm types and distinctions among subpopulation genetic structures.

A long-term goal is to characterize the full range of genetic diversity within Streptococcus pyogenes as it exists in the world today. Since the emm locus is subject to strong diversifying selection, emm type was used as a guide for identifying a genetically diverse set of strains. This report contains a description of multilocus sequence typing based on seven housekeeping loci for 495 isolates representing 158 emm types, yielding 238 unique combinations of sequence type and emm type. A genotypic marker for tissue site preference (emm pattern) revealed that only 17% of the emm types displayed the marker representing strong preference for infection at the throat and that 39% of emm types had the marker for skin tropism, whereas 41% of emm types harbored the marker for no obvious tissue site preference. As a group, the emm types bearing the emm pattern marker indicative of no obvious tissue site preference were far less likely to have two distinct emm types associated with the same sequence type than either of the two subpopulations having markers for strong tissue tropisms (P < 0.002). In addition, all genetic diversification events clearly ascribed to a recombinational mechanism involved strains of only two of the emm pattern-defined subpopulations, those representing skin specialists and generalists. The findings suggest that the population genetic structure differs for the tissue-defined subpopulations of S. pyogenes. The observed differences may partly reflect differential host immune selection pressures.

Antigens, Bacterial↗
PubMed1995

Antigenic determinants of Streptococcus pyogenes ribosomes.

An attempt has been made to identify the ribosomal proteins responsible for the production of antibodies upon immunization of monkeys with 70S ribosomes of Streptococcus pyogenes group A 29 M type. Identification was carried out by immunoblotting after isolation and separation of the proteins of 70S, 50S and 30S ribosomal particles on one- and two-dimensional gel electrophoresis. Three major proteins of S. pyogenes 70S ribosomes with clearly expressed antigenic properties were identified by Western blotting. One of these proteins belonged to the 50S subunit and the other two--to the 30S ribosomal subunit. We assume that these proteins represent those of group A streptococci. As a result the antibodies are produced first of all against these antigenic proteins in contrast to the others evolutionary conservative ribosomal proteins.

Animals↗
PubMed1996

Streptococcal pyrogenic exotoxin A release, distribution, and role in a murine model of fasciitis and multiorgan failure due to Streptococcus pyogenes.

The role of streptococcal pyrogenic exotoxin A (SPEA) was evaluated in a murine model of fasciitis and multiorgan failure due to a toxigenic strain of Streptococcus pyogenes. Increased serum levels of SPEA at 15 and 21 h were associated with a survival time of <24 h. Levels of SPEA correlated with interleukin-6 levels. Immunostaining showed SPEA localized to renal and hepatic cells. Neutralizing rabbit antibody to SPEA was administered to mice challenged with S. pyogenes, but no effect on survival was observed. Vaccination of mice with recombinant SPEA enhanced mortality due to streptococcal infection, despite the development of neutralizing immunity to the toxin prior to infection. Hence, SPEA is produced systemically during S. pyogenes soft-tissue infection, and increased levels are associated with reduced survival. In this model, however, SPEA did not appear to play a dominant role in pathogenesis; passive immunization against SPEA was not protective, and active immunization enhanced mortality.

Animals↗
PubMed1995

High level expression of Streptococcus pyogenes erythrogenic toxin A (SPE A) in Escherichia coli and its rapid purification by HPLC.

The speA gene encoding streptococcal erythrogenic toxin A (SPE A) from Streptococcus pyogenes bacteriophage T12 was overexpressed in Escherichia coli under the control of the T7 promoter. Since most of the expressed protein was found in the periplasmic space, an osmotic shock extraction with 0.5 M sucrose resulted in a highly enriched preparation of SPE A. An additional two-step purification employing high pressure liquid chromatography resulted in a purified SPE A protein.

Bacterial Proteins↗
PubMed1993

Observations on the role of tumor necrosis factor-alpha in a murine model of shock due to Streptococcus pyogenes.

OBJECTIVE: To examine the effect of a monoclonal antibody to tumor necrosis factor-alpha (TNF-alpha) in a murine model of shock due to Streptococcus pyogenes. DESIGN: Prospective, multiexperimental, randomized, controlled trial. SETTING: University hospital research laboratory. INTERVENTIONS: An LD90 murine model of Gram-positive shock using S. pyogenes, associated with the presence of significant concentrations of TNF-alpha in the circulation. Prophylactic administration of antibody with concomitant saline controls. A 500-micrograms TN3-19.12 (hamster monoclonal antibody to recombinant murine TNF), or saline, by intravenous injection was administered. MEASUREMENTS AND MAIN RESULTS: Administration of 0.3 mL of 6 x 10(8) colony-forming units/mL of S. pyogenes H250 to mice resulted in 90% to 100% mortality rates in 72 hrs. Serum TNF-alpha concentrations peaked at 2 hrs after bacterial challenge and were 67.7 +/- 18.6 ng/mL. Treatment with anti-TNF-alpha monoclonal antibody abolished the serum TNF-alpha concentrations but did not affect the mortality rate. Serum endotoxin concentrations were < 50 pg/mL before challenge and at 0.5, 1, 2, 5, and 24 hrs after challenge. CONCLUSIONS: Pretreatment with an anti-TNF monoclonal antibody was not protective in this model of S. pyogenes sepsis, despite the presence of significant amounts of TNF in the circulation. These data suggest that TNF-alpha may not play such a crucial role in the pathogenesis of shock due to S. pyogenes.

Animals↗
PubMed1986

Experimental tympanosclerosis following infection with Streptococcus pyogenes and vitamin D3 intoxication.

A rat animal model was used to study the ultrastructure of submucosal calcifications induced in the middle ear following inoculation with Streptococcus pyogenes and high doses of parenteral vitamin D3. The morphological changes present in affected animals resembled the classical picture of tympanosclerosis. While calcification occurred about bacterial remnants and myelin structures, the most important calcification centers were lysosomal and non-lysosomal matrix vesicles in the extracellular spaces. These formed band-like calcifications close to the basal membrane without affecting the epithelial layer. This animal model offers the possibility of studying the effect of various therapeutic regimens in the treatment of the dynamic tympanosclerotic process.

Animals↗
PubMed1981

[Isolation and characterization of erythrogenic toxins of Streptococcus pyogenes 3. communication: comparative studies of type A erythrogenic toxins (author's transl)].

The production of type A erythrogenic toxin was determined in 11 strains of Streptococcus pyogenes (serological group A). All strains produced this toxin, at quantities varying between 16 mg/l (strain "Smith") and 0.03 mg/l (strain T18). The erythrogenic toxins of 5 strains were purified by adsorption to silicate, elution, precipitation with ammonium sulfate, treatment with calcium phosphate, CM-Sepharose chromatography and gel filtration on Sephacryl S200. The preparations were found to be homogenous in SDS electrophoresis and isoelectric focusing (m.w. between 27 000 an 28 000; i.p. 52). They were serologically identical by immunodiffusion (Ouchterlony), and no spur formation was seen with crude concentrates of the toxins produced by the remainder of the strains.

Bacterial Proteins↗