scholarly journals Survival of Bactericidal Antibiotic Treatment by a Persister Subpopulation of Listeria monocytogenes

2013 ◽  
Vol 79 (23) ◽  
pp. 7390-7397 ◽  
Author(s):  
Gitte M. Knudsen ◽  
Yin Ng ◽  
Lone Gram
Keyword(s):  
Listeria Monocytogenes ◽  
Stationary Phase ◽  
Antibiotic Treatment ◽  
Bacterial Species ◽  
Treatment Success ◽  
Stationary Phase Culture ◽  
Content Type ◽  
Bacterial Physiology ◽  
Treatment Regimens ◽  
Fermentable Carbohydrates

ABSTRACTListeria monocytogenescan cause the serious infection listeriosis, which despite antibiotic treatment has a high mortality. Understanding the response ofL. monocytogenesto antibiotic exposure is therefore important to ensure treatment success. Some bacteria survive antibiotic treatment by formation of persisters, which are a dormant antibiotic-tolerant subpopulation. The purpose of this study was to determine whetherL. monocytogenescan form persisters and how bacterial physiology affects the number of persisters in the population. A stationary-phase culture ofL. monocytogeneswas adjusted to 108CFU ml−1, and 103to 104CFU ml−1survived 72-h treatment with 100 μg of norfloxacin ml−1, indicating a persister subpopulation. This survival was not caused by antibiotic resistance as regrown persisters were as sensitive to norfloxacin as the parental strain. Higher numbers of persisters (105to 106) were surviving when older stationary phase or surface-associated cells were treated with 100 μg of norfloxacin ml−1. The number of persisters was similar when a ΔsigBmutant and the wild type were treated with norfloxacin, but the killing rate was higher in the ΔsigBmutant. Dormant norfloxacin persisters could be activated by the addition of fermentable carbohydrates and subsequently killed by gentamicin; however, a stable surviving subpopulation of 103CFU ml−1remained. Nitrofurantoin that has a growth-independent mode of action was effective against both growing and dormant cells, suggesting that eradication of persisters is possible. Our study addsL. monocytogenesto the list of bacterial species capable of surviving bactericidal antibiotics in a dormant stage, and this persister phenomenon should be borne in mind when developing treatment regimens.

scholarly journals Copper-Induced Expression of a Transmissible Lipoprotein Intramolecular Transacylase Alters Lipoprotein Acylation and the Toll-Like Receptor 2 Response to Listeria monocytogenes

2019 ◽  
Vol 201 (13) ◽  
Author(s):  
Krista M. Armbruster ◽  
Gloria Komazin ◽  
Timothy C. Meredith
Keyword(s):  
Listeria Monocytogenes ◽  
Bacterial Species ◽  
Acyl Chain ◽  
Constitutive Expression ◽  
Innate Immune ◽  
Copper Resistance ◽  
Toll Like Receptor ◽  
General Role ◽  
Content Type ◽  
Toll Like Receptor 2

ABSTRACT Bacterial lipoproteins are globular proteins anchored to the extracytoplasmic surfaces of cell membranes through lipidation at a conserved N-terminal cysteine. Lipoproteins contribute to an array of important cellular functions for bacteria, as well as being a focal point for innate immune system recognition through binding to Toll-like receptor 2 (TLR2) heterodimer complexes. Although lipoproteins are conserved among nearly all classes of bacteria, the presence and type of α-amino-linked acyl chain are highly variable and even strain specific within a given bacterial species. The reason for lyso-lipoprotein formation and N-acylation variability in general is presently not fully understood. In Enterococcus faecalis, lipoproteins are anchored by an N-acyl-S-monoacyl-glyceryl cysteine (lyso form) moiety installed by a chromosomally encoded lipoprotein intramolecular transacylase (Lit). Here, we describe a mobile genetic element common to environmental isolates of Listeria monocytogenes and Enterococcus spp. encoding a functional Lit ortholog (Lit2) that is cotranscribed with several well-established copper resistance determinants. Expression of Lit2 is tightly regulated, and induction by copper converts lipoproteins from the diacylglycerol-modified form characteristic of L. monocytogenes type strains to the α-amino-modified lyso form observed in E. faecalis. Conversion to the lyso form through either copper addition to media or constitutive expression of lit2 decreases TLR2 recognition when using an activated NF-κB secreted embryonic alkaline phosphatase reporter assay. While lyso formation significantly diminishes TLR2 recognition, lyso-modified lipoprotein is still predominantly recognized by the TLR2/TLR6 heterodimer. IMPORTANCE The induction of lipoprotein N-terminal remodeling in response to environmental copper in Gram-positive bacteria suggests a more general role in bacterial cell envelope physiology. N-terminal modification by lyso formation, in particular, simultaneously modulates the TLR2 response in direct comparison to their diacylglycerol-modified precursors. Thus, use of copper as a frontline antimicrobial control agent and ensuing selection raises the potential of diminished innate immune sensing and enhanced bacterial virulence.

scholarly journals Regulation of OmpA Translation and Shigella dysenteriae Virulence by an RNA Thermometer

2019 ◽  
Vol 88 (3) ◽  
Author(s):  
Erin R. Murphy ◽  
Johanna Roßmanith ◽  
Jacob Sieg ◽  
Megan E. Fris ◽  
Hebaallaha Hussein ◽  
...  
Keyword(s):  
In Silico ◽  
Bacterial Species ◽  
Regulation Of Gene Expression ◽  
Structure And Function ◽  
Shigella Dysenteriae ◽  
Content Type ◽  
Bacterial Physiology ◽  
Wide Range ◽  
Rna Thermometer ◽  
And Function

ABSTRACT RNA thermometers are cis-acting riboregulators that mediate the posttranscriptional regulation of gene expression in response to environmental temperature. Such regulation is conferred by temperature-responsive structural changes within the RNA thermometer that directly result in differential ribosomal binding to the regulated transcript. The significance of RNA thermometers in controlling bacterial physiology and pathogenesis is becoming increasingly clear. This study combines in silico, molecular genetics, and biochemical analyses to characterize both the structure and function of a newly identified RNA thermometer within the ompA transcript of Shigella dysenteriae. First identified by in silico structural predictions, genetic analyses have demonstrated that the ompA RNA thermometer is a functional riboregulator sufficient to confer posttranscriptional temperature-dependent regulation, with optimal expression observed at the host-associated temperature of 37°C. Structural studies and ribosomal binding analyses have revealed both increased exposure of the ribosomal binding site and increased ribosomal binding to the ompA transcript at permissive temperatures. The introduction of site-specific mutations predicted to alter the temperature responsiveness of the ompA RNA thermometer has predictable consequences for both the structure and function of the regulatory element. Finally, in vitro tissue culture-based analyses implicate the ompA RNA thermometer as a bona fide S. dysenteriae virulence factor in this bacterial pathogen. Given that ompA is highly conserved among Gram-negative pathogens, these studies not only provide insight into the significance of riboregulation in controlling Shigella virulence, but they also have the potential to facilitate further understanding of the physiology and/or pathogenesis of a wide range of bacterial species.

scholarly journals The Arginine Deiminase Pathway Impacts Antibiotic Tolerance during Biofilm-Mediated Streptococcus pyogenes Infections

mBio ◽  
2020 ◽  
Vol 11 (4) ◽  
Author(s):  
Jeffrey A. Freiberg ◽  
Yoann Le Breton ◽  
Janette M. Harro ◽  
Devon L. Allison ◽  
Kevin S. McIver ◽  
...  
Keyword(s):  
Treatment Failure ◽  
Antibiotic Treatment ◽  
Streptococcus Pyogenes ◽  
Bacterial Infections ◽  
Bacterial Species ◽  
Arginine Deiminase ◽  
Antibiotic Tolerance ◽  
Human Pathogen ◽  
Biofilm Growth ◽  
Content Type

ABSTRACT Bacterial biofilms are responsible for a variety of serious human infections and are notoriously difficult to treat due to their recalcitrance to antibiotics. Further work is necessary to elicit a full understanding of the mechanism of this antibiotic tolerance. The arginine deiminase (ADI) pathway is responsible for bacterial pH maintenance and is highly expressed during biofilm growth in multiple bacterial species. Using the group A Streptococcus (GAS) as a model human pathogen, the ADI pathway was demonstrated to contribute to biofilm growth. The inability of antibiotics to reduce GAS populations when in a biofilm was demonstrated by in vitro studies and a novel animal model of nasopharyngeal infection. However, disruption of the ADI pathway returned GAS biofilms to planktonic levels of antibiotic sensitivity, suggesting the ADI pathway is influential in biofilm-related antibiotic treatment failure and provides a new strategic target for the treatment of biofilm infections in GAS and potentially numerous other bacterial species. IMPORTANCE Biofilm-mediated bacterial infections are a major threat to human health because of their recalcitrance to antibiotic treatment. Through the study of Streptococcus pyogenes, a significant human pathogen that is known to form antibiotic-tolerant biofilms, we demonstrated the role that a bacterial pathway known for responding to acid stress plays in biofilm growth and antibiotic tolerance. This not only provides some insight into antibiotic treatment failure in S. pyogenes infections but also, given the widespread nature of this pathway, provides a potentially broad target for antibiofilm therapies. This discovery has the potential to impact the treatment of many different types of recalcitrant biofilm infections.

scholarly journals Bactericidal Action of Gatifloxacin, Rifampin, and Isoniazid on Logarithmic- and Stationary-Phase Cultures of Mycobacterium tuberculosis

2005 ◽  
Vol 49 (2) ◽  
pp. 627-631 ◽  
Author(s):  
C. N. Paramasivan ◽  
S. Sulochana ◽  
G. Kubendiran ◽  
P. Venkatesan ◽  
D. A. Mitchison
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Stationary Phase ◽  
Bactericidal Activity ◽  
Bactericidal Action ◽  
Duration Of Treatment ◽  
Stationary Phase Culture ◽  
Treatment Regimens ◽  
Phase Culture ◽  
Bactericidal Activities ◽  
Strain H37rv

ABSTRACT The bactericidal activity of gatifloxacin, alone and in combination with isoniazid and rifampin, was studied on both exponential- and stationary-phase cultures of Mycobacterium tuberculosis strain H37Rv. On log-phase cultures, the bactericidal activity of gatifloxacin at 4 μg/ml was rapid and was very similar to that of isoniazid. At concentrations of 0.25 and 4 μg/ml, gatifloxacin enhanced the activity of isoniazid. Killing of the stationary-phase culture was biphasic. During the first 2 days, gatifloxacin at 4 μg/ml slightly increased the limited bactericidal activities of isoniazid and rifampin. However, no further additional bactericidal activity was found during further incubation with isoniazid alone or when gatifloxacin was added to either isoniazid or rifampin. This suggested that the stationary-phase culture contained a mixture of occasionally dividing bacilli that were killed during the first 2 days and true static persisters in the residual population that mimicked those in human lesions. In view of the failure of gatifloxacin to add to the sterilizing activity of isoniazid or rifampin during days 2 to 6 of exposure in the stationary-phase culture, it is unlikely to be a sterilizing drug that can be used to shorten the duration of treatment appreciably when it is added to present treatment regimens.

scholarly journals Complete Genome Sequences of Clinical Pandoraea fibrosis Isolates

2020 ◽  
Vol 9 (13) ◽  
Author(s):  
Miranda E. Pitt ◽  
Son H. Nguyen ◽  
Tânia P. S. Duarte ◽  
Louise F. Roddam ◽  
Mark A. T. Blaskovich ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Respiratory Tract ◽  
Cystic Fibrosis Patient ◽  
Antibiotic Treatment ◽  
Complete Genome ◽  
Bacterial Species ◽  
Genome Sequences ◽  
Gram Negative ◽  
Content Type

Pandoraea fibrosis is a newly identified Gram-negative bacterial species that was isolated from the respiratory tract of an Australian cystic fibrosis patient. The complete assembled genome sequences of two consecutive isolates (second isolate collected 11 months after antibiotic treatment) from the same individual are presented here.

scholarly journals Identification of Conserved and Species-Specific Functions of the Listeria monocytogenes PrsA2 Secretion Chaperone

2015 ◽  
Vol 83 (10) ◽  
pp. 4028-4041 ◽  
Author(s):  
Laty A. Cahoon ◽  
Nancy E. Freitag
Keyword(s):  
Listeria Monocytogenes ◽  
Protein Translocation ◽  
Functional Complementation ◽  
Broth Culture ◽  
Cell Physiology ◽  
Gram Positive ◽  
Content Type ◽  
Bacterial Physiology ◽  
Gram Positive Bacteria ◽  
Species Specific

The Gram-positive bacteriumListeria monocytogenesis a facultative intracellular pathogen that relies on the regulated secretion and activity of a variety of proteins that sustain life within diverse environments. PrsA2 has recently been identified as a secreted peptidyl-prolylcis/transisomerase and chaperone that is dispensable for bacterial growth in broth culture but essential forL. monocytogenesvirulence. Following host infection, PrsA2 contributes to the proper folding and activity of secreted proteins that are required for bacterial replication within the host cytosol and for bacterial spread to adjacent cells. PrsA2 is one member of a family of Gram-positive secretion chaperones that appear to play important roles in bacterial physiology; however, it is not known how these proteins recognize their substrate proteins or the degree to which their function is conserved across diverse Gram-positive species. We therefore examined PrsA proteins encoded by a variety of Gram-positive bacteria for functional complementation ofL. monocytogenesmutants lackingprsA2. PrsA homologues encoded byBacillus subtilis,Streptococcus pyogenes,Streptococcus pneumoniae,Streptococcus mutans,Staphylococcus aureus, andLactococcus lactiswere examined for functional complementation of a variety ofL. monocytogenesPrsA2-associated phenotypes central toL. monocytogenespathogenesis and bacterial cell physiology. Our results indicate that while selected aspects of PrsA2 function are broadly conserved among diverse Gram-positive bacteria, PrsA2 exhibits unique specificity forL. monocytogenestarget proteins required for pathogenesis. TheL. monocytogenesPrsA2 chaperone thus appears evolutionarily optimized for virulence factor secretion within the host cell cytosol while still maintaining aspects of activity relevant to more general features of Gram-positive protein translocation.

scholarly journals Breaking the Vicious Cycle of Antibiotic Killing and Regrowth of Biofilm-ResidingPseudomonas aeruginosa

2018 ◽  
Vol 62 (12) ◽  
Author(s):  
Mathias Müsken ◽  
Vinay Pawar ◽  
Timo Schwebs ◽  
Heike Bähre ◽  
Sebastian Felgner ◽  
...  
Keyword(s):  
Treatment Success ◽  
Antimicrobial Treatment ◽  
Vicious Cycle ◽  
Chronic Infections ◽  
Treatment Protocols ◽  
Content Type ◽  
Treatment Regimens ◽  
Biofilm Bacteria ◽  
Time Required

ABSTRACTBiofilm-residing bacteria embedded in an extracellular matrix are protected from diverse physicochemical insults. In addition to the general recalcitrance of biofilm bacteria, high bacterial loads in biofilm-associated infections significantly diminish the efficacy of antimicrobials due to a low per-cell antibiotic concentration. Accordingly, present antimicrobial treatment protocols that have been established to serve the eradication of acute infections fail to clear biofilm-associated chronic infections. In the present study, we applied automated confocal microscopy onPseudomonas aeruginosato monitor dynamic killing of biofilm-grown bacteria by tobramycin and colistin in real time. We revealed that the time required for surviving bacteria to repopulate the biofilm could be taken as a measure for effectiveness of the antimicrobial treatment. It depends on the (i) nature and concentration of the antibiotic, (ii) duration of antibiotic treatment, (iii) application as monotherapy or combination therapy, and (iv) interval of drug administration. The vicious cycle of killing and repopulation of biofilm bacteria could also be broken in anin vivomodel system by applying successive antibiotic dosages at intervals that do not allow full reconstitution of the biofilm communities. Treatment regimens that consider the important aspects of antimicrobial killing kinetics bear the potential to improve control of biofilm regrowth. This is an important and underestimated factor that is bound to ensure sustainable treatment success of chronic infections.

scholarly journals Task Distribution between Acetate and Acetoin Pathways To Prolong Growth inLactococcus lactisunder Respiration Conditions

2018 ◽  
Vol 84 (18) ◽  
Author(s):  
Bénédicte Cesselin ◽  
Christel Garrigues ◽  
Martin B. Pedersen ◽  
Célia Roussel ◽  
Alexandra Gruss ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Stationary Phase ◽  
Lactococcus Lactis ◽  
Time Course ◽  
Biomass Yield ◽  
Fine Tuning ◽  
Ph Homeostasis ◽  
Content Type ◽  
Growth And Survival ◽  
Bacterial Physiology

ABSTRACTLactococcus lactisis the main bacterium used for food fermentation and is a candidate for probiotic development. In addition to fermentation growth, supplementation with heme under aerobic conditions activates a cytochrome oxidase, which promotes respiration metabolism. In contrast to fermentation, in which cells consume energy to produce mainly lactic acid, respiration metabolism dramatically changes energy metabolism, such that massive amounts of acetic acid and acetoin are produced at the expense of lactic acid. Our goal was to investigate the metabolic changes that correlate with significantly improved growth and survival during respiration growth. Using transcriptional time course analyses, mutational analyses, and promoter-reporter fusions, we uncover two main pathways that can explain the robust growth and stability of respiration cultures. First, the acetate pathway contributes to biomass yield in respiration without affecting medium pH. Second, the acetoin pathway allows cells to cope with internal acidification, which directly affects cell density and survival in stationary phase. Our results suggest that manipulation of these pathways will lead to fine-tuning respiration growth, with improved yield and stability.IMPORTANCELactococcus lactisis used in food and biotechnology industries for its capacity to produce lactic acid, aroma, and proteins. This species grows by fermentation or by an aerobic respiration metabolism when heme is added. Whereas fermentation leads mostly to lactic acid production, respiration produces acetate and acetoin. Respiration growth leads to greatly improved bacterial growth and survival. Our study aims at deciphering mechanisms of respiration metabolism that have a major impact on bacterial physiology. Our results showed that two metabolic pathways (acetate and acetoin) are key elements of respiration. The acetate pathway contributes to biomass yield. The acetoin pathway is needed for pH homeostasis, which affects metabolic activities and bacterial viability in stationary phase. This study clarifies key metabolic elements that are required to maintain the growth advantage conferred by respiration metabolism and has potential uses in strain optimization for industrial and biomedical applications.

scholarly journals Systematic Analysis of c-di-GMP Signaling Mechanisms and Biological Functions in Dickeya zeae EC1

mBio ◽  
2020 ◽  
Vol 11 (6) ◽  
Author(s):  
Yufan Chen ◽  
Jianuan Zhou ◽  
Mingfa Lv ◽  
Zhibin Liang ◽  
Matthew R. Parsek ◽  
...  
Keyword(s):  
Caulobacter Crescentus ◽  
Bacterial Species ◽  
Economic Losses ◽  
Signaling Proteins ◽  
Dependent Manner ◽  
Content Type ◽  
Bacterial Physiology ◽  
Diguanylate Cyclases ◽  
Genes Encoding ◽  
Rice Plantations

ABSTRACT Dickeya zeae is an important and aggressive bacterial phytopathogen that can cause substantial economic losses in banana and rice plantations. We previously showed that c-di-GMP signaling proteins (cyclases/phosphodiesterases) in D. zeae strain EC1 play a significant role in the bacterial sessile-to-motile transition. To determine whether there is any synergistic effect among these c-di-GMP signaling proteins, we prepared a series of mutant strains by generating consecutive in-frame deletions of the genes encoding diguanylate cyclases (which make c-di-GMP) and phosphodiesterases (which break down c-di-GMP), respectively, using EC1 as a parental strain. The results showed that the complete deletion of all the putative diguanylate cyclases resulted in significantly increased bacterial motility and abrogated biofilm formation but did not appear to affect pathogenicity and virulence factor production. In contrast, the deletion of all the c-di-GMP phosphodiesterase genes disabled motility and prevented the invasion of EC1 into rice seeds. By measuring the c-di-GMP concentrations and swimming motility of all the mutants, we propose that c-di-GMP controlled swimming behavior through a multitiered program in a c-di-GMP concentration-dependent manner, which could be described as an L-shaped regression curve. These features are quite different from those that have been shown for other bacterial species such as Salmonella and Caulobacter crescentus. Further analysis identified three c-di-GMP signaling proteins, i.e., PDE10355, DGC14945, and PDE14950, that play dominant roles in influencing the global c-di-GMP pool of strain EC1. The findings from this study highlight the complexity and plasticity of c-di-GMP regulatory circuits in different bacterial species. IMPORTANCE Dickeya zeae is the etiological agent of bacterial foot rot disease, which can cause massive economic losses in banana and rice plantations. Genome sequence analysis showed that D. zeae strain EC1 contains multiple c-di-GMP turnover genes, but their roles and regulatory mechanisms in bacterial physiology and virulence remain vague. By generating consecutive in-frame deletion mutants of the genes encoding c-di-GMP biosynthesis and degradation, respectively, we analyzed the individual and collective impacts of these c-di-GMP metabolic genes on the c-di-GMP global pool, bacterial physiology, and virulence. The significance of our study is in identifying the mechanism of c-di-GMP signaling in strain EC1 more clearly, which expands the c-di-GMP regulating patterns in Gram-negative species. The methods and experimental designs in this research will provide a valuable reference for the exploration of the complex c-di-GMP regulation mechanisms in other bacteria.

scholarly journals Peroral Ciprofloxacin Therapy Impairs the Generation of a Protective Immune Response in a Mouse Model for Salmonella enterica Serovar Typhimurium Diarrhea, while Parenteral Ceftriaxone Therapy Does Not

2012 ◽  
Vol 56 (5) ◽  
pp. 2295-2304 ◽  
Author(s):  
Kathrin Endt ◽  
Lisa Maier ◽  
Rina Käppeli ◽  
Manja Barthel ◽  
Benjamin Misselwitz ◽  
...  
Keyword(s):  
Immune Response ◽  
Mouse Model ◽  
Antibiotic Treatment ◽  
Salmonella Enterica ◽  
Adaptive Immune Response ◽  
Content Type ◽  
Fecal Shedding ◽  
Treatment Regimens ◽  
Adaptive Immune ◽  
Serovar Typhimurium

ABSTRACTNontyphoidalSalmonella(NTS) species cause self-limiting diarrhea and sometimes severe disease. Antibiotic treatment is considered only in severe cases and immune-compromised patients. The beneficial effects of antibiotic therapy and the consequences for adaptive immune responses are not well understood. We used a mouse model forSalmonelladiarrhea to assess the effects ofper ostreatment with ciprofloxacin (15 mg/kg of body weight intragastrically 2 times/day, 5 days) or parenteral ceftriaxone (50 mg/kg intraperitoneally, 5 days), two common drugs used in human patients. The therapeutic and adverse effects were assessed with respect to generation of a protective adaptive immune response, fecal pathogen excretion, and the emergence of nonsymptomatic excreters. In the mouse model, both therapies reduced disease severity and reduced the level of fecal shedding. In line with clinical data, in most animals, a rebound of pathogen gut colonization/fecal shedding was observed 2 to 12 days after the end of the treatment. Yet, levels of pathogen shedding and frequency of appearance of nonsymptomatic excreters did not differ from those for untreated controls. Moreover, mice treated intraperitoneally with ceftriaxone developed an adaptive immunity protecting the mice from enteropathy in wild-typeSalmonella entericaserovar Typhimurium challenge infections. In contrast, the mice treated intragastrically with ciprofloxacin were not protected. Thus, antibiotic treatment regimens can disrupt the adaptive immune response, but treatment regimens may be optimized in order to preserve the generation of protective immunity. It might be of interest to determine whether this also pertains to human patients. In this case, the mouse model might be a tool for further mechanistic studies.

Sign in / Sign up

Export Citation Format

Share Document