scholarly journals Bacterial Silver Resistance Gained by Cooperative Interspecies Redox Behavior

2018 ◽  
Vol 62 (8) ◽  
Author(s):  
Michael Muller
Keyword(s):  
Hydrogen Peroxide ◽  
Antimicrobial Activity ◽  
Broad Spectrum ◽  
Active Metabolite ◽  
Chronic Wounds ◽  
Therapeutic Option ◽  
Content Type ◽  
E Coli ◽  
Redox Active ◽  
Hydrogen Peroxide Formation

ABSTRACT Silver has emerged as an important therapeutic option for wound infections in recent years due to its broad-spectrum antimicrobial activity. The silver cation (Ag+), but not the bulk metal (Ag0), is highly toxic for most microorganisms, although resistance due to genetic modification or horizontal gene transfer does occur. Pseudomonas aeruginosa, however, achieves silver resistance by producing the redox-active metabolite pyocyanin that reduces Ag+ to nontoxic Ag0. Pyocyanin also possesses broad-spectrum antimicrobial activity. Many microbial species reduce pyocyanin, which reduces molecular oxygen to antimicrobial hydrogen peroxide. In this study, it was hypothesized that both Ag+ and oxygen would act as competing terminal electron acceptors for pyocyanin, thus acting as a universal microbial protectant from Ag+ while avoiding hydrogen peroxide formation. Escherichia coli and Staphylococcus aureus efficiently reduced pyocyanin and generated hydrogen peroxide, while Ag+ markedly reduced the amount of hydrogen peroxide produced. Although unable to reduce directly Ag+ to Ag0 on their own, E. coli and S. aureus did so when pyocyanin was present, resulting in increased survival when exposed to Ag+. Coincubation experiments with either E. coli or S. aureus with P. aeruginosa demonstrated increased survival for those species to Ag+, but only if pyocyanin was present. These data demonstrate that microorganisms that display no intrinsic silver resistance may survive and proliferate under potentially toxic conditions, provided their environment contains a suitable redox-active metabolite-producing bacterium. Chronic wounds are often polymicrobial in nature, with pyocyanin-producing P. aeruginosa bacteria frequently being present; therefore, redox-based silver resistance may compromise treatment efforts.

scholarly journals Comparison of Antibacterial Activity ofLactobacillus plantarumStrains Isolated from Two Different Kinds of Regional Cheeses from Poland: Oscypek and Korycinski Cheese

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Aleksandra Ołdak ◽  
Dorota Zielińska ◽  
Anna Rzepkowska ◽  
Danuta Kołożyn-Krajewska
Keyword(s):  
Hydrogen Peroxide ◽  
Antimicrobial Activity ◽  
Antibacterial Activity ◽  
Broad Spectrum ◽  
Antimicrobial Properties ◽  
Antagonistic Activity ◽  
Antimicrobial Compounds ◽  
E Coli ◽  
Unpasteurized Milk ◽  
Protective Cultures

Oscypek and korycinski are traditional Polish cheeses, exclusively produced in Tatra and in Podlasie region, respectively, produced from raw, unpasteurized milk. The 29Lactobacillus plantarumstrains were isolated on MRS agar from 12 cheese samples and used as a material for study. The main purpose of the work was to assess the antimicrobial properties and recognition of selected strains for the unique antagonistic activity and preservation role in food. It has been found that the highest antimicrobial activity was observed in the case ofL. monocytogenesstrains; however, the level of that activity was different depending on theLb. plantarumstrain. Strains from oscypek produced broad spectrum, and a few strains isolated from korycinski cheese produced a narrow spectrum of antimicrobial compounds, other than organic acids and hydrogen peroxide. Moreover, the antagonistic activity shown byLb. plantarumstrains is connected with the source from which a given strain was isolated. Strains isolated from oscypek cheese represented stronger activity againstL. monocytogenes, whereas strains isolated from korycinski cheese were more active againstE. coli. StrainsLb. plantarumOs13 and Kor14 could be considered as good candidates for protective cultures to extend durability of food products.

scholarly journals Inactivation of Escherichia coli by Polychromatic Simulated Sunlight: Evidence for and Implications of a Fenton Mechanism Involving Iron, Hydrogen Peroxide, and Superoxide

2013 ◽  
Vol 80 (3) ◽  
pp. 935-942 ◽  
Author(s):  
Michael B. Fisher ◽  
Kara L. Nelson
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Enteric Bacteria ◽  
Growth Conditions ◽  
Simulated Sunlight ◽  
Wild Type ◽  
Intracellular Iron ◽  
Content Type ◽  
E Coli ◽  
Degree Of Sensitization

ABSTRACTSunlight inactivation ofEscherichia colihas previously been shown to accelerate in the presence of oxygen, exogenously added hydrogen peroxide, and bioavailable forms of exogenously added iron. In this study, mutants unable to effectively scavenge hydrogen peroxide or superoxide were found to be more sensitive to polychromatic simulated sunlight (without UVB wavelengths) than wild-type cells, while wild-type cells grown under low-iron conditions were less sensitive than cells grown in the presence of abundant iron. Furthermore, prior exposure to simulated sunlight was found to sensitize cells to subsequent hydrogen peroxide exposure in the dark, but this effect was attenuated for cells grown with low iron. Mutants deficient in recombination DNA repair were sensitized to simulated sunlight (without UVB wavelengths), but growth in the presence of iron chelators reduced the degree of sensitization conferred by this mutation. These findings support the hypothesis that hydrogen peroxide, superoxide, and intracellular iron all participate in the photoinactivation ofE. coliand further suggest that the inactivation rate of enteric bacteria in the environment may be strongly dependent on iron availability and growth conditions.

Antimicrobial activity of raw soybean, soybean flour and roasted soybean extracted by ethanol-hexane method

2017 ◽  
Vol 119 (10) ◽  
pp. 2277-2286 ◽  
Author(s):  
Sireerat Laodheerasiri ◽  
Nirasha Horana Pathirage
Keyword(s):  
Antimicrobial Activity ◽  
Antimicrobial Activities ◽  
Diffusion Method ◽  
Antimicrobial Compounds ◽  
Soybean Flour ◽  
Hexane Extraction ◽  
Disk Diffusion Method ◽  
Content Type ◽  
E Coli ◽  
Inhibitory Compounds

Purpose The purpose of this paper is to determine the antimicrobial compounds extracted from various types of soybean materials; raw soybean, soybean flour and roasted soybean. Bacteria growth inhibition was tested in E.coli and S. aureus by disk diffusion method. Efficiency of antimicrobial activities were compared among the extracted solution. Design/methodology/approach Soybean (Glycine max) isoflavones contain the ability to inhibit the growth of many strains of microorganisms. The solid-liquid extraction, ethanol-hexane extraction, was modified to isolate the inhibitory compounds from the three different types of soybean materials. All crude extracts at various concentrations performed under different extracted solutions (75, 50, 25, 12.5, 6.25 and 3.125 percent) were tested with E. coli. and S. aureus to determine the antimicrobial activities and the minimum inhibition concentration (MIC). Disk diffusion method was chosen to study the antimicrobial activity of isoflavones. Findings Soybean flour extract inhibited the growth of E. coli and S. aureus more effective than roasted soybean and raw soybean, respectively. The MIC of inhibitory compounds extracted from soybean flour was 6.25 percent (0.031 mg/ml), roasted soybean was 25 percent (0.125 mg/ml) and raw soybean was 50 percent (0.250 mg/ml). Crude extracts of soybean flour and roasted soybean showed better results than raw soybean. All the three of extracted soybeans inhibited the growth of E. coli better than S. aureus. Originality/value Ethanol-hexane extraction was successfully used to isolate the antimicrobial compounds from raw soybean, soybean flour and roasted soybean. Comparison of antimicrobial activity showed that soybean flour contained the highest inhibition activity.

scholarly journals Characterizing the Mechanism of Action of an Ancient Antimicrobial, Manuka Honey, against Pseudomonas aeruginosa Using Modern Transcriptomics

mSystems ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Daniel Bouzo ◽  
Nural N. Cokcetin ◽  
Liping Li ◽  
Giulia Ballerin ◽  
Amy L. Bottomley ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antimicrobial Activity ◽  
Mechanism Of Action ◽  
Broad Spectrum ◽  
Bacterial Resistance ◽  
Resistant Bacteria ◽  
Antibiotics Resistance ◽  
Manuka Honey ◽  
Content Type ◽  
Bacterial Membranes

ABSTRACT Manuka honey has broad-spectrum antimicrobial activity, and unlike traditional antibiotics, resistance to its killing effects has not been reported. However, its mechanism of action remains unclear. Here, we investigated the mechanism of action of manuka honey and its key antibacterial components using a transcriptomic approach in a model organism, Pseudomonas aeruginosa. We show that no single component of honey can account for its total antimicrobial action, and that honey affects the expression of genes in the SOS response, oxidative damage, and quorum sensing. Manuka honey uniquely affects genes involved in the explosive cell lysis process and in maintaining the electron transport chain, causing protons to leak across membranes and collapsing the proton motive force, and it induces membrane depolarization and permeabilization in P. aeruginosa. These data indicate that the activity of manuka honey comes from multiple mechanisms of action that do not engender bacterial resistance. IMPORTANCE The threat of antimicrobial resistance to human health has prompted interest in complex, natural products with antimicrobial activity. Honey has been an effective topical wound treatment throughout history, predominantly due to its broad-spectrum antimicrobial activity. Unlike traditional antibiotics, honey-resistant bacteria have not been reported; however, honey remains underutilized in the clinic in part due to a lack of understanding of its mechanism of action. Here, we demonstrate that honey affects multiple processes in bacteria, and this is not explained by its major antibacterial components. Honey also uniquely affects bacterial membranes, and this can be exploited for combination therapy with antibiotics that are otherwise ineffective on their own. We argue that honey should be included as part of the current array of wound treatments due to its effective antibacterial activity that does not promote resistance in bacteria.

scholarly journals Human Bile Reduces Antimicrobial Activity of Selected Antibiotics against Enterococcus faecalis and Escherichia coliIn Vitro

2017 ◽  
Vol 61 (8) ◽  
Author(s):  
Beatrix Wulkersdorfer ◽  
David Jaros ◽  
Sabine Eberl ◽  
Stefan Poschner ◽  
Walter Jäger ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Enterococcus Faecalis ◽  
Bacterial Infections ◽  
Lung Surfactant ◽  
Strong Impact ◽  
Bacterial Killing ◽  
Human Bile ◽  
Content Type ◽  
E Coli ◽  
Growth Controls

ABSTRACT It has been known from previous studies that body fluids, such as cerebrospinal fluid, lung surfactant, and urine, have a strong impact on the bacterial killing of many anti-infective agents. However, the influence of human bile on the antimicrobial activity of antibiotics is widely unknown. Human bile was obtained and pooled from 11 patients undergoing cholecystectomy. After sterilization of the bile fluid by gamma irradiation, its effect on bacterial killing was investigated for linezolid (LZD) and tigecycline (TGC) against Enterococcus faecalis ATCC 29212. Further, ciprofloxacin (CIP), meropenem (MEM), and TGC were tested against Escherichia coli ATCC 25922. Time-kill curves were performed in pooled human bile and Mueller-Hinton broth (MHB) over 24 h. Bacterial counts (in CFU per milliliter after 24 h) of bile growth controls were approximately equal to MHB growth controls for E. coli and approximately 2-fold greater for E. faecalis, indicating a promotion of bacterial growth by bile for the latter strain. Bile reduced the antimicrobial activity of CIP, MEM, and TGC against E. coli as well as the activity of LZD and TGC against E. faecalis. This effect was strongest for TGC against the two strains. Degradation of TGC in bile was identified as the most likely explanation. These findings may have important implications for the treatment of bacterial infections of the gallbladder and biliary tract and should be explored in more detail.

scholarly journals Study on gamma-irradiation degradation of chitosan swollen in H₂O₂ solution and its antimicrobial activity for E. coli

2014 ◽  
Vol 4 (4) ◽  
pp. 1-8
Author(s):  
Xuan Du Dang ◽  
Phuoc Phuc Bui ◽  
Thi Thuy Tran ◽  
Anh Quoc Le ◽  
Van Phu Dang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Antimicrobial Activity ◽  
Gel Permeation Chromatography ◽  
Food Preservation ◽  
Hydrogen Peroxide Solution ◽  
Γ Irradiation ◽  
E Coli ◽  
Structure Changes ◽  
Radiation Degradation ◽  
Ft Ir

Degradation of chitosan in swollen state with hydrogen peroxide solution (5% w/v) by γ-irradiation was investigated. Molecular weight (Mw) of irradiated chitosan was determined by gel permeation chromatography (GPC). Fourier transform infrared (FT-IR) and ultraviolet-visible (UV-vis) spectrawere analyzed to study the structure changes of degraded chitosan. The results showed that the chitosan of low Mw ~30-45 kDawas efficiently prepared by γ-irradiation of chitosan swollen in hydrogen peroxide solution at low dose less than 20kGy. The main structure as well as the degree of deacetylation of the degraded chitosan was almost no significant change. Furthermore, the radiation degradation yield (Gs) was remarkably enhanced by the presence of H2O2. The obtained low Mw chitosan revealed high antimicrobial activity for E. colithat can be used for food preservation and other purposes as well.

scholarly journals Manganese Is Required for the Rapid Recovery of DNA Synthesis following Oxidative Challenge in Escherichia coli

2019 ◽  
Vol 201 (24) ◽  
Author(s):  
Corinne R. Hutfilz ◽  
Natalie E. Wang ◽  
Chettar A. Hoff ◽  
Jessica A. Lee ◽  
Brandy J. Hackert ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Dna Synthesis ◽  
Genomic Dna ◽  
Rapid Recovery ◽  
Content Type ◽  
E Coli ◽  
Oxidative Challenge ◽  
Alternative Enzymes ◽  
Iron And Manganese

ABSTRACT Divalent metals such as iron and manganese play an important role in the cellular response to oxidative challenges and are required as cofactors by many enzymes. However, how these metals affect replication after oxidative challenge is not known. Here, we show that replication in Escherichia coli is inhibited following a challenge with hydrogen peroxide and requires manganese for the rapid recovery of DNA synthesis. We show that the manganese-dependent recovery of DNA synthesis occurs independent of lesion repair, modestly improves cell survival, and is associated with elevated rates of mutagenesis. The Mn-dependent mutagenesis involves both replicative and translesion polymerases and requires prior disruption by H2O2 to occur. Taking these findings together, we propose that replication in E. coli is likely to utilize an iron-dependent enzyme(s) that becomes oxidized and inactivated during oxidative challenges. The data suggest that manganese remetallates these or alternative enzymes to allow genomic DNA replication to resume, although with reduced fidelity. IMPORTANCE Iron and manganese play important roles in how cell’s cope with oxygen stress. However, how these metals affect the ability of cells to replicate after oxidative challenges is not known. Here, we show that replication in Escherichia coli is inhibited following a challenge with hydrogen peroxide and requires manganese for the rapid recovery of DNA synthesis. The manganese-dependent recovery of DNA synthesis occurs independently of lesion repair and modestly improves survival, but it also increases the mutation rate in cells. The results imply that replication in E. coli is likely to utilize an iron-dependent enzyme(s) that becomes oxidized and inactivated during oxidative challenges. We propose that manganese remetallates these or alternative enzymes to allow genomic DNA replication to resume, although with reduced fidelity.

scholarly journals Antimicrobial Activity Evaluation of Tebipenem (SPR859), an Orally Available Carbapenem, against a Global Set of Enterobacteriaceae Isolates, Including a Challenge Set of Organisms

2019 ◽  
Vol 63 (6) ◽  
Author(s):  
S. J. Ryan Arends ◽  
Paul R. Rhomberg ◽  
Nicole Cotroneo ◽  
Aileen Rubio ◽  
Robert K. Flamm ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Activity ◽  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Tract Infection ◽  
Broth Microdilution ◽  
Wild Type ◽  
Content Type ◽  
E Coli

ABSTRACT The antimicrobial activity of tebipenem and other carbapenem agents were tested in vitro against a set of recent clinical isolates responsible for urinary tract infection (UTI), as well as against a challenge set. Isolates were tested by reference broth microdilution and included Escherichia coli (101 isolates), Klebsiella pneumoniae (208 isolates), and Proteus mirabilis (103 isolates) species. Within each species tested, tebipenem showed equivalent MIC50/90 values to those of meropenem (E. coli MIC50/90, ≤0.015/0.03 mg/liter; K. pneumoniae MIC50/90, 0.03/0.06 mg/liter; and P. mirabilis MIC50/90, 0.06/0.12 mg/liter) and consistently displayed MIC90 values 8-fold lower than imipenem. Tebipenem and meropenem (MIC50, 0.03 mg/liter) showed equivalent MIC50 results against wild-type, AmpC-, and/or extended-spectrum β-lactamase (ESBL)-producing isolates. Tebipenem also displayed MIC50/90 values 4- to 8-fold lower than imipenem against the challenge set. All carbapenem agents were less active (MIC50, ≥8 mg/liter) against isolates carrying carbapenemase genes. These data confirm the in vitro activity of the orally available agent tebipenem against prevalent UTI Enterobacteriaceae species, including those producing ESBLs and/or plasmid AmpC enzymes.

Antimicrobial Activity of SPC13, New Antimicrobial Peptide Purified from Scolopendra polymorpha Venom

2020 ◽  
Vol 18 (3) ◽  
pp. 233-238
Author(s):  
Rodríguez-Alejandro C.I. ◽  
M.C. Gutiérrez
Keyword(s):  
Antimicrobial Activity ◽  
Antimicrobial Peptide ◽  
Broad Spectrum ◽  
Bioactive Peptides ◽  
Histone H3 ◽  
Bacteriostatic Activity ◽  
E Coli ◽  
Potential Source ◽  
Pharmacological Interest ◽  
Animal Venoms

Introduction: Currently animal venoms are considered a potential source of numerous bioactive peptides of biochemical and pharmacological interest, such as peptides with antithrombotic, anticoagulant and antimicrobial activity. Methods: Such is the case of the venom from the genus Scolopendromorpha, where numerous PAMs ranging from 2.5 to 4.4 kDa have been purified, they are broad spectrum isolates only of S. subspinipes mutilans. Results: In this study, an antimicrobial peptide (SPC13) of 13 kDa, present in the venom of Scolopendra polymorpha was purified by electroelution and presented antimicrobial activity against S. aureus and P. aeruginosa with MIC of 45 and 192.5 μg/ml respectively, as well as bacteriostatic activity against E. coli at a concentration of 155μg/ml. Conclusion: Additionally, this peptide has a 20.5% hemolytic activity. A partial sequence of SPC13 showed 98% identity with the histone H3 reported in S. viridis (GenkBank: DQ222181.1).

scholarly journals Escherichia coli Pyruvate Dehydrogenase Complex Is an Important Component of CXCL10-Mediated Antimicrobial Activity

2015 ◽  
Vol 84 (1) ◽  
pp. 320-328 ◽  
Author(s):  
Kirsten M. Schutte ◽  
Debra J. Fisher ◽  
Marie D. Burdick ◽  
Borna Mehrad ◽  
Amy J. Mathers ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Activity ◽  
Cell Surface ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Gene Encoding ◽  
Content Type ◽  
E Coli ◽  
Novel Therapeutic Strategies ◽  
Dehydrogenase Complex

Chemokines are best recognized for their role within the innate immune system as chemotactic cytokines, signaling and recruiting host immune cells to sites of infection. Certain chemokines, such as CXCL10, have been found to play an additional role in innate immunity, mediating CXCR3-independent killing of a diverse array of pathogenic microorganisms. While this is still not clearly understood, elucidating the mechanisms underlying chemokine-mediated antimicrobial activity may facilitate the development of novel therapeutic strategies effective against antibiotic-resistant Gram-negative pathogens. Here, we show that CXCL10 exerts antibacterial effects on clinical and laboratory strains ofEscherichia coliand report that disruption of pyruvate dehydrogenase complex (PDHc), which converts pyruvate to acetyl coenzyme A, enablesE. colito resist these antimicrobial effects. Through generation and screening of a transposon mutant library, we identified two mutants with increased resistance to CXCL10, both with unique disruptions of the gene encoding the E1 subunit of PDHc,aceE. Resistance to CXCL10 also occurred following deletion of eitheraceForlpdA, genes that encode the remaining two subunits of PDHc. Although PDHc resides within the bacterial cytosol, electron microscopy revealed localization of immunogold-labeled CXCL10 to the bacterial cell surface in both theE. coliparent andaceEdeletion mutant strains. Taken together, our findings suggest that while CXCL10 interacts with an as-yet-unidentified component on the cell surface, PDHc is an important mediator of killing by CXCL10. To our knowledge, this is the first description of PDHc as a key bacterial component involved in the antibacterial effect of a chemokine.

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