scholarly journals Antibiotic in myrrh from Commiphora molmol preferentially kills nongrowing bacteria

2020 ◽  
pp. FSO458
Author(s):  
Mrinal K Bhattacharjee ◽  
Tahrir Alenezi
Keyword(s):  
Growth Inhibition ◽  
Soft Agar ◽  
Bacterial Cells ◽  
Persister Cells ◽  
Resistance Development ◽  
Development Method ◽  
Continue Growth

Aim: To demonstrate that myrrh oil preferentially kills nongrowing bacteria and causes no resistance development. Method: Growth inhibition was determined on regular plates or plates without nutrients, which were later overlaid with soft agar containing nutrients to continue growth. Killing experiments were done in broth and in buffer without nutrients. Results: Bacterial cells were inhibited preferentially in the absence of nutrients or when growth was halted by a bacteriostatic antibiotic. After five passages in myrrh oil, surviving colonies showed no resistance to the antibiotic. Conclusion: Myrrh oil has the potential to be a commercially viable antibiotic that kills persister cells and causes no resistance development. This is a rare example of an antibiotic that can preferentially kill nongrowing bacteria.

scholarly journals Microbial Photoinactivation by Visible Light Results in Limited Loss of Membrane Integrity

Antibiotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 341
Author(s):  
Katharina Hoenes ◽  
Richard Bauer ◽  
Barbara Spellerberg ◽  
Martin Hessling
Keyword(s):  
Visible Light ◽  
Pseudomonas Fluorescens ◽  
Bacterial Cell ◽  
Bacterial Species ◽  
Membrane Integrity ◽  
Cell Lysis ◽  
Microbial Inactivation ◽  
Bacterial Cells ◽  
Resistance Development ◽  
Transmission Electron

Interest in visible light irradiation as a microbial inactivation method has widely increased due to multiple possible applications. Resistance development is considered unlikely, because of the multi-target mechanism, based on the induction of reactive oxygen species by wavelength specific photosensitizers. However, the affected targets are still not completely identified. We investigated membrane integrity with the fluorescence staining kit LIVE/DEAD® BacLight™ on a Gram positive and a Gram negative bacterial species, irradiating Staphylococcus carnosus and Pseudomonas fluorescens with 405 nm and 450 nm. To exclude the generation of viable but nonculturable (VBNC) bacterial cells, we applied an ATP test, measuring the loss of vitality. Pronounced uptake of propidium iodide was only observed in Pseudomonas fluorescens at 405 nm. Transmission electron micrographs revealed no obvious differences between irradiated samples and controls, especially no indication of an increased bacterial cell lysis could be observed. Based on our results and previous literature, we suggest that visible light photoinactivation does not lead to rapid bacterial cell lysis or disruption. However, functional loss of membrane integrity due to depolarization or inactivation of membrane proteins may occur. Decomposition of the bacterial envelope following cell death might be responsible for observations of intracellular component leakage.

scholarly journals Bacterial Persister Cell Formation and Dormancy

2013 ◽  
Vol 79 (23) ◽  
pp. 7116-7121 ◽  
Author(s):  
Thomas K. Wood ◽  
Stephen J. Knabel ◽  
Brian W. Kwan
Keyword(s):  
Stationary Phase ◽  
Cell Formation ◽  
Genetic Change ◽  
Bacterial Cells ◽  
Mechanistic Studies ◽  
Chronic Infections ◽  
Persister Cells ◽  
Metabolic State ◽  
Dormant State ◽  
Persister Cell

ABSTRACTBacterial cells may escape the effects of antibiotics without undergoing genetic change; these cells are known as persisters. Unlike resistant cells that grow in the presence of antibiotics, persister cells do not grow in the presence of antibiotics. These persister cells are a small fraction of exponentially growing cells (due to carryover from the inoculum) but become a significant fraction in the stationary phase and in biofilms (up to 1%). Critically, persister cells may be a major cause of chronic infections. The mechanism of persister cell formation is not well understood, and even the metabolic state of these cells is debated. Here, we review studies relevant to the formation of persister cells and their metabolic state and conclude that the best model for persister cells is still dormancy, with the latest mechanistic studies shedding light on how cells reach this dormant state.

scholarly journals Discovery and development of new antimicrobial agents.

1990 ◽  
Vol 3 (1) ◽  
pp. 13-31 ◽  
Author(s):  
T D Gootz
Keyword(s):  
Bacterial Resistance ◽  
Antimicrobial Agents ◽  
Bacterial Cells ◽  
Beta Lactams ◽  
Resistance Development ◽  
Safety Testing ◽  
The Past ◽  
Body Of Knowledge ◽  
New Antibiotics ◽  
The Impact

The unprecedented growth in the number of new antibiotics over the past two decades has been the result of extensive research efforts that have exploited the growing body of knowledge describing the interactions of antibiotics with their targets in bacterial cells. Information gained from one class of antimicrobial agents has often been used to advance the development of other classes. In the case of beta-lactams, information on structure-activity relationships gleaned from penicillins and cephalosporins was rapidly applied to the cephamycins, monobactams, penems, and carbapenems in order to discover broad-spectrum agents with markedly improved potency. These efforts have led to the introduction of many new antibiotics that demonstrate outstanding clinical efficacy and improved pharmacokinetics in humans. The current review discusses those factors that have influenced the rapid proliferation of new antimicrobial agents, including the discovery of new lead structures from natural products and the impact of bacterial resistance development in the clinical setting. The development process for a new antibiotic is discussed in detail, from the stage of early safety testing in animals through phase I, II, and III clinical trials.

scholarly journals Inhibition of hemolytic activity of Streptococcus pyogenes in mechanisms of antibacterial action of zinc ions

2019 ◽  
pp. 16-23
Author(s):  
S. B. Cheknev ◽  
E. I. Vostrova ◽  
M. A. Sarycheva ◽  
A. V. Vostrov
Keyword(s):  
Growth Inhibition ◽  
Streptococcus Pyogenes ◽  
Hemolytic Activity ◽  
Inhibitory Action ◽  
Bacterial Culture ◽  
Copper Ions ◽  
Zinc Ions ◽  
Bacterial Cells ◽  
Bacterial Cultures ◽  
Culture Growth

Aim. The work was performed with the purpose to study a hemolytic activity in the culture of S.pyogenes under the inhibitory action of millimolar concentrations of zinc ions.Materials and methods. Suspensions of S.pyogenes bacteria which contained 108 CFU/ml were sown by the lawns into the standard Petri dishes coated with the supplemented Blood Nutrient Agar. 30 min later the salt solutions of zinc or copper which contained the metals at the concentrations ranged between 5 x 10-3 M to 5 x 10-1 M were added by the 5 μl drops on the surfaces of the lawns with use of 36-channel stamp replicator. Then the dishes with bacterial cultures were incubated for 24 hrs at 37°C followed by measuring diameter of the area of culture growth inhibition and of the area of inhibition of hemolysis. The study was performed with use of controls towards measuring the state of bacterial cells obtained from different zones of the areas.Results. In presence of the zinc ions concentrations ranged between 50 to 500 mM the area of the growth inhibition of S.pyogenes was surrounded on the lawn of the bacterial culture by the area of the inhibition of hemolysis where the growth inhibition of S.pyogenes was not registered. Copper ions did not form such an area of the hemolysis inhibition.Conclusion. Inhibitory action of zinc ions on the hemolytic S.pyogenes activity in the culture seems to be specific and reversible, and is discussed in a context of the antivirulent zinc ions properties.

scholarly journals Environmental conditions define the energetics of bacterial dormancy and its antibiotic susceptibility

2020 ◽  
Author(s):  
L Mancini ◽  
T Pilizota
Keyword(s):  
Drug Susceptibility ◽  
Cell Physiology ◽  
Environmental Cues ◽  
Bacterial Cells ◽  
Infection Site ◽  
Persister Cells ◽  
Energy Profiles ◽  
Dormant Cells ◽  
Clinical Interest ◽  
High Concentrations

ABSTRACTBacterial cells that halt growth but maintain viability and the capacity to regrow are termed dormant and have been shown to transiently tolerate high concentrations of antimicrobials. Dormancy has been seen in both tolerant and persister cells and is therefore of substantial clinical interest, as both can lead to infection recalcitrance and facilitate the development of antibiotic resistance. In this work, we look at dormancies induced by environmental cues that target different aspects of cell physiology by measuring the energy profiles they elicit in single dormant cells. Our simultaneous measurements of ATP concentration, proton motive force (PMF) and cytoplasmic pH reveal that dormant cells can exist in various energy states, offering a solution to the apparent mutual incompatibility of previous experimental results. We then test whether the energetic makeup is associated with survival to antibiotics of different classes. We find that for certain drugs growth arrest remains the dominant mechanism enabling survival, while for others, like ciprofloxacin, the most energetic cells remain almost untouched by the drug. Our results support a novel relationship between environment and drug susceptibility of dormant cells and suggest that knowledge of the conditions present at the infection site is necessary to design appropriate treatments.

scholarly journals Determining the Development of Persisters in Extensively Drug-Resistant Acinetobacter baumannii upon Exposure to Polymyxin B-Based Antibiotic Combinations Using Flow Cytometry

2019 ◽  
Vol 64 (3) ◽  
Author(s):  
Fiona Hui-Sian Wong ◽  
Yiying Cai ◽  
Hui Leck ◽  
Tze-Peng Lim ◽  
Jocelyn Qi-Min Teo ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Acinetobacter Baumannii ◽  
Polymyxin B ◽  
Live Cells ◽  
Drug Resistant ◽  
Bacterial Cells ◽  
Persister Cells ◽  
Content Type ◽  
Initial Inoculum ◽  
Extensively Drug Resistant

ABSTRACT Polymyxin B-based combinations are increasingly prescribed as a last-line option against extensively drug-resistant (XDR) Acinetobacter baumannii. It is unknown if such combinations can result in the development of nondividing persister cells in XDR A. baumannii. We investigated persister development upon exposure of XDR A. baumannii to polymyxin B-based antibiotic combinations using flow cytometry. Time-kill studies (TKSs) were conducted in three nonclonal XDR A. baumannii strains with 5 log10 CFU/ml bacteria against polymyxin B alone and polymyxin B-based two-drug combinations over 24 h. At different time points, samples were obtained and enumerated by viable plating and flow cytometry. Propidium iodide and carboxyfluorescein succinimidyl ester dyes were used to differentiate between live and dead cells and between dividing and nondividing cells, respectively, at the single-cell level, and nondividing live cells were resuscitated and characterized phenotypically. Our results from viable plating showed that polymyxin B plus meropenem and polymyxin B plus rifampin were each bactericidal (>99.9% kill compared to the initial inoculum) against 2/3 XDR A. baumannii strains at 24 h. By flow cytometry, however, none of the combinations were bactericidal against XDR A. baumannii at 24 h. Further analysis using cellular dyes in flow cytometry revealed that upon exposure to polymyxin B-based combinations, XDR A. baumannii entered a viable but nondividing persister state. These bacterial cells reinitiated division upon the removal of antibiotic pressure and did not have a growth deficit compared to the parent strain. We conclude that persister cells develop in XDR A. baumannii upon exposure to polymyxin B-based combinations and that nonplating methods appear to complement viable-plating methods in describing the killing activity of polymyxin B-based combinations against XDR A. baumannii.

scholarly journals The Fatty Acid Signaling Moleculecis-2-Decenoic Acid Increases Metabolic Activity and Reverts Persister Cells to an Antimicrobial-Susceptible State

2014 ◽  
Vol 80 (22) ◽  
pp. 6976-6991 ◽  
Author(s):  
Cláudia N. H. Marques ◽  
Aleksey Morozov ◽  
Penny Planzos ◽  
Hector M. Zelaya
Keyword(s):  
Fatty Acid ◽  
Cell Number ◽  
Antimicrobial Treatment ◽  
Bacterial Cells ◽  
Chronic Infections ◽  
Persister Cells ◽  
Decenoic Acid ◽  
Signaling Molecule ◽  
Content Type ◽  
Persister Cell

ABSTRACTPersister cells, which are tolerant to antimicrobials, contribute to biofilm recalcitrance to therapeutic agents. In turn, the ability to kill persister cells is believed to significantly improve efforts in eradicating biofilm-related, chronic infections. While much research has focused on elucidating the mechanism(s) by which persister cells form, little is known about the mechanism or factors that enable persister cells to revert to an active and susceptible state. Here, we demonstrate thatcis-2-decenoic acid (cis-DA), a fatty acid signaling molecule, is able to change the status ofPseudomonas aeruginosaandEscherichia colipersister cells from a dormant to a metabolically active state without an increase in cell number. This cell awakening is supported by an increase of the persister cells' respiratory activity together with changes in protein abundance and increases of the transcript expression levels of several metabolic markers, includingacpP, 16S rRNA,atpH, andppx. Given that most antimicrobials target actively growing cells, we also explored the effect ofcis-DA on enhancing antibiotic efficacy in killing persister cells due to their inability to keep a persister cell state. Compared to antimicrobial treatment alone, combinational treatments of persister cell subpopulations with antimicrobials andcis-DA resulted in a significantly greater decrease in cell viability. In addition, the presence ofcis-DA led to a decrease in the number of persister cells isolated. We thus demonstrate the ability of a fatty acid signaling molecule to revert bacterial cells from a tolerant phenotype to a metabolically active, antimicrobial-sensitive state.

scholarly journals Epitranscriptomic Reader HNRNPA2B1 Confers Endocrine Resistance to Breast Cancer Cells

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. A807-A808
Author(s):  
Carolyn M Klinge ◽  
Belinda J Petri ◽  
Kellianne M Piell
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Growth Inhibition ◽  
Cancer Cells ◽  
Metastatic Disease ◽  
Colony Size ◽  
Breast Cancer Cells ◽  
Endocrine Resistance ◽  
Soft Agar ◽  
Mcf 7

Abstract Despite new combination therapies improving survival of breast cancer patients with estrogen receptor α (ER+) tumors, the molecular mechanisms for endocrine-resistant metastatic disease remain unresolved. HNRNPA2B1 (Heterogeneous Nuclear Ribonucleoprotein A2/B1), an RNA binding protein that functions as reader of the N(6)-methyladenosine (m6A) mark in transcribed RNA, is upregualted in tamoxifen- and fulvestrant-resistant, estrogen receptor (ERα)+ LCC9 and LY2 cells derived from MCF-7 endocrine-sensitive luminal A breast cancer cells (1). The miRNA-seq transcriptome of MCF-7 cells transiently overexpressing HNRNPA2B1 (A2B1) identified gene ontology (GO) pathways including “cellular response to steroid hormone signaling and estradiol” and “positive regulation of protein ser/thr kinase activity”. Modest (~ 4.5-fold) stable HNRNPA2B1 overexpression in MCF-7 cells (MCF-7-A2B1) results in ablation of growth inhibition by 4-hydroxytamoxifen (4-OHT) and fulvestrant. This was not due to loss or decrease of ERα; in fact, ERα was increased. Conversely, transient knockdown of HNRNPA2B1 in LCC9 and LY2 cells sensitized the cells to growth inhibition by 4-OHT and fulvestrant while reducing ERα. MCF-7-A2B1 cells showed increased migration, invasion, clonogenicity, soft agar colony size, and markers of epithelial-to-mesenchymal transition. Like LCC9 cells, MCF-7-A2B1 cells showed activation of AKT and MAPK and high androgen receptor (AR). Treatment of MCF-7-A2B1 cells with either PI3K inhibitor Wortmannin or MEK inhibitor PD98059 inhibited soft agar colony formation and reduced colony size. Knockdown of HNRNPA2B1 in MCF-7-A2B1 reduces clonogenicity, but had no effect on the clonogenicity of either LCC9 or LY2 cells. These data suggest a role for HNRNPA2B1 in promoting the initiation of acquired endocrine-resistance by activating ser/thr kinase growth factor signaling pathways. Selective inhibition of HNRNPA2B1 may be a target to prevent acquistion of endocrine therapy resistance, but not treat established metastatic disease. Reference: (1) Klinge CM, Piell KM, Tooley CS, Rouchka EC. HNRNPA2/B1 is upregulated in endocrine-resistant LCC9 breast cancer cells and alters the miRNA transcriptome when overexpressed in MCF-7 cells. Scientific reports 2019; 9:9430

scholarly journals Chemotaxis of Marinobacter adhaerens and Its Impact on Attachment to the Diatom Thalassiosira weissflogii

2012 ◽  
Vol 78 (19) ◽  
pp. 6900-6907 ◽  
Author(s):  
Eva C. Sonnenschein ◽  
Desalegne Abebew Syit ◽  
Hans-Peter Grossart ◽  
Matthias S. Ullrich
Keyword(s):  
Bacterial Chemotaxis ◽  
Gene Clusters ◽  
Soft Agar ◽  
Bacterial Cells ◽  
Aggregate Formation ◽  
Thalassiosira Weissflogii ◽  
Interspecies Interactions ◽  
Wild Type ◽  
Content Type ◽  
Matter Flux

ABSTRACTAlga-bacterium interactions are crucial for aggregate formation and carbon cycling in aquatic systems. To understand the initiation of these interactions, we investigated bacterial chemotaxis within a bilateral model system.Marinobacter adhaerensHP15 has been demonstrated to attach to the diatomThalassiosira weissflogiiand induce transparent exopolymeric particle and aggregate formation.M. adhaerenspossesses one polar flagellum and is highly motile. Bacterial cells were attracted to diatom cells, as demonstrated by addition of diatom cell homogenate or diatom culture supernatant to soft agar, suggesting that chemotaxis might be important for the interaction ofM. adhaerenswith diatoms. Three distinct chemotaxis-associated gene clusters were identified in the genome sequence ofM. adhaerens, with the clusters showing significant sequence similarities to those ofPseudomonas aeruginosaPAO1. Mutations in the genescheA,cheB,chpA, andchpB, which encode histidine kinases and methylesterases and which are putatively involved in either flagellum-associated chemotaxis or pilus-mediated twitching motility, were generated and mutants with the mutations were phenotypically analyzed. ΔcheAand ΔcheBmutants were found to be swimming deficient, and all four mutants were impaired in biofilm formation on abiotic surfaces. Comparison of the HP15 wild type and its chemotaxis mutants in cocultures with the diatom revealed that the fraction of bacteria attaching to the diatom decreased significantly for mutants in comparison to that for the wild type. Our results highlight the importance ofM. adhaerenschemotaxis in initiation of its interaction with the diatom. In-depth knowledge of these basic processes in interspecies interactions is pivotal to obtain a systematic understanding of organic matter flux and nutrient cycling in marine ecosystems.

Sign in / Sign up

Export Citation Format

Share Document