Biological Characterization and Inhibition of Streptococcus pyogenes ZUH1 Causing Chronic Cystitis by Crocus sativus Methanol Extract, Bee Honey Alone or in Combination with Antibiotics: An In Vitro Study.

Streptococcus pyogenes (S. pyogenes) ZUH1 was isolated and characterized using morphological, cultural and biochemical methods. The results showed that the marker genes (namely spyCEP, ssa, sic, sdaB and speG) indicating group A streptococci (GAS) were detected in the S. pyogenes genome. The results showed that the S. pyogenes strain was inhibited by Crocus sativus methanol extract (CSME), bee honey (BH) and catfish glycoprotein (CFG). The inhibitory activity of these natural agents were compared with standard antibiotics such as Ceftazidime (30 µg/mL), Cefoperazone (75 µg/mL), Cefoxitin (30 µg/mL) and Imipenem (10 µg/mL). There was a synergistic effect between certain antibiotics and CSME. GC-MS and IR analysis of CSME showed different cyclic ketones, aldehydes, esters, alcohols and acids. The main compounds were tetradecanoic acid, safranal and isophorone. Transmission electron microscopy (TEM) images of S. pyogenes cells treated with CSME showed signs of an irregular wrinkled outer surface, fragmentation, adhesion and aggregation of damaged bacterial cells or cellular debris. The marker genes (spyCEP, ssa, sic, sdaB and speG) could be used as a rapid diagnostic tool for GAS. CSME, BH and CFG showed distinctive anti-streptococcal activity either alone or in combinations with antibiotics; their action on S. pyogenes cells was studied by TEM. There was a synergistic effect between antibiotics and Crocus sativus, bee honey, and glycoprotein against S. pyogenes ZUH1. The action of natural agents on the pathogenic cells was shown using TEM.

Methanol extract of Lonicera caerulea var. emphyllocalyx fruit has antibacterial and anti-biofilm activity against Streptococcus pyogenes in vitro.

Streptococcus pyogenes causes several infectious diseases such as tonsillitis, cellulitis, and streptococcal toxic shock syndrome. As antibiotics are used for the general treatment of S. pyogenes infection, cases of treatment failure due to drug-resistant bacteria have increased. Lonicera caerulea var. emphyllocalyx (LCE) has been used as a folk medicine in northern Japan (Hokkaido). In this study, we investigated the antibacterial effect of methanol extracts of the fruit, stem, and leaf of LCE (LCEEs) against S. pyogenes using disk diffusion assay. As LCEE (fruit) had the strongest antibacterial activity among the three LCEEs, we focused on functional analysis of antibacterial effects of LCEE (fruit). LCEE (fruit) suppressed the growth of S. pyogenes in a dose-dependent manner. Morphological analysis by transmission electron microscopy demonstrated that LCEE (fruit) damaged the shape of S. pyogenes. Microplate and confocal laser microscopy analysis showed that biofilm formation was also suppressed by LCEE (fruit) in a dose-dependent manner. To further evaluate the surface structure of these biofilms, we performed hydrophobic analysis, which demonstrated that LCEE (fruit) reduced the hydrophobicity of the bacterial surface structure. Our data demonstrated that LCEE (fruit) had anti-bacterial and anti-biofilm effects on S. pyogenes in vitro, suggesting that the direct anti-bacterial effects of the LCEE (fruit) may be useful for treatment of local S. pyogenes infection.

Pooled analysis of the phase 3 REVIVE trials: randomised, double-blind studies to evaluate the safety and efficacy of iclaprim versus vancomycin for treatment of acute bacterial skin and skin-structure infections.

Iclaprim, a diaminopyrimidine antimicrobial, was compared with vancomycin for treatment of patients with acute bacterial skin and skin-structure infections (ABSSSIs) in two studies (REVIVE-1 and REVIVE-2). Here, the efficacy and tolerability of iclaprim in a pooled analysis of results from both studies was explored. REVIVE-1 and REVIVE-2 were phase 3, double-blind, randomised, multicentre, active-controlled, non-inferiority (margin of 10%) trials, each designed to enrol 600 patients with ABSSSI using identical study protocols. Iclaprim 80 mg and vancomycin 15 mg/kg were administered intravenously every 12 h for 5-14 days. The primary endpoint was a ≥20% reduction from baseline in lesion size [early clinical response (ECR)] at the early time point (ETP) (48-72 h after starting study drug) in the intent-to-treat population. In REVIVE-1, ECR at the ETP was 80.9% with iclaprim versus 81.0% with vancomycin (treatment difference -0.13%, 95% CI -6.42% to 6.17%). In REVIVE-2, ECR was 78.3% with iclaprim versus 76.7% with vancomycin (treatment difference 1.58%, 95% CI -5.10% to 8.26%). The pooled ECR was 79.6% with iclaprim versus 78.8% with vancomycin (treatment difference 0.75%, 95% CI -3.84 to 5.35%). Iclaprim and vancomycin were comparable for the incidence of mostly mild adverse events, except for a higher incidence of elevated serum creatinine with vancomycin (n = 7) compared with iclaprim (n = 0). Iclaprim achieved non-inferiority compared with vancomycin for ECR at the ETP and secondary endpoints with a similar safety profile in two phase 3 studies for treatment of ABSSSI suspected or confirmed as caused by Gram-positive pathogens. [Clinical Trials Registration. NCT02600611 and NCT02607618.].

Essential oils from Origanum vulgare and Salvia officinalis exhibit antibacterial and anti-biofilm activities against Streptococcus pyogenes.

In the present study, essential oils (EOs) extracted from oregano, sage, cloves, and ginger were evaluated for the phytochemical profile, antibacterial, and anti-biofilm activities against Streptococcus pyogenes. The broth microdilution method was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of EOs. The minimum biofilm inhibitory concentrations (MBICs) were determined using MTT assay and fixed biofilms were observed through scan electron microscopy. The oregano and sage EOs showed the lowest MIC as well as MBC of 0.25-0.5 mg/mL. Time kill assay results showed that oregano and sage EOs exhibited bactericidal effects within 5 min and 4 h, respectively. Both oregano and sage extracts acts as a potent anti-biofilm agent with dual actions, preventing and eradicating the biofilm. The microscopic visualization of biofilms treated with EOs have shown morphological and density changes compared to the untreated control. Oregano EO was constituted predominantly carvacrol (91.6%) and in sage EO, higher levels of α-thujone (28.5%) and camphor (16.6%) were revealed. EOs of oregano and sage inhibit the growth and biofilm formation of S. pyogenes. Effective concentrations of oregano and sage EOs and their phytochemicals can be used in developing potential plant-derived antimicrobial agents in the management of streptococcal pharyngitis.

Inhibition of streptococcal pyrogenic exotoxin B using allicin from garlic.

Streptococcal pyrogenic exotoxin B (SpeB) is an important virulence factor of group A streptococci (GAS) and inactivation of SpeB results in the significantly decreased virulence of the bacterium. The protein is secreted as an inactive zymogen of 40 KDa (SpeBz) and undergoes proteolytic truncation to result in a 28 KDa mature active protease (SpeBm). In this study the effect of allicin on the proteolytic activity of SpeBm was evaluated using azocasein assay. Allicin neutralized the SpeBm proteolytic activity in a concentration dependent manner (IC50 = 15.71 ± 0.45 µg/ml). The loss of activity was completely reversed by subsequent treatment with a reducing agent, dithiothreitol (DTT; 10 mM final concentration), suggesting that allicin likely inhibits the SpeBm by forming a disulfide linkage with an active thiol group in its active site. This mechanism of action was further confirmed with the fact that DTT did not reverse the SpeBm activity in the presence of E-64, a cysteine protease-specific inhibitor, which works specially by forming a thioether linkage with free sulfhydryl groups in enzymes active site. The MIC of allicin against GAS was found to be 32 µg/ml. Exposure of GAS culture to allicin (25 µg/ml) inhibited maturation of SpeBz to the SpeBm. In conclusion, the results of this study suggest that allicin inhibits the maturation of SpeBz and proteolytic activity of SpeBm and could be a potential therapeutic agent for the treatment of GAS infections.

In vitro evaluation of the wound healing activity of Drypetes klainei stem bark extracts.

ETHNOPHARMACOLOGICAL RELEVANCE: Drypetes klainei Pierre ex Pax is used in Cameroon by Baka Pygmies in the wound healing process and for the treatment of burns. AIM OF THE STUDY: To validate the traditional use of D. klainei Pierre ex Pax stem bark extracts through the evaluation of their antimicrobial properties and their ability to improve wound healing process in fibroblast cell cultures. MATERIALS AND METHODS: The antimicrobial properties of D. klainei extracts were evaluated against Staphylococcus aureus ATCC 6538, Streptococcus pyogenes ATCC 19615, Escherichia coli ATCC 10536, Candida albicans ATCC 10231, on the basis of the minimum inhibitory concentration (MIC) and the minimum bactericidal-fungicidal concentration (MBC-MFC) by the macrodilution method. The extracts abilities to accelerate wound healing were studied on murine and human fibroblasts in terms of cell viability and migration (scratch wound-healing assay). RESULTS: All the extracts were non-toxic against the selected microorganisms at the tested concentrations, and significantly improve wound healing process in vitro, compared to untreated controls. However, the defatted methanol extract was active at lower concentrations, compared to the water extract. CONCLUSIONS: The ability of both water and defatted methanol extracts to accelerate scratch wound closure in fibroblast cultures may support the traditional use of D. klainei stem bark in the treatment of skin lesions (such as burns) even if no antimicrobial activity was evidenced.

Antimicrobial activity of Anonna mucosa (Jacq.) grown in vivo and obtained by in vitroculture.

Brazilian flora includes numerous species of medicinal importance that can be used to develop new drugs. Plant tissue culture offers strategies for conservation and use of these species allowing continuous production of plants and bioactive substances. Annona mucosa has produced substances such as acetogenins and alkaloids that exhibit antimicrobial activities. The widespread use of antibiotics has led to an increase in multidrug-resistant bacteria, which represents a serious risk of infection. In view of this problem, the aim of this work was to evaluate the antibacterial potential of extracts of A. mucosa obtained by in vitro techniques and also cultured under in vivo conditions. Segments from seedlings were inoculated onto different culture media containing the auxin picloram and the cytokinin kinetin at different concentrations. The calluses obtained were used to produce cell suspension cultures. The materials were subjected to methanol extraction and subsequent fractionation in hexane and dichloromethane. The antimicrobial activity against 20 strains of clinical relevance was evaluated by the macrodilution method at minimum inhibitory and minimum bactericidal concentrations. The extracts showed selective antimicrobial activity, inhibiting the growth of Streptococcus pyogenes and Bacillus thuringiensis at different concentrations. The plant tissue culture methods produced plant materials with antibacterial properties, as well as in vivo grown plants. The antibacterial activity of material obtained through biotechnological procedures of A. mucosa is reported here for the first time.

Antimicrobial activity of Anonna mucosa (Jacq.) grown in vivo and obtained by in vitroculture

Brazilian flora includes numerous species of medicinal importance that can be used to develop new drugs. Plant tissue culture offers strategies for conservation and use of these species allowing continuous production of plants and bioactive substances. Annona mucosa has produced substances such as acetogenins and alkaloids that exhibit antimicrobial activities. The widespread use of antibiotics has led to an increase in multidrug-resistant bacteria, which represents a serious risk of infection. In view of this problem, the aim of this work was to evaluate the antibacterial potential of extracts of A. mucosa obtained by in vitro techniques and also cultured under in vivo conditions. Segments from seedlings were inoculated onto different culture media containing the auxin picloram and the cytokinin kinetin at different concentrations. The calluses obtained were used to produce cell suspension cultures. The materials were subjected to methanol extraction and subsequent fractionation in hexane and dichloromethane. The antimicrobial activity against 20 strains of clinical relevance was evaluated by the macrodilution method at minimum inhibitory and minimum bactericidal concentrations. The extracts showed selective antimicrobial activity, inhibiting the growth of Streptococcus pyogenes and Bacillus thuringiensis at different concentrations. The plant tissue culture methods produced plant materials with antibacterial properties, as well as in vivo grown plants. The antibacterial activity of material obtained through biotechnological procedures of A. mucosa is reported here for the first time.

Essential oil of Artemisia vestita exhibits potent in vitro and in vivo antibacterial activity: Investigation of the effect of oil on biofilm formation, leakage of potassium ions and survival curve measurement.

The aim of the present study was to investigate the chemical composition of the essential oil of Artemisia vestita and to determine the antibacterial activity of the essential oil and its two major components, grandisol and 1,8­cineole, against certain respiratory infection­causing bacterial strains, in vitro and in vivo. The chemical composition of the essential oil was analyzed using gas chromatography­mass spectrometry. A micro­well dilution method was used to determine the minimum inhibition concentration (MIC) values of the essential oil and its major constituents. A model of Streptococcus pyogenes infection in mice was used to determine its in vivo activities. Lung and blood samples were obtained to assess bacterial cell counts. Toxicity evaluation of the essential oil and its components was completed by performing biochemical analysis of the serum, particularly monitoring aspartate transaminase, alanine transaminase, urea and creatinine. The essential oil exhibited potent antibacterial activity, whereas the two major constituents were less potent. The essential oil exhibited MIC values between 20 and 80 µg/ml, while the values of the two constituents were between 130 and 200 µg/ml. Scanning electron microscopy results demonstrated that the essential oil inhibited biofilm formation and altered its architecture. Survival curves indicated that the essential oil led to a reduction in the viability of different bacteria. The essential oil also induced significant leakage of potassium ions from S. pyogenes. The essential oil (100 µg/mouse) and grandisol (135 µg/mouse) significantly reduced the number of viable bacterial cells in the lungs (P<0.01). However, intake of 100 µg/mouse of essential oil or grandisol 135 µg/mouse once or twice each day for 9 days did not produce any toxic effects in the mice. In conclusion, the in vitro and in vivo results suggested that the essential oil of A. vestita and one of its major constituents, grandisol, can significantly inhibit the growth of different bacterial strains.

Streptococcus pyogenes arginine and citrulline catabolism promotes infection and modulates innate immunity.

A bacterium's ability to acquire nutrients from its host during infection is an essential component of pathogenesis. For the Gram-positive pathogen Streptococcus pyogenes, catabolism of the amino acid arginine via the arginine deiminase (ADI) pathway supplements energy production and provides protection against acid stress in vitro. Its expression is enhanced in murine models of infection, suggesting an important role in vivo. To gain insight into the function of the ADI pathway in pathogenesis, the virulence of mutants defective in each of its enzymes was examined. Mutants unable to use arginine (ΔArcA) or citrulline (ΔArcB) were attenuated for carriage in a murine model of asymptomatic mucosal colonization. However, in a murine model of inflammatory infection of cutaneous tissue, the ΔArcA mutant was attenuated but the ΔArcB mutant was hyperattenuated, revealing an unexpected tissue-specific role for citrulline metabolism in pathogenesis. When mice defective for the arginine-dependent production of nitric oxide (iNOS(-/-)) were infected with the ΔArcA mutant, cutaneous virulence was rescued, demonstrating that the ability of S. pyogenes to utilize arginine was dispensable in the absence of nitric oxide-mediated innate immunity. This work demonstrates the importance of arginine and citrulline catabolism and suggests a novel mechanism of virulence by which S. pyogenes uses its metabolism to modulate innate immunity through depletion of an essential host nutrient.

Ação dos medicamentos homeopáticos Arnica montana, Gelsemium sempervirens, Belladonna, Mercurius solubillis e nosódio sobre o crescimento in vitro da bactéria Streptococcus pyogenes / Action of homeopathic medicines Arnica montana, Gelsemium sempervirens,Belladonna, Mercurius solubillis and nosode on in vitro growth of Streptococcus pyogenes

Introdução: As bactérias são os micro-organismos com maior potencial patogênico para o ser humano. As infecções causadas por elas são na sua maioria graves e devem ser tratadas com drogas antibacterianas. Uma dessas bactérias patogênicas é Streptococcus pyogenes, causadora de diversas infecções, incluindo amigdalite, erisipela e ndocardite, sendo que em alguns pacientes ocorre febre reumática como complicação pós-infecção. Diversos trabalhos na literatura demonstram efeitos biológicos em bactérias após contato com soluções ultra-diluídas. Embasados nessas informações, propusemos avaliar o efeito dos medicamentos homeopáticos Belladonna (Bell), Mercurius solubillis (Merc), Gelsemium sempervirens (Gels) e nosódio de S. pyogenes no crescimento in vitro da bactéria S. pyogenes. Arnica montana (Arn) foi usado no presente trabalho como controle, por não ser, aparentemente, indicada no tratamento de infecções bacterianas. Materiais e métodos: Os medicamentos foram utilizados nas diluições de 12cH e 30cH, nas concentrações de 2, 4 e 6 gotas em 3 mL de meio BHI (Brain Heart Infusion) com 100µL da bactérias na concentração 0,5 da escala de McFarland. A solução foi incubada a 37ºC por 20 horas e submetida à leitura em espectrofotômetro a 600nm. Resultados: Os medicamentos nosódio e Bell nas diluições 12cH e 30cH com 2, 4 ou 6 gotas inibiram significativamente o crescimento in vitro de S. pyogenes, enquanto Arn 30cH na concentração de 6 gotas estimulou esse crescimento. Conclusão: Medicamentos homeopáticos podem ter ação sobre o crescimento in vitro de bactérias, sendo que essa ação pode estar relacionada a sua aplicação clínica. (AU)

Introduction: Bacteria are the microorganisms with greatest pathogenic potential for human beings. The infections caused by bacteria are usually serious and require treatment with antibacterial drugs. One of such pathogenic bacteria is Streptococcus pyogenes, which is associated with several infections diseases, including tonsillitis, erysipela and endocarditis, being that rheumatic fever might occur as a post-infection complication. There are records in the literature of biological effects in bacteria subjected to ultra-diluted solutions. On those grounds, we sought to test the effects of homeopathic medicines Belladonna (Bell), Mercurius solubillis (Merc), Gelsemium sempervirens (Gels) and S. pyogenes nosode on the in vitro growth of S. pyogenes. Arnica montana (Arn) was used as control, as it is believed not to have any effect in the treatment of infections. Materials and methods: The homeopathic medicines were used in dilutions 12cH and 30cH in concentration 2, 4 and 6 drops/3 mL of BHI (Brain Heart Infusion) with 100 µL of bacteria in concentration 0.5 McFarland scale. The solution was incubated at 37 ºC for 20 hours and read in spectrophotometer at 600 nm. Results: Medicines nosode and Bell in dilution 12cH and 30cH and concentration 2, 4 and 6 drops induced significant inhibition of the in vitro growth of S. pyogenes; Arn30cH in concentration 6 drops promoted bacterial growth. Conclusion: Homeopathic medicines might have an action on the in vitro growth of bacteria, which might be related with their clinical applications. (AU)

Ação dos medicamentos homeopáticos Arnica montana, Gelsemium sempervirens, Belladonna, Mercurius solubillis e nosódio sobre o crescimento in vitro da bactéria Streptococcus pyogenes / Action of homeopathic medicines Arnica montana, Gelsemium sempervirens,Belladonna, Mercurius solubillis and nosode on in vitro growth of Streptococcus pyogenes

Introdução: As bactérias são os micro-organismos com maior potencial patogênico para o ser humano. As infecções causadas por elas são na sua maioria graves e devem ser tratadas com drogas antibacterianas. Uma dessas bactérias patogênicas é Streptococcus pyogenes, causadora de diversas infecções, incluindo amigdalite, erisipela e ndocardite, sendo que em alguns pacientes ocorre febre reumática como complicação pós-infecção. Diversos trabalhos na literatura demonstram efeitos biológicos em bactérias após contato com soluções ultra-diluídas. Embasados nessas informações, propusemos avaliar o efeito dos medicamentos homeopáticos Belladonna (Bell), Mercurius solubillis (Merc), Gelsemium sempervirens (Gels) e nosódio de S. pyogenes no crescimento in vitro da bactéria S. pyogenes. Arnica montana (Arn) foi usado no presente trabalho como controle, por não ser, aparentemente, indicada no tratamento de infecções bacterianas. Materiais e métodos: Os medicamentos foram utilizados nas diluições de 12cH e 30cH, nas concentrações de 2, 4 e 6 gotas em 3 mL de meio BHI (Brain Heart Infusion) com 100µL da bactérias na concentração 0,5 da escala de McFarland. A solução foi incubada a 37ºC por 20 horas e submetida à leitura em espectrofotômetro a 600nm. Resultados: Os medicamentos nosódio e Bell nas diluições 12cH e 30cH com 2, 4 ou 6 gotas inibiram significativamente o crescimento in vitro de S. pyogenes, enquanto Arn 30cH na concentração de 6 gotas estimulou esse crescimento. Conclusão: Medicamentos homeopáticos podem ter ação sobre o crescimento in vitro de bactérias, sendo que essa ação pode estar relacionada a sua aplicação clínica.

Introduction: Bacteria are the microorganisms with greatest pathogenic potential for human beings. The infections caused by bacteria are usually serious and require treatment with antibacterial drugs. One of such pathogenic bacteria is Streptococcus pyogenes, which is associated with several infections diseases, including tonsillitis, erysipela and endocarditis, being that rheumatic fever might occur as a post-infection complication. There are records in the literature of biological effects in bacteria subjected to ultra-diluted solutions. On those grounds, we sought to test the effects of homeopathic medicines Belladonna (Bell), Mercurius solubillis (Merc), Gelsemium sempervirens (Gels) and S. pyogenes nosode on the in vitro growth of S. pyogenes. Arnica montana (Arn) was used as control, as it is believed not to have any effect in the treatment of infections. Materials and methods: The homeopathic medicines were used in dilutions 12cH and 30cH in concentration 2, 4 and 6 drops/3 mL of BHI (Brain Heart Infusion) with 100 µL of bacteria in concentration 0.5 McFarland scale. The solution was incubated at 37 ºC for 20 hours and read in spectrophotometer at 600 nm. Results: Medicines nosode and Bell in dilution 12cH and 30cH and concentration 2, 4 and 6 drops induced significant inhibition of the in vitro growth of S. pyogenes; Arn30cH in concentration 6 drops promoted bacterial growth. Conclusion: Homeopathic medicines might have an action on the in vitro growth of bacteria, which might be related with their clinical applications.

Antibacterial performance of nanoscaled visible-light responsive platinum-containing titania photocatalyst in vitro and in vivo.

BACKGROUND: Traditional antibacterial photocatalysts are primarily induced by ultraviolet light to elicit antibacterial reactive oxygen species. New generation visible-light responsive photocatalysts were discovered, offering greater opportunity to use photocatalysts as disinfectants in our living environment. Recently, we found that visible-light responsive platinum-containing titania (TiO2-Pt) exerted high performance antibacterial property against soil-borne pathogens even in soil highly contaminated water. However, its physical and photocatalytic properties, and the application in vivo have not been well-characterized. METHODS: Transmission electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, ultraviolet-visible absorption spectrum and the removal rate of nitrogen oxides were therefore analyzed. The antibacterial performance under in vitro and in vivo conditions was evaluated. RESULTS: The apparent quantum efficiency for visible light illuminated TiO2-Pt is relatively higher than several other titania photocatalysts. The killing effect achieved approximately 2 log reductions of pathogenic bacteria in vitro. Illumination of injected TiO2-Pt successfully ameliorated the subcutaneous infection in mice. CONCLUSIONS: This is the first demonstration of in vivo antibacterial use of TiO2-Pt nanoparticles. When compared to nanoparticles of some other visible-light responsive photocatalysts, TiO2-Pt nanoparticles induced less adverse effects such as exacerbated platelet clearance and hepatic cytotoxicity in vivo. GENERAL SIGNIFICANCE: These findings suggest that the TiO2-Pt may have potential application on the development of an antibacterial material in both in vitro and in vivo settings.

Antimicrobial activity of different Finnish monofloral honeys against human pathogenic bacteria.

The antimicrobial activity and phenolic compounds of five Finnish honey products against important human pathogens Streptococcus pneumoniae, S. pyogenes, Staphylococcus aureus, and methicillin-resistant S. aureus were analyzed. Microbroth dilution method and HPLC-DAD were used in antimicrobial testing and phenolic compound determination, respectively. Significant antimicrobial activity (p < 0.01) against all the tested pathogens was found from willow herb (Epilobium angustifolium), heather (Calluna vulgaris), and buckwheat (Fagopyrum esculentum) honeys. This is the first report on antimicrobial activity of Finnish monofloral honeys against streptococcal and staphylococcal bacteria. To our knowledge this is also the first report on the antimicrobial effect of honey against S. pneumoniae.

Study of streptococcal hemoprotein receptor (Shr) in iron acquisition and virulence of M1T1 group A streptococcus.

Streptococcus pyogenes (group A streptococcus, GAS) is a human bacterial pathogen of global significance, causing severe invasive diseases associated with serious morbidity and mortality. To survive within the host and establish an infection, GAS requires essential nutrients, including iron. The streptococcal hemoprotein receptor (Shr) is a surface-localized GAS protein that binds heme-containing proteins and extracellular matrix components. In this study, we employ targeted allelic exchange mutagenesis to investigate the role of Shr in the pathogenesis of the globally disseminated serotype M1T1 GAS. The shr mutant exhibited a growth defect in iron-restricted medium supplemented with ferric chloride, but no significant differences were observed in neutrophil survival, antimicrobial peptide resistance, cell surface charge, fibronectin-binding or adherence to human epithelial cells and keratinocytes, compared with wild-type. However, the shr mutant displayed a reduction in human blood proliferation, laminin-binding capacity and was attenuated for virulence in in vivo models of skin and systemic infection. We conclude that Shr augments GAS adherence to laminin, an important extracellular matrix attachment component. Furthermore, Shr-mediated iron uptake contributes to GAS growth in human blood, and is required for full virulence of serotype M1T1 GAS in mouse models of invasive disease.

Biosynthesis of silver nanoparticles from Tribulus terrestris and its antimicrobial activity: a novel biological approach.

In the recent decades, increased development of green synthesis of nanoparticles is inevitable because of its incredible applications in all fields of science. There were numerous work have been produced based on the plant and its extract mediated synthesis of nanoparticles, in this present study to explore that the novel approaches for the biosynthesis of silver nanoparticles using plant fruit bodies. The plant, Tribulus terrestris L. fruit bodies are used in this study, where the dried fruit body extract was mixed with silver nitrate in order to synthesis of silver nanoparticles. The active phytochemicals present in the plant were responsible for the quick reduction of silver ion (Ag(+)) to metallic silver nanoparticles (Ag(0)). The reduced silver nanoparticles were characterized by Transmission Electron Microscope (TEM), Atomic Force Microscope (AFM), XRD, FTIR, UV-vis spectroscopy. The spherical shaped silver nanoparticles were observed and it was found to be 16-28 nm range of sizes. The diffraction pattern also confirmed that the higher percentage of silver with fine particles size. The antibacterial property of synthesized nanoparticles was observed by Kirby-Bauer method with clinically isolated multi-drug resistant bacteria such as Streptococcus pyogens, Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis and Staphylococcus aureus. The plant materials mediated synthesis of silver nanoparticles have comparatively rapid and less expensive and wide application to antibacterial therapy in modern medicine.

Potential antibiotic and anti-infective effects of rhodomyrtone from Rhodomyrtus tomentosa (Aiton) Hassk. on Streptococcus pyogenes as revealed by proteomics.

Rhodomyrtone from Rhodomyrtus tomentosa (Aiton) Hassk. leaf extract has a strong antibacterial activity against the bacterial pathogen Streptococcus pyogenes. Our previous studies indicated that the bactericidal activity of rhodomyrtone might involve intracellular targets. In the present studies we followed a proteomics approach to investigate the mode of action of rhodomyrtone on S. pyogenes. For this purpose, S. pyogenes was cultivated in the presence of 0.39 µg/ml rhodomyrtone, which corresponds to 50% of the minimal inhibitory concentration. The results show that the amounts of various enzymes associated with important metabolic pathways were strongly affected, which is consistent with the growth-inhibiting effect of rhodomyrtone. Additionally, cells of S. pyogenes grown in the presence of rhodomyrtone produced reduced amounts of known virulence factors, such as the glyceraldehyde-3-phosphate dehydrogenase, the CAMP factor, and the streptococcal pyrogenic exotoxin C. Taken together, these findings indicate that rhodomyrtone has both antimicrobial and anti-infective activities, which make it an interesting candidate drug.

Inhibition of group A streptococcal infection by Melaleuca alternifolia (tea tree) oil concentrate in the murine model.

AIMS: To investigate the effect of a water-soluble Melaleuca alternifolia concentrate (MAC) on group A streptococcus (GAS; Streptococcus pyogenes)-induced necrotizing fasciitis. METHODS AND RESULTS: MAC pretreatment (1% and 2% v/v) was able to protect mice from GAS infection in an air pouch model. GAS-induced mouse death and skin injury were inhibited dose dependently by MAC. Administration of MAC at 6 h post-GAS infection partially delayed mouse death. Surveys of the exudates of the air pouch of MAC-treated mice revealed that the survival of infiltrating cells was prolonged, the bacteria were eliminated, and the production of inflammatory cytokines was inhibited. MAC could directly inhibit the growth of GAS in vitro, and the minimal inhibitory concentration (MIC) of MAC for GAS was determined as 0.05% v/v using the time-kill assay. Furthermore, a sub-MIC dose of MAC not only enhanced the bactericidal activity of RAW264.7 macrophage cells against GAS but also increased susceptibility of GAS for blood clearance. CONCLUSIONS: These results suggest that MAC may inhibit GAS-induced skin damage and mouse death by directly inhibiting GAS growth and enhancing the bactericidal activity of macrophages. SIGNIFICANCE AND IMPACT OF THE STUDY: Our results provide scientific data on the use of MAC for the treatment of GAS-induced necrotizing fasciitis in the murine model.

Effect of antibiotics on group A Streptococcus exoprotein production analyzed by two-dimensional gel electrophoresis.

High-dose clindamycin (CLDM) and benzylpenicillin (PCG) are the recommended chemotherapeutic remedies for toxic shock-like syndrome caused by group A streptococci. One reason for this is that it has been shown that CLDM suppresses the expression of some exoproteins, e.g., SpeB, SpeA, and streptolysin O (Slo). We analyzed the effects of antibiotics on the production of whole exoproteins by two-dimensional gel electrophoresis. Unexpectedly, we found that the levels of several exoproteins, Slo, NAD(+)-glycohydrolase (Nga), M protein, and Sic, were increased by CLDM treatment, although we also confirmed previous findings that the levels of various exoproteins, including SpeB, were decreased. The increases in exoprotein levels were also detected by using other protein synthesis inhibitor antibiotics: erythromycin, kanamycin, tetracycline, chloramphenicol, and linezolid. Peptidoglycan synthesis inhibitors (such as PCG, cefazolin, and imipenem), DNA replication inhibitors (such as gatifloxacin), and an RNA polymerase inhibitor (rifampin) did not have significant effects on exoprotein production. The combination of CLDM and PCG had no advantageous effects with regard to exoprotein production compared to the effect achieved with CLDM alone. We also analyzed the transcriptional levels of slo and nga by reverse transcription-PCR and found that this change was also detected at the transcriptional level. Furthermore, the phenomenon was seen not only in strains of the M1 serotype but also in strains of the other M serotypes. Our study suggests that the clinical effectiveness of CLDM might be due to the inhibition of the production of a limited number of exoproteins.

[Vitamin K as a stimulator of microbial growth]. / Vitamin K kak stimuliator rosta mikroorganizmov.

The stimulating action of vitamin K, contained in medicinal plants as vitamin K natural complexes and in Vikasol and Menadion, the pharmaceutical preparations of vitamin K, on the growth of pathogenic microorganisms was determined. The stimulating action of group K vitamins should be taken into consideration in the development of nutrient media.