scholarly journals In VitroEmergence of High Persistence upon Periodic Aminoglycoside Challenge in the ESKAPE Pathogens

2016 ◽  
Vol 60 (8) ◽  
pp. 4630-4637 ◽  
Author(s):  
Joran Elie Michiels ◽  
Bram Van den Bergh ◽  
Natalie Verstraeten ◽  
Maarten Fauvart ◽  
Jan Michiels
Keyword(s):  
Genetic Resistance ◽  
Fold Increase ◽  
Clinical Diagnostics ◽  
High Dose ◽  
Cross Tolerance ◽  
Bacterial Populations ◽  
Content Type ◽  
Interval Therapy ◽  
Eskape Pathogens

ABSTRACTHealth care-associated infections present a major threat to modern medical care. Six worrisome nosocomial pathogens—Enterococcus faecium,Staphylococcus aureus,Klebsiella pneumoniae,Acinetobacter baumannii,Pseudomonas aeruginosa, andEnterobacterspp.—are collectively referred to as the “ESKAPE bugs.” They are notorious for extensive multidrug resistance, yet persistence, or the phenotypic tolerance displayed by a variant subpopulation, remains underappreciated in these pathogens. Importantly, persistence can prevent eradication of antibiotic-sensitive bacterial populations and is thought to act as a catalyst for the development of genetic resistance. Concentration- and time-dependent aminoglycoside killing experiments were used to investigate persistence in the ESKAPE pathogens. Additionally, a recently developed method for the experimental evolution of persistence was employed to investigate adaptation to high-dose, extended-interval aminoglycoside therapyin vitro. We show that ESKAPE pathogens exhibit biphasic killing kinetics, indicative of persister formation.In vitrocycling between aminoglycoside killing and persister cell regrowth, evocative of clinical high-dose extended-interval therapy, caused a 37- to 213-fold increase in persistence without the emergence of resistance. Increased persistence also manifested in biofilms and provided cross-tolerance to different clinically important antibiotics. Together, our results highlight a possible drawback of intermittent, high-dose antibiotic therapy and suggest that clinical diagnostics might benefit from taking into account persistence.

scholarly journals In VitroAnalyses of the Effects of Heparin and Parabens on Candida albicans Biofilms and Planktonic Cells

2011 ◽  
Vol 56 (1) ◽  
pp. 148-153 ◽  
Author(s):  
Marisa H. Miceli ◽  
Stella M. Bernardo ◽  
T. S. Neil Ku ◽  
Carla Walraven ◽  
Samuel A. Lee
Keyword(s):  
Candida Albicans ◽  
Metabolic Activity ◽  
Biofilm Formation ◽  
High Dose ◽  
Dependent Manner ◽  
Planktonic Cells ◽  
Content Type ◽  
Heparin Sodium ◽  
The Individual

ABSTRACTInfections and thromboses are the most common complications associated with central venous catheters. Suggested strategies for prevention and management of these complications include the use of heparin-coated catheters, heparin locks, and antimicrobial lock therapy. However, the effects of heparin onCandida albicansbiofilms and planktonic cells have not been previously studied. Therefore, we sought to determine thein vitroeffect of a heparin sodium preparation (HP) on biofilms and planktonic cells ofC. albicans. Because HP contains two preservatives, methyl paraben (MP) and propyl paraben (PP), these compounds and heparin sodium without preservatives (Pure-H) were also tested individually. The metabolic activity of the mature biofilm after treatment was assessed using XTT [2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide] reduction and microscopy. Pure-H, MP, and PP caused up to 75, 85, and 60% reductions of metabolic activity of the mature preformedC. albicansbiofilms, respectively. Maximal efficacy against the mature biofilm was observed with HP (up to 90%) compared to the individual compounds (P< 0.0001). Pure-H, MP, and PP each inhibitedC. albicansbiofilm formation up to 90%. A complete inhibition of biofilm formation was observed with HP at 5,000 U/ml and higher. When tested against planktonic cells, each compound inhibited growth in a dose-dependent manner. These data indicated that HP, MP, PP, and Pure-H havein vitroantifungal activity againstC. albicansmature biofilms, formation of biofilms, and planktonic cells. Investigation of high-dose heparin-based strategies (e.g., heparin locks) in combination with traditional antifungal agents for the treatment and/or prevention ofC. albicansbiofilms is warranted.

scholarly journals In VitroActivities of Daptomycin-, Vancomycin-, and Teicoplanin-Loaded Polymethylmethacrylate against Methicillin-Susceptible, Methicillin-Resistant, and Vancomycin-Intermediate Strains of Staphylococcus aureus

2011 ◽  
Vol 55 (12) ◽  
pp. 5480-5484 ◽  
Author(s):  
Yuhan Chang ◽  
Wen-Chien Chen ◽  
Pang-Hsin Hsieh ◽  
Dave W. Chen ◽  
Mel S. Lee ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
High Performance ◽  
Low Dose ◽  
Antibacterial Activities ◽  
High Dose ◽  
Bone Cements ◽  
Antibacterial Effects ◽  
Methicillin Resistant ◽  
Content Type

ABSTRACTThe objective of this study was to evaluate the antibacterial effects of polymethylmethacrylate (PMMA) bone cements loaded with daptomycin, vancomycin, and teicoplanin against methicillin-susceptibleStaphylococcus aureus(MSSA), methicillin-resistantStaphylococcus aureus(MRSA), and vancomycin-intermediateStaphylococcus aureus(VISA) strains. Standardized cement specimens made from 40 g PMMA loaded with 1 g (low-dose), 4 g (middle-dose) or 8 g (high-dose) antibiotics were tested for elution characteristics and antibacterial activities. The patterns of release of antibiotics from the cement specimens were evaluated usingin vitrobroth elution assay with high-performance liquid chromatography. The activities of broth elution fluid against differentStaphylococcus aureusstrains (MSSA, MRSA, and VISA) were then determined. The antibacterial activities of all the tested antibiotics were maintained after being mixed with PMMA. The cements loaded with higher dosages of antibiotics showed longer elution periods. Regardless of the antibiotic loading dose, the teicoplanin-loaded cements showed better elution efficacy and provided longer inhibitory periods against MSSA, MRSA, and VISA than cements loaded with the same dose of vancomycin or daptomycin. Regarding the choice of antibiotics for cement loading in the treatment ofStaphylococcus aureusinfection, teicoplanin was superior in terms of antibacterial effects.

scholarly journals Effects of Methanogenic Inhibitors on Methane Production and Abundances of Methanogens and Cellulolytic Bacteria inIn VitroRuminal Cultures

2011 ◽  
Vol 77 (8) ◽  
pp. 2634-2639 ◽  
Author(s):  
Zhenming Zhou ◽  
Qingxiang Meng ◽  
Zhongtang Yu
Keyword(s):  
Methane Production ◽  
Volatile Fatty Acids ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Cellulolytic Bacteria ◽  
Bacterial Populations ◽  
Content Type ◽  
Specific Pcr ◽  
Methanogen Population ◽  
Propynoic Acid

ABSTRACTThe objective of this study was to systematically evaluate and compare the effects of select antimethanogen compounds on methane production, feed digestion and fermentation, and populations of ruminal bacteria and methanogens usingin vitrocultures. Seven compounds, including 2-bromoethanesulphonate (BES), propynoic acid (PA), nitroethane (NE), ethyltrans-2-butenoate (ETB), 2-nitroethanol (2NEOH), sodium nitrate (SN), and ethyl-2-butynote (EB), were tested at a final concentration of 12 mM. Ground alfalfa hay was included as the only substrate to simulate daily forage intake. Compared to no-inhibitor controls, PA, 2NEOH, and SN greatly reduced the production of methane (70 to 99%), volatile fatty acids (VFAs; 46 to 66%), acetate (30 to 60%), and propionate (79 to 82%), with 2NEOH reducing the most. EB reduced methane production by 23% without a significant effect on total VFAs, acetate, or propionate. BES significantly reduced the propionate concentration but not the production of methane, total VFAs, or acetate. ETB or NE had no significant effect on any of the above-mentioned measurements. Specific quantitative-PCR (qPCR) assays showed that none of the inhibitors significantly affected total bacterial populations but that they did reduce theFibrobacter succinogenespopulation. SN reduced theRuminococcus albuspopulation, while PA and 2NEOH increased the populations of bothR. albusandRuminococcus flavefaciens. Archaeon-specific PCR-denaturing gradient gel electrophoresis (DGGE) showed that all the inhibitors affected the methanogen population structure, while archaeon-specific qPCR revealed a significant decrease in methanogen population in all treatments. These results showed that EB, ETB, NE, and BES can effectively reduce the total population of methanogens but that they reduce methane production to a lesser extent. The results may guide futureinvivostudies to develop effective mitigation of methane emission from ruminants.

scholarly journals Albumin Enhances Caspofungin Activity against Aspergillus Species by Facilitating Drug Delivery to Germinating Hyphae

2015 ◽  
Vol 60 (3) ◽  
pp. 1226-1233 ◽  
Author(s):  
Petros Ioannou ◽  
Aggeliki Andrianaki ◽  
Tonia Akoumianaki ◽  
Irene Kyrmizi ◽  
Nathaniel Albert ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Cell Culture ◽  
Antifungal Agents ◽  
Fold Increase ◽  
Culture Conditions ◽  
The Other ◽  
Related Factors ◽  
Content Type

The modestin vitroactivity of echinocandins againstAspergillusimplies that host-related factors augment the action of these antifungal agentsin vivo. We found that, in contrast to the other antifungal agents (voriconazole, amphotericin B) tested, caspofungin exhibited a profound increase in activity against variousAspergillusspecies under conditions of cell culture growth, as evidenced by a ≥4-fold decrease in minimum effective concentrations (MECs) (P= 0. 0005). Importantly, the enhanced activity of caspofungin againstAspergillusspp. under cell culture conditions was strictly dependent on serum albumin and was not observed with the other two echinocandins, micafungin and anidulafungin. Of interest, fluorescently labeled albumin bound preferentially on the surface of germinatingAspergillushyphae, and this interaction was further enhanced upon treatment with caspofungin. In addition, supplementation of cell culture medium with albumin resulted in a significant, 5-fold increase in association of fluorescently labeled caspofungin withAspergillushyphae (P< 0.0001). Collectively, we found a novel synergistic interaction between albumin and caspofungin, with albumin acting as a potential carrier molecule to facilitate antifungal drug delivery toAspergillushyphae.

scholarly journals Efficacy of Biocides Used in the Modern Food Industry To Control Salmonella enterica, and Links between Biocide Tolerance and Resistance to Clinically Relevant Antimicrobial Compounds

2012 ◽  
Vol 78 (9) ◽  
pp. 3087-3097 ◽  
Author(s):  
Orla Condell ◽  
Carol Iversen ◽  
Shane Cooney ◽  
Karen A. Power ◽  
Ciara Walsh ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Food Industry ◽  
Multidrug Resistant ◽  
Cross Resistance ◽  
Antimicrobial Compounds ◽  
Cross Tolerance ◽  
Content Type ◽  
Food Grade ◽  
High Level

ABSTRACTBiocides play an essential role in limiting the spread of infectious disease. The food industry is dependent on these agents, and their increasing use is a matter for concern. Specifically, the emergence of bacteria demonstrating increased tolerance to biocides, coupled with the potential for the development of a phenotype of cross-resistance to clinically important antimicrobial compounds, needs to be assessed. In this study, we investigated the tolerance of a collection of susceptible and multidrug-resistant (MDR)Salmonella entericastrains to a panel of seven commercially available food-grade biocide formulations. We explored their abilities to adapt to these formulations and their active biocidal agents, i.e., triclosan, chlorhexidine, hydrogen peroxide, and benzalkonium chloride, after sequential rounds ofin vitroselection. Finally, cross-tolerance of different categories of biocidal formulations, their active agents, and the potential for coselection of resistance to clinically important antibiotics were investigated. Six of seven food-grade biocide formulations were bactericidal at their recommended working concentrations. All showed a reduced activity against both surface-dried and biofilm cultures. A stable phenotype of tolerance to biocide formulations could not be selected. Upon exposure ofSalmonellastrains to an active biocidal compound, a high-level of tolerance was selected for a number ofSalmonellaserotypes. No cross-tolerance to the different biocidal agents or food-grade biocide formulations was observed. Most tolerant isolates displayed changes in their patterns of susceptibility to antimicrobial compounds. Food industry biocides are effective against planktonicSalmonella. When exposed to sublethal concentrations of individual active biocidal agents, tolerant isolates may emerge. This emergence was associated with changes in antimicrobial susceptibilities.

scholarly journals In VivoTransmission of an IncA/C Plasmid in Escherichia coli Depends on Tetracycline Concentration, and Acquisition of the Plasmid Results in a Variable Cost of Fitness

2015 ◽  
Vol 81 (10) ◽  
pp. 3561-3570 ◽  
Author(s):  
Timothy J. Johnson ◽  
Randall S. Singer ◽  
Richard E. Isaacson ◽  
Jessica L. Danzeisen ◽  
Kevin Lang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
High Dose ◽  
Broad Host Range ◽  
Antibiotic Administration ◽  
Dose Administration ◽  
Content Type ◽  
E Coli ◽  
The Impact ◽  
Selection Of

ABSTRACTIncA/C plasmids are broad-host-range plasmids enabling multidrug resistance that have emerged worldwide among bacterial pathogens of humans and animals. Although antibiotic usage is suspected to be a driving force in the emergence of such strains, few studies have examined the impact of different types of antibiotic administration on the selection of plasmid-containing multidrug resistant isolates. In this study, chlortetracycline treatment at different concentrations in pig feed was examined for its impact on selection and dissemination of an IncA/C plasmid introduced orally via a commensalEscherichia colihost. Continuous low-dose administration of chlortetracycline at 50 g per ton had no observable impact on the proportions of IncA/C plasmid-containingE. colifrom pig feces over the course of 35 days. In contrast, high-dose administration of chlortetracycline at 350 g per ton significantly increased IncA/C plasmid-containingE. coliin pig feces (P< 0.001) and increased movement of the IncA/C plasmid to other indigenousE. colihosts. There was no evidence of conjugal transfer of the IncA/C plasmid to bacterial species other thanE. coli.In vitrocompetition assays demonstrated that bacterial host background substantially impacted the cost of IncA/C plasmid carriage inE. coliandSalmonella.In vitrotransfer and selection experiments demonstrated that tetracycline at 32 μg/ml was necessary to enhance IncA/C plasmid conjugative transfer, while subinhibitory concentrations of tetracyclinein vitrostrongly selected for IncA/C plasmid-containingE. coli. Together, these experiments improve our knowledge on the impact of differing concentrations of tetracycline on the selection of IncA/C-type plasmids.

scholarly journals Tagging Frogs with Passive Integrated Transponders Causes Disruption of the Cutaneous Bacterial Community and Proliferation of Opportunistic Fungi

2014 ◽  
Vol 80 (15) ◽  
pp. 4779-4784 ◽  
Author(s):  
Rachael E. Antwis ◽  
Gerardo Garcia ◽  
Andrea L. Fidgett ◽  
Richard F. Preziosi
Keyword(s):  
Bacterial Community ◽  
Microbial Communities ◽  
Bacterial Communities ◽  
Pathogenic Fungus ◽  
Fold Increase ◽  
Bacterial Strains ◽  
Opportunistic Fungi ◽  
Content Type ◽  
Pit Tagging

ABSTRACTSymbiotic bacterial communities play a key role in protecting amphibians from infectious diseases including chytridiomycosis, caused by the pathogenic fungusBatrachochytrium dendrobatidis. Events that lead to the disruption of the bacterial community may have implications for the susceptibility of amphibians to such diseases. Amphibians are often marked both in the wild and in captivity for a variety of reasons, and although existing literature indicates that marking techniques have few negative effects, the response of cutaneous microbial communities has not yet been investigated. Here we determine the effects of passive integrated transponder (PIT) tagging on culturable cutaneous microbial communities of captive Morelet's tree frogs (Agalychnis moreletii) and assess the isolated bacterial strains for anti-B. dendrobatidisactivityin vitro. We find that PIT tagging causes a major disruption to the bacterial community associated with the skin of frogs (∼12-fold increase in abundance), as well as a concurrent proliferation in resident fungi (up to ∼200-fold increase). Handling also caused a disruption the bacterial community, although to a lesser extent than PIT tagging. However, the effects of both tagging and handling were temporary, and after 2 weeks, the bacterial communities were similar to their original compositions. We also identify two bacterial strains that inhibitB. dendrobatidis, one of which increased in abundance on PIT-tagged frogs at 1 day postmarking, while the other was unaffected. These results show that PIT tagging has previously unobserved consequences for cutaneous microbial communities of frogs and may be particularly relevant for studies that intend to use PIT tagging to identify individuals involved in trials to develop probiotic treatments.

scholarly journals Advanced Quantification Methods To Improve the 18b Dormancy Model for Assessing the Activity of Tuberculosis Drugs In Vitro

2020 ◽  
Vol 64 (7) ◽  
Author(s):  
E. D. Pieterman ◽  
M. J. Sarink ◽  
C. Sala ◽  
S. T. Cole ◽  
J. E. M. de Steenwinkel ◽  
...  
Keyword(s):  
Drug Development ◽  
Area Under The Curve ◽  
High Dose ◽  
Current Form ◽  
Content Type ◽  
Solid Media ◽  
Development Pipeline ◽  
The Difference ◽  
Time Kill

ABSTRACT One of the reasons for the lengthy tuberculosis (TB) treatment is the difficulty to treat the nonmultiplying mycobacterial subpopulation. In order to assess the ability of (new) TB drugs to target this subpopulation, we need to incorporate dormancy models in our preclinical drug development pipeline. In most available dormancy models, it takes a long time to create a dormant state, and it is difficult to identify and quantify this nonmultiplying condition. The Mycobacterium tuberculosis 18b strain might overcome some of these problems, because it is dependent on streptomycin for growth and becomes nonmultiplying after 10 days of streptomycin starvation but still can be cultured on streptomycin-supplemented culture plates. We developed our 18b dormancy time-kill kinetics model to assess the difference in the activity of isoniazid, rifampin, moxifloxacin, and bedaquiline against log-phase growth compared to the nonmultiplying M. tuberculosis subpopulation by CFU counting, including a novel area under the curve (AUC)-based approach as well as time-to-positivity (TTP) measurements. We observed that isoniazid and moxifloxacin were relatively more potent against replicating bacteria, while rifampin and high-dose bedaquiline were equally effective against both subpopulations. Moreover, the TTP data suggest that including a liquid culture-based method could be of additional value, as it identifies a specific mycobacterial subpopulation that is nonculturable on solid media. In conclusion, the results of our study underline that the time-kill kinetics 18b dormancy model in its current form is a useful tool to assess TB drug potency and thus has its place in the TB drug development pipeline.

scholarly journals Evaluation of Standard- and High-Dose Daptomycin versus Linezolid against Vancomycin-Resistant Enterococcus Isolates in anIn VitroPharmacokinetic/Pharmacodynamic Model with Simulated Endocardial Vegetations

2012 ◽  
Vol 56 (6) ◽  
pp. 3174-3180 ◽  
Author(s):  
Ashley D. Hall ◽  
Molly E. Steed ◽  
Cesar A. Arias ◽  
Barbara E. Murray ◽  
Michael J. Rybak
Keyword(s):  
Bactericidal Activity ◽  
Optimal Dose ◽  
Pharmacodynamic Model ◽  
Colony Count ◽  
High Dose ◽  
Vancomycin Resistant Enterococcus ◽  
Content Type ◽  
Sustained Reduction ◽  
Vancomycin Resistant

ABSTRACTDaptomycin MICs for enterococci are typically 1- to 2-fold higher than those forStaphylococcus aureus, and there is an imminent need to establish the optimal dose for appropriate treatment of enterococcal infections. We investigated the bactericidal activity of daptomycin at various dose exposures compared to that of linezolid against vancomycin-resistant enterococcus (VRE) in anin vitropharmacokinetic/pharmacodynamic model utilizing simulated endocardial vegetations over 96 h. Daptomycin at doses of 6, 8, 10, and 12 mg/kg of body weight/day and linezolid at a dose of 600 mg every 12 h were evaluated against two clinical vancomycin-resistantEnterococcus faeciumstrains (EFm11499 and 09-184D1051), one of which was linezolid resistant (09-184D1051), and one clinical vancomycin-resistantEnterococcus faecalisstrain (EFs11496). Daptomycin MICs were 4, 2, and 0.5 μg/ml for EFm11499, 09-184D1051, and EFs11496, respectively. Bactericidal activity, defined as a ≥3 log10CFU/g reduction from the initial colony count, was demonstrated against all three isolates with all doses of daptomycin; however, bactericidal activity was not sustained with the daptomycin 6- and 8-mg/kg/day regimens. Linezolid was bacteriostatic against EFm11499 and displayed no appreciable activity against 09-184D1051 or EFs11496. Concentration-dependent killing was displayed with more sustained reduction in colony count (3.58 to 6.46 and 5.89 to 6.56 log10CFU/g) at 96 h for the simulated regimen of daptomycin at doses of 10 and 12 mg/kg/day, respectively (P≤ 0.012). NoE. faeciummutants with reduced susceptibility were recovered at any dosage regimen; however, theE. faecalisstrain developed reduced daptomycin susceptibility with daptomycin at 6, 8, and 10 but not at 12 mg/kg/day. Daptomycin displayed a dose-dependent response against three VRE isolates, with high-dose daptomycin producing sustained bactericidal activity. Further research is warranted.

scholarly journals In VivoEfficacy of Human Simulated Regimens of Carbapenems and Comparator Agents against NDM-1-Producing Enterobacteriaceae

2013 ◽  
Vol 58 (3) ◽  
pp. 1671-1677 ◽  
Author(s):  
Dora E. Wiskirchen ◽  
Patrice Nordmann ◽  
Jared L. Crandon ◽  
David P. Nicolau
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Similar Efficacy ◽  
Infection Model ◽  
High Dose ◽  
Wild Type ◽  
Prolonged Infusion ◽  
Content Type

ABSTRACTDoripenem and ertapenem have demonstrated efficacy against several NDM-1-producing isolatesin vivo, despite having high MICs. In this study, we sought to further characterize the efficacy profiles of humanized regimens of standard (500 mg given every 8 h) and high-dose, prolonged infusion of doripenem (2 g given every 8 h, 4-h infusion) and 1 g of ertapenem given intravenously every 24 h and the comparator regimens of ceftazidime at 2 g given every 8 h (2-h infusion), levofloxacin at 500 mg every 24 h, and aztreonam at 2 g every 6 h (1-h infusion) against a wider range of isolates in a murine thigh infection model. An isogenic wild-type strain and NDM-1-producingKlebsiella pneumoniaeand eight clinical NDM-1-producing members of the familyEnterobacteriaceaewere tested in immunocompetent- and neutropenic-mouse models. The wild-type strain was susceptible to all of the agents, while the isogenic NDM-1-producing strain was resistant to ceftazidime, doripenem, and ertapenem. Clinical NDM-1-producing strains were resistant to nearly all five of the agents (two were susceptible to levofloxacin). In immunocompetent mice, all of the agents produced ≥1-log10CFU reductions of the isogenic wild-type and NDM-1-producing strains after 24 h. Minimal efficacy of ceftazidime, aztreonam, and levofloxacin against the clinical NDM-1-producing strains was observed. However, despitein vitroresistance, ≥1-log10CFU reductions of six of eight clinical strains were achieved with high-dose, prolonged infusion of doripenem and ertapenem. Slight enhancements of doripenem activity over the standard doses were obtained with high-dose, prolonged infusion for three of the four isolates tested. Similar efficacy observations were noted in neutropenic mice. These data suggest that carbapenems are a viable treatment option for infections caused by NDM-1-producingEnterobacteriaceae.

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