scholarly journals Pharmacodynamics of ClpP-Activating Antibiotic Combinations against Gram-Positive Pathogens

2019 ◽  
Vol 64 (1) ◽  
Author(s):  
Nader Mroue ◽  
Anu Arya ◽  
Autumn Brown Gandt ◽  
Cameron Russell ◽  
Angel Han ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
High Density ◽  
Infection Model ◽  
Drug Resistant ◽  
Gram Positive ◽  
Bacterial Killing ◽  
Resistance Development ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Vancomycin Resistant

ABSTRACT It is often difficult to cure endocarditis, osteomyelitis, and device-associated infections caused by Gram-positive pathogens, despite therapy with clinically appropriate antibiotics. This may be due to antibiotic tolerance or resistance development. Acyldepsipeptides (ADEPs) are a class of bactericidal compounds active against a variety of clinically important Gram-positive bacteria, including staphylococci, streptococci, and enterococci. ADEPs activate caseinolytic protease P (ClpP), killing high-density, nondividing cultures of bacteria that are tolerant to approved classes of antibiotics. Acyldepsipeptide analog 4 (ADEP4) was active against a panel of drug-resistant Gram-positive pathogens in MIC assays, with no preexisting resistance detected. Killing of stationary-phase cultures was observed when ADEP4 was combined with multiple classes of approved antibiotics. Additionally, a hollow-fiber infection model was used to assess the effects of ADEP4 antibiotic combinations on bacterial killing and resistance development. These studies were performed on high-density cultures of methicillin-resistant S. aureus (MRSA), methicillin-susceptible S. aureus (MSSA), and vancomycin-resistant Enterococcus faecalis (VRE). None of the approved antibiotics linezolid, ampicillin, and oxacillin tested alone had bactericidal activity under these conditions. ADEP4 initially caused killing, but regrowth of the culture was apparent within 96 h due to resistance. Combinations of ADEP4 with linezolid or oxacillin caused substantially improved killing of MRSA or MSSA cultures, respectively, and no regrowth due to resistance was observed. The combination of ADEP4 and ampicillin eradicated cultures of VRE to the limit of detection within 52 h. These data suggest that combining ClpP activators with traditional antibiotics may be a good strategy to treat complicated Gram-positive infections.

scholarly journals Activities of Oxadiazole Antibacterials against Staphylococcus aureus and Other Gram-Positive Bacteria

2018 ◽  
Vol 62 (8) ◽  
Author(s):  
Sara Ceballos ◽  
Choon Kim ◽  
Derong Ding ◽  
Shahriar Mobashery ◽  
Mayland Chang ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Gram Positive ◽  
Methicillin Resistant ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Vancomycin Resistant Enterococci ◽  
Vancomycin Resistant ◽  
Mrsa Strains

ABSTRACT The activities of four oxadiazoles were investigated with 210 methicillin-resistant Staphylococcus aureus (MRSA) strains. MIC50 and MIC90 values of 1 to 2 and 4 μg/ml, respectively, were observed. We also evaluated the activity of oxadiazole ND-421 against other staphylococci and enterococci and in the presence of oxacillin for selected MRSA strains. The MIC for ND-421 is lowered severalfold in combination with oxacillin, as they synergize. The MIC90 of ND-421 against vancomycin-resistant enterococci is ≤1 μg/ml.

scholarly journals Bactericidal Activities of Two Daptomycin Regimens against Clinical Strains of Glycopeptide Intermediate-ResistantStaphylococcus aureus, Vancomycin-ResistantEnterococcus faecium, and Methicillin-ResistantStaphylococcus aureus Isolates in an In Vitro Pharmacodynamic Model with Simulated Endocardial Vegetations

2001 ◽  
Vol 45 (2) ◽  
pp. 454-459 ◽  
Author(s):  
Ronda L. Akins ◽  
Michael J. Rybak
Keyword(s):  
Limit Of Detection ◽  
Infection Model ◽  
Infection Site ◽  
Gram Positive ◽  
Killing Effect ◽  
Vancomycin Resistant ◽  
Cell Membrane Transport ◽  
Bactericidal Activities ◽  
Lipopeptide Antibiotic

ABSTRACT Daptomycin is an investigational lipopeptide antibiotic active against gram-positive organisms. The mechanism of action is unique, resulting in interference with cell membrane transport. The bactericidal activity of daptomycin was evaluated against glycopeptide-intermediate susceptible Staphylococcus aureus(GISA), vancomycin-resistant Enterococcus faecium (VREF), and methicillin-resistant S. aureus (MRSA) in an in vitro infection model with simulated endocardial vegetations. Simulated regimens of daptomycin at 6 mg/kg/day (D6) and 10 mg/kg/day (D10) were utilized. MICs and MBCs for daptomycin were determined in the absence and in the presence of albumin with the following results (MIC/MBC): for GISA-992, 0.5/1.0 and 16/16; for VREF-590, 2.0/2.0 and 32/32; and for MRSA-494, 0.25/0.25 and 1.0/4.0 μg/ml, respectively. During the first 8 h daptomycin significantly reduced the inoculum for all organisms. Daptomycin at 6 mg/kg/day and 10 mg/kg/day had log10 CFU/g reductions of 5 and 6, 3.4 and 5, and 6.4 and 6.5 by 8 h for GISA-992, VREF-590, and MRSA-494, respectively. Against both GISA-992 and VREF-590, the D10 regimen achieved the limit of detection at 72 h, with D6 regimens showing slight regrowth. A concentration-dependent killing effect was noted to occur, with daptomycin demonstrating a more rapid and greater kill from the D10 versus the D6 regimen. The results of this study suggest that daptomycin demonstrates significant (P < 0.05) activity against gram-positive organisms in a simulated sequestered infection site.

scholarly journals Antibacterial Efficacy of EravacyclineIn Vivoagainst Gram-Positive and Gram-Negative Organisms

2016 ◽  
Vol 60 (8) ◽  
pp. 5001-5005 ◽  
Author(s):  
Marguerite L. Monogue ◽  
Abrar K. Thabit ◽  
Yukihiro Hamada ◽  
David P. Nicolau
Keyword(s):  
Cumulative Dose ◽  
Dose Response ◽  
Bacterial Count ◽  
Infection Model ◽  
Gram Positive ◽  
Bacterial Killing ◽  
Gram Negative ◽  
Content Type

ABSTRACTMembers of the tetracycline class are frequently classified as bacteriostatic. However, recent findings have demonstrated an improved antibacterial killing profile, often achieving ≥3 log10bacterial count reduction, when such antibiotics have been given for periods longer than 24 h. We aimed to study this effect with eravacycline, a novel fluorocycline, given in an immunocompetent murine thigh infection model over 72 h against two methicillin-resistantStaphylococcus aureus(MRSA) isolates (eravacycline MICs = 0.03 and 0.25 μg/ml) and threeEnterobacteriaceaeisolates (eravacycline MICs = 0.125 to 0.25 μg/ml). A humanized eravacycline regimen, 2.5 mg/kg of body weight given intravenously (i.v.) every 12 h (q12h), demonstrated progressively enhanced activity over the 72-h study period. A cumulative dose response in which bacterial density was reduced by more than 3 log10CFU at 72 h was noted over the study period in the two Gram-positive isolates, and eravacycline performed similarly to comparator antibiotics (tigecycline, linezolid, and vancomycin). A cumulative dose response with eravacycline and comparators (tigecycline and meropenem) over the study period was also observed in the Gram-negative isolates, although more variability in bacterial killing was observed for all antibacterial agents. Overall, a bacterial count reduction of ≥3 log was achieved in one of the three isolates with both eravacycline and tigecycline, while meropenem achieved a similar endpoint against two of the three isolates. Bactericidal activity is typically definedin vitroover 24 h; however, extended regimen studiesin vivomay demonstrate an improved correlation with clinical outcomes by better identification of antimicrobial effects.

scholarly journals Cerecidins, Novel Lantibiotics from Bacillus cereus with Potent Antimicrobial Activity

2014 ◽  
Vol 80 (8) ◽  
pp. 2633-2643 ◽  
Author(s):  
Jian Wang ◽  
Li Zhang ◽  
Kunling Teng ◽  
Shutao Sun ◽  
Zhizeng Sun ◽  
...  
Keyword(s):  
Bacillus Cereus ◽  
Multidrug Resistant ◽  
Regulator Gene ◽  
Gram Positive ◽  
Content Type ◽  
Pcr Screening ◽  
Gram Positive Bacteria ◽  
Immunity Genes ◽  
Natural Variants ◽  
Vancomycin Resistant

ABSTRACTLantibiotics are ribosomally synthesized and posttranslationally modified antimicrobial peptides that are widely produced by Gram-positive bacteria, including many species of theBacillusgroup. In the present study, one novel gene cluster coding lantibiotic cerecidins was unveiled inBacillus cereusstrain As 1.1846 through genomic mining and PCR screening. The designatedcerlocus is different from that of conventional class II lantibiotics in that it included seven tandem precursorcerAgenes, one modification gene (cerM), two processing genes (cerTandcerP), one orphan regulator gene (cerR), and two immunity genes (cerFandcerE). In addition, one unprecedented quorum sensing component,comQXPA, was inserted betweencerMandcerR. The expression of cerecidins was not detected in this strain ofB. cereus, which might be due to repressed transcription ofcerM. We constitutively coexpressedcerAgenes andcerMinEscherichia coli, and purified precerecidins were proteolytically processed with the endoproteinase GluC and a truncated version of putative serine protease CerP. Thus, two natural variants of cerecidins A1 and A7 were obtained which contained two terminal nonoverlapping thioether rings rarely found in lantibiotics. Both cerecidins A1 and A7 were active against a broad spectrum of Gram-positive bacteria. Cerecidin A7, especially its mutant Dhb13A, showed remarkable efficacy against multidrug-resistantStaphylococcus aureus(MDRSA), vancomycin-resistantEnterococcus faecalis(VRE), and evenStreptomyces.

scholarly journals Pharmacodynamics of Fosfomycin: Insights into Clinical Use for Antimicrobial Resistance

2015 ◽  
Vol 59 (9) ◽  
pp. 5602-5610 ◽  
Author(s):  
F. Docobo-Pérez ◽  
G. L. Drusano ◽  
A. Johnson ◽  
J. Goodwin ◽  
S. Whalley ◽  
...  
Keyword(s):  
Bacterial Resistance ◽  
Infection Model ◽  
Drug Resistant ◽  
Time Curve ◽  
Bacterial Killing ◽  
Unbound Fraction ◽  
Content Type ◽  
E Coli ◽  
Resistant Mutants ◽  
Tract Infections

ABSTRACTThe aim of this study was to improve the understanding of the pharmacokinetic-pharmacodynamic relationships of fosfomycin against extended-spectrum beta-lactamase (ESBL)-producingEscherichia colistrains that have different fosfomycin MICs. Our methods included the use of a hollow fiber infection model with three clinical ESBL-producingE. colistrains. Human fosfomycin pharmacokinetic profiles were simulated over 4 days. Preliminary studies conducted to determine the dose ranges, including the dose ranges that suppressed the development of drug-resistant mutants, were conducted with regimens from 12 g/day to 36 g/day. The combination of fosfomycin at 4 g every 8 h (q8h) and meropenem at 1 g/q8h was selected for further assessment. The total bacterial population and the resistant subpopulations were determined. No efficacy was observed against the Ec42444 strain (fosfomycin MIC, 64 mg/liter) at doses of 12, 24, or 36 g/day. All dosages induced at least initial bacterial killing against Ec46 (fosfomycin MIC, 1 mg/liter). High-level drug-resistant mutants appeared in this strain in response to 12, 15, and 18 g/day. In the study arms that included 24 g/day, once or in a divided dose, a complete extinction of the bacterial inoculum was observed. The combination of meropenem with fosfomycin was synergistic for bacterial killing and also suppressed all fosfomycin-resistant clones of Ec2974 (fosfomycin MIC, 1 mg/liter). We conclude that fosfomycin susceptibility breakpoints (≤64 mg/liter according to CLSI [forE. coliurinary tract infections only]) should be revised for the treatment of serious systemic infections. Fosfomycin can be used to treat infections caused by organisms that demonstrate lower MICs and lower bacterial densities, although relatively high daily dosages (i.e., 24 g/day) are required to prevent the emergence of bacterial resistance. The ratio of the area under the concentration-time curve for the free, unbound fraction of fosfomycin versus the MIC (fAUC/MIC) appears to be the dynamically linked index of suppression of bacterial resistance. Fosfomycin with meropenem can act synergistically againstE. colistrains in preventing the emergence of fosfomycin resistance.

scholarly journals Isolation and Structural Elucidation of Brevibacillin, an Antimicrobial Lipopeptide from Brevibacillus laterosporus That Combats Drug-Resistant Gram-Positive Bacteria

2016 ◽  
Vol 82 (9) ◽  
pp. 2763-2772 ◽  
Author(s):  
Xu Yang ◽  
En Huang ◽  
Chunhua Yuan ◽  
Liwen Zhang ◽  
Ahmed E. Yousef
Keyword(s):  
High Performance ◽  
Resistant Bacteria ◽  
Drug Resistant ◽  
Gram Positive ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Brevibacillus Laterosporus ◽  
Antimicrobial Lipopeptide ◽  
Spoilage Bacteria ◽  
Alkaline Conditions

ABSTRACTA new environmental bacterial strain exhibited strong antimicrobial characteristics against methicillin-resistantStaphylococcus aureus, vancomycin-resistant strains ofEnterococcus faecalisandLactobacillus plantarum, and other Gram-positive bacteria. The producer strain, designated OSY-I1, was determined to beBrevibacillus laterosporusvia morphological, biochemical, and genetic analyses. The antimicrobial agent was extracted from cells of OSY-I1with isopropanol, purified by high-performance liquid chromatography, and structurally analyzed using mass spectrometry (MS) and nuclear magnetic resonance (NMR). The MS and NMR results, taken together, uncovered a linear lipopeptide consisting of 13 amino acids and an N-terminal C6fatty acid (FA) chain, 2-hydroxy-3-methylpentanoic acid. The lipopeptide (FA-Dhb-Leu-Orn-Ile-Ile-Val-Lys-Val-Val-Lys-Tyr-Leu-valinol, where Dhb is α,β-didehydrobutyric acid and valinol is 2-amino-3-methyl-1-butanol) has a molecular mass of 1,583.0794 Da and contains three modified amino acid residues: α,β-didehydrobutyric acid, ornithine, and valinol. The compound, designated brevibacillin, was determined to be a member of a cationic lipopeptide antibiotic family. In addition to its potency against drug-resistant bacteria, brevibacillin also exhibited low MICs (1 to 8 μg/ml) against selected foodborne pathogenic and spoilage bacteria, such asListeria monocytogenes,Bacillus cereus, andAlicyclobacillus acidoterrestris. Purified brevibacillin showed no sign of degradation when it was held at 80°C for 60 min, and it retained at least 50% of its antimicrobial activity when it was held for 22 h under acidic or alkaline conditions. On the basis of these findings, brevibacillin is a potent antimicrobial lipopeptide which is potentially useful to combat drug-resistant bacterial pathogens and foodborne pathogenic and spoilage bacteria.

scholarly journals Draft Genome Sequence of Brevibacillus laterosporus OSY-I1, a Strain That Produces Brevibacillin, Which Combats Drug-Resistant Gram-Positive Bacteria

2017 ◽  
Vol 5 (41) ◽  
Author(s):  
Xu Yang ◽  
En Huang ◽  
Mustafa Yesil ◽  
Lingzi Xiaoli ◽  
Edward G. Dudley ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Genome Sequence ◽  
Draft Genome ◽  
Draft Genome Sequence ◽  
Drug Resistant ◽  
Gram Positive ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Brevibacillus Laterosporus ◽  
Antimicrobial Lipopeptide

ABSTRACT Brevibacillus laterosporus OSY-I1 is a Gram-positive spore-forming bacterium isolated from soil. The bacterium produces brevibacillin, an antimicrobial lipopeptide effective against several drug-resistant Gram-positive bacteria. Here, we present the draft genome sequence of the strain OSY-I1 and the gene cluster responsible for the biosynthesis of brevibacillin.

DNA Binding Ligands with Excellent Antibiotic Potency Against Drug-Resistant Gram-Positive Bacteria.

ChemInform ◽  
2003 ◽  
Vol 34 (6) ◽  
Author(s):  
Roland W. Buerli ◽  
Yigong Ge ◽  
Sarah White ◽  
Eldon E. Baird ◽  
Sofia M. Touami ◽  
...  
Keyword(s):  
Dna Binding ◽  
Drug Resistant ◽  
Gram Positive ◽  
Gram Positive Bacteria

scholarly journals Antimicrobial Nodule-Specific Cysteine-Rich Peptides Induce Membrane Depolarization-Associated Changes in the Transcriptome of Sinorhizobium meliloti

2013 ◽  
Vol 79 (21) ◽  
pp. 6737-6746 ◽  
Author(s):  
Hilda Tiricz ◽  
Attila Szűcs ◽  
Attila Farkas ◽  
Bernadett Pap ◽  
Rui M. Lima ◽  
...  
Keyword(s):  
Stress Responses ◽  
Sinorhizobium Meliloti ◽  
Antimicrobial Agents ◽  
Cellular Functions ◽  
Gram Positive ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Peptide Family ◽  
Wide Range ◽  
Natural Target

ABSTRACTLeguminous plants establish symbiosis with nitrogen-fixing alpha- and betaproteobacteria, collectively called rhizobia, which provide combined nitrogen to support plant growth. Members of the inverted repeat-lacking clade of legumes impose terminal differentiation on their endosymbiotic bacterium partners with the help of the nodule-specific cysteine-rich (NCR) peptide family composed of close to 600 members. Among the few tested NCR peptides, cationic ones had antirhizobial activity measured by reduction or elimination of the CFU and uptake of the membrane-impermeable dye propidium iodide. Here, the antimicrobial spectrum of two of these peptides, NCR247 and NCR335, was investigated, and their effect on the transcriptome of the natural targetSinorhizobium melilotiwas characterized. Both peptides were able to kill quickly a wide range of Gram-negative and Gram-positive bacteria; however, their spectra were only partially overlapping, and differences were found also in their efficacy on given strains, indicating that the actions of NCR247 and NCR335 might be similar though not identical. Treatment ofS. meliloticultures with either peptide resulted in a quick downregulation of genes involved in basic cellular functions, such as transcription-translation and energy production, as well as upregulation of genes involved in stress and oxidative stress responses and membrane transport. Similar changes provoked mainly in Gram-positive bacteria by antimicrobial agents were coupled with the destruction of membrane potential, indicating that it might also be a common step in the bactericidal actions of NCR247 and NCR335.

scholarly journals In Vitro and In Vivo Activities of DA-7867, a New Oxazolidinone, against Aerobic Gram-Positive Bacteria

2005 ◽  
Vol 49 (6) ◽  
pp. 2498-2500 ◽  
Author(s):  
Eun Jeong Yoon ◽  
Yeong Woo Jo ◽  
Sung Hak Choi ◽  
Tae Ho Lee ◽  
Jae Keol Rhee ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Streptococcus Pneumoniae ◽  
Gram Positive ◽  
Methicillin Resistant ◽  
Gram Positive Bacteria ◽  
Vancomycin Resistant Enterococci ◽  
Infection Models ◽  
Vancomycin Resistant

ABSTRACT In vitro and in vivo activities of DA-7867 were assessed against methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and penicillin-resistant Streptococcus pneumoniae. All isolates were inhibited by DA-7867 at ≤0.78 μg/ml, a four-times-lower concentration than that of inhibition by linezolid. For murine infection models, DA-7867 also exhibited greater efficacy than linezolid against all isolates tested.

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