scholarly journals Evolution of Enterococcus faecium to A Combination of Daptomycin and Fosfomycin Reveals Distinct and Diverse Adaptive Strategies

2021 ◽  
Author(s):  
Adeline Supandy ◽  
Heer H Mehta ◽  
Truc T Tran ◽  
William R Miller ◽  
Rutan Zhang ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Adaptive Strategies ◽  
Membrane Dynamics ◽  
Combination Therapies ◽  
Front Line ◽  
Important Public Health ◽  
Public Health Threat ◽  
Biochemical Mechanisms ◽  
Vancomycin Resistant

Infections caused by vancomycin-resistant Enterococcus faecium (VREfm) are an important public health threat. VREfm have become increasingly resistant to the front-line antibiotic, daptomycin (DAP). As such, the use of DAP combination therapies (like fosfomycin [FOS]), has received increased attention. Antibiotic combinations could extend the efficacy of current available antibiotics and potentially delay the onset of further resistance. We investigated the potential for E. faecium HOU503, a clinical VREfm isolate that is DAP and FOS susceptible, to develop resistance to a DAP-FOS combination. Of particular interest was whether the genetic drivers for DAP-FOS resistance might be epistatic and, thus, potentially decrease the efficacy of a combinatorial approach in either inhibiting VREfm or in delaying the onset of resistance. We show that resistance to DAP-FOS could be achieved by independent mutations to proteins responsible for cell wall synthesis for FOS and in altering membrane dynamics for DAP. However, we did not observe genetic drivers that exhibited substantial cross-drug epistasis that could undermine DAP-FOS combination. Of interest was that FOS resistance in HOU503 was largely mediated by changes in phosphoenolpyruvate (PEP) flux as a result of mutations in pyruvate kinase (pyk). Increasing PEP flux could be a readily accessible mechanism for FOS resistance in many pathogens. Importantly, we show that HOU503 were able to develop DAP resistance through a variety of biochemical mechanisms and were able to employ different adaptive strategies. Finally, we showed that the addition of FOS can prolong the efficacy of DAP, significantly extending the timeline to resistance in vitro.

scholarly journals Characterization of Vancomycin-Resistant Enterococcus faecium Isolates from the United States and Their Susceptibility In Vitro to Dalfopristin-Quinupristin

1998 ◽  
Vol 42 (5) ◽  
pp. 1088-1092 ◽  
Author(s):  
G. M. Eliopoulos ◽  
C. B. Wennersten ◽  
H. S. Gold ◽  
T. Schülin ◽  
M. Souli ◽  
...  
Keyword(s):  
United States ◽  
Enterococcus Faecium ◽  
Multiple Drug Resistance ◽  
The United States ◽  
Multiple Drug ◽  
Data Set ◽  
Vancomycin Resistant ◽  
High Level

ABSTRACT In the course of clinical studies with the investigational streptogramin antimicrobial dalfopristin-quinupristin, isolates of vancomycin-resistant Enterococcus faecium were referred to our laboratory from across the United States. Seventy-two percent of the strains were of the VanA type, phenotypically and genotypically, while 28% were of the VanB type. High-level resistance to streptomycin or gentamicin was observed in 86 and 81%, respectively, of the VanA strains but in only 69 and 66%, respectively, of the VanB strains. These enterococci were resistant to ampicillin (MIC for 50% of the isolates tested [MIC50] and MIC90, 128 and 256 μg/ml, respectively) and to the other approved agents tested, with the exception of chloramphenicol (MIC90, 8 μg/ml) and novobiocin (MIC90, 1 μg/ml). Considering all of the isolates submitted, dalfopristin-quinupristin inhibited 86.4% of them at concentrations of ≤1 μg/ml and 95.1% of them at ≤2 μg/ml. However, for the data set comprised of only the first isolate submitted for each patient, 94.3% of the strains were inhibited at concentrations of ≤1 μg/ml and 98.9% were inhibited at concentrations of ≤2 μg/ml. Multiple drug resistance was very common among these isolates of vancomycin-resistant E. faecium, while dalfopristin-quinupristin inhibited the majority at concentrations that are likely to be clinically relevant.

scholarly journals In Vitro Activity of Trovafloxacin against Bacteroides fragilis in Mixed Culture with either Escherichia coli or a Vancomycin- Resistant Strain of Enterococcus faecium Determined by an Anaerobic Time-Kill Technique

2001 ◽  
Vol 45 (1) ◽  
pp. 243-251 ◽  
Author(s):  
Lorna E. T. Stearne ◽  
Clarissa Kooi ◽  
Wil H. F. Goessens ◽  
Irma A. J. M. Bakker-Woudenberg ◽  
Inge C. Gyssens
Keyword(s):  
Escherichia Coli ◽  
Resistant Strain ◽  
Enterococcus Faecium ◽  
Mixed Cultures ◽  
E Coli ◽  
Abdominal Abscesses ◽  
Pure Cultures ◽  
Vancomycin Resistant ◽  
Time Kill

ABSTRACT To determine the efficacy of trovafloxacin as a possible treatment for intra-abdominal abscesses, we have developed an anaerobic time-kill technique using different inocula to study the in vitro killing ofBacteroides fragilis in pure culture or in mixed culture with either Escherichia coli or a vancomycin-resistant strain of Enterococcus faecium (VREF). With inocula of 5 × 105 CFU/ml and trovafloxacin concentrations of ≤2 μg/ml, a maximum observed effect (E max) of ≥6.1 (log10 CFU/ml) was attained with all pure and mixed cultures within 24 h. With inocula of 108CFU/ml, a similar E max and a similar concentration to produce 50% of E max(EC50) for B. fragilis were found in both pure cultures and mixed cultures with E. coli. However, to produce a similar killing of B. fragilis in the mixed cultures with VREF, a 14-fold increase in the concentration of trovafloxacin was required. A vancomycin-susceptible strain of E. faecium and a trovafloxacin-resistant strain of E. coli were also found to confer a similar “protective” effect on B. fragilis against the activity of trovafloxacin. Using inocula of 109 CFU/ml, the activity of trovafloxacin was retained for E. coli and B. fragilis and was negligible against VREF. We conclude that this is a useful technique to study the anaerobic killing of mixed cultures in vitro and may be of value in predicting the killing of mixed infections in vivo. The importance of using mixed cultures and not pure cultures is clearly shown by the difference in the killing of B. fragilis in the mixed cultures tested. Trovafloxacin will probably be ineffective in the treatment of infections involving large numbers of enterococci. However, due to its ability to retain activity against large cultures of B. fragilis and E. coli, trovafloxacin could be beneficial in the treatment of intra-abdominal abscesses.

scholarly journals Development of in Vitro Resistance to Daptomycin in Enterococcus Faecium and Estimation of Its Fitness Cost

2020 ◽  
Author(s):  
Weiliang Zeng ◽  
Tao Chen ◽  
Qing Wu ◽  
Ye Xu ◽  
Kaihang Yu ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Biofilm Formation ◽  
Galleria Mellonella ◽  
Resistance Mechanisms ◽  
Fitness Cost ◽  
Resistant Bacteria ◽  
Infection Model ◽  
Dynamic Resistance ◽  
Vancomycin Resistant

Abstract BackgroundDaptomycin has broad-spectrum antibacterial activity against Gram-positive pathogens, but recent studies have revealed cases where daptomycin has failed to treat multidrug-resistant bacteria, such as vancomycin-resistant Enterococcus faecium. However, the resistance evolution of E. faecium to daptomycin in vitro and fitness cost remain unclear. In this study, we sought to analyze the resistance development and mechanism of E. faecium to datomycin, and futher to investigate the relationship between daptomycin resistance and fitness cost.MethodsTo investigate the development of daptomycin resistance in E. faecium, 6 daptomycin-susceptible (DAP-S) clinical isolates, including 3 vancomycin-resistant E. faecium (VRE) and 3 vancomycin-susceptible E. faecium (VSE), were exposured to daptomycin in vitro by serial passage experiment. Then the different resistance mechanisms of daptomycin-resistant (DAP-R) mutants were analyzed by polymerase chain reaction (PCR), cytochrome C binding assay and transmission electron microscopy. Furthermore, we also estimated the changes of fitness cost among each highly DAP-R mutants by bacterial growth curve measurement, in vitro competition experiments, infection model of Galleria mellonella larvae and biofilm formation assays.ResultsIn vitro, a total of 21 DAP-R mutants with minimal inhibitory concentration (MIC) of 4 to 512 μg/mL were obtained, and these mutants carried more than one mutation of LiaFSR and YycFG system encoding genes. More positive charges were detected among highly DAP-R mutants than parent isolates, and the cell walls of SC1174-D and SC1762-D mutants were remarkly thicker than those of the parent isolates. In comparison with parent isolates, besides, the growth, competition ability and virulence were significantly reduced, while the biofilm formation capacity was markedly elevated among each highly DAP-R mutants.ConclusionsOur findings suggest that E. faecium isolates are able to rapidly acquire DAP resistance in vitro through different dynamic resistance mechanisms, which often accompany by significant fitness cost. Intriguingly, DAP and glycopeptide antibiotics may present collateral-sensitivity during E. faecium acquired DAP resistance in vitro.

scholarly journals ddcP, pstB, and excess D-lactate impact synergism between vancomycin and chlorhexidine against Enterococcus faecium 1,231,410

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0249631
Author(s):  
Pooja Bhardwaj ◽  
Moutusee Z. Islam ◽  
Christi Kim ◽  
Uyen Thy Nguyen ◽  
Kelli L. Palmer
Keyword(s):  
Enterococcus Faecium ◽  
Whole Genome ◽  
Vancomycin Resistant Enterococci ◽  
Control Hospital ◽  
Skin Antisepsis ◽  
Life Threatening ◽  
Membrane Bound ◽  
Vancomycin Resistant ◽  
Hospital Associated Infections

Vancomycin-resistant enterococci (VRE) are important nosocomial pathogens that cause life-threatening infections. To control hospital-associated infections, skin antisepsis and bathing utilizing chlorhexidine is recommended for VRE patients in acute care hospitals. Previously, we reported that exposure to inhibitory chlorhexidine levels induced the expression of vancomycin resistance genes in VanA-type Enterococcus faecium. However, vancomycin susceptibility actually increased for VanA-type E. faecium in the presence of chlorhexidine. Hence, a synergistic effect of the two antimicrobials was observed. In this study, we used multiple approaches to investigate the mechanism of synergism between chlorhexidine and vancomycin in the VanA-type VRE strain E. faecium 1,231,410. We generated clean deletions of 7 of 11 pbp, transpeptidase, and carboxypeptidase genes in this strain (ponA, pbpF, pbpZ, pbpA, ddcP, ldtfm, and vanY). Deletion of ddcP, encoding a membrane-bound carboxypeptidase, altered the synergism phenotype. Furthermore, using in vitro evolution, we isolated a spontaneous synergy escaper mutant and utilized whole genome sequencing to determine that a mutation in pstB, encoding an ATPase of phosphate-specific transporters, also altered synergism. Finally, addition of excess D-lactate, but not D-alanine, enhanced synergism to reduce vancomycin MIC levels. Overall, our work identified factors that alter chlorhexidine and vancomycin synergism in a model VanA-type VRE strain.

scholarly journals Antimicrobial Constituents from Machaerium Pers.: Inhibitory Activities and Synergism of Machaeriols and Machaeridiols against Methicillin-Resistant Staphylococcus aureus, Vancomycin-Resistant Enterococcus faecium, and Permeabilized Gram-Negative Pathogens

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 6000
Author(s):  
Ilias Muhammad ◽  
Melissa R. Jacob ◽  
Mohamed A. Ibrahim ◽  
Vijayasankar Raman ◽  
Mallika Kumarihamy ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Enterococcus Faecium ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Polymyxin B ◽  
Synergistic Activity ◽  
Vancomycin Resistant Enterococcus ◽  
Methicillin Resistant ◽  
Vancomycin Resistant ◽  
Mrsa Strains

Two new epimeric bibenzylated monoterpenes machaerifurogerol (1a) and 5-epi-machaerifurogerol (1b), and four known isoflavonoids (+)-vestitol (2), 7-O-methylvestitol (3), (+)-medicarpin (4), and 3,8-dihydroxy-9-methoxypterocarpan (5) were isolated from Machaerium Pers. This plant was previously assigned as Machaerium multiflorum Spruce, from which machaeriols A-D (6–9) and machaeridiols A-C (10–12) were reported, and all were then re-isolated, except the minor compound 9, for a comprehensive antimicrobial activity evaluation. Structures of the isolated compounds were determined by full NMR and mass spectroscopic data. Among the isolated compounds, the mixture 10 + 11 was the most active with an MIC value of 1.25 μg/mL against methicillin-resistant Staphylococcus aureus (MRSA) strains BAA 1696, −1708, −1717, −33591, and vancomycin-resistant Enterococcus faecium (VRE 700221) and E. faecalis (VRE 51299) and vancomycin-sensitive E. faecalis (VSE 29212). Compounds 6–8 and 10–12 were found to be more potent against MRSA 1708, and 6, 11, and 12 against VRE 700221, than the drug control ciprofloxacin and vancomycin. A combination study using an in vitro Checkerboard method was carried out for machaeriols (7 or 8) and machaeridiols (11 or 12), which exhibited a strong synergistic activity of 12 + 8 (MIC 0.156 and 0.625 µg/mL), with >32- and >8-fold reduction of MIC’s, compared to 12, against MRSA 1708 and −1717, respectively. In the presence of sub-inhibitory concentrations on polymyxin B nonapeptide (PMBN), compounds 10 + 11, 11, 12, and 8 showed activity in the range of 0.5–8 µg/mL for two strains of Acinetobacter baumannii, 2–16 µg/mL against Pseudomonas aeruginosa PAO1, and 2 µg/mL against Escherichia coli NCTC 12923, but were inactive (MIC > 64 µg/mL) against the two isolates of Klebsiella pneumoniae.

scholarly journals β-Lactams Enhance Daptomycin Activity against Vancomycin-Resistant Enterococcus faecalis and Enterococcus faecium inIn VitroPharmacokinetic/Pharmacodynamic Models

2015 ◽  
Vol 59 (5) ◽  
pp. 2842-2848 ◽  
Author(s):  
Jordan R. Smith ◽  
Katie E. Barber ◽  
Animesh Raut ◽  
Michael J. Rybak
Keyword(s):  
Body Weight ◽  
Combination Therapy ◽  
Enterococcus Faecalis ◽  
Enterococcus Faecium ◽  
Single Agent ◽  
Vancomycin Resistant Enterococcus ◽  
Content Type ◽  
Vancomycin Resistant ◽  
Combination Regimens

ABSTRACTEnterococcus faecalisandEnterococcus faeciumare frequently resistant to vancomycin and β-lactams. In enterococcal infections with reduced glycopeptide susceptibility, combination therapy is often administered. Our objective was to conduct pharmacokinetic/pharmacodynamic (PK/PD) models to evaluate β-lactam synergy with daptomycin (DAP) against resistant enterococci. OneE. faecalisstrain (R6981) and twoE. faeciumstrains (R6370 and 8019) were evaluated. DAP MICs were obtained. All strains were evaluated for response to LL37, an antimicrobial peptide, in the presence and absence of ceftaroline (CPT), ertapenem (ERT), and ampicillin (AMP). After 96 h,in vitromodels were run simulating 10 mg DAP/kg body weight/day, 600 mg CPT every 8 h (q8h), 2 g AMP q4h, and 1 g ERT q24h, both alone and in combination against all strains. DAP MICs were 2, 4, and 4 μg/ml for strains R6981, R6370, and 8019, respectively. PK/PD models demonstrated bactericidal activity with DAP-CPT, DAP-AMP, and DAP-ERT combinations against strain 8019 (P< 0.001 and log10CFU/ml reduction of >2 compared to any single agent). Against strains R6981 and R6370, the DAP-AMP combination demonstrated enhancement against R6370 but not R6981, while the combinations of DAP-CPT and DAP-ERT were bactericidal, demonstrated enhancement, and were statistically superior to all other regimens at 96 h (P< 0.001) against both strains. CPT, ERT, and AMP similarly augmented LL37 killing against strain 8019. In strains R6981 and R6370, CPT and ERT aided LL37 more than AMP (P< 0.001). Compared to DAP alone, combination regimens provide better killing and prevent resistance. Clinical research involving DAP combinations is warranted.

scholarly journals Impact of Daptomycin Dose Exposure Alone or in Combination with β-Lactams or Rifampin against Vancomycin-Resistant Enterococci in an In Vitro Biofilm Model

2020 ◽  
Vol 64 (5) ◽  
Author(s):  
Seyedehameneh Jahanbakhsh ◽  
Nivedita B. Singh ◽  
Juwon Yim ◽  
Razieh Kebriaei ◽  
Jordan R. Smith ◽  
...  
Keyword(s):  
Bactericidal Activity ◽  
Enterococcus Faecium ◽  
Biofilm Reactor ◽  
Content Type ◽  
Biofilm Model ◽  
Vancomycin Resistant Enterococci ◽  
Dosing Regimens ◽  
Vancomycin Resistant ◽  
Reactor Models

ABSTRACT Enterococcus faecium strains are commonly resistant to vancomycin and β-lactams. In addition, E. faecium often causes biofilm-associated infections and these infections are difficult to treat. In this context, we investigated the activity of dosing regimens using daptomycin (DAP) (8, 10, 12, and 14 mg/kg of body weight/day) alone and in combination with ceftaroline (CPT), ampicillin (AMP), ertapenem (ERT), and rifampin (RIF) against 2 clinical strains of biofilm-producing vancomycin-resistant Enterococcus faecium (VREfm), namely, strains S447 and HOU503, in an in vitro biofilm model. HOU503 harbors common LiaS and LiaR substitutions, whereas S447 lacks mutations associated with the LiaFSR pathway. MIC results demonstrated that both strains were susceptible to DAP and resistant to CPT, AMP, ERT, and RIF. The 168-h pharmacokinetic/pharmacodynamic (PK/PD) CDC biofilm reactor models (simulating human antibiotic exposures) were used with titanium and polyurethane coupons to evaluate the efficacy of antibiotic combinations. DAP 12 and 14 achieved bactericidal activity against S447 but lacked such effect against HOU503. Addition of ERT and RIF enhanced DAP activity, allowing DAP 8 and 10 plus ERT or RIF to produce bactericidal activity against both strains at 168 h. While DAP 8 and 10 plus CPT improved killing, they did not reach bactericidal reduction against S447. Combination of AMP, CPT, ERT, or RIF resulted in enhanced and bactericidal activity for DAP against HOU503 at 168 h. Our data provide further support for the use of combinations of DAP with AMP, ERT, CPT, and RIF in infections caused by biofilm producing VREfm. Further research involving DAP combinations against biofilm-producing enterococci is warranted.

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