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PubMed1997

Antibiotic resistance in Streptococcus pneumoniae, Haemophilus influenzae and Streptococcus pyogenes in respiratory tract infections in outpatients.

Sensitivity patterns of Streptococcus pneumoniae, Haemophilus influenzae and Streptococcus pyogenes were studied prospectively in an outpatient population seeking medical advice for respiratory tract infections (RTI) in the Southern parts of Stockholm. In total, 3,214 nasopharyngeal and 1,907 throat swabs were cultured during January-February 1996. 32% of the patients had received antibiotics during the previous year. Reduced penicillin sensitivity in S. pneumoniae was rare (1.3%) and only seen in patients treated with antibiotics during the previous 4 months. Beta-lactamase production in H. influenzae was found in 13.4% of patients who had been treated with antibiotics during the last 4 months and in 7.9% of the others. No resistance (< 1%) to erythromycin was seen in S. pyogenes. In this population-based surveillance, the levels of resistance in common respiratory tract pathogens were thus low and correlated to previous antibiotic treatment. Strict indications for antibiotic treatment in uncomplicated RTI are advocated to maintain a low resistance rate. Penicillin is still the drug of choice in patients without frequent recurrences of RTI in a setting similar to the one studied.

Adolescent↗

PubMed2001

In vitro selection of resistance to clindamycin related to alterations in the attenuator of the erm(TR) gene of Streptococcus pyogenes UCN1 inducibly resistant to erythromycin.

A clinical isolate of Streptococcus pyogenes UCN1 intermediate to erythromycin (MIC 1 mg/L) and susceptible to clindamycin (MIC 0.03 mg/L) harboured an inducible erm(TR) gene encoding a ribosomal methylase. We have selected in vitro, in the presence of concentrations of clindamycin ranging from 0.12 to 1 mg/L, one-step mutants that are highly resistant to this antibiotic (MIC 64 mg/L) at a frequency of 10(-7). By contrast, in an erythromycin-susceptible strain of S. pyogenes UCN5, mutants could be selected only by a low concentration of clindamycin (0.12 mg/L) at a frequency of 10(-9). Clindamycin resistance in four of six S. pyogenes UCN1 mutants was associated with deletions of 163 and 6 bp, as well as a tandem duplication of 101 bp in the regulatory sequence of the erm(TR) gene. The role of these structural alterations in clindamycin resistance was demonstrated by cloning the erm(TR) gene from the wild-type and mutant strains in Escherichia coli DB10, a mutant susceptible to macrolides. Clindamycin resistance was expressed only when the erm(TR) gene was preceded by an altered attenuator. Mutations could lead to the formation of mRNA secondary structures accounting for the accessibility of the ribosome-binding site and the initiation codon of the ErmTR methylase to the ribosomes, and subsequently for the translation of the erm(TR) transcripts. The easy selection in one step of mutants resistant to high levels of clindamycin by concentrations of this antibiotic ranging from four to 40 times the MIC leads us to recommend caution in the use of clindamycin therapy in group A Streptococcus infections.

Anti-Bacterial Agents↗

PubMed1975

Immunogenicity of ribosomal vaccines isolated from group A, type 14 Streptococcus pyogenes.

A ribosomal preparation isolated from group A, type 14 Streptococcus pyogenes protected mice against a challenge of 1,000 mean lethal doses. Optimal immunization consisted of subcutaneous administration of 326 mug of protein with Freund incomplete adjuvant. Animals immunized with higher or lower antigen concentrations showed decreased survival. Freund incomplete adjuvant was necessary to insure optimum immunization. Immunochemical studies showed no M protein or C carbohydrate present in the ribosomal preparation. Mice optimally immunized with the type 14 ribosomal preparation were protected against heterologous challenge with M types 2, 5, 8, and 12. Protein-free ribonucleic acid extracts isolated from the type 14 ribosomal preparation did not protect mice against homologous challenge. But ribonucleic acid-free protein extracts showed 100% protection in mice after homologous challenge.

Animals↗

PubMed1996

Antitumor effect of Streptococcus pyogenes by inducing hydrogen peroxide production.

The Su strain of Streptococcus pyogenes (S-coccus)-derived anticancer preparation, OK-432, which is immobilized by heating in the presence of penicillin G, is well known to have an immunopotentiating activity through activation of natural killer cells in vivo. In this study, a streptococcal anticancer preparation stronger than OK-432 was prepared. Live streptococci (S-cocci) of the Su strain were induced to acquire H202-producing ability by treatment with serum under aerobic conditions. The resulting preparation no longer possessed hemolytic activity, and was not viable. The serum-treated S-coccus preparation activated natural killer cells as well as OK-432 did, and had stronger antitumor activity than OK-432 did. These results suggest that the serum-treated S-coccus preparation would be a useful tool for chemotherapy, in addition to immunotherapy, for the treatment of cancer.

Adjuvants, Immunologic↗

PubMed1998

Improvement of the indirect hemagglutination test for the detection of antibodies to Streptococcus pyogenes.

An indirect hemagglutination test for a seroepidemiological survey of Streptococcus pyogenes infection was standardized. This is an improved modification of the indirect hemagglutination test which utilizes an unstable reagent prepared with fresh blood cells. Two types of bacterial antigens represented by extracellular products and purified streptolysin O were assayed, but only the former antigen gave good results. Pretreatment of the bacterial antigen with 0.15 M NaOH and neutralization to pH 5.5, as well as postfixation of sensitized red cells with 0.1% glutaraldehyde at 56 degrees C for 30 min were found to be essential to give long stability to the reagent in liquid suspension, at least 9 months at 4 degrees C. A total of 564 serum samples with high, moderate and low anti-streptolysin O antibodies as determined by the neutralization assay were studied by the indirect hemagglutination test using the new reagent. The sensitivity, specificity, efficiency, positive predictive value and negative predictive value of the test in relation to the neutralization assay were 0.950, 0.975, 0.963, 0.973, and 0.955, respectively. The kappa agreement index between the two techniques was high (0.926) and ranked as "almost perfect". Antibody levels detected by both techniques also presented a high positive correlation (rs = 0.726). Five reagent batches successively produced proved to be reproducible. Thus, the improved indirect hemagglutination test seems to be useful for public health laboratories.

Antigens, Bacterial↗

PubMed1980

Production of L-forms of Streptococcus pyogenes and their antitumor effects.

Unstable L-forms of Streptococcus pyogenes were effectively isolated when protoplasts induced by muralysin were cultivated on a gradient plate containing penicillin-G. By this method, L-forms were obtained from the strains of serotype 3 and 4, from which they had been considered to be difficult to obtain. After 30 to 40 subcultures, two L-form strains (L-forms of Su and C-512) were successfully transferred into fluid medium without serum and penicillin. The antitumor effects of these stable L-forms were compared with these parent cocci. Treatment of the L-form of Su, which has antitumor effect, showed a considerable prolongation of life span in mice inoculated with Meth-A ascites tumor. On the other hand, the L-form of C-512, which has no antitumor effect, produced no effect on the tumor growth. Using two different transplantable tumors, the antitumor properties of th L-form of Su were investigated by comparing them with protoplast and cell wall fraction derived from the Su strain. In ascites tumors, the L-form treatment showed visible effects, while the cell wall produced no inhibitory effect. On the contrary, in solid tumors the antitumor effects obtained by the administration of the cell wall were never improved by the L-form. In both types of tumor, L-form showed antitumor activities similar to protoplast.

Animals↗

PubMed1993

Inactivation of the streptococcal erythrogenic toxin B gene (speB) in Streptococcus pyogenes.

Streptococcal proteinase precursor (SPP) is a zymogen secreted by Streptococcus pyogenes that becomes activated to a cysteine proteinase. SPP has been shown to be immunologically identical to streptococcal erythrogenic toxin B (SPE B), and sequence comparison has shown a high degree of homology between the two proteins. In this study, we have constructed a speB mutant strain of S. pyogenes by insertional inactivation. An internal fragment of the cloned speB gene in plasmid pCR1000 was replaced with an erythromycin resistance determinant, and the recombinant plasmid was introduced into strain NZ131 by electrotransformation. Following the selection of erythromycin-resistant clones, Southern hybridization experiments confirmed the presence of the recombinant plasmid containing the erm gene in the chromosome of the resistant strains. Analysis of extracellular proteins produced by the wild-type and speB mutant strains by Ouchterlony immunodiffusion and isoelectric focusing revealed the presence of SPE B in the wild-type strain but not the speB mutant. Additionally, SPP, which has an isoelectric focusing pattern similar to that of SPE B and reacts with SPE B antiserum, was not detected among the extracellular proteins of the speB mutant strain. Proteinase activity as assayed by two different methods was present in the extracellular proteins produced by the wild-type strain, but the speB mutant strain had no extracellular proteinase activity. The mutant strain had a growth rate similar to that of the wild-type strain and produced normal levels of other extracellular products, suggesting that proteinase was not essential for viability as previously suggested. Our data are consistent with the view that a single gene (speB) produces a single protein that has been identified and/or assayed as either SPE B or SPP.

Bacterial Proteins↗

PubMed1983

Cytotoxicity and inhibition of normal collagen synthesis in mouse fibroblasts by lipoteichoic acid from Streptococcus pyogenes type 12.

The toxicity of lipoteichoic acid (LTA) from Streptococcus pyogenes type 12 was investigated by using mouse fibroblasts in culture in the absence of serum. Morphologically, while low concentrations of LTA elicited a subtle effect characterized by progressive cellular degeneration with practically no release of protein, larger concentrations (greater than 50 micrograms/ml) of this amphiphile resulted in rapid death of cell monolayers. Metabolic studies utilized a concentration of LTA (17.5 micrograms/ml) which caused the smallest change in cell morphology in the least number of mouse fibroblast cells per monolayer. Under these conditions, cell monolayers showed an increase of 450% in their content of collagenous protein after exposure to LTA. However, the amount of such material secreted remained unchanged. Also, changes in the type of collagenous protein formed were observed after exposure to LTA. Collagenous protein accumulating intracellularly was found to be practically hydroxyproline-free. However, collagenous protein secreted by this cell line showed a significantly reduced content of hydroxyproline as compared with control cells unexposed to this coccal membrane component. Column chromatographic studies confirmed that the collagenous protein secreted by monolayers exposed to LTA was defective (under hydroxylated). It was concluded that LTA does not affect the amount of collagenous protein secreted. However, it does increase the amount of this protein formed and retained by this cell line as well as causing a reduction in the hydroxylation of proline in both intracellular and secreted collagenous material. A possible relationship between abnormal basement membrane morphology and disturbed collagen synthesis in post-streptococcal glomerulonephritis as related to LTA is discussed.

Animals↗

PubMed1998

Extensive genetic diversity among clinical isolates of Streptococcus pyogenes serotype M5.

The genetic diversity of clinical isolates of Streptococcus pyogenes serotype M5 has been characterized. Strain genotypes were defined by macrorestriction profile, 16S ribotype, emm gene subtype, insertion element IS1239 profile, and exotoxin gene determinant. By these criteria, clinical isolates of M5 constituted a multiplicity of strain clusters rather than a homogeneous population as found for certain serotypes. Distance matrices and an unrooted tree were constructed from macrorestriction data with three rarely cutting endonucleases, determined by PFGE. A single IS1239 profile was common to 85% of isolates but there was great diversity of both ribotype and macrorestriction profile, and 18 different emm gene subtypes were detected by PCR-RFLP. DNA sequence analysis of the antigen-coding 5' (hypervariable) region of emm gene amplicons (about 240 bp) showed that 14/18 exhibited up to 6% divergence. Four amplicons had highly divergent sequences--corresponding to those previously determined for emm6, emm11, emm18 and emm77. Further serological and hybridization studies were used to analyse the discrepancy between the Lancefield serotype of these strains (M5) and their emm genotype. Overall, this study shows a high degree of genetic diversity in serotype M5, with implications for the Lancefield scheme itself, for the epidemiology of group A streptococci, and for recombinant DNA strategies for M protein-based vaccine development.

Amino Acid Sequence↗

PubMed2001

A 49-residue peptide from adhesin F1 of Streptococcus pyogenes inhibits fibronectin matrix assembly.

F1 is an adhesin of Streptococcus pyogenes which binds the N-terminal 70-kDa region of fibronectin with high affinity. The fibronectin binding region of F1 is comprised of a 43-residue upstream domain and a repeat domain comprised of five tandem 37-residue sequences. We investigated the effects of these domains on the assembly of fibronectin matrix by human dermal fibroblasts, MG63 osteosarcoma cells, or fibroblasts derived from fibronectin-null stem cells. Subequimolar or equimolar concentrations of recombinant proteins containing both the upstream and repeat domains or just the repeat domain enhanced binding of fibronectin or its N-terminal 70-kDa fragment to cell layers; higher concentrations of these recombinant proteins inhibited binding. The enhanced binding did not result in greater matrix assembly and was caused by increased ligand binding to substratum. In contrast, recombinant or synthetic protein containing the 43 residues of the upstream domain and the first 6 residues from the repeat domain exhibited monophasic inhibition with an IC(50) of approximately 10 nm. Truncation of the 49-residue sequence at its N or C terminus caused loss of inhibitory activity. The 49-residue upstream sequence blocked incorporation of both endogenous cellular fibronectin and exogenous plasma fibronectin into extracellular matrix and inhibited binding of 70-kDa fragment to fibronectin-null cells in a fibronectin-free system. Inhibition of matrix assembly by the 49-mer had no effect on cell adhesion to substratum, cell growth, formation of focal contacts, or formation of stress fibers. These results indicate that the 49-residue upstream sequence of F1 binds in an inhibitory mode to N-terminal parts of exogenous and endogenous fibronectin which are critical for fibronectin fibrillogenesis.

Adhesins, Bacterial↗

PubMed2006

Azithromycin-sulfonamide conjugates as inhibitors of resistant Streptococcus pyogenes strains.

Novel hybrid compounds 6a-6d, conjugates of 15-membered azalides and sulfonamides, i.e. unsubstituted, 4-aryl- and 4-heteroaryl-aminosulfonyl derivatives of 9a-[N'-(phenylcarbamoyl)]-9-deoxo-9-dihydro-9a-aza-9a-homoerythromycin A were synthesized and characterized by IR, one- and two-dimensional NMR spectroscopies and MALDI-TOF and MS/MS mass spectrometry. The new compounds were evaluated in vitro against a panel of sensitive and resistant Gram-positive and Gram-negative bacterial strains. 9a-{N'-[4-(Aminosulfonyl)phenyl]carbamoyl}--(6a) and 9a-{N'-[4-(phenylaminosulfonyl)phenyl]carbamoyl}--(6b) derivatives showed improvements in activity against inducible resistant Streptococcus pyogenes in comparison with macrolide antibiotic azithromycin and starting material 9-deoxo-9-dihydro-9a-aza-9a-homoerythromycin A (2). In addition, the synthesized azithromycin-sulfonamide conjugates 6a-6d showed good antibacterial activity against sensitive S. pyogenes and Streptococcus pneumoniae strains. The kinetics of degradation in the artificial gastric juice showed that the most active compounds, 6a and 6b, exhibited azithromycin like stability. The cleavage of the cladinose sugar was found to be the main decomposition pathway leading to inactive 7a and 7b, prepared also as analytical standards by the alternative synthetic route together with 7c and 7d.

Acetaldehyde↗

PubMed1997

Constitutive expression of fibronectin binding in Streptococcus pyogenes as a result of anaerobic activation of rofA.

Protein F is a fibronectin-binding surface protein of Streptococcus pyogenes (group A streptococcus) that mediates adherence to host cells. A gene product encoded by rofA activates transcription of the gene that encodes protein F (prtF) and was identified in a strain of S. pyogenes that expressed high levels of protein F under all conditions tested. Insertional inactivation of rofA in this strain results in a phenotype similar to that of other strains where high-level transcription of prtF occurs only in response to increased oxygen tension. In this study, we have compared the regulation of prtF and rofA in O2-regulated and constitutive strains in order to gain further insight into the function of rofA. Comparison of the prtF and rofA transcripts by S1 nuclease and primer extension assays indicated that the same promoters for each transcript are used in both O2-regulated and constitutive strains. However, analyses of rofA-lacZ reporter alleles revealed that a key difference between strains involves regulation of rofA itself. In O2-regulated strains, expression of rofA was elevated following culture under conditions of reduced O2 tension. However, a much more robust activation of rofA expression was observed when constitutive strains were grown under similar conditions. Exchange of reporter and rofA alleles between strains demonstrated that host genetic background, and not the sequence of the respective rofA allele or regulatory region, dictates the expression phenotype. Activation of rofA required RofA, and RofA was shown to bind specifically to DNA containing the promoters for rofA and prtF. Finally, overexpression of either allele of rofA caused constitutive expression of prtF regardless of host background. These data suggest a model where anaerobic expression of prtF in constitutive hosts is controlled at the level of transcription of rofA and implicate additional factors in this regulatory pathway.

Adhesins, Bacterial↗

PubMed1997

Insertional inactivation of streptolysin S expression is associated with altered riboflavin metabolism in Streptococcus pyogenes.

Transposon Tn916 mutagenesis was used to create a mutant of Streptococcus pyogenes M type 3, designated ISS417, in which the ability to produce streptolysin S (SLS) and several other exoproteins was impaired. Concomitantly, the mutant became dependent upon riboflavin for growth and was able to grow in Todd Hewitt broth (THB) when supplemented with riboflavin or riboflavinrich yeast extract. The parent strain was apparently able to utilize THB-derived components as a substitute for riboflavin, while the mutant was not. Although the parent strain grew well in synthetic medium, it was unable to produce SLS, except when it was supplemented with a small amount of THB. Thus, a component of THB was able to "trigger" SLS formation in the parent strain. The mutant grew well in this medium, but was unable to produce SLS even when it was supplemented with THB. Southern hybridization analysis revealed that the ISS417 mutant harbours a single transposon insertion in its chromosome. Phage transduction experiments showed that the riboflavin dependency and the inability to make SLS phenotypes are co-transducible. The pleotrophic properties of the ISS417 mutant differ from those reported for insertional inactivation of the mga locus which regulates production of a number of surface proteins in S. pyogenes and the sar locus which regulates production of a number of exoproteins in Staphylococcus aureus. In view of the possibility that there exist a genetic linkage between the riboflavin biosynthetic pathway and expression of the oxygen-stable SLS, we hypothesize that SLS has a role in the growth economy of S. pyogenes.

Bacterial Proteins↗

PubMed1976

Defective synthesis of lipid intermediates for peptidoglycan formation in a stabilized L-form of Streptococcus pyogenes.

Membrane preparations obtained from a stabilized L-form of Streptococcus pyogenes are incapable of synthesizing peptidoglycan from uridine-5'-diphospho-N-acetyl-D-muramyl-L-Ala-D-iso-Glu-L-Lys-D-Ala-D-Ala and uridine-5'-diphospho-N-acetyl-D-glucosamine, in contrast with similar preparations from the parental streptococcus. Furthermore, 50-fold higher levels of lipid intermediates which serve as membrane-bound substrates for peptidoglycan synthesis are synthesized in reaction mixtures containing streptococcal membranes than with similar preparations from the L-form. These observations suggest that the inability of this stabilized L-form to form a cell wall in vivo lies, at least in part, in its failure to synthesize significant quantities of the lipid substrates for peptidoglycan synthesis.

Adenosine Triphosphate↗

PubMed1990

Complete nucleotide sequence of the streptococcal C5a peptidase gene of Streptococcus pyogenes.

Streptococcal C5a peptidase (SCP), a recently discovered virulence factor of Streptococcus pyogenes, specifically cleaves the human serum chemotaxin C5a near its carboxyl terminus, destroying its ability to serve as a chemoattractant. We previously localized the SCP gene, scpA, to the 5.8-kb insert of the recombinant plasmid pTT1. Here we present the complete nucleotide sequence of scpA and its flanking regions. The gene initiates at a TTG codon and consists of 3501 base pairs, specifying a precursor protein of 128,252 daltons. Sequences resembling the promoter and ribosome-binding site of Gram-positive organisms are found upstream of scpA. The predicted amino acid sequence reveals the presence of a 31-residue signal peptide, putative cell wall spanning and membrane anchor domains. Regions of SCP show significant similarity to the sequences involved in the formation of the active site of the prokaryotic serine protease subtilisin. Results of Southern hybridization studies indicate that sequences highly similar to that of scpA are present in all serotypes of S. pyogenes tested.

Adhesins, Bacterial↗

PubMed1988

Streptococcus pyogenes bacteraemia: an old enemy subdued, but not defeated.

Bacteraemia with Streptococcus pyogenes (Group A haemolytic streptococci) was reviewed in patients admitted to University Hospital, Nottingham over a period of 7 years. Altogether, 40 cases were encountered, representing 2% of all cases of bacteraemia. Mortality was 35%. Most cases were community-acquired and 28% of patients were less than 40 years of age. A third of the patients were previously fit. The most common sources of bacteraemia were the skin and soft tissue (23 patients) and the respiratory tract (eight patients). Shock was recorded in 40% of cases and carried a 60% mortality. This feature of streptococcal bacteremia has not received sufficient attention in the past. Despite its unique susceptibility to penicillin, S. pyogenes continues to pose a challenge to the physician.

Adolescent↗

PubMed2003

Identification of B- and T-cell epitopes within the fibronectin-binding domain of the SfbI protein of Streptococcus pyogenes.

The fibronectin-binding repeats of the SfbI protein of Streptococcus pyogenes constitute the minimal domain able to confer protection against lethal infection. We investigated the presence of B- and T-cell epitopes within this region in congenic mice. One linear B-cell epitope was recognized by BALB/b and BALB/k mice, whereas two epitopes were found in BALB/c animals. A unique T-cell epitope was recognized by all three mouse strains. All identified epitopes clustered in a 30-amino-acid fragment. These results suggest that this polypeptide may be suitable for incorporation into a polyepitope-based vaccine formulation against S. pyogenes.

Adhesins, Bacterial↗

PubMed2006

Analysis of the role of CovR and CovS in the dissemination of Streptococcus pyogenes in invasive skin disease.

The global regulatory two-component system CovR/S controls expression of about 15% of the Streptococcus pyogenes (group A streptococcus; GAS) genome. Recently, we found that CovS plays a pivotal role in general stress response of this strictly human pathogen. Therefore, we expected that both CovS and CovR might affect virulence. In this work, mice were inoculated subcutaneously with isogenic nonpolar covR and covS deletion-substitution mutants and the isogenic wild-type strain. The covS mutant behaved like the wild-type parental strain in terms of resulting lesion appearance and invasive disease leading to death. This is in agreement with previous results suggesting that the absence of its cognate sensor kinase does not affect the ability of CovR to become phosphorylated and cause repression of its regulon. However, two different covR deletion-substitution mutants caused significantly less invasive disease and death in the mice than the wild-type parental strain, although the local lesions produced by the covR mutants were more severe and purulent than those resulting from the wild-type GAS strain. Thus, it appears that production of CovR increases the ability of S. pyogenes to cause severe invasive disease in this mouse model and therefore is an important virulence factor for this organism.

Animals↗