PubMed Health⌕ Search

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 721 records · Page 40Linked to original sources
PubMed2005

Asymptomatic infection by Streptococcus pyogenes in schoolchildren and diagnostic usefulness of antideoxyribonuclease B.

This study is designed to evaluate the immune status of schoolchildren with respect to Streptococcus pyogenes, and to ascertain the usefulness of antideoxyribonuclease B (ADNase B). Antistreptolysin O (ASO) and ADNase B concentrations were measured quantitatively in 266 serum samples from healthy elementary school children in Seoul. Simultaneously, throat cultures were taken in order to isolate S. pyogenes and other beta-hemolytic streptococci (BHS). The upper limits of the normal (ULN) concentration of ASO and ADNase B were 326 IU/mL, and 362 IU/mL, respectively. The correlation between ADNase B (y) and ASO (x) was y = 0.4x+173 (r = 0.46). Mean ADNase B level (392 IU/mL) was significantly higher in children with S. pyogenes than in those with non-group A BHS (236 IU/mL) or no BHS (234 IU/ mL). Some schoolchildren were proven, via ASO and ADNase B tests, to be harboring asymptomatic S. pyogenes infections. The high ULN of ASO and ADNase B in schoolchildren should be carefully considered, in order to interpret the data collected from the patients. We could add the ADNase B test to our set of diagnostic tools, which would allow us to more accurately detect and diagnose streptococcal infections, as ADNase B was more specifically related to the results of throat cultures, and there was little correlation between ASO and ADNase B.

Antibodies, Bacterial↗
PubMed1976

Adaptation of an osmotically fragile L-form of Streptococcus pyogenes to physiological osmotic conditions and its ability to destroy human heart cells in tissue culture.

An osmotically fragile L-form of Streptococcus pyogenes, type 12, was quickly rendered osmotically stable by decreasing the sodium chloride content of the growth medium and with the temporary use of oleic acid. The change from osmotic fragility to stability was accompanied by changes in cell yield, generation time, saturated/unsaturated fatty acid ratio of the membrane, and cytoplasmic protein composition. Finally, this resulting osmotically stable L-form survived and was capable of rapidly destroying Girardi human heart cells in tissue culture.

Cell Survival↗
PubMed1992

Duplication of a DNA sequence homologous to genes for immunoglobulin receptors and M proteins in Streptococcus pyogenes.

The nucleotide sequence of an open reading frame of 355 amino acids downstream of the IgA-binding protein gene arp4 in Streptococcus pyogenes M-type 4 has been determined. Analysis of the deduced amino acid sequence for the open reading frame shows an extensive homology to streptococcal M proteins and immunoglobulin binding proteins. Expression of the open reading frame has not been detected and the function may be as a genetic reservoir in the generation of new immunoglobulin receptors and antigenic variants of M proteins.

Amino Acid Sequence↗
PubMed1989

Serine and tyrosine protein kinase activities in Streptococcus pyogenes. Phosphorylation of native and synthetic peptides of streptococcal M proteins.

Two forms of protein kinase activity were isolated from crude extracts of Streptococcus pyogenes and partially purified by ion exchange chromatography and affinity chromatography. The phosphorylation activities were shown to be insensitive to cAMP, required the presence of divalent cations, and eluted from a Sephadex G-200 column with approximate molecular masses of 60 and 45 kDa, respectively. Both enzymes were capable of phosphorylating eukaryotic proteins and synthetic polypeptides in addition to endogenous and heterologous prokaryotic proteins at serine and tyrosine residues. Firm evidence for tyrosine kinase activity was obtained by the use of a tyrosine kinase-specific substrate, a 4:1 glutamate:tyrosine copolymer. Both protein kinases phosphorylated HPr, a phosphocarrier protein of the phosphotransferase system isolated from S. pyogenes and Bacillus stearothermophilus, but failed to phosphorylate HPr isolated from Escherichia coli. Both also phosphorylated a native polypeptide fragment (pep M24) as well as synthetic peptide copies of M protein, the major virulence determinant of group A streptococci. These results indicate that prokaryotic protein kinases are capable of phosphorylating eukaryotic proteins and suggest that the protein kinases of streptococci may play an important role not only in the phosphotransferase system but also in the virulence properties of these organisms.

Amino Acid Sequence↗
PubMed2002

Pharmacodynamics of moxifloxacin against Streptococcus pyogenes in an in vitro kinetic model.

The aim of the present study was to investigate the pharmacodynamics of moxifloxacin against strains of Streptococcus pyogenes with different susceptibilities to erythromycin by using an in vitro kinetic model simulating human pharmacokinetics of moxifloxacin at oral doses of 400 and 200 mg, respectively. When the different strains of S. pyogenes were exposed to the higher dose, the number of bacteria was reduced below the detection limit after 12 h and no regrowth was noted during the following 12 h. At the lower dose there was regrowth of the strains with constitutive and inducible erythromycin resistance of the MLS(B) phenotype. Replication assays of the regrowing bacteria indicated that the failure of moxifloxacin to kill the MLS(B) strains at the lower dose was likely caused by the emergence of preexisting resistant subpopulations. Thus, the present study indicates that the presently used 400-mg dose seems to have an advantage over the lower dose in that the risk for selection of resistant subpopulations is minimized.

Anti-Infective Agents↗
PubMed1988

Purification and characterization of a novel cytotoxic substance from cell-free extract of Streptococcus pyogenes.

A cytotoxic substance designated as streptococcal cytotoxic protein (SCP) was isolated from a cell-free extract of the Su strain of Streptococcus pyogenes possessing cytotoxic and antitumor activity. SCP was purified with a series of column chromatography and preparative PAGE to give a homogeneous single band as revealed by PAGE analysis. The purified SCP has a molecular mass of 165 kDa, composed of four 43 kDa subunits, and its pI is 4.3. SCP was sensitive to proteinases and was labile to heat and at acidic or alkaline pH. SCP showed inhibitory effects on the [3H]thymidine, [3H]uridine and [3H]leucine uptakes and on the growth of cells, and released 51Cr from cells when the protein was added to the cultures of Ehrlich ascites carcinoma (EAC), mouse mammary tumor (MM-2), leukemia (L-1210) and NIH-3T3 mammalian cells in vitro. SCP also showed an antitumor effect on EAC or MM-2 tumor-bearing mice but not on L-1210 tumor-bearing mice in vivo.

Amino Acids↗
PubMed1999

Growth-phase-dependent expression of virulence factors in an M1T1 clinical isolate of Streptococcus pyogenes.

The effect of growth phase on expression of virulence-associated factors was studied by Northern hybridization in an M1T1 clinical isolate of Streptococcus pyogenes. Expression of M protein, C5a peptidase, and capsule was maximal in the exponential phase of growth, while streptococcal pyrogenic exotoxins A and B and mitogenic factor were maximally expressed in later phases of growth.

Bacterial Proteins↗
PubMed1957

Studies on Streptococcus pyogenes. III. The effect of trypsin and a cationic detergent on the structure, permeability, and metabolism of the cell.

Electron microscopic observations of Streptococcus pyogenes (strain S43, type 6) treated with trypsin and cetyltrimethylammonium bromide (Cetab) are presented. The concentration of trypsin necessary to remove the M protein antigen was shown to bring about a partial digestion of the cells. The cell protoplasm and protoplasmic membrane were affected. No microscopic changes appeared in the cell wall. Cetab did not alter the appearance of the cells. Both trypsin and detergent altered the permeability of the cell so that citrulline and carbamylphosphate were metabolized. Cells exhibiting enzyme activity on these substrates after Cetab treatment were characterized by the release of lysine, glutamic acid, nucleic acid, and other cellular material. Enzymes responsible for the metabolism of arginine, citrulline, and carbamylphosphate were shown to reside in the cell protoplasm. Cells which had lost their viability after Cetab treatment still possessed the ability to utilize the latter substrates. Under similar conditions the metabolism of glucose did not occur. Normal cells were shown to possess the ability to fluoresce in the presence of a dye. The intensity of the fluorescence was reduced by trypsin treatment.

Ammonium Compounds↗
PubMed1988

Occurrence of mucoid M-18 Streptococcus pyogenes in a central Ohio pediatric population.

During a 1-year period from October 1986 through September 1987, we recovered 116 mucoid, hemolytic Streptococcus pyogenes isolates from clinical specimens collected from patients seen at our pediatric institution. A total of 102 isolates were from throat cultures (101 for pharyngitis, 1 for acute rheumatic fever), 13 were from other superficial body sites, and 1 was from pleural fluid. All of 40 mucoid isolates tested to date were determined to be M-type 18 strains. A direct latex agglutination test for group A carbohydrate antigen in throat swab specimens was equally sensitive in detecting M-18 mucoid and nonmucoid strains (45 of 77 [58%] and 795 of 1,186 [67%], respectively; not significant, P greater than 0.05). Antimicrobial susceptibility tests performed with 40 mucoid and 40 nonmucoid isolates against penicillin and nine other antimicrobial agents showed all strains to be susceptible, with no difference in MICs. All isolates tested were also considered fully susceptible to the bactericidal activity of penicillin. Further studies are needed to establish the relative virulence of M-18 strains and their possible association with the resurgence of acute rheumatic fever in central Ohio and other areas of the United States.

Anti-Bacterial Agents↗
PubMed1983

Mechanism of inducer expulsion in Streptococcus pyogenes: a two-step process activated by ATP.

The mechanism of methyl-beta-D-thiogalactoside-phosphate (TMG-P) expulsion from Streptococcus pyogenes was studied. The expulsion elicited by glucose was not due to exchange vectorial transphosphorylation between the expelled TMG and the incoming glucose since more beta-galactoside was displaced than glucose taken up, and the stoichiometry between TMG and glucose transport was inconstant. Instead, two distinct and sequential reactions, intracellular dephosphorylation of TMG-P followed by efflux of free TMG, mediated the expulsion. This was shown by temporary accumulation of free TMG effected by competitive inhibition of its efflux and by the aid of arsenate, which arrested dephosphorylation of TMG-P but did not affect efflux of free TMG formed intracellularly before arsenate addition. The competitive inhibition of TMG efflux by its structural analogs suggests that a transport protein facilitates the expulsion. Iodoacetate or fluoride prevented TMG-P dephosphorylation and its expulsion. However, provision of ATP via the arginine deiminase pathway restored these activities in the presence of the glycolytic inhibitors and stimulated expulsion in their absence. Other amino acids tested did not promote this restoration, and canavanine or norvaline severely inhibited it. Arginine without glucose neither elicited the dephosphorylation nor evoked the expulsion of TMG-P. Ionophores or ATPase inhibitors did not prevent the expulsion as elicited by glucose or its restoration by arginine. The results suggest that activation of the dephosphorylation-expulsion mechanism occurs independently of a functional glycolytic pathway, requires ATP provision, and is possibly due to protein phosphorylation controlled by a yet unknown metabolite. The in vivo phosphorylation of a protein (approximate molecular weight - 10,000) under the conditions of expulsion was demonstrated.

Adenosine Triphosphatases↗
PubMed1999

Phenotypes and genotypes of erythromycin-resistant Streptococcus pyogenes strains in Italy and heterogeneity of inducibly resistant strains.

A total of 387 clinical strains of erythromycin-resistant (MIC, >/=1 microg/ml) Streptococcus pyogenes, all isolated in Italian laboratories from 1995 to 1998, were examined. By the erythromycin-clindamycin double-disk test, 203 (52.5%) strains were assigned to the recently described M phenotype, 120 (31.0%) were assigned to the inducible macrolide, lincosamide, and streptogramin B resistance (iMLS) phenotype, and 64 (16.5%) were assigned to the constitutive MLS resistance (cMLS) phenotype. The inducible character of the resistance of the iMLS strains was confirmed by comparing the clindamycin MICs determined under normal testing conditions and those determined after induction by pregrowth in 0.05 microg of erythromycin per ml. The MICs of erythromycin, clarithromycin, azithromycin, josamycin, spiramycin, and the ketolide HMR3004 were then determined and compared. Homogeneous susceptibility patterns were observed for the isolates of the cMLS phenotype (for all but one of the strains, HMR3004 MICs were 0.5 to 8 microg/ml and the MICs of the other drugs were >128 microg/ml) and those of the M phenotype (resistance only to the 14- and 15-membered macrolides was recorded, with MICs of 2 to 32 microg/ml). Conversely, heterogeneous susceptibility patterns were observed in the isolates of the iMLS phenotype, which were subdivided into three distinct subtypes designated iMLS-A, iMLS-B, and iMLS-C. The iMLS-A strains (n = 84) were highly resistant to the 14-, 15-, and 16-membered macrolides and demonstrated reduced susceptibility to low-level resistance to HMR3004. The iMLS-B strains (n = 12) were highly resistant to the 14- and 15-membered macrolides, susceptible to the 16-membered macrolides (but highly resistant to josamycin after induction), and susceptible to HMR3004 (but intermediate or resistant after induction). The iMLS-C strains (n = 24) had lower levels of resistance to the 14- and 15-membered macrolides (with erythromycin MICs increasing two to four times after induction), were susceptible to the 16-membered macrolides (but resistant to josamycin after induction), and remained susceptible to HMR3004, also after induction. The erythromycin resistance genes in 100 isolates of the different groups were investigated by PCR. All cMLS and iMLS-A isolates tested had the ermAM (ermB) gene, whereas all iMLS-B and iMLS-C isolates had the ermTR gene (neither methylase gene was found in isolates of other groups). The M isolates had only the macrolide efflux (mefA) gene, which was also found in variable proportions of cMLS, iMLS-A, iMLS-B, and iMLS-C isolates. The three iMLS subtypes were easily differentiated by a triple-disk test set up by adding a josamycin disk to the erythromycin and clindamycin disks of the conventional double-disk test. Tetracycline resistance was not detected in any isolate of the iMLS-A subtype, whereas it was observed in over 90% of both iMLS-B and iMLS-C isolates.

Anti-Bacterial Agents↗
PubMed2006

Enhanced protection against Streptococcus pyogenes infection by intranasal vaccination with a dual antigen component M protein/SfbI lipid core peptide vaccine formulation.

We investigated the efficacy of a synthetic Streptococcus pyogenes vaccine targeting two virulence factors using the Lipid Core Peptide (LCP) delivery system. BALB/c mice were immunised intranasally with LCPs containing peptides encompassing T-cell and B-cell epitopes of the conserved C-repeat region of the M protein (J8) or the fibronectin-binding repeats region (FNBR) of SfbI, or a combination formulation containing peptides representing both antigens. LCPs were co-administered with the TLR2/6 agonist MALP-2 as mucosal adjuvant. Humoral and cellular immune responses stimulated at systemic and mucosal levels were strongest in mice immunised with the dual antigen formulation. Mice were completely protected following a respiratory challenge with a lethal dose of a heterologous S. pyogenes strain, whereas there was 70% and 90% survival in mice immunised with LCP-J8 and LCP-FNBR, respectively. This is the first report demonstrating the elicitation of better protective immunity by a dual antigen component S. pyogenes vaccine.

Adhesins, Bacterial↗
PubMed1993

Cloning, characterization and overexpression of a Streptococcus pyogenes gene encoding a new type of mitogenic factor.

A new type of mitogenic factor, termed MF, has been found in the culture supernatant of Streptococcus pyogenes and its N-terminal amino acid sequence has been determined. On the basis of this sequence, an S. pyogenes gene encoding MF was cloned and its nucleotide sequence was determined. The MF gene includes a long, open reading frame with 813 nucleotides capable of encoding the MF precursor protein with 271 amino acids. Removal of the putative 43 residues as a signal peptide results in the mature MF protein with 228 amino acids. The molecular mass of the mature MF is calculated as 25,363 which is consistent with the previously determined value of 25,370 for MF secreted from S. pyogenes. Neither nucleotide nor amino acid sequence homology was found between the mature MF and other streptococcal pyrogenic exotoxins, such as SPE A, SPE B and SPE C. The mature MF was recombinantly overexpressed as a fusion protein with glutathione S-transferase in Escherichia coli. The recombinant protein showed mitogenic activity in rabbit peripheral blood lymphocytes and immunoreactivity with the rabbit antiserum raised against the secreted MF from S. pyogenes. These data indicate that a unique gene encoding MF was cloned from S. pyogenes.

Amino Acid Sequence↗
PubMed2005

Colonisation rates of Streptococcus pyogenes and Staphylococcus aureus in the oropharynx of a young adult population.

There are very few reports on the rates of oropharyngeal colonisation by Streptococcus pyogenes and Staphylococcus aureus in young adults. The present study found colonisation rates of 9.6% and 26.2%, respectively. These rates are two-fold higher than historical rates, indicating that these organisms may be more prevalent than thought previously. This finding may have important clinical consequences in certain populations, and requires further investigation.

Adolescent↗
PubMed1997

Identification of Streptococcus pyogenes on tonsillar epithelium during infection.

Epithelial cells were swabbed from the tonsillar surfaces of 5 patients with acute tonsillitis culture-positive for Streptococcus pyogenes. By using 10 nm gold particles conjugated to antiserum to S. pyogenes it was possible to trace the actual microorganisms when examined in a transmission electron microscope. The S. pyogenes bacteria, usually in pairs, were attached to the epithelial surface by their pili. The bacteria often formed a hollow in the epithelial cell surface. Coccus-shaped bacteria expressing positive affinity to immunogold-labelled antiserum were intermingled with bacteria, often rods, having no affinity whatsoever to the antiserum. With the immunocytological technique outlined in this study it is possible to study more closely cellular/bacterial adhesion mechanisms.

Adolescent↗
PubMed1973

Cation reversal of inhibition of growth by valinomycin in Streptococcus pyogenes and Clostridium sporogenes.

Study of the antimicrobial spectrum of valinomycin revealed that, in addition to the gram-positive bacteria reported in literature, Streptococcus pyogenes and Clostridium sporogenes are also susceptible to this antibiotic. The minimal inhibitory concentrations (MIC) of the antibiotic for S. pyogenes grown aerobically and anaerobically did not differ markedly, negating the hypothesis that oxidative phosphorylation is involved in the mechanism of action of this antibiotic. This conclusion is further strengthened by the inhibition of growth of C. sporogenes, an obligate anaerobe. In a medium with a low K(+) concentration, the MIC for S. pyogenes was 0.02 mug/ml, the lowest ever recorded for this antibiotic. The inhibition of growth of S. pyogenes and C. sporogenes was readily reversed by addition of K(+) to the medium, indicating a compensation for net efflux of K(+) from the cells when the transmembrane potential reached equilibrium. In contrast to these bacteria, Bacillus subtilis was less susceptible to the antibiotic when the potassium concentration of the medium was low. The addition of potassium in the presence of valinomycin increased the inhibition of growth, which appears to result from dissipation of metabolic energy as in the mitochondrial system.

Aerobiosis↗
PubMed2001

Systemic and mucosal immunizations with fibronectin-binding protein FBP54 induce protective immune responses against Streptococcus pyogenes challenge in mice.

The purpose of this study was to examine the suitability of fibronectin-binding protein FBP54 as a putative vaccine for Streptococcus pyogenes infections. When the distribution of the fbp54 gene among the clinical isolates representing various M serotypes was tested by PCR and Southern blot assays, it was found that all of the strains possess this gene. Furthermore, a significant increase in immunoglobulin G (IgG) antibody titers against FBP54 was observed in sera from patients with S. pyogenes infections compared with those from healthy volunteers (P < 0.005). Mice were immunized with FBP54 subcutaneously, orally, or nasally. An enzyme-linked immunosorbent assay revealed that antigen-specific IgG antibodies were induced in the sera of immunized mice, while high salivary levels of IgA antibodies were detected after oral and nasal immunizations. Mice subcutaneously or orally immunized with FBP54 survived significantly longer following the challenge with S. pyogenes than did nonimmunized mice (P < 0.001). These results indicate that FBP54 is a promising vaccine for the prevention of S. pyogenes infections.

Adhesins, Bacterial↗