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S. Pyogenes (s + pyogene)
Selected AbstractsEvasion of macrophage scavenger receptor A-mediated recognition by pathogenic streptococciEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 11 2008Thomas Areschoug Abstract PRR recognize conserved structures on pathogenic microbes and are important for the defense against invading microorganisms. However, accumulating evidence indicates that many pathogens have evolved mechanisms to avoid recognition by PRR. One type of PRR is the macrophage scavenger receptor A (SR-A), which has been shown to play an important role in recognition and non-opsonic phagocytosis of pathogenic bacteria. The bacterial ligands for SR-A have been suggested to be LPS or lipoteichoic acid. Here, we use murine bone marrow-derived macrophages to analyze the role of SR-A in non-opsonic phagocytosis of two major Gram-positive pathogens, Streptococcus agalactiae (group B streptococcus; GBS) and Streptococcus pyogenes. We show that the polysaccharide capsule of GBS and the surface M protein of S. pyogenes, two important virulence factors, prevent SR-A-mediated non-opsonic phagocytosis of streptococci. The sialic acid moiety of the GBS capsule was crucial for its ability to prevent recognition by SR-A. Moreover, we show that a ligand on GBS recognized by SR-A in the absence of capsule is the surface lipoprotein Blr. These findings represent the first example of a microbial strategy to prevent recognition by SR-A and suggest that bacterial surface proteins may be of importance as ligands for SR-A. [source] Peripheral blood mononuclear cells proliferation and Th1/Th2 cytokine production in response to streptococcal M protein in psoriatic patientsINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 5 2006Rolando Pérez-Lorenzo Background, Psoriasis is a chronic skin disease that is probably a T cell-mediated autoimmune condition which is strongly associated with streptococcal throat infections. Although some groups have associated the involved response with different streptococcal antigens, M protein has been described as the major virulence factor of Streptococcus pyogenes. Thus, it is necessary to describe some features of the cellular responses to this streptococcal antigen. Methods, Proliferation and Th1/Th2 cytokine production of peripheral blood mononuclear cells (PBMC) in response to total soluble extracts from type M5 S. pyogenes with (TSE37Sp) and without (M,TSESp) M protein were analyzed in 10 psoriatic patients and 10 healthy controls. Results, PBMC from both patients and controls proliferated to both extracts. Responses to M,TSESp were significantly lower than those to TSE37Sp (P < 0.05). PBMC IL-2 and ,IFN production after TSE37Sp stimulus was much higher than after M,TSESp antigenic stimulation in both groups (P < 0.05). Meanwhile, IL-4 production was quite low in both groups and in response to both extracts. We found a differential production of IL-10 between groups. PBMC from healthy controls responded to TSE37Sp with a much higher production of this cytokine as compared to the responses showed to M,TSESp while the cells from psoriatic patients responded without differences in the production of IL-10. Conclusion, Results obtained suggest an important Th1 response to M protein in psoriatic patients which could be associated with the cellular responses involved in psoriasis, while healthy subjects respond in a probably non-Th2 IL-10 producing regulatory T cells fashion. [source] Interactions between surface proteins of Streptococcus pyogenes and coagulation factors modulate clotting of human plasmaJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 2 2003H. Herwald Summary., Invasive and toxic infections caused by Streptococcus pyogenes are connected with high morbidity and mortality. Typical symptoms of these infections are hypotension, edema formation, tissue necrosis, and bleeding disorders. Here we report that components of the coagulation system including fibrinogen, factors V, XI, and XII, and H-kininogen, are assembled at the surface of S. pyogenes through specific interactions with bacterial surface proteins. In plasma environment, absorption of fibrinogen by S. pyogenes causes a hypocoagulatory state resulting in prolonged clotting times and impaired fibrin network formation. Moreover, the binding of coagulation factors and the subsequent activation of the coagulation system at the bacterial surface lead to the formation of a fibrin network covering S. pyogenes bacteria adhering to epithelial cells. The results suggest that interactions between S. pyogenes and components of the coagulation system contribute to some of the symptoms seen in severe infections caused by this important human pathogen. [source] Repression of virulence genes by phosphorylation-dependent oligomerization ofCsrR at target promoters in S. pyogenesMOLECULAR MICROBIOLOGY, Issue 4 2001Alita A. Miller csrRS encodes a two-component regulatory system that represses the transcription of a number of virulence factors in Streptococcus pyogenes, including the hyaluronic acid capsule and pyrogenic exotoxin B. CsrRS-regulated virulence factors have diverse functions during pathogenesis and are differentially expressed throughout growth. This suggests that multiple signals induce CsrRS-mediated gene regulation, or that regulated genes respond differently to CsrR, or both. As a first step in dissecting the csrRS signal transduction pathway, we determined the mechanism by which CsrR mediates the repression of its target promoters. We found that phosphorylated CsrR binds directly to all but one of the promoters of its regulated genes, with different affinities. Phosphorylation of CsrR enhances both oligomerization and DNA binding. We defined the binding site of CsrR at each of the regulated promoters using DNase I and hydroxyl radical footprinting. Based on these results, we propose a model for differential regulation by CsrRS. [source] Vulvar Disease in Children: A Clinical Audit of 130 CasesPEDIATRIC DERMATOLOGY, Issue 1 2000Gayle Fischer M.D. Of the patients, 41 (33%) had atopic or irritant dermatitis, 23 (18%) had lichen sclerosus, 21 (17%) had psoriasis, 15 (12%) had vulvar lesions, most often hemangiomas and nevi, and 13 (10%) had streptococcal vulvovaginitis. Diagnoses less frequently seen were staphylococcal folliculitis (four patients), labial fusion (three patients), genital warts (two patients), molluscum contagiosum of the vulva only (one patient), vulvar bullous pemphigoid (two patients), scabies nodules (one patient), erythema annulare centrifugum (one patient), tinea (two patients), and vitiligo (one patient). We also encountered vulvar presentations of systemic diseases (varicella, staphylococcal scalded skin syndrome, and Henoch,Schönlein purpura, all one patient each). We did not see candidal vulvovaginitis in this age group nor did we encounter bacterial infection with pathogens other than Staphylococcus aureus and S. pyogenes. [source] Investigation of risk factors for tonsillopharyngitis with macrolide resistant Streptococcus pyogenes in Turkish childrenPEDIATRICS INTERNATIONAL, Issue 6 2002Abstract Background: Streptococcus pyogenes is the most important causative agent of tonsillopharyngitis. Although penicillin is the drug of choice in streptococcal tonsillopharyngitis, macrolides are recommended drugs in patients who have an allergy to penicillin. However, resistance to macrolides is an important problem in some regions of the world. Risk factors for resistance development have not been investigated sufficiently. Objectives: To investigate the risk factors for the development of tonsillopharyngitis with macrolide resistant S. pyogenes. Methods: Three hundred and forty-five children with tonsillopharyngitis caused by S. pyogenes were investigated for various risk factors. Streptococcus pyogenes isolated from children's throat culture were examined for erythromycin, clarithromycin and azithromycin susceptibility. Results: Two hundred and sixty-three children were found eligible for the analysis of risk factors. Resistances to erythromycin, clarithromycin and azithromycin were detected as 3.8, 4.2 and 4.2%, respectively. Macrolide use of the family members in the last 3 months (odds ratio = 7.04, P = 0.005) has been determined to be a risk factor for the development of tonsillopharyngitis with macrolide resistant S. pyogenes. Conclusion: Restriction of macrolide antibiotic use appears to be the most important measure to prevent the development of tonsillopharyngitis with resistant S. pyogenes. [source] Bacteriologic Comparison of Tonsil Core in Recurrent Tonsillitis and Tonsillar Hypertrophy,THE LARYNGOSCOPE, Issue 12 2007Jin Hyeok Jeong MD Abstract Objectives: Although many bacteriology studies on tonsillar diseases have been completed, all have been confined to children and were characterized by a paucity of cases. The purpose of this study was to analyze the underlying bacterial pathogens in tonsillar disease. Methods: A retrospective study was performed on 824 patients who underwent elective tonsillectomy with or without adenoidectomy. We analyzed the differences between the bacterial pathogens in recurrent tonsillitis and tonsillar hypertrophy with regard to age, season, and antibiotic sensitivity. Results: Among 824 cases, 966 bacterial strains from the tonsil core were isolated. In recurrent tonsillitis, Staphylococcus aureus was the most common pathogen (30.3%), followed by Haemophilus influenzae (15.5%) and group A ,-hemolytic Streptococcus (Streptococcus pyogenes, 14.4%). In patients over 14 years of age, quite differently from other age groups, Klebsiella pneumoniae was isolated at a significantly higher percentage. In tonsillar hypertrophy, H. influenzae was isolated most commonly (31.4%) regardless of age, followed by S. pyogenes (24.2%), S. aureus (22.9%), and Streptococcus pneumoniae (12.6%). Furthermore, mixed infection was common because of its high resistance to penicillin. In both groups, S. pneumoniae was more common in younger patients, whereas K. pneumoniae was relatively common in adults. We found no differences in the detection rate by season; however, H. influenzae was frequently isolated in the tonsillar hypertrophy group regardless of seasonal variations. We also found no difference in the antibiotic sensitivity between the two groups; however, strains resistant to penicillin were relatively prevalent and showed a high sensitivity to third-generation cephalosporin. Conclusions: We observed some differences in the types of bacteria in the tonsillar core between the recurrent tonsillitis and tonsillar hypertrophy groups. Our study indicates that essential bacteria have been changing and, thus, we need to change our choice of antibiotics. [source] Synthesis and antibacterial properties of peptidyl derivatives and cyclopeptides structurally based upon the inhibitory centre of human cystatin C: Dissociation of antiproteolytic and antibacterial effectsAPMIS, Issue 7-8 2000FRANCISZEK Kasprzykowski Cysteine protease-inhibiting proteins of the cystatin superfamily can inhibit the replication of certain viruses and bacteria. The inhibitory centre of human cystatin C, the most widely distributed human cystatin, comprises three peptide segments. The present work describes the synthesis and antibacterial activity of 27 new peptidyl derivatives or cyclopeptides based upon the aminoterminal segment Arg8 -Leu9 -Val10 -Gly11. Fourteen of the new compounds displayed antibacterial activity against from 1 up to 9 of 17 clinically important bacterial species tested. Antiproteolytic activity of a compound was usually not required for its antibacterial capacity. Peptidyl diazomethanes generally had a very narrow antibacterial spectrum, inhibiting only Streptococcus pyogenes, whereas cyclopeptides and peptidyl derivatives of the general structure X-Arg-Leu-NH-CH(iPr)-CH2 -NH-Y had a much wider spectrum. The most potent of these substances displayed approximately equal minimal inhibitory and bactericidal concentrations of about 20 ,g/ml for both Staphylococcus aureus and S. pyogenes and were devoid of antiproteolytic activity. Several of the new substances could protect mice against lethal intraperitoneal challenge with S. pyogenes. Though their target remains to be disclosed, the group of substances here reported might be promising for the development of antibacterial drugs and the discovery of novel principles of action. [source] Metabolic effects of static magnetic fields on streptococcus pyogenesBIOELECTROMAGNETICS, Issue 6 2007A.C. Morrow Abstract This study aimed to develop a simple experimental system utilising bacterial cells to investigate the dose responses resulting from exposures to static magnetic flux densities ranging from 0.05 to 0.5 T on viability, bacterial metabolism and levels of DNA damage in Streptococcus pyogenes. Exposure of S. pyogenes to a field of 0.3 T at 24 °C under anaerobic conditions resulted in a significant (P,<,0.05) decrease in growth rate, with an increased mean generation time of 199,±,6 min compared to the control cells at 165,±,6 min (P,<,0.05). Conversely, exposure to magnetic fields of 0.5 T significantly accelerated the growth rate at 24 °C compared to control cells, with a decreased mean generation time of 147,±,4 min (P,<,0.05). The patterns of metabolite release from cells incubated in phosphate buffered saline (PBS) at 24 °C and exposed to different magnetic flux densities (0.05,0.5 T) were significantly (P,<,0.05) altered, compared to non-exposed controls. Concentrations of metabolites, with the exception of aspartic acid (r,=,0.44), were not linearly correlated with magnetic flux density, with all other r,<,0.20. Instead, "window" effects were observed, with 0.25,0.3 T eliciting the maximal release of the majority of metabolites, suggesting that magnetic fields of these strengths had significant impacts on metabolic homeostasis in S. pyogenes. The exposure of cells to 0.3 T was also found to significantly reduce the yield of 8-hydroxyguanine in extracted DNA compared to controls, suggesting some possible anti-oxidant protection to S. pyogenes at this field strength. Bioelectromagnetics 28:439,445, 2007. © 2007 Wiley-Liss, Inc. [source] Streptococcus pyogenes induces oncosis in macrophages through the activation of an inflammatory programmed cell death pathwayCELLULAR MICROBIOLOGY, Issue 1 2009Oliver Goldmann Summary Macrophages are crucial components of the host defence against Streptococcus pyogenes. Here, we demonstrate the ability of S. pyogenes to kill macrophages through the activation of an inflammatory programmed cell death pathway. Macrophages exposed to S. pyogenes exhibited extensive cytoplasmic vacuolization, cellular and organelle swelling and rupture of the plasma membrane typical of oncosis. The cytotoxic effect of S. pyogenes on macrophages is mediated by the streptococcal cytolysins streptolysin S and streptolysin O and does not require bacterial internalization. S. pyogenes -induced death of macrophages was not affected by the addition of osmoprotectant, implicating the activation of an orchestrated cell death pathway rather than a simple osmotic lysis. This programme cell death pathway involves the loss of mitochondria transmembrane potential (,,m) and was inhibited by the addition of exogenous glycine, which has been shown to prevent necrotic cell death by blocking the opening of death channels in the plasma membrane. The production of reactive oxygen species and activation of calpains were identified as mediators of the cell death process. We conclude that activation of the inflammatory programmed cell death pathway in macrophages could constitute an important pathogenic mechanism by which S. pyogenes evades host immune defences and causes disease. [source] Activity of telithromycin compared with seven other agents against 1039 Streptococcus pyogenes pediatric isolates from ten centers in central and eastern EuropeCLINICAL MICROBIOLOGY AND INFECTION, Issue 7 2003B. Bozdogan In total, 1039 pediatric Streptococcus pyogenes isolates from Bulgaria, Croatia, the Czech Republic, Hungary, Latvia, Lithuania, Poland, Romania, Slovakia and Slovenia were studied. All strains were susceptible to penicillin G, levofloxacin, and quinupristin,dalfopristin, 91,100% to telithromycin, and 82,100% to erythromycin, azithromycin, and clarithromycin, and 90,100% to clindamycin. Macrolide resistance occurred mainly in Slovakia (25%), the Czech Republic (17.3%), and Croatia (15.8%). Overall, 9.7% of S. pyogenes isolates were erythromycin resistant due to erm(B) - or erm(A) -encoded methylases (72.3%) or to a mef(A) -encoded efflux pump (25.7%). One strain had alterations of both 23S rRNA (A2058G Escherichia coli numbering) and ribosomal protein L22 (G95D). [source] Viridans group streptococci: a reservoir of resistant bacteria in oral cavitiesCLINICAL MICROBIOLOGY AND INFECTION, Issue 2 2002A. Bryskier The worldwide spread of erythromycin A-resistant streptococci, including Streptococcus pneumoniae, is of concern. Many studies have demonstrated that the viridans group streptococci can be a reservoir of erythromycin A resistance. Within oral streptoccoci, an important difference in the susceptibility pattern has been noted. The purpose of this short editorial is to highlight the importance of this group of bacteria as a reservoir of resistance to erythromycin A and the possible transfer of resistance to S. pneumoniae and S. pyogenes. [source] | ||||||||||||||||||||||