scholarly journals Redox Balance via Lactate Dehydrogenase Is Important for Multiple Stress Resistance and Virulence in Enterococcus faecalis

2013 ◽  
Vol 81 (8) ◽  
pp. 2662-2668 ◽  
Author(s):  
Nosheen Fatima Rana ◽  
Nicolas Sauvageot ◽  
Jean-Marie Laplace ◽  
YinYin Bao ◽  
Ingolf Nes ◽  
...  

ABSTRACTEnterococcus faecalisis a highly stress resistant opportunistic pathogen. The intrinsic ruggedness of this bacterium is supposed to be the basis of its capacity to colonize the hostile environments of hospitals and to cause several kinds of infections. We show in this work that general resistance to very different environmental stresses depends on the ability ofE. faecalisto maintain redox balance via lactate dehydrogenase (LDH). Furthermore, LDH-deficient mutants are less successful than the wild type at colonizing host organs in a murine model of systemic infection. Taken together, our results, as well as those previously published forStaphylococcus aureus(A. R. Richardson, S. J. Libby, and F. C. Fang, Science 319:1672–1676, 2008), identify LDH as an attractive drug target. These drugs may have additional applications, as in the fight against glycopeptide antibiotic-resistant bacteria and even cancer.

2015 ◽  
Vol 59 (7) ◽  
pp. 4094-4105 ◽  
Author(s):  
Jennifer L. Dale ◽  
Julian Cagnazzo ◽  
Chi Q. Phan ◽  
Aaron M. T. Barnes ◽  
Gary M. Dunny

ABSTRACTThe emergence of multidrug-resistant bacteria and the limited availability of new antibiotics are of increasing clinical concern. A compounding factor is the ability of microorganisms to form biofilms (communities of cells encased in a protective extracellular matrix) that are intrinsically resistant to antibiotics.Enterococcus faecalisis an opportunistic pathogen that readily forms biofilms and also has the propensity to acquire resistance determinants via horizontal gene transfer. There is intense interest in the genetic basis for intrinsic and acquired antibiotic resistance inE. faecalis, since clinical isolates exhibiting resistance to multiple antibiotics are not uncommon. We performed a genetic screen using a library of transposon (Tn) mutants to identifyE. faecalisbiofilm-associated antibiotic resistance determinants. Five Tn mutants formed wild-type biofilms in the absence of antibiotics but produced decreased biofilm biomass in the presence of antibiotic concentrations that were subinhibitory to the parent strain. Genetic determinants responsible for biofilm-associated antibiotic resistance include components of the quorum-sensing system (fsrA,fsrC, andgelE) and two glycosyltransferase (GTF) genes (epaIandepaOX). We also found that the GTFs play additional roles inE. faecalisresistance to detergent and bile salts, maintenance of cell envelope integrity, determination of cell shape, polysaccharide composition, and conjugative transfer of the pheromone-inducible plasmid pCF10. TheepaOXgene is located in a variable extended region of the enterococcal polysaccharide antigen (epa) locus. These data illustrate the importance of GTFs inE. faecalisadaptation to diverse growth conditions and suggest new targets for antimicrobial design.


2014 ◽  
Vol 83 (1) ◽  
pp. 372-378 ◽  
Author(s):  
Elisabeth Kernbauer ◽  
Katie Maurer ◽  
Victor J. Torres ◽  
Bo Shopsin ◽  
Ken Cadwell

Mutations that alter virulence and antibiotic susceptibility arise and persist duringStaphylococcus aureusbacteremia. However, an experimental system demonstrating transmission following bacteremia has been lacking, and thus implications of within-host adaptation for between-host transmission are unknown. We report thatS. aureusdisseminates to the gastrointestinal tract of mice following intravenous injection and readily transmits to cohoused naive mice. Both intestinal dissemination and transmission were linked to the production of virulence factors based on gene deletion studies of thesaeandagrtwo-component systems. Furthermore, antimicrobial selection for antibiotic-resistantS. aureusdisplaced susceptibleS. aureusfrom the intestine of infected hosts, which led to the preferential transmission and dominance of antibiotic-resistant bacteria among cohoused untreated mice. These findings establish an animal model to investigate gastrointestinal dissemination and transmission ofS. aureusand suggest that adaptation during the course of systemic infection has implications beyond the level of a single host.


2020 ◽  
Vol 9 (20) ◽  
Author(s):  
Natalia Purta ◽  
Taylor Miller-Ensminger ◽  
Adelina Voukadinova ◽  
Alan J. Wolfe ◽  
Catherine Putonti

Here, we introduce the 2.8-Mbp draft genome of Enterococcus faecalis strain UMB0843, isolated from the female urinary tract. E. faecalis is a leading cause of nosocomial infections, and many strains are often resistant to multiple antibiotics. We focus our genome analysis on the multiple genes involved in antibiotic resistance in this strain.


2019 ◽  
Vol 87 (11) ◽  
Author(s):  
M. Al-Zubidi ◽  
M. Widziolek ◽  
E. K. Court ◽  
A. F. Gains ◽  
R. E. Smith ◽  
...  

ABSTRACTThe Gram-positive opportunistic pathogenEnterococcus faecalisis frequently responsible for nosocomial infections in humans and represents one of the most common bacteria isolated from recalcitrant endodontic (root canal) infections.E. faecalisis intrinsically resistant to several antibiotics routinely used in clinical settings (such as cephalosporins and aminoglycosides) and can acquire resistance to vancomycin (vancomycin-resistant enterococci). The resistance ofE. faecalisto several classes of antibiotics and its capacity to form biofilms cause serious therapeutic problems. Here, we report the isolation of several bacteriophages that targetE. faecalisstrains isolated from the oral cavity of patients suffering root canal infections. All phages isolated wereSiphoviridaewith similar tail lengths (200 to 250 nm) and icosahedral heads. The genome sequences of three isolated phages were highly conserved with the exception of predicted tail protein genes that diverge in sequence, potentially reflecting the host range. The properties of the phage with the broadest host range (SHEF2) were further characterized. We show that this phage requires interaction with components of the major and variant region enterococcal polysaccharide antigen to engage in lytic infection. Finally, we explored the therapeutic potential of this phage and show that it can eradicateE. faecalisbiofilms formedin vitroon a standard polystyrene surface but also on a cross-sectional tooth slice model of endodontic infection. We also show that SHEF2 cleared a lethal infection of zebrafish when applied in the circulation. We therefore propose that the phage described here could be used to treat a broad range of antibiotic-resistantE. faecalisinfections.


mBio ◽  
2018 ◽  
Vol 9 (3) ◽  
Author(s):  
Roberto Adamo ◽  
Immaculada Margarit

ABSTRACT Antibiotics and vaccines have greatly impacted human health in the last century by dramatically reducing the morbidity and mortality associated with infectious diseases. The recent challenge posed by the emergence of multidrug-resistant bacteria could possibly be addressed by novel immune prophylactic and therapeutic approaches. Among the newly threatening pathogens, Klebsiella pneumoniae is particularly worrisome in the nosocomial setting, and its surface polysaccharides are regarded as promising antigen candidates. The majority of Klebsiella carbapenem-resistant strains belong to the sequence type 158 (ST258) lineage, with two main clades expressing capsular polysaccharides CPS1 and CPS2. In a recent article, S. D. Kobayashi and colleagues (mBio 9:e00297-18, 2018, https://doi.org/10.1128/mBio.00297-18) show that CPS2-specific IgGs render ST258 clade 2 bacteria more sensitive to human serum and phagocytic killing. E. Diago-Navarro et al. (mBio 9:e00091-18, 2018, https://doi.org/10.1128/mBio.00091-18) generated two murine monoclonal antibodies recognizing distinct glycotopes of CPS2 that presented functional activity against multiple ST258 strains. These complementary studies represent a step toward the control of this dangerous pathogen.


2019 ◽  
Vol 63 (12) ◽  
Author(s):  
Feiruz Alamiri ◽  
Kristian Riesbeck ◽  
Anders P. Hakansson

ABSTRACT HAMLET (human alpha-lactalbumin made lethal to tumor cells) is a protein-lipid complex derived from human milk that was first described for its tumoricidal activity. Later studies showed that HAMLET also has direct bactericidal activity against select species of bacteria, with highest activity against Streptococcus pneumoniae. Additionally, HAMLET in combination with various antimicrobial agents can make a broad range of antibiotic-resistant bacterial species sensitive to antibiotics. Here, we show that HAMLET has direct antibacterial activity not only against pneumococci but also against Streptococcus pyogenes (group A streptococci [GAS]) and Streptococcus agalactiae (group B streptococci [GBS]). As with pneumococci, HAMLET treatment of GAS and GBS resulted in depolarization of the bacterial membrane, followed by membrane permeabilization and death, which was able to be inhibited by calcium and sodium transport inhibitors. Treatment of clinical antibiotic-resistant isolates of S. pneumoniae, GAS, and GBS with sublethal concentrations of HAMLET in combination with antibiotics decreased the MICs of the antibiotics into the sensitive range. This effect could also be blocked by ion transport inhibitors, suggesting that HAMLET’s bactericidal and combination treatment effects used similar mechanisms. Finally, we show that HAMLET potentiated the effects of erythromycin against erythromycin-resistant bacteria more effectively than penicillin G potentiated killing bacteria resistant to erythromycin. These results show that HAMLET effectively (i) kills three different species of pathogenic streptococci by similar mechanisms and also (ii) potentiates the activities of macrolides and lincosamides more effectively than combination treatment with beta-lactams. These findings suggest a potential therapeutic role for HAMLET in repurposing antibiotics currently causing treatment failures in patients.


2019 ◽  
Vol 63 (6) ◽  
Author(s):  
Michael S. M. Brouwer ◽  
Kamaleddin H. M. E. Tehrani ◽  
Michel Rapallini ◽  
Yvon Geurts ◽  
Arie Kant ◽  
...  

ABSTRACT Food for human consumption is screened widely for the presence of antibiotic-resistant bacteria to assess the potential for transfer of resistant bacteria to the general population. Here, we describe an Enterobacter cloacae complex isolated from imported seafood that encodes two carbapenemases on two distinct plasmids. Both enzymes belong to Ambler class A β-lactamases, the previously described IMI-2 and a novel family designated FLC-1. The hydrolytic activity of the novel enzyme against aminopenicillins, cephalosporins, and carbapenems was determined.


2014 ◽  
Vol 82 (12) ◽  
pp. 5099-5109 ◽  
Author(s):  
Paula Gaspar ◽  
Firas A. Y. Al-Bayati ◽  
Peter W. Andrew ◽  
Ana Rute Neves ◽  
Hasan Yesilkaya

ABSTRACTStreptococcus pneumoniaeis a fermentative microorganism and causes serious diseases in humans, including otitis media, bacteremia, meningitis, and pneumonia. However, the mechanisms enabling pneumococcal survival in the host and causing disease in different tissues are incompletely understood. The available evidence indicates a strong link between the central metabolism and pneumococcal virulence. To further our knowledge on pneumococcal virulence, we investigated the role of lactate dehydrogenase (LDH), which converts pyruvate to lactate and is an essential enzyme for redox balance, in the pneumococcal central metabolism and virulence using an isogenicldhmutant. Loss of LDH led to a dramatic reduction of the growth rate, pinpointing the key role of this enzyme in fermentative metabolism. The pattern of end products was altered, and lactate production was totally blocked. The fermentation profile was confirmed byin vivonuclear magnetic resonance (NMR) measurements of glucose metabolism in nongrowing cell suspensions of theldhmutant. In this strain, a bottleneck in the fermentative steps is evident from the accumulation of pyruvate, revealing LDH as the most efficient enzyme in pyruvate conversion. An increase in ethanol production was also observed, indicating that in the absence of LDH the redox balance is maintained through alcohol dehydrogenase activity. We also found that the absence of LDH renders the pneumococci avirulent after intravenous infection and leads to a significant reduction in virulence in a model of pneumonia that develops after intranasal infection, likely due to a decrease in energy generation and virulence gene expression.


2011 ◽  
Vol 77 (20) ◽  
pp. 7255-7260 ◽  
Author(s):  
Murugan Subbiah ◽  
Shannon M. Mitchell ◽  
Jeffrey L. Ullman ◽  
Douglas R. Call

ABSTRACTIt is generally assumed that antibiotic residues in soils select for antibiotic-resistant bacteria. This assumption was tested by separately adding 10 different antibiotics (≥200 ppm) to three soil-water slurries (silt-loam, sand-loam, and sand; 20% soil [wt/vol]) and incubating mixtures for 24 h at room temperature. The antibiotic activity of the resultant supernatant was assessed by culturing a sensitiveEscherichia colistrain in the filter-sterilized supernatant augmented with Luria-Bertani broth. We found striking differences in the abilities of supernatants to suppress growth of the indicatorE. coli. Ampicillin, cephalothin, cefoxitin, ceftiofur, and florfenicol supernatants completely inhibited growth while bacterial growth was uninhibited in the presence of neomycin, tetracycline, and ciprofloxacin supernatants. High-performance liquid chromatography (HPLC) analysis demonstrated that cefoxitin and florfenicol were almost completely retained in the supernatants, whereas tetracycline and ciprofloxacin were mostly removed. Antibiotic dissipation in soil, presumably dominated by adsorption mechanisms, was sufficient to neutralize 200 ppm of tetracycline; this concentration is considerably higher than reported contamination levels. Soil pellets from the tetracycline slurries were resuspended in a minimal volume of medium to maximize the interaction between bacteria and soil particles, but sensitive bacteria were still unaffected by tetracycline (P= 0.6). Thus, residual antibiotics in soil do not necessarily exert a selective pressure, and the degree to which the pharmaceutical remains bioactive depends on the antibiotic. Efforts to control antibiotic contamination would be better directed toward compounds that retain biological activity in soils (e.g., cephalosporins and florfenicol) because these are the antibiotics that could exert a selective pressure in the environment.


2015 ◽  
Vol 112 (14) ◽  
pp. 4453-4458 ◽  
Author(s):  
Michael B. Harbut ◽  
Catherine Vilchèze ◽  
Xiaozhou Luo ◽  
Mary E. Hensler ◽  
Hui Guo ◽  
...  

Infections caused by antibiotic-resistant bacteria are a rising public health threat and make the identification of new antibiotics a priority. From a cell-based screen for bactericidal compounds againstMycobacterium tuberculosisunder nutrient-deprivation conditions we identified auranofin, an orally bioavailable FDA-approved antirheumatic drug, as having potent bactericidal activities against both replicating and nonreplicatingM. tuberculosis. We also found that auranofin is active against other Gram-positive bacteria, includingBacillus subtilisandEnterococcus faecalis, and drug-sensitive and drug-resistant strains ofEnterococcus faeciumandStaphylococcus aureus. Our biochemical studies showed that auranofin inhibits the bacterial thioredoxin reductase, a protein essential in many Gram-positive bacteria for maintaining the thiol-redox balance and protecting against reactive oxidative species. Auranofin decreases the reducing capacity of target bacteria, thereby sensitizing them to oxidative stress. Finally, auranofin was efficacious in a murine model of methicillin-resistantS. aureusinfection. These results suggest that the thioredoxin-mediated redox cascade of Gram-positive pathogens is a valid target for the development of antibacterial drugs, and that the existing clinical agent auranofin may be repurposed to aid in the treatment of several important antibiotic-resistant pathogens.


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