Persister cells: formation, resuscitation and combative therapies

AbstractPersister cells, or superfits, have been strongly implicated in the recalcitrance and recurrence of chronic bacterial infection through the dormant (metabolically reduced) phenotype they display and the tolerance to antimicrobial agents this dormancy grants them. The complex biochemical events that lead to the formation of persister cells are not completely understood, though much research has linked the degradation of type II toxin/antitoxin systems and reduced cellular ATP levels to the rise in stress response molecules (where (p)ppGpp is of particular interest), which induce this dormant state. The equally complex mechanism of resuscitation is initiated by the cells’ ability to sense nutrient availability via chemotaxis systems. Levels of secondary messenger proteins (i.e., cAMP) within the cell are reduced to allow the resuscitation of ribosomes, by ribosomal resuscitation factor HflX, to reinstate protein synthesis and, therefore, growth to re-populate. Techniques of superfit eradication utilise one, or more, of three approaches (i) direct killing, (ii) re-sensitising persister cells to conventional antimicrobials, or (iii) prevention of persister formation though few laboratory findings have been translated to clinical practice. This work will outline current findings in the field with a critical approach, where possible.

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Targeting Type II Toxin–Antitoxin Systems as Antibacterial Strategies

Toxins ◽

10.3390/toxins12090568 ◽

2020 ◽

Vol 12 (9) ◽

pp. 568

Author(s):

Marcin Równicki ◽

Robert Lasek ◽

Joanna Trylska ◽

Dariusz Bartosik

Keyword(s):

Pathogenic Bacteria ◽

Antimicrobial Agents ◽

Protein Targeting ◽

Bactericidal Effect ◽

Host Cells ◽

Bacterial Toxin ◽

Type Ii ◽

Human Pathogens ◽

Persister Cells ◽

Molecular Nature

The identification of novel targets for antimicrobial agents is crucial for combating infectious diseases caused by evolving bacterial pathogens. Components of bacterial toxin–antitoxin (TA) systems have been recognized as promising therapeutic targets. These widespread genetic modules are usually composed of two genes that encode a toxic protein targeting an essential cellular process and an antitoxin that counteracts the activity of the toxin. Uncontrolled toxin expression may elicit a bactericidal effect, so they may be considered “intracellular molecular bombs” that can lead to elimination of their host cells. Based on the molecular nature of antitoxins and their mode of interaction with toxins, TA systems have been classified into six groups. The most prevalent are type II TA systems. Due to their ubiquity among clinical isolates of pathogenic bacteria and the essential processes targeted, they are promising candidates for the development of novel antimicrobial strategies. In this review, we describe the distribution of type II TA systems in clinically relevant human pathogens, examine how these systems could be developed as the targets for novel antibacterials, and discuss possible undesirable effects of such therapeutic intervention, such as the induction of persister cells, biofilm formation and toxicity to eukaryotic cells.

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Type II diabetes and its therapy in clinical practice – results from the standardised non‐interventional registry SIRTA

International Journal of Clinical Practice ◽

10.1111/ijcp.12497 ◽

2014 ◽

Vol 68 (12) ◽

pp. 1442-1453 ◽

Cited By ~ 1

Author(s):

B. Gallwitz ◽

K. Kusterer ◽

S. Hildemann ◽

K. Fresenius

Keyword(s):

Clinical Practice ◽

Type Ii Diabetes ◽

Type Ii

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The Oxazolidinone Linezolid Inhibits Initiation of Protein Synthesis in Bacteria

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.42.12.3251 ◽

1998 ◽

Vol 42 (12) ◽

pp. 3251-3255 ◽

Cited By ~ 314

Author(s):

Steve M. Swaney ◽

Hiroyuki Aoki ◽

M. Clelia Ganoza ◽

Dean L. Shinabarger

Keyword(s):

Protein Synthesis ◽

Complex Formation ◽

Antimicrobial Agents ◽

Ribosomal Subunit ◽

Multidrug Resistant ◽

Binary Complex ◽

Initiation Complex ◽

Ribosomal Subunits ◽

Bacterial Translation

ABSTRACT The oxazolidinones represent a new class of antimicrobial agents which are active against multidrug-resistant staphylococci, streptococci, and enterococci. Previous studies have demonstrated that oxazolidinones inhibit bacterial translation in vitro at a step preceding elongation but after the charging ofN-formylmethionine to the initiator tRNA molecule. The event that occurs between these two steps is termed initiation. Initiation of protein synthesis requires the simultaneous presence of N-formylmethionine-tRNA, the 30S ribosomal subunit, mRNA, GTP, and the initiation factors IF1, IF2, and IF3. An initiation complex assay measuring the binding of [3H]N-formylmethionyl-tRNA to ribosomes in response to mRNA binding was used in order to investigate the mechanism of oxazolidinone action. Linezolid inhibited initiation complex formation with either the 30S or the 70S ribosomal subunits fromEscherichia coli. In addition, complex formation withStaphylococcus aureus 70S tight-couple ribosomes was inhibited by linezolid. Linezolid did not inhibit the independent binding of either mRNA or N-formylmethionyl-tRNA toE. coli 30S ribosomal subunits, nor did it prevent the formation of the IF2–N-formylmethionyl-tRNA binary complex. The results demonstrate that oxazolidinones inhibit the formation of the initiation complex in bacterial translation systems by preventing formation of theN-formylmethionyl-tRNA–ribosome–mRNA ternary complex.

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Reassessing the Role of Type II Toxin-Antitoxin Systems in Formation ofEscherichia coliType II Persister Cells

mBio ◽

10.1128/mbio.00640-18 ◽

2018 ◽

Vol 9 (3) ◽

Cited By ~ 71

Author(s):

Frédéric Goormaghtigh ◽

Nathan Fraikin ◽

Marta Putrinš ◽

Thibaut Hallaert ◽

Vasili Hauryliuk ◽

...

Keyword(s):

Antibiotic Treatment ◽

Bacterial Infections ◽

Bacterial Population ◽

Transient State ◽

Health Concern ◽

Type Ii ◽

Direct Link ◽

Persister Cells ◽

Content Type ◽

High Fluorescence

ABSTRACTPersistence is a reversible and low-frequency phenomenon allowing a subpopulation of a clonal bacterial population to survive antibiotic treatments. Upon removal of the antibiotic, persister cells resume growth and give rise to viable progeny. Type II toxin-antitoxin (TA) systems were assumed to play a key role in the formation of persister cells inEscherichia colibased on the observation that successive deletions of TA systems decreased persistence frequency. In addition, the model proposed that stochastic fluctuations of (p)ppGpp levels are the basis for triggering activation of TA systems. Cells in which TA systems are activated are thought to enter a dormancy state and therefore survive the antibiotic treatment. Using independently constructed strains and newly designed fluorescent reporters, we reassessed the roles of TA modules in persistence both at the population and single-cell levels. Our data confirm that the deletion of 10 TA systems does not affect persistence to ofloxacin or ampicillin. Moreover, microfluidic experiments performed with a strain reporting the induction of theyefM-yoeBTA system allowed the observation of a small number of type II persister cells that resume growth after removal of ampicillin. However, we were unable to establish a correlation between high fluorescence and persistence, since the fluorescence of persister cells was comparable to that of the bulk of the population and none of the cells showing high fluorescence were able to resume growth upon removal of the antibiotic. Altogether, these data show that there is no direct link between induction of TA systems and persistence to antibiotics.IMPORTANCEWithin a growing bacterial population, a small subpopulation of cells is able to survive antibiotic treatment by entering a transient state of dormancy referred to as persistence. Persistence is thought to be the cause of relapsing bacterial infections and is a major public health concern. Type II toxin-antitoxin systems are small modules composed of a toxic protein and an antitoxin protein counteracting the toxin activity. These systems were thought to be pivotal players in persistence until recent developments in the field. Our results demonstrate that previous influential reports had technical flaws and that there is no direct link between induction of TA systems and persistence to antibiotics.

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Perioperative antimicrobial prophylaxis in adult patients: The first multicenter clinical practice audit with intervention in Greek surgical departments

Infection Control and Hospital Epidemiology ◽

10.1017/ice.2020.1276 ◽

2020 ◽

pp. 1-8

Author(s):

Elisavet Chorafa ◽

Elias Iosifidis ◽

Sotirios Tsiodras ◽

Athanasios Skoutelis ◽

Eleni Kourkouni ◽

...

Keyword(s):

Clinical Practice ◽

Antimicrobial Agents ◽

Antimicrobial Prophylaxis ◽

Surgical Site Infections ◽

Audit And Feedback ◽

Elective Surgical Procedures ◽

Before And After ◽

Greek Hospitals ◽

Practice Audit ◽

Perioperative Antimicrobial Prophylaxis

Abstract Objective: To audit clinical practice and implement an intervention to promote appropriate use of perioperative antimicrobial prophylaxis (PAP). Design: Prospective multicenter before-and-after study. Setting: This study was conducted in 7 surgical departments of 3 major Greek hospitals. Methods: Active PAP surveillance in adults undergoing elective surgical procedures was performed before and after implementation of a multimodal intervention. The surveillance monitored use of appropriate antimicrobial agent according to international and local guidelines, appropriate timing and duration of PAP, overall compliance with all 3 parameters and the occurrence of surgical site infections (SSIs). The intervention included education, audit, and feedback. Results: Overall, 1,447 patients were included: 768 before and 679 after intervention. Overall compliance increased from 28.2% to 43.9% (P = .001). Use of antimicrobial agents compliant to international guidelines increased from 89.6% to 96.3% (P = .001). In 4 of 7 departments, compliance with appropriate timing was already >90%; an increase from 44.3% to 73% (P = .001) and from 20.4% to 60% (P = .001), respectively, was achieved in 2 other departments, whereas a decrease from 64.1% to 10.9% (P = .001) was observed in 1 department. All but one department achieved a shorter PAP duration, and most achieved duration of ~2 days. SSIs significantly decreased from 6.9% to 4% (P = .026). After the intervention, it was 2.3 times more likely for appropriate antimicrobial use, 14.7 times more likely to administer an antimicrobial for the appropriate duration and 5.3 times more likely to administer an overall appropriate PAP. Conclusion: An intervention based on education, audit, and feedback can significantly contribute to improvement of appropriate PAP administration; further improvement in duration is needed.

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Certain Aspects of Silver and Silver Nanoparticles in Wound Care: A Minireview

Journal of Nanomaterials ◽

10.1155/2016/7614753 ◽

2016 ◽

Vol 2016 ◽

pp. 1-10 ◽

Cited By ~ 48

Author(s):

Marek Konop ◽

Tatsiana Damps ◽

Aleksandra Misicka ◽

Lidia Rudnicka

Keyword(s):

Silver Nanoparticles ◽

Clinical Practice ◽

Pathogenic Bacteria ◽

Antimicrobial Agents ◽

Antifungal Agents ◽

Wound Care ◽

Wound Dressings ◽

Major Health Problem ◽

Major Health ◽

Bactericidal Effects

Resistance to antimicrobial agents by pathogenic bacteria has emerged in recent years and is a major health problem. In this context silver and silver nanoparticles (AgNP) have been known to have inhibitory and bactericidal effects and was used throughout history for treatment of skin ulcer, bone fracture, and supporting wound healing. In all of these applications prevention and treatment of bacterial colonized/infected wounds are critical. In this context silver and its derivatives play an important role in health care. Silver is widely used in clinical practice in the form of silver nitrate and/or silver sulfadiazine. In the last few years silver nanoparticles entered into clinical practice as both antimicrobial and antifungal agents. In addition, nanosilver is used in coating medical devices (catheters) and as component of wound dressings. In this paper we present summarized information about silver and nanoparticles made of silver in the context of their useful properties, especially antibacterial ones, being of a great interest for researchers and clinicians.

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T3 potentiates the adrenergic stimulation of type II 5'-deiodinase activity in cultured rat brown adipocytes

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1996.271.1.e15 ◽

1996 ◽

Vol 271 (1) ◽

pp. E15-E23 ◽

Cited By ~ 3

Author(s):

A. Hernandez ◽

M. J. Obregon

Keyword(s):

Protein Synthesis ◽

Adrenergic Receptors ◽

Inhibitory Action ◽

De Novo ◽

Type Ii ◽

Adrenergic Stimulation ◽

Beta Adrenergic Receptors ◽

Brown Adipocytes ◽

De Novo Protein Synthesis ◽

Stimulation Of

Iodothyronine type II 5'-deiodinase (5'D-II) activities were studied in cultures of rat brown adipocytes. In the presence of serum, the adrenergically stimulated 5'D-II activities were very low. In the absence of serum, adenosine 3',5'-cyclic monophosphate (cAMP) analogues stimulated 5'D-II activity. Thyroxine (T4) inhibited these increases. Norepinephrine slightly increased 5'D-II activity in hypothyroid conditions, but 3,5,3'-triiodothyronine (T3) strongly potentiated the adrenergic stimulation of 5'D-II (20-fold). T3 amplification of the adrenergic stimulation was via beta-adrenergic receptors, specifically mimicked by beta3-agonists, but it was not observed using cAMP analogues. The stimulatory effect of T3 predominated over the inhibitory action of T4, increased with exposure to T3, and required de novo protein synthesis. The half-life of 5'D-II was 30 min, suggesting that stabilization of 5'D-II did not occur. The effect was only observed in differentiated adipocytes. Retinoic acid has similar although smaller effects than T3. In conclusion, the presence of T3 is required and strongly potentiates the noradrenergic stimulation of 5'D-II activity in rat brown adipocytes.

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Tractable targets for meropenem-sparing antimicrobial stewardship interventions

JAC-Antimicrobial Resistance ◽

10.1093/jacamr/dlz042 ◽

2019 ◽

Vol 1 (2) ◽

Cited By ~ 1

Author(s):

Clark D Russell ◽

Ian F Laurenson ◽

Morgan H Evans ◽

Claire L Mackintosh

Keyword(s):

Clinical Practice ◽

Antimicrobial Stewardship ◽

Antimicrobial Agents ◽

Tertiary Care ◽

Real Life ◽

Lessons Learned ◽

Source Control ◽

First Line ◽

Escalation Therapy ◽

Clinical Records

Abstract Background As meropenem is a restricted antimicrobial, lessons learned from its real-life usage will be applicable to antimicrobial stewardship (AMS) more generally. Objectives To retrospectively evaluate meropenem usage at our institution to identify targets for AMS interventions. Methods Patients receiving meropenem documented with an ‘alert antimicrobial’ form at two tertiary care UK hospitals were identified retrospectively. Clinical records and microbiology results were reviewed. Results A total of 107 adult inpatients receiving meropenem were identified. This was first-line in 47% and escalation therapy in 53%. Source control was required in 28% of cases after escalation, for predictable reasons. Those ultimately requiring source control had received more prior antimicrobial agents than those who did not (P = 0.03). Meropenem was rationalized in 24% of cases (after median 4 days). Positive microbiology enabled rationalization (OR 12.3, 95% CI 2.7–55.5, P = 0.001) but rates of appropriate sampling varied. In cases with positive microbiology where meropenem was not rationalized, continuation was retrospectively considered clinically and microbiologically necessary in 8/40 cases (0/17 empirical first-line usage). Rationalization was more likely when meropenem susceptibility was not released on the microbiology report (OR 5.2, 95% CI 1.3–20.2, P = 0.02). Input from an infection specialist was associated with a reduced duration of meropenem therapy (P < 0.0001). Early review by an infection specialist has the potential to further facilitate rationalization. Conclusions In real-life clinical practice, core aspects of infection management remain tractable targets for AMS interventions: microbiological sampling, source control and infection specialist input. Further targets include supporting rationalization to less familiar carbapenem-sparing antimicrobials, restricting first-line meropenem usage and selectively reporting meropenem susceptibility.

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