Evolution of Resistance to Continuously Increasing Streptomycin Concentrations in Populations of Escherichia coli

The evolution of antibiotic resistance in bacteria has become one of the defining problems in modern biology. Bacterial resistance to antimicrobial therapy threatens to eliminate one of the pillars of the practice of modern medicine. Yet, in spite of the importance of this problem, only recently have the dynamics of the shift from antibiotic sensitivity to resistance in a bacterial population been studied. In this study, a novel chemostat method was used to observe the evolution of resistance to streptomycin in a sensitive population ofEscherichia coli, which grew while the concentration of antibiotic was constantly increasing. The results indicate that resistant mutants remain at a low frequency for longer than expected and do not begin to rise to a high frequency until the antibiotic concentrations are above the measured MIC, creating a “lull period” in which there were few bacterial cells growing in the chemostats. Overall, mutants resistant to streptomycin were found in >60% of the experimental trial replicates. All of the mutants detected were found to have MICs far above the maximum levels of streptomycin to which they were exposed and reached a high frequency within 96 h.

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ANALYSIS OF MICROFLORA IN MODERN OUTPATIENT CLINIC

Archiv Euromedica ◽

10.35630/2199-885x/2020/10/26 ◽

2020 ◽

Vol 10 (1) ◽

pp. 92-93

Author(s):

Mikhail Pahomov ◽

Artyom Morozov ◽

Alexey Sergeev ◽

Evgeny Mokhov, ◽

Nikolay Sergeev ◽

...

Keyword(s):

Escherichia Coli ◽

Staphylococcus Aureus ◽

Antibiotic Resistance ◽

Streptococcus Pyogenes ◽

Resistance Genes ◽

Bacterial Resistance ◽

Antibiotic Sensitivity ◽

Modern Medicine ◽

Resistance To Antibiotics ◽

The Right

Antibiotic resistance is a global problem of modern medicine. In the research a microflora of out-patient department visitors in 2018–2019 was examined. It was revealed that the most often microbes were Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli. The dynamics of bacterial resistance to antibiotics was also analyzed. The multiple bacterial resistance to antibiotics were detected. The data show a rapid resistance genes spread among non-hospital strains, which necessitates constant monitoring of antibiotic sensitivity in order to develop the right tactics to combat antibiotic resistance.

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Dual Roles of Capsular Extracellular Polymeric Substances in Photocatalytic Inactivation of Escherichia coli: Comparison of E. coli BW25113 and Isogenic Mutants

Applied and Environmental Microbiology ◽

10.1128/aem.00775-15 ◽

2015 ◽

Vol 81 (15) ◽

pp. 5174-5183 ◽

Cited By ~ 22

Author(s):

Guocheng Huang ◽

Dehua Xia ◽

Taicheng An ◽

Tsz Wai Ng ◽

Ho Yin Yip ◽

...

Keyword(s):

Escherichia Coli ◽

Direct Contact ◽

Extracellular Polymeric Substances ◽

Bacterial Resistance ◽

Bacterial Cells ◽

Dual Roles ◽

Content Type ◽

Photocatalytic Inactivation ◽

Isogenic Mutants ◽

Inactivation Of Bacteria

ABSTRACTThe dual roles of capsular extracellular polymeric substances (EPS) in the photocatalytic inactivation of bacteria were demonstrated in a TiO2-UVA system, by comparing wild-typeEscherichia colistrain BW25113 and isogenic mutants with upregulated and downregulated production of capsular EPS. In a partition system in which direct contact between bacterial cells and TiO2particles was inhibited, an increase in the amount of EPS was associated with increased bacterial resistance to photocatalytic inactivation. In contrast, when bacterial cells were in direct contact with TiO2particles, an increase in the amount of capsular EPS decreased cell viability during photocatalytic treatment. Taken together, these results suggest that although capsular EPS can protect bacterial cells by consuming photogenerated reactive species, it also facilitates photocatalytic inactivation of bacteria by promoting the adhesion of TiO2particles to the cell surface. Fluorescence microscopy and scanning electron microscopy analyses further confirmed that high capsular EPS density led to more TiO2particles attaching to cells and forming bacterium-TiO2aggregates. Calculations of interaction energy, represented by extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) potential, suggested that the presence of capsular EPS enhances the attachment of TiO2particles to bacterial cells via acid-base interactions. Consideration of these mechanisms is critical for understanding bacterium-nanoparticle interactions and the photocatalytic inactivation of bacteria.

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Improved cytocompatibility and antibacterial properties of zinc-substituted brushite bone cement based on β-tricalcium phosphate

Journal of Materials Science Materials in Medicine ◽

10.1007/s10856-021-06575-x ◽

2021 ◽

Vol 32 (9) ◽

Author(s):

Inna V. Fadeeva ◽

Margarita A. Goldberg ◽

Ilya I. Preobrazhensky ◽

Georgy V. Mamin ◽

Galina A. Davidova ◽

...

Keyword(s):

Escherichia Coli ◽

Tricalcium Phosphate ◽

Bacterial Resistance ◽

Antibacterial Properties ◽

Modern Medicine ◽

Physiological Solution ◽

Final Phase ◽

Bone Replacement ◽

Challenging Tasks ◽

Murine Fibroblast

AbstractFor bone replacement materials, osteoconductive, osteoinductive, and osteogenic properties are desired. The bacterial resistance and the need for new antibacterial strategies stand among the most challenging tasks of the modern medicine. In this work, brushite cements based on powders of Zinc (Zn) (1.4 wt%) substituted tricalcium phosphate (β-TCP) and non-substituted β-TCP were prepared and investigated. Their initial and final phase composition, time of setting, morphology, pH evolution, and compressive strength are reported. After soaking for 60 days in physiological solution, the cements transformed into a mixture of brushite and hydroxyapatite. Antibacterial activity of the cements against Enterococcus faecium, Escherichia coli, and Pseudomonas aeruginosa bacteria strains was attested. The absence of cytotoxicity of cements was proved for murine fibroblast NCTC L929 cells. Moreover, the cell viability on the β-TCP cement containing Zn2+ ions was 10% higher compared to the β-TCP cement without zinc. The developed cements are perspective for applications in orthopedics and traumatology.

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PBP4 and PBP5 are involved in regulating exopolysaccharide synthesis during Escherichia coli biofilm formation

Microbiology ◽

10.1099/mic.0.001031 ◽

2021 ◽

Vol 167 (3) ◽

Author(s):

Sathi Mallick ◽

Shanti Kiran ◽

Tapas Kumar Maiti ◽

Anindya S. Ghosh

Keyword(s):

Escherichia Coli ◽

Biofilm Formation ◽

Type Species ◽

Pentose Phosphate ◽

Bacterial Cells ◽

Surface Adhesion ◽

Content Type ◽

Penicillin Binding Proteins ◽

E Coli ◽

Link Type

Escherichia coli low-molecular-mass (LMM) Penicillin-binding proteins (PBPs) help in hydrolysing the peptidoglycan fragments from their cell wall and recycling them back into the growing peptidoglycan matrix, in addition to their reported involvement in biofilm formation. Biofilms are external slime layers of extra-polymeric substances that sessile bacterial cells secrete to form a habitable niche for themselves. Here, we hypothesize the involvement of Escherichia coli LMM PBPs in regulating the nature of exopolysaccharides (EPS) prevailing in its extra-polymeric substances during biofilm formation. Therefore, this study includes the assessment of physiological characteristics of E. coli CS109 LMM PBP deletion mutants to address biofilm formation abilities, viability and surface adhesion. Finally, EPS from parent CS109 and its ΔPBP4 and ΔPBP5 mutants were purified and analysed for sugars present. Deletions of LMM PBP reduced biofilm formation, bacterial adhesion and their viability in biofilms. Deletions also diminished EPS production by ΔPBP4 and ΔPBP5 mutants, purification of which suggested an increased overall negative charge compared with their parent. Also, EPS analyses from both mutants revealed the appearance of an unusual sugar, xylose, that was absent in CS109. Accordingly, the reason for reduced biofilm formation in LMM PBP mutants may be speculated as the subsequent production of xylitol and a hindrance in the standard flow of the pentose phosphate pathway.

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Bacterial Secretions of Nonpathogenic Escherichia coli Elicit Inflammatory Pathways: a Closer Investigation of Interkingdom Signaling

mBio ◽

10.1128/mbio.00025-15 ◽

2015 ◽

Vol 6 (2) ◽

Cited By ~ 33

Author(s):

Amin Zargar ◽

David N. Quan ◽

Karen K. Carter ◽

Min Guo ◽

Herman O. Sintim ◽

...

Keyword(s):

Escherichia Coli ◽

Epithelial Cells ◽

Negative Feedback ◽

Cell Contact ◽

Bacterial Cells ◽

Content Type ◽

Phenotypic Differences ◽

E Coli ◽

Autoinducer 2 ◽

Human Epithelial Cells

ABSTRACTThere have been many studies on the relationship between nonpathogenic bacteria and human epithelial cells; however, the bidirectional effects of the secretomes (secreted substances in which there is no direct bacterium-cell contact) have yet to be fully investigated. In this study, we use a transwell model to explore the transcriptomic effects of bacterial secretions from two different nonpathogenicEscherichia colistrains on the human colonic cell line HCT-8 using next-generation transcriptome sequencing (RNA-Seq).E. coliBL21 and W3110, while genetically very similar (99.1% homology), exhibit key phenotypic differences, including differences in their production of macromolecular structures (e.g., flagella and lipopolysaccharide) and in their secretion of metabolic byproducts (e.g., acetate) and signaling molecules (e.g., quorum-sensing autoinducer 2 [AI-2]). After analysis of differential epithelial responses to the respective secretomes, this study shows for the first time that a nonpathogenic bacterial secretome activates the NF-κB-mediated cytokine-cytokine receptor pathways while also upregulating negative-feedback components, including the NOD-like signaling pathway. Because of AI-2's relevance as a bacterium-bacterium signaling molecule and the differences in its secretion rates between these strains, we investigated its role in HCT-8 cells. We found that the expression of the inflammatory cytokine interleukin 8 (IL-8) responded to AI-2 with a pattern of rapid upregulation before subsequent downregulation after 24 h. Collectively, these data demonstrate that secreted products from nonpathogenic bacteria stimulate the transcription of immune-related biological pathways, followed by the upregulation of negative-feedback elements that may serve to temper the inflammatory response.IMPORTANCEThe symbiotic relationship between the microbiome and the host is important in the maintenance of human health. There is a growing need to further understand the nature of these relationships to aid in the development of homeostatic probiotics and also in the design of novel antimicrobial therapeutics. To our knowledge, this is the first global-transcriptome study of bacteria cocultured with human epithelial cells in a model to determine the transcriptional effects of epithelial cells in which epithelial and bacterial cells are allowed to “communicate” with each other only through diffusible small molecules and proteins. By beginning to demarcate the direct and indirect effects of bacteria on the gastrointestinal (GI) tract, two-way interkingdom communication can potentially be mediated between host and microbe.

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A Stringent Analysis of Polyphosphate Dynamics inEscherichia coli

Journal of Bacteriology ◽

10.1128/jb.00070-19 ◽

2019 ◽

Vol 201 (9) ◽

Author(s):

Michael Downey

Keyword(s):

Escherichia Coli ◽

Infection Control ◽

Bacterial Species ◽

Stringent Response ◽

Industrial Applications ◽

Bacterial Cells ◽

Inescherichia Coli ◽

Content Type ◽

Polyphosphate Accumulation ◽

Inorganic Phosphates

ABSTRACTDuring stress, bacterial cells activate a conserved pathway called the stringent response that promotes survival. Polyphosphates are long chains of inorganic phosphates that modulate this response in diverse bacterial species. In this issue, Michael J. Gray provides an important correction to the model of how polyphosphate accumulation is regulated during the stringent response inEscherichia coli(M. J. Gray, J. Bacteriol, 201:e00664-18, 2019,https://doi.org/10.1128/JB.00664-18). With other recent publications, this study provides a revised framework for understanding how bacterial polyphosphate dynamics might be exploited in infection control and industrial applications.

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Bacteriophage Lambda: a Paradigm Revisited

Journal of Virology ◽

10.1128/jvi.02177-09 ◽

2010 ◽

Vol 84 (13) ◽

pp. 6876-6879 ◽

Cited By ~ 23

Author(s):

Paul C. M. Fogg ◽

Heather E. Allison ◽

Jon R. Saunders ◽

Alan J. McCarthy

Keyword(s):

Escherichia Coli ◽

Sequence Analysis ◽

High Frequency ◽

Southern Hybridization ◽

Integration Site ◽

Bacteriophage Lambda ◽

Rare Event ◽

Low Frequency ◽

E Coli ◽

Very Low Frequency

ABSTRACT Bacteriophage lambda has an archetypal immunity system, which prevents the superinfection of its Escherichia coli lysogens. It is now known that superinfection can occur with toxigenic lambda-like phages at a high frequency, and here we demonstrate that the superinfection of a lambda lysogen can lead to the acquisition of additional lambda genomes, which was confirmed by Southern hybridization and quantitative PCR. As many as eight integration events were observed but at a very low frequency (6.4 × 10−4) and always as multiple insertions at the established primary integration site in E. coli. Sequence analysis of the complete immunity region demonstrated that these multiply infected lysogens were not immunity mutants. In conclusion, although lambda superinfection immunity can be confounded, it is a rare event.

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Genome-Wide Transcriptional Profiling of the Escherichia coli Response to a Proline-Rich Antimicrobial Peptide

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.48.9.3260-3267.2004 ◽

2004 ◽

Vol 48 (9) ◽

pp. 3260-3267 ◽

Cited By ~ 26

Author(s):

Linda Tomasinsig ◽

Marco Scocchi ◽

Romina Mettulio ◽

Margherita Zanetti

Keyword(s):

Escherichia Coli ◽

Bacterial Resistance ◽

Transcriptional Profiling ◽

Transcriptional Response ◽

Bacterial Cells ◽

Experimental Conditions ◽

Bacterial Membranes ◽

Transcriptional Alterations ◽

Proline Rich Peptide ◽

Bacterial Genes

ABSTRACT Most antimicrobial peptides (AMPs) impair the viability of target bacteria by permeabilizing bacterial membranes. However, the proline-rich AMPs have been shown to kill susceptible organisms without causing significant membrane perturbation and may act by inhibiting the activity of bacterial targets. To gain initial insight into the events that follow interaction of a proline-rich peptide with bacterial cells, we used DNA macroarray technology to monitor transcriptional alterations of Escherichia coli in response to challenge with a subinhibitory concentration of the proline-rich Bac7(1-35). Substantial changes in the expression levels of 70 bacterial genes from various functional categories were detected. Among these, 26 genes showed decreased expression, while 44 genes, including genes that are potentially involved in bacterial resistance to antimicrobials, showed increased expression. The generation of a transcriptional response under the experimental conditions used is consistent with the ability of Bac7(1-35) to interact with bacterial components and affect biological processes in this organism.

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Transposition of Tn1213Encoding the PER-1 Extended-Spectrum β-Lactamase

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02453-17 ◽

2018 ◽

Vol 62 (3) ◽

pp. e02453-17 ◽

Cited By ~ 2

Author(s):

Stefano Mancini ◽

Laurent Poirel ◽

Nicolas Kieffer ◽

Patrice Nordmann

Keyword(s):

Escherichia Coli ◽

Low Frequency ◽

Insertion Sequences ◽

Content Type ◽

Very Low Frequency ◽

Extended Spectrum

ABSTRACTPER-1 is an extended-spectrum β-lactamase that is encoded by a gene located in composite transposon Tn1213made by two distinct insertion sequences, namely, ISPa12and ISPa13. In vitromobilization performed inEscherichia colishows that Tn1213is functional and is able to mobilize theblaPER-1gene, although at a very low frequency (ca. 1 × 10−9).

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Metabolomics of Escherichia coli Treated with the Antimicrobial Carbon Monoxide-Releasing Molecule CORM-3 Reveals Tricarboxylic Acid Cycle as Major Target

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00643-19 ◽

2019 ◽

Vol 63 (10) ◽

Cited By ~ 4

Author(s):

Sandra M. Carvalho ◽

Joana Marques ◽

Carlos C. Romão ◽

Lígia M. Saraiva

Keyword(s):

Escherichia Coli ◽

Carbon Monoxide ◽

Tricarboxylic Acid Cycle ◽

Redox Homeostasis ◽

Glutamate Synthase ◽

Tca Cycle ◽

Tricarboxylic Acid ◽

Bacterial Cells ◽

Content Type ◽

Iron Sulfur

ABSTRACT In the last decade, carbon monoxide-releasing molecules (CORMs) have been shown to act against several pathogens and to be promising antimicrobials. However, the understanding of the mode of action and reactivity of these compounds on bacterial cells is still deficient. In this work, we used a metabolomics approach to probe the toxicity of the ruthenium(II) complex Ru(CO)3Cl(glycinate) (CORM-3) on Escherichia coli. By resorting to 1H nuclear magnetic resonance, mass spectrometry, and enzymatic activities, we show that CORM-3-treated E. coli accumulates larger amounts of glycolytic intermediates, independently of the oxygen growth conditions. The work provides several evidences that CORM-3 inhibits glutamate synthesis and the iron-sulfur enzymes of the tricarboxylic acid (TCA) cycle and that the glycolysis pathway is triggered in order to establish an energy and redox homeostasis balance. Accordingly, supplementation of the growth medium with fumarate, α-ketoglutarate, glutamate, and amino acids cancels the toxicity of CORM-3. Importantly, inhibition of the iron-sulfur enzymes glutamate synthase, aconitase, and fumarase is only observed for compounds that liberate carbon monoxide. Altogether, this work reveals that the antimicrobial action of CORM-3 results from intracellular glutamate deficiency and inhibition of nitrogen and TCA cycles.

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