SEARCH · PubMed Health

Results for “Streptococcus pyogenes”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 397 records · Page 22Linked to original sources

PubMed1988

Proliferative response of human T lymphocytes to a vaccinal preparation of ribosomes from Streptococcus pyogenes.

The in vitro lymphocyte-activating properties of a ribosomal preparation of Streptococcus pyogenes were investigated. The preparation was mitogenic for human lymphocytes with a peak of 3H-thymidine incorporation occurring after 3-5 days of culture. The response was abolished by removal of CD3-positive cells and by alteration of accessory cells by exposure to L-leucine methyl ester. Most of the cells synthesizing DNA at the end of the culture expressed CD4 or CD8 but not CD20 antigens. No immunoglobulin synthesis was demonstrable. Although the same preparation was shown to be a T-independent polyclonal B-cell activator of murine cells, it preferentially triggers T cells in humans.

Bacterial Vaccines↗

PubMed1987

Antitumor activity of streptococcal acid glycoprotein produced by Streptococcus pyogenes Su.

Streptococcal acid glycoprotein (SAGP) was purified from the cultured cells of Streptococcus pyogenes Su, and its in vitro and in vivo antitumor activities were investigated in comparison with those of OK-432, a cell preparation of S. pyogenes Su which is used clinically as a potent antitumor agent. SAGP inhibited the growth of several tumor cell lines in vitro at less than 0.1 microgram/ml, while it did not affect the growth of the other tumor and normal cell lines even at 10 micrograms/ml. This selective cytotoxicity is a unique characteristic of SAGP. OK-432 did not show cytotoxicity in vitro. SAGP also showed a considerable life-span-prolonging effect on mice bearing Meth A tumor and inhibited the growth of sarcoma 180 tumor implanted im. The comparison of antitumor activities between SAGP and OK-432 definitely suggested a difference in the mechanisms of their actions, even though they were derived from the same bacterial strain.

Animals↗

PubMed2005

Characterisation of fluoroquinolone-resistant clinical isolates of Streptococcus pyogenes in Barcelona, Spain.

Resistance mechanisms and clonal relationships were determined for six Streptococcus pyogenes isolates with low- or high-level ciprofloxacin resistance. Four isolates displayed reduced susceptibility to ciprofloxacin and levofloxacin and had alterations in ParC: Ser80-->Pro (isolate emm3.1); Ser79-->Ala (two isolates emm6.0); and a double substitution Ser79-->Phe and Ala121-->Val (isolate emm12.27). Two isolates (emm12.26) displayed high-level resistance to ciprofloxacin and levofloxacin, as well as to other quinolones. These isolates had the same double substitution in ParC as isolate emm12.27, and an additional substitution (Ser81-->Tyr) in GyrA. Resistance patterns, emm typing and sequencing of the quinolone resistance-determining regions defined two clusters containing three and two isolates, respectively.

Amino Acid Substitution↗

PubMed1995

Regulation of host cell recognition in Streptococcus pyogenes.

Protein F, a fibronectin-binding protein, and the M protein of Streptococcus pyogenes both play important roles in directing adherence to different populations of host cells in the skin. Expression of both proteins is regulated in response to alterations in atmosphere. Transcriptional control of mry, a positive-acting regulator of expression of the gene which encodes the M protein (emm) in response, to elevated levels of CO2, is a mechanism for control of emm expression in response to atmosphere. Expression of protein F is controlled at the level of transcription in response to the concentration of O2, and its expression is stimulated in the presence of superoxide. Further support for a role of superoxide in regulation of prtF expression comes from the observation that an S. pyogenes mutant which contains an insertionally inactivated gene for superoxide dismutase (sod) becomes hypersensitive to superoxide and will express prtF constitutively. A second strain also demonstrates constitutive expression of prtF but contains a functional sod. Complementation analyses in this strain using a prtF allele cloned from a regulating host and a novel method for shuttle mutagenesis which utilized the transposon mini-gamma delta have been used to identify rofA, a positive-acting regulator of prtF expression. A model for the role of the surface proteins, F and M and their regulatory genes mry and rofA in streptococcal infections of the skin will be discussed.

Antigens, Bacterial↗

PubMed2004

Antimicrobial susceptibility and macrolide resistance genes in Streptococcus pyogenes collected in Austria and Hungary.

A total of 341 clinical isolates of Streptococcus pyogenes from Vienna, Austria and three Hungarian cities were tested for susceptibility to four macrolides and 12 other antibiotics. All isolates were fully susceptible to penicillin and the other beta-lactams tested. A high level of tetracycline resistance was found in Austria (26.7%) and in Hungary (30.5%). The rate of resistance to erythromycin, clarithromycin and azithromycin was 4.7% in Vienna and 3.7% in the Hungarian communities. In both countries, the MIC(90) values of erythromycin and clarithromycin were 0.12 mg/L and the MIC(90) of josamycin was 0.5mg/L. The M phenotype of resistance conferred by the mefA genes was predominant (n = 9) among the macrolide-resistant isolates (n = 14).

Anti-Bacterial Agents↗

PubMed1998

Different endosomal proteolysis requirements for antigen processing of two T-cell epitopes of the M5 protein from viable Streptococcus pyogenes.

We studied endosomal proteolysis of the surface fibrillar M5 protein from viable Streptococcus pyogenes as an essential step involved in major histocompatibility complex class II-restricted antigen processing of two immunodominant CD4(+) T-cell epitopes (17-31/Ed and 308-319/Ad). Intracellular proteolysis of viable streptococci for presentation of 17-31, bound by serine proteinase cleavage sites, was mediated by serine proteinases, whereas processing of soluble recombinant M5 protein required in addition cysteine proteinases. Furthermore, processing of 17-31 was resistant to ammonium chloride and thus was not dependent on endosome acidification. Cysteine and serine proteinase cleavage sites were located adjacent to 308-319, and its processing was dependent on serine, cysteine, and aspartic proteinases, as well as on endosomal acidification. The data suggest that antigen processing of two major T-cell epitopes on streptococcal M5 protein occurred in different endosomal compartments by different classes of intracellular proteinases.

Amino Acid Sequence↗

PubMed2005

Close correlation of streptococcal DNase B (sdaB) alleles with emm genotypes in Streptococcus pyogenes.

DNase B is a major nuclease and a possible virulence factor in Streptococcus pyogenes. The allelic diversity of streptococcal DNase B (sdaB) gene was investigated in 83 strains with 14 emm genotypes. Of the 15 alleles identified, 11 alleles carried only synonymous nucleotide substitutions. On the other hand, 4 alleles had a non-synonymous substitution other than synonymous substitutions, resulting in the substitution of a single amino acid. The distribution of each allele was generally emm genotype-specific. Only sdaB7 was found in both emm2 and emm4. The promoter region was highly conserved and DNase B protein was similarly expressed in all alleles.

Alleles↗

PubMed1995

[Systemic infection due to group A Streptococcus pyogenes].

A 47-year-old woman developed oedematous swelling of the skin over the left hip and leg, with joint pains and reddening over joints of the hands and left ankle. 2 months before her son had had scarlet fever, following which the patient had two episodes of fever. Shortly before hospitalization she was treated with a glucocorticoid because a rheumatic disease had been suspected. On admission the blood sedimentation rate was 58/90, the white cell count was 15.100/microliters with left shift in the differential count. The swellings in arms and legs became abscesses which were incised. An abscess over the left buttock, diagnosed by 67-gallium whole-body scintigraphy, was also treated surgically. On the day of admission penicillin (10 mill. IU three times daily intravenously) and, from the 4th day onwards, gentamicin (80 mg three times daily intravenously) were administered. Histological examination of fascia and muscle biopsies revealed nonspecific inflammation without signs of malignancy, white blood culture grew group A Streptococcus pyogenes. 20 days after the surgical intervention the patient was discharged in full health. Necrotizing fasciitis caused by Streptococcus pyogenes has become more frequent in the last few years and has often been accompanied by severe systemic complications.

Fasciitis↗

PubMed2003

Mutations and horizontal transmission have contributed to sulfonamide resistance in Streptococcus pyogenes.

Two variants of dihydropteroate synthase (DHPS) were found among sulfonamide-resistant Streptococcus pyogenes, one of which was characterized by a 2-amino-acid addition in a conserved part of the enzyme. The enzyme kinetics of both variants was compared with the kinetics of DHPS from a sulfonamide-susceptible S. pyogenes. The most striking difference was a substantially elevated Ki for both variants, but variations in Km for both of its substrates p-aminobenzoic acid (p-AB) and dihydropteridine-pyrophosphate (pteridine) were also found. In the resistance variant lacking additions, the amino acid at position 213 was changed by site-directed mutagenesis from a Gly to an Arg, which resulted in a lower Ki. The corresponding change from an Arg to a Gly in the DHPS from a susceptible isolate led to a substantially increased Ki, confirming the importance of this amino acid difference for the resistance. Nucleotide sequence determinations of the complete folate operon revealed in some isolates a mosaic pattern of differences compared to the wild type, not only in the genes coding for DHPS and GTP cyclohydrolase (GTPCH) noted earlier but also in genes coding for dihydroneopterin aldolase (DHNA) and hydroxymethylpterin pyrophosphokinase (HPPK). Regions of sequence differences were interspersed with regions of complete identity in a mosaic pattern, indicating a dispersed pattern of uptake of foreign DNA in the resistant isolates.

Amino Acid Sequence↗

PubMed1987

Mechanism and regulation of phosphate transport in Streptococcus pyogenes.

In contrast to results reported with other bacteria, uptake of 32Pi in Streptococcus pyogenes was found to occur rapidly in starved cultures and to be strongly and immediately inhibited by addition of exogenous glycolytic energy sources (such as glucose) and nonglycolytic sources of ATP (such as arginine). Preincubation of starved cells with NaF, iodoacetate, or arsenate eliminated the inhibiting effect of glucose but not that of arginine. In accordance with the hypothesis that transport was attributable to Pi-Pi exchange, uptake and efflux of 32Pi in the presence of trans unlabeled Pi exhibited similar characteristics and were largely eliminated by reduction of the trans Pi concentration. Neither process was inhibited appreciably by pretreatment of cells with ionophores or metabolic inhibitors, but both processes were abolished by exposure to p-chloromercuribenzoate. Inhibition by both exogenous energy sources resulted in a reduction in the maximal velocity of transport (Vmax). Whereas arginine also caused a shift in the apparent Michaelis-Menten constant (Km) to larger values, glucose did not alter the Km. On the basis of the results reported, we propose that the rate of Pi exchange is determined positively by the intracellular and extracellular concentrations of Pi and negatively by ATP or metabolites thereof. The mechanism of ATP action is unknown but could involve either covalent or noncovalent modification of the carrier protein.

Adenosine Triphosphate↗

PubMed1977

The isolation of Streptococcus pyogenes from throat swabs.

Simulated throat swabs were prepared with known numbers of Streptococcus pyogenes; some were suspended in pasteurised human saliva and an equal number in saline. Two types of commercially available swabs were tested; these were composed of (1) plain, buffered, cotton wool, and (2) albumen-coated cotton wool. The mean recovery rates of first platings on solid media from albumen-coated and plain cotton-wool swabs were similar (8-2% and 8-3%) and the mean recovery rates from platings 1-4 were also similar (6-6% and 6-5%). The greater the delay in plating, the less were the chances of recovery of streptococci, although the viability of these was significantly prolonged on swabs held at 4 degrees C. Similar results were again produced by both types of swabs; processing swabs in saliva, however, produced by both types of swabs; processing swabs in saliva, however, produced a recovery rate that was 1-2% greater than the rate for the saline series. Swabs were also agitated or squeezed by forceps in nutrient broth to release any organisms they contained, and standard samples of the broth were then plated on solid media. Counts thus obtained indicated that about 50% of the original inoculum was still viable and could be recovered from the broth; in comparison, recoveries from initial direct plating of the swabs were low. No demonstrable toxic effect was produced by the cotton wool in these experiments.

Albumins↗

PubMed1992

M protein gene typing of Streptococcus pyogenes by nonradioactively labeled oligonucleotide probes.

A new approach for the typing of Streptococcus pyogenes is described. Oligonucleotide probes of 30 nucleotides in length were derived from currently known sequences of the N-terminal regions of M protein genes (emm genes). The oligonucleotides were labeled with digoxigenin-dUTP and hybridized to dot-blotted genomic DNA from 116 group A streptococcal strains of serotypes M-1, M-2, M-3, M-5, M-6, M-12, M-18, M-19, M-24, and M-49. Hybridization reactions were visualized with a chemiluminescent substrate. In comparison with conventional serological typing of expressed M proteins, the binding of the probes to the corresponding emm genes exhibited 100% sensitivity and specificity. The results emphasize the high degree of type-specific conservation of the N-terminal regions of emm genes from reference strains and epidemiologically unrelated U.S. and European clinical isolates. The existence of two distinct genetic subgroups among eight investigated M-49 strains was unequivocally shown by hybridization assays and further confirmed by nucleotide sequence data obtained from four selected M-49 strains. Because oligonucleotide probes are relatively easy to prepare, easy to handle, and known to give consistent interlaboratory results, the "oligotyping" technique appears to offer potential advantages over conventional serological typing methods.

Antigens, Bacterial↗

PubMed2002

PolC-type polymerase III of Streptococcus pyogenes and its use in screening for chemical inhibitors.

The polC gene from Streptococcus pyogenes (S. pyogenes, strain SF370) has been cloned and expressed in Escherichia coli (E. coli) as a fusion protein containing an N-terminal histidine tag. The purified recombinant enzyme showed an apparent molecular mass of 160 kDa on SDS-PAGE and a specific activity of 3.5 nmol/min/mg when assayed in the presence of calf thymus DNA and the four deoxyribonucleoside triphosphates. This activity was inhibited by TMAU, a specific inhibitor of PolC. To facilitate kinetic studies, and high-throughput assays, a double-stranded oligo DNA primer/template was used as a substrate. The minimum requirement for the length of the substrate was a 20-base oligo primer annealed to a 35-base template. PolC activity was detected either by a filter-binding format or by a novel homogeneous scintillation proximity assay (SPA). Sensitivity to inhibition by anilinouracil analogs was improved by incorporating three deoxycytidines in the template strand as the first 3 bases to be copied by the polymerase. Inhibition of PolC activity by trimethyleneanilinouracil by the filtration and SPA methods gave comparable results, but the SPA assay uses less radioactive label, is less time-consuming, and is amenable to high-throughput formatting.

Animals↗

PubMed1994

Elucidation of the structure of SA-FF22, a lanthionine-containing antibacterial peptide produced by Streptococcus pyogenes strain FF22.

The antibacterial peptide SA-FF22, produced by the pathogen Streptococcus pyogenes strain FF22 was purified and features of its primary and secondary structure were characterised. Mass spectrometry demonstrated the pure peptide had a mass of 2794Da while, amino acid analysis revealed the presence of the unusual, thioether amino acids lanthionine and 3-methyllanthionine; thus SA-FF22 is a member of the group of antibacterial polypeptides termed lantibiotics. Furthermore, amino acid sequencing showed a unique sequence which was blocked at position 23 by a residue of the unsaturated amino acid 2,3-didehydrobutyrine. Carboxypeptidase-Y digestion could be used to demonstrate that serine occupies the C-terminal position only after complete oxidation of the thioether amino acid bridges, suggesting that the three-dimensional structure of the native peptide may prevent access of the enzyme to the C-terminus. Fragmentation of the native peptide with a variety of proteolytic enzymes failed to yield a peptide containing less than all three of the cross-linked lanthionine and methyllanthionine residues and demonstrated that all three thioether bridges overlapped. Analysis of the circular dichroism of SA-FF22 in various concentrations of 2,2,2-trifluoroethanol in water, SDS micelles and in the presence of artificial phospholipid vesicles suggested that there is significant change in its secondary structure from aqueous to lipophilic environments.

Alanine↗

PubMed2000

Contribution of NADH oxidase to aerobic metabolism of Streptococcus pyogenes.

An understanding of how the heme-deficient gram-positive bacterium Streptococcus pyogenes establishes infections in O(2)-rich environments requires careful analysis of the gene products important in aerobic metabolism. NADH oxidase (NOXase) is a unique flavoprotein of S. pyogenes and other lactic acid bacteria which directly catalyzes the four-electron reduction of O(2) to H(2)O. To elucidate a putative role for this enzyme in aerobic metabolism, NOXase-deficient mutants were constructed by insertional inactivation of the gene that encodes NOXase. Characterization of the resulting mutants revealed that growth in rich medium under low-O(2) conditions was indistinguishable from that of the wild type. However, the mutants were unable to grow under high-O(2) conditions and demonstrated enhanced sensitivity to the superoxide-generating agent paraquat. Mutants cultured in liquid medium under conditions of carbohydrate limitation and high O(2) tension were characterized by an extended lag phase, a reduction in growth, and a greater accumulation of H(2)O(2) in the growth medium compared to the wild-type strain. All of these mutant phenotypes could be overcome by the addition of glucose. Either the addition of catalase to the culture medium of the mutants or the introduction of a heterologous NADH peroxidase into the mutants eliminated the accumulation of H(2)O(2) and rescued the growth defect of the mutants under high-O(2) conditions in carbohydrate-limited liquid medium. Taken together, these data show that NOXase is important for aerobic metabolism and essential in environments high in O(2) with carbohydrate limitation.

Aerobiosis↗

PubMed1979

Quantitative immunoelectrophoretic analysis of Streptococcus pyogenes membrane.

The antigenic composition and molecular structure of the plasma membrane of Streptococcus pyogenes (group A; M type 6) were studied by crossed immunoelectrophoresis (XIE) and other related quantitative immunoelectrophoretic techniques. After establishment of a reference pattern of 29 immunoprecipitates, the relative differences in amounts of individual antigens contained in membranes isolated from cells that were harvested during the exponential or stationary phase of growth were examined. Relative increases and decreases in amounts of individual antigens were estimated from the areas subtended by immunoprecipitates after XIE of Triton X-100 extracts. The asymmetric distribution of antigens on the inner and outer surfaces of the membrane was established in absorption experiments with intact, stable protoplasts. Of the 29 immunoprecipitates, 8 appeared to contain antigens exposed on the outer surface of the membrane, whereas 11 appeared to contain antigens either located on the inner surface or unexposed. Six antigens appeared to have limited exposure on the outer surface, and four others remain to be assigned. Certain immunoprecipitates were characterized with respect to enzymatic activity or interaction with the lectin concanavalin A. Reduced nicotinamide adenine dinucleotide dehydrogenase (EC 1.6.99.3), adenosine triphosphatase (EC 3.6.1.3), and polynucleotide phosphorylase (EC 2.3.7.8) were demonstrated by zymogram techniques. The latter two activities were present within the same immunoprecipitate, suggesting the occurrence of a multienzyme complex. In addition, the areas under the immunoprecipitates containing the three enzymatic activities were not affected by absorption of antimembrane immunoglobulin with intact protoplasts and thus appeared to be located on the inner surface of the membrane. The results from absorption experiments also suggested that the exposure of outer protoplast surface antigens was greater on protoplasts from exponential-phase cells than on those from stationary-phase cells, even when found in increased amounts in the latter.

Adenosine Triphosphatases↗

PubMed1994

A novel site-specific recombinase encoded by the Streptococcus pyogenes plasmid pSM19035.

Genetic evidence suggests that the beta protein encoded by the Streptococcus pyogenes plasmid pSM19035 is involved both in the resolution of plasmid multimers into monomers and in DNA inversion. In this report we show that the highly purified beta protein is unable to mediate DNA recombination unless a host factor(s) is provided. In the presence of the host factor(s), the beta protein is able to catalyze in vitra intramolecular recombination between two specific sites on supercoiled templates: DNA resolution was obtained when the two recombination sites were directly oriented, whereas DNA inversion was the product if the recombination sites were in inverse orientation. In the absence of the host factor(s) the beta protein forms a specific complex with its target site. The beta protein binding site has been localized by DNase I footprinting to an 85 bp region that can be divided into two discrete sites (I and II). These sites are about 34 bp in length, they are separated by about 16 bp, and contain two 12 to 13 bp imperfectly conserved sequences (half-sites) with dyad axis symmetry. The protein binds co-operatively to sites I and II; between 3.6 and 4.2 beta protein protomers are required to saturate the DNA substrate. These data, together with gel retardation assays, suggest that the protein binds to DNA as two dimers, one to each discrete site, and that the dimers probably interact with each other. The beta protein binding site, though it resembles that of other DNA resolvases of the Tn3/gamma delta (Tn1000) family, differs in that only two adjacent sites are found (sites I and II), while those DNA resolvases normally bind to three adjacent sites. The results presented here suggest that a host factor(s) could work as an accessory effector to compensate for the absence of the third binding site.

Bacterial Proteins↗

PubMed2000

Resistance to multiple fluoroquinolones in a clinical isolate of Streptococcus pyogenes: identification of gyrA and parC and specification of point mutations associated with resistance.

A strain of Streptococcus pyogenes resistant to multiple fluoroquinolones was isolated from the blood of an immunocompromised patient. Resistance to fluoroquinolones in S. pyogenes has not been previously studied. Compared to 10 sensitive strains of S. pyogenes, the fluoroquinolone-resistant clinical isolate of S. pyogenes presented point mutations in gyrA, predicting that serine-81 was changed to phenylalanine and that methionine-99 was changed to leucine, and in parC, predicting that serine-79 was changed to tyrosine. The mechanism of fluoroquinolone resistance in this isolate of S. pyogenes appears to be analogous to previously reported mechanisms for Streptococcus pneumoniae.

Anti-Infective Agents↗