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PubMed1983

Demonstration of a receptor for mouse and human serum albumin in Streptococcus pyogenes.

A new type of surface receptor for serum albumin was detected in strains of Streptococcus pyogenes (group A). This receptor, called type e, was different from albumin receptors in other streptococcal species. Only mouse and human serum albumin was bound to the receptor. The albumin-binding capacity was high: 2 X 10(8) bacterial organisms bound 11 micrograms of mouse albumin. The receptor was stable even when treated at 100 degrees C for 5 min. Binding of albumin was not mediated by lipoteichoic acid (LTA) because of lack of correlation to surface LTA, restricted albumin reactivity, and positive binding in presence of 2% Tween 20. Presence of albumin receptor type e correlated to presence of M-protein as measured by growth in the bactericidal test. All 51 M-protein positive group A streptococcal strains tested could bind mouse albumin whereas only 3 out of 8 M-protein negative strains showed positive binding (P less than 0.001). The sensitivity to trypsin digestion suggests that the albumin receptor is of protein nature or mediated by a protein.

Animals↗

PubMed1994

The mode of action of SA-FF22, a lantibiotic isolated from Streptococcus pyogenes strain FF22.

SA-FF22 is a lanthionine-containing bacteriocidal peptide isolated from Streptococcus pyogenes strain FF22. The peptide interacts closely with non-energised artificial phospholipid vesicles, as evidenced by a 'blue shift' in the fluorescent emissions associated with a tryptophan residue within the peptide sequence. Furthermore, SA-FF22 induced efflux of radiolabelled amino acids from artificially energised cytoplasmic membrane vesicles and arrested uptake of amino acids by intact cells. By measuring the decrease in membrane potential of both starved and energised SA-FF22-treated cells, and through the use of artificial planar membranes, a potential of approximately 100 mV was deduced as the minimum required to induce pore formation by SA-FF22. This threshold potential is independent of the orientation of the applied voltage (i.e. trans or cis orientations are equally effective). Single channel conductance measurements suggested that the pores formed by SA-FF22 are relatively unstable, short-lived and approximately 0.5-0.6 nm in diameter. This is somewhat smaller than those of the previously described, pore-forming lantibiotics and should not allow significant efflux of large molecules such as ATP. Thus, death of affected cells seems to result from membrane-potential disruption and subsequent exhaustion of the cells.

Alanine↗

PubMed2001

Genetic dissection of the Streptococcus pyogenes M1 protein: regions involved in fibronectin binding and intracellular invasion.

Entry of serotype M1 Streptococcus pyogenes into host cells depends on binding of the host glycoprotein fibronectin (Fn) by the bacterial M1 protein. The present study was undertaken to localize the Fn binding region in M1 and assess other potential functions of M1. A set of recombinant M1 protein fragments were assayed for their capacities to bind Fn and inhibit ingestion of streptococci by epithelial cells. M1 protein, M6 protein and internally-deleted derivatives of M1 were expressed on the surface of Lactococcus lactis. Lactococci that expressed M1 or M6 protein bound Fn and were efficiently taken up by epithelial cells. Deletion of both the N-terminal A and B repeats regions of M1 abrogated Fn binding and intracellular invasion. Deletion of either the A domain (M1DeltaA) or B repeats (M1DeltaB) significantly reduced, but did not completely eliminate, Fn binding indicating that M1 protein may possess two independent Fn binding sites. Fn binding by the M1DeltaA or M1DeltaB proteins was insufficient for efficient invasion, however, suggesting that M protein binding alters the structure of Fn that, in turn, affects the interaction between Fn and epithelial cells. Although expression of M1, M6 or M1DeltaB proteins led to aggregation of lactococcal cells, aggregation did not significantly contribute to invasion efficiency.

Amino Acid Sequence↗

PubMed1995

Molecular subtyping of prevalent M serotypes of Streptococcus pyogenes causing invasive disease.

Reproducible methodologies and a scheme for high-resolution genotyping of Streptococcus pyogenes were defined with respect to a study of six predominant M serotypes causing invasive group A streptococcal disease in the United Kingdom. Serotype reference strains were compared with nine clinical isolates of each serotype from patients with diseases such as pneumonia, puerperal sepsis, toxic shock-like-syndrome, cellulitis, or necrotizing fasciitis. Four enzymes were evaluated for their discriminatory power in 16S rRNA gene-specific ribotyping. Discriminatory power was greatest with EcoRI, which generated serotype-specific ribotypes, and with SacI, which could subdivide strains of the same M serotype. Twenty-five combined ribotypes were found among the 60 strains, and the indices of discriminatory power (D values) of this method varied from 0.51 within serotype M1 to 0.98 within strains of serotype M5. Macrorestriction with the rarely cutting endonuclease SmaI and pulsed-field gel electrophoresis gave D values varying from 0.37 within serotype M1 to the maximal 1.0 within serotype M5. Comparison of macrorestriction profiles revealed various degrees of genetic heterogeneity within M serotypes. Strains of M1, M3, M6, and M11 exhibited clonally related macrorestriction profiles, while those of R28 and M5 strains were consistent with polyphyletic origin.

Antigens, Bacterial↗

PubMed2004

Rgg regulates growth phase-dependent expression of proteins associated with secondary metabolism and stress in Streptococcus pyogenes.

The transcriptional regulatory protein Rgg coordinates amino acid catabolism and virulence factor expression in Streptococcus pyogenes. We used a proteomic approach to compare cytoplasmic proteins isolated from S. pyogenes wild-type strain NZ131 (serotype M49) to proteins isolated from an rgg mutant strain during the exponential and stationary phases of growth. Proteins were separated by two-dimensional gel electrophoresis, and 125 protein spots of interest were identified by tandem mass spectrometry. Comparative analysis of proteins isolated from the isogenic strains revealed that growth phase-associated regulation of enzymes involved in the metabolism of arginine (ArcABC), histidine (HutI), and serine (SdhA) was abrogated in the rgg mutant strain, which synthesized the proteins in the exponential phase of growth. In contrast, the enzymes were detected only among wild-type proteins isolated from organisms in the stationary phase of growth. The differences in protein composition were correlated with previously described metabolic changes. In addition, proteins associated with thermal and oxidative stress responses, including ClpE and ClpL, were present in samples isolated from the rgg mutant strain but not in samples isolated from the wild-type strain. The rgg mutant strain was more tolerant to elevated temperature and puromycin than the wild-type strain; however, the mutant was less tolerant to paraquat. We concluded that Rgg is a global regulatory factor that contributes to growth phase-dependent synthesis of proteins associated with secondary metabolism and oxidative and thermal stress responses.

Amino Acids↗

PubMed1967

International survey of the distribution of serotypes of Streptococcus pyogenes (group A streptococci).

To determine whether there are major differences in the distribution of Streptococcus pyogenes serotypes in different countries and to compare the typing results obtained in different laboratories with the same cultures, an international survey of the distribution of such serotypes was carried out in 1964-65 in 12 laboratories in different parts of the world.The cultures typed were a representative selection of those causing disease in each country, were as far as possible uninfluenced by seasonal changes and local prevalences, and included separate collections from cases of scarlet fever, sore throat, and other streptococcal diseases.Typing was carried out by the T-agglutination method in 12 laboratories and by the M-precipitation method as well in 8. Between 80% and 98% of the cultures were typable by T-agglutination in the different laboratories, and between 23% and 56% by M-precipitation.Some T-agglutination patterns were associated with a single M-antigen but others included members of several M-types. The same M-antigen was rarely found in streptococci with different T-agglutination patterns. The two methods could therefore conveniently be used as a combined system of typing.Certain streptococcal types were relatively common in most countries, but there were considerable national differences in type-distribution. Separate analysis of the cultures obtained from individual streptococcal diseases showed that there were also differences in type-distribution between streptococci isolated from scarlet fever, from sore throat, and from septic lesions not associated with the respiratory tract.

Antigens↗

PubMed2001

Specific interactions between F1 adhesin of Streptococcus pyogenes and N-terminal modules of fibronectin.

Protein F1 is a surface protein of Streptococcus pyogenes that mediates high affinity binding to fibronectin (Fn) and facilitates S. pyogenes adherence and penetration into cells. The smallest portion of F1 known to retain the full binding potential of the intact protein is a stretch of 49 amino acids known as the functional upstream domain (FUD). Synthetic and recombinant versions of FUD were labeled with fluorescein isothiocyanate and used in fluorescence anisotropy experiments. These probes bound to Fn or the 70-kDa fragment of Fn with dissociation constants of 8-30 nm. Removal of the N-terminal seven residues of FUD did not cause a change in binding affinity. Further N- or C-terminal truncations resulted in complete loss of binding activity. Analysis of recombinant versions of the 70-kDa fragment that lacked one or several type I modules indicates that residues 1-7 of the 49-mer bind to type I modules I1 and I2 of the 27-kDa subfragment and the C-terminal residues bind to modules I4 and I5. Fluorescein isothiocyanate-labeled 49-mer also bound with lower affinity to large Fn fragments that lack the five type I modules of the 27-kDa fragment but contain the other seven type 1 modules of Fn. These results indicate that, although FUD has a general affinity for type I modules, high affinity binding of FUD to Fn is mediated by specific interactions with N-terminal type I modules.

Adhesins, Bacterial↗

PubMed1993

Role of interferon in the protective effect of an immunomodulator derived from the Su strain of Streptococcus pyogenes A3 against viral myocarditis in mice.

OK432 (preparation derived from the Su strain of Streptococcus pyogenes A3; Picibanil, CAS 39325-01-4) is an immunomodulator. The treatment of mice with OK432 enhances their resistance to encephalomyocarditis virus (EMCV) along with a concomitant increase of interferon (IFN) titer and natural killer (NK) cell activity. To ascertain whether IFN or NK cell activity may play a crucial role in the mechanism of resistance, we compared these strains: EMCV resistant C57BL mice, C3H mice with myocarditis and DBA/2 mice with both myocarditis and diabetes mellitus. Although IFN production in all three kinds of mice was significantly increased on day 3 after inoculation, NK cell activity in EMCV resistant C57BL mice was significantly lower than that in C3H and DBA/2 mice. The lower antiviral resistance of mice treated with both OK432 and anti-interferon antibody (aIFN) was accompanied by a reduction of serum IFN titer, irrespective of the reduction in NK cell activity. Decreased activation of NK cells by anti-asialo GM1 monoclonal antibody (aNK) of OK432-treated mice also resulted in higher viral titers. However, these titers of both OK432 and aNK-treated mice were significantly lower than those of both OK432 and aIFN-treated mice. The degree of elevation of viral titer showed the following trend: OK432 and a IFN-treated mice > OK432 and aNK-treated mice >> OK432-treated mice. Moreover, histological changes of the heart in OK432 and aIFN-treated mice were significantly (p < 0.05) more severe than that in OK432 and aNK-treated and that in OK432-treated infected mice 7 days after inoculation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvants, Immunologic↗

PubMed2000

In vitro activity of the new ketolide telithromycin compared with those of macrolides against Streptococcus pyogenes: influences of resistance mechanisms and methodological factors.

One hundred and seven clinical isolates of Streptococcus pyogenes, 80 susceptible to macrolides and 27 resistant to erythromycin A (MIC >0.5 microgram/ml), were examined. The erythromycin A-lincomycin double-disk test assigned 7 resistant strains to the M-phenotype, 8 to the inducible macrolide, lincosamide, and streptogramin B resistance (iMLS(B)) phenotype, and 12 to the constitutive MLS(B) resistance (cMLS(B)) phenotype. MICs of erythromycin A, clarithromycin, azithromycin, roxithromycin, and clindamycin were determined by a broth microdilution method. MICs of telithromycin were determined by three different methods (broth microdilution, agar dilution, and E-test methods) in an ambient air atmosphere and in a 5 to 6% CO(2) atmosphere. Erythromycin A resistance genes were investigated by PCR in the 27 erythromycin A-resistant isolates. MICs of erythromycin A and clindamycin showed six groups of resistant strains, groups A to F. iMLS(B) strains (A, B, and D groups) are characterized by two distinct patterns of resistance correlated with genotypic results. A- and B-group strains were moderately resistant to 14- and 15-membered ring macrolides and highly susceptible to telithromycin. All A- and B-group isolates harbored erm TR gene, D-group strains, highly resistant to macrolides and intermediately resistant to telithromycin (MICs, 1 to 16 microgram/ml), were all characterized by having the ermB gene. All M-phenotype isolates (C group), resistant to 14- and 15-membered ring macrolides and susceptible to clindamycin and telithromycin, harbored the mefA gene. All cMLS(B) strains (E and F groups) with high level of resistance to macrolides, lincosamide, and telithromycin had the ermB gene. The effect of 5 to 6% CO(2) was remarkable on resistant strains, by increasing MICs of telithromycin from 1 to 6 twofold dilutions against D-E- and F-group isolates.

Anti-Bacterial Agents↗

PubMed2000

Streptococcus pyogenes resistance to erythromycin in relation to macrolide consumption in Spain (1986-1997).

The relationship between Streptococcus pyogenes resistance to erythromycin and macrolide consumption in Spain was studied. Erythromycin resistance was highly correlated with the consumption of total macrolides (r = 0.88, P<0.01). When macrolides were grouped into posological subgroups according to their pharmacokinetic and pharmacodynamic properties and analysed separately, erythromycin resistance appeared to be related mainly to those macrolides taken twice daily (bd) (r = 0.86, P<0.01) and those taken once daily (od) (r = 0.87, P<0.01), but not to those taken four (qds) or three times a day (tds) (r = -0.04, P: = 0.90). A progressive increase in the erythromycin resistance curve was seen after the consecutive introduction of both bd and od macrolides, which contributed to the increase in the total macrolide consumption, replacing tds macrolide prescription. Although this ecological analysis cannot establish an unequivocal causal relationship between antibiotic consumption and S. pyogenes resistance, the data are consistent with the hypothesis that widespread use of macrolides, mainly of bd and od macrolides, resulted in an increased prevalence of S. pyogenes resistant to erythromycin in Spain.

Anti-Bacterial Agents↗

PubMed1996

Pharmacodynamic effects of sub-MICs of benzylpenicillin against Streptococcus pyogenes in a newly developed in vitro kinetic model.

The pharmacodynamic effects of benzylpenicillin against Streptococcus pyogenes were studied in a new in vitro kinetic model in which bacterial outflow was prevented by a filter membrane. Following the administration of an initial dose of antibiotic, decreasing concentrations were produced by dilution of the medium. A magnetic stirrer was placed above the filter to avoid blockage of the membrane and to ensure homogeneous mixing of the culture. Repeated samplings were easily provided through a silicon diaphragm. Streptococci were exposed to a single dose corresponding to 1.5, 10, 100, or 500 x the MIC of benzylpenicillin and also to an initial concentration of 10 x the MIC of benzylpenicillin, followed by exposure to a repeated dose after 8 h yielding 10 or 1.5 x the MIC. Experiments were also performed with 10 x the MIC of benzylpenicillin with a half-life of 3 h or an initial half-life of 1.1 h that was altered to 3 h at the time point at which the antibiotic concentrations and MIC intersected. Bacterial killing and regrowth were followed by determining viable counts. The post-MIC effect (PME) was defined as the difference in time for the numbers of CFU in the culture vessel to increase 1 log10 CFU/ml, calculated from the numbers obtained at the time when the antibiotic concentration had declined to the MIC, and the corresponding time for a control culture, grown in a glass tube without antibiotic, to increase 1 log10 CFU/ml. To determine how much of the PME was attributable to subinhibitory concentrations, penicillinase was added to a part of the culture drawn from the flask at the time when the antibiotic concentration had fallen to the MIC. The longest PME was found in the experiments in which the half-life was extended from 1.1 to 3 h at the MIC. This illustrated that sub-MICs are sufficient to prevent regrowth. However, when the half-life was 3 h during the whole experiment, the PME was shorter, indicating that when concentrations decline slowly penicillin-binding proteins will already be present in amounts sufficient for regrowth at the time when the MIC is reached. The PME may prove to be a more reliable factor than the in vitro postantibiotic effect or postantibiotic sub-MIC effect for the design of optimal dosing schedules, since the PME, like the in vivo postantibiotic effect, includes the effects of subinhibitory concentrations and therefore better reflects the clinical situation with fluctuating antibiotic concentrations.

Colony Count, Microbial↗

PubMed1996

Streptococcus pyogenes infection in mice.

We inoculated 5 to 7-week-old female C3HeB/FeJ mice with Streptococcus pyogenes strain B514-Sm (type M50) by both an intranasal and intratracheal route and characterized the resulting illness. Following intranasal inoculation, the animals developed signs of illness within 1 to 8 days post-inoculation which correlated with acute, suppurative, bronchopneumonia during histopathologic analysis; however, the relationship of response to dose was non-linear, as seen previously in a small group of mice. Intratracheal inoculations were then performed to increase the quantitative reliability of the model. Following intratracheal inoculation, the animals succumbed to an illness that was indistinguishable from that seen after intranasal inoculation, and the incidence of pneumonia followed a steep dose response curve. The dose at which 50% of the animals exhibited signs of respiratory illness within 72 h was 1.0 x 10(7) colony forming units. All of the animals that appeared ill had lung lesions as determined by gross and histopathologic examination. Bacteraemia followed pneumonia in two-thirds of the intratracheally inoculated animals, indicating that the S. pyogenes had crossed tissue barriers. We hope that this model will be useful in future studies concerning the role of suspected streptococcal virulence factors in the later stages of pathogenesis of invasive S. pyogenes infection.

Animals↗

PubMed1986

Type 1 M protein of Streptococcus pyogenes. N-terminal sequence and peptic fragments.

Limited proteolysis of the surface of type 1 Streptococcus pyogenes by pepsin gives rise to fragment Pep M1 of Mr 20270 as the main product which covers the N-terminal part of the M protein. The amino acid sequence was determined of the N-terminal region of the M protein representing the most exposed part of the molecule on the surface fibrils of streptococcal cells, which seems to be very important for the differentiation of the individual serological types. The sequence differs from the homologous N-terminal sequences of types 5, 6 and 24, and shows a homology with sequences repeating in the chain of type 24. Fragment Pep M1 binds to fibrinogen; the absence of its 30 N-terminal amino acid residues, however, abolishes this interaction which is believed to play a role in the virulence of S. pyogenes.

Amino Acid Sequence↗

PubMed2003

emm Gene distribution among erythromycin-resistant and -susceptible Italian isolates of Streptococcus pyogenes.

The phenotypes and genetic determinants for macrolide resistance were determined for 167 erythromycin-resistant Streptococcus pyogenes strains. A cMLS phenotype was shown in 18% of the erythromycin-resistant strains, while inducible resistance was apparent in 31% and the M phenotype was apparent in 50%. The emm gene type of this set of resistant isolates and that of 48 erythromycin-sensitive isolates were determined. emm2 and emm48 were recorded only in the resistant strains of the M phenotype, while approximately all of the strains harboring the emm22 gene had the cMLS phenotype. More than 80% of the emm89-positive strains had the iMLS phenotype, and the same portion of emm4 strains presented the M phenotype. emm3 is recorded only among sensitive strains. The distribution of frequencies of the genetic determinant for the virulence factor M protein was significantly different both among organisms of different types of resistance and between resistant and sensitive populations of S. pyogenes under study.

Bacterial Proteins↗

PubMed2006

Fluoroquinolone resistance in invasive Streptococcus pyogenes isolates due to spontaneous mutation and horizontal gene transfer.

Fluoroquinolone resistance in Streptococcus pyogenes has been described only anecdotally. In this study we describe two invasive ciprofloxacin-resistant S. pyogenes isolates (ciprofloxacin MICs, 8 mg/liter), one of which shows evidence of interspecies recombination. The quinolone resistance-determining regions of gyrA and parC were sequenced. In both isolates, there was no evidence for an efflux pump and no mutation in gyrA. Both isolates had an S79F mutation in parC that is known to confer fluoroquinolone resistance. In addition, a D91N mutation in parC, which is not related to fluoroquinolone resistance but is a feature of the parC sequence of Streptococcus dysgalactiae, was found in one isolate. The parC nucleotide sequence of that isolate showed greater diversity than that of S. pyogenes. A GenBank search and phylogenetic analysis suggest that this isolate acquired resistance by horizontal gene transfer from S. dysgalactiae. Statistical testing for recombination confirmed interspecies recombination of a 90-bp sequence containing the S79F mutation from S. dysgalactiae. For the other isolate, we could confirm that it acquired resistance by spontaneous mutation by identifying the susceptible ancestor in an outbreak setting.

Adult↗

PubMed2000

Virulent aggregates of Streptococcus pyogenes are generated by homophilic protein-protein interactions.

Many strains of the important human pathogen Streptococcus pyogenes form aggregates when grown in vitro in liquid medium. The present studies demonstrate that this property is crucial for the adherence, the resistance to phagocytosis and the virulence of S. pyogenes. A conserved sequence of 19 amino acid residues (designated AHP) was identified in surface proteins of common S. pyogenes serotypes. This sequence was found to promote bacterial aggregation through homophilic protein-protein interactions between AHP-containing surface proteins of neighbouring bacteria. A synthetic AHP peptide inhibited S. pyogenes aggregation, reduced the survival of S. pyogenes in human blood and attenuated its virulence in mice. In contrast, mutant bacteria devoid of surface proteins containing AHP-related sequences did not aggregate or adhere to epithelial cells. These bacteria are also rapidly killed in human blood and show reduced virulence in mice, underlining the pathogenic significance of the AHP sequence and S. pyogenes aggregation.

Amino Acid Sequence↗

PubMed2001

Restoration of Mga function to a Streptococcus pyogenes strain (M Type 50) that is virulent in mice.

The Mga protein in B514Sm, a Streptococcus pyogenes strain isolated as a mouse pathogen, contains amino acid substitutions at conserved sites that render the protein defective. Replacement of mga50 with the functional homolog mga4.1 restored full expression of Mga-regulated proteins. Restoration of Mga function did not affect fibrinogen binding, nor did it affect virulence in several mouse models of group A streptococcus infection.

Animals↗

PubMed1996

[Antibiotic resistance to erythromycin, clindamycin and tetracycline of 573 strains of Streptococcus pyogenes (1992-1994)].

BACKGROUND: The aim of this study was to know the antibiotic resistence of Streptococcus pyogenes to erythromycine, clindamycine and/or tetracycline in community samples. The second aim was to determine the existence of multiresistant strains and to know the relationship between resistant strains, clinical samples and age of the patient. METHOD: A retrospective analysis was performed in all the strains of S. pyogenes isolated from January 1992 to December 1994. Antibiotic sensitivity was studied by MIC by the microdilution method using the Pasco semiautomatic system. RESULTS: During the study period 573 beta hemolytic streptococci were identified as S. pyogenes. The global resistance to erythromycine (2.8%), clindamycine (1.4%) and tetracycline (7.3%) remains at low levels but has significantly increased in the case of erythromycine (p < 0.05) and tetracycline (p < 0.05) over these 3 years. The incidence of strains resistant to clindamycine has also increased slowly although this rise is not significant. Five strains (0.9%) were not sensitive to the three antibiotics studied, 4 being isolated in the last trimester of 1994 in pharyngeal exudates. S. pyogenes resistant to erythromycine was most frequently isolated from cutaneous lesions and in pediatric patients (under the age of 14 years). CONCLUSIONS: These results confirm the trend towards an increase in the number of strains of S. pyogenes resistant to erythromycine, clindamycine and/or tetracycline, being most often found in cutaneous lesions and pediatric patients.

Anti-Bacterial Agents↗