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Peyrusson F, Nguyen TK, Buyck JM, Lemaire S, Wang G, Seral C, Tulkens PM, Van Bambeke F. In Vitro Models for the Study of the Intracellular Activity of Antibiotics. Methods Mol Biol 2021; 2357:239-251. [PMID: 34590263 DOI: 10.1007/978-1-0716-1621-5_16] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Intracellular bacteria are poorly responsive to antibiotic treatment. Pharmacological studies are thus needed to determine the antibiotics which are the most potent or effective against intracellular bacteria as well as to explore the reasons for poor bacterial responsiveness. An in vitro pharmacodynamic model is described, consisting of (1) phagocytosis of preopsonized bacteria by eukaryotic cells, (2) elimination of noninternalized bacteria with gentamicin, (3) incubation of infected cells with antibiotics, and (4) determination of surviving bacteria by viable cell counting and normalization of the counts based on sample protein content. The use of strains expressing fluorescent proteins under the control of an inducible promoter allows to follow intracellular bacterial division at the individual level and therefore to monitor bacterial persisters that do not multiply anymore.
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Affiliation(s)
- Frédéric Peyrusson
- Pharmacologie Cellulaire et Moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - Tiep K Nguyen
- Pharmacologie Cellulaire et Moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - Julien M Buyck
- Pharmacologie Cellulaire et Moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium.,INSERM U1070 "Pharmacology of Anti-infective Agents", Université de Poitiers, Poitiers, France
| | - Sandrine Lemaire
- Pharmacologie Cellulaire et Moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium.,GSK Biologicals, Rixensart, Belgium
| | - Gang Wang
- Pharmacologie Cellulaire et Moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - Cristina Seral
- Pharmacologie Cellulaire et Moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium.,Department of Microbiology, Hospital Clínico Universitario Lozano Blesa, Zaragoza, Spain
| | - Paul M Tulkens
- Pharmacologie Cellulaire et Moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - Françoise Van Bambeke
- Pharmacologie Cellulaire et Moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium.
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Algorri M, Wong-Beringer A. Differential effects of antibiotics on neutrophils exposed to lipoteichoic acid derived from Staphylococcus aureus. Ann Clin Microbiol Antimicrob 2020; 19:50. [PMID: 33143710 PMCID: PMC7641855 DOI: 10.1186/s12941-020-00392-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 10/20/2020] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Persistent bacteremia occurs in at least 30% of patients with Staphylococcus aureus bloodstream infection (SAB) and may be attributable to a dysregulated host immune response. Neutrophils interact with a variety of S. aureus microbial factors, including lipoteichoic acid (LTA), to activate phagocytic function in a concentration-dependent manner. Antibiotics have been shown to exert both direct antimicrobial action as well as immunomodulatory effects. In this study, we compared the effects of different anti-staphylococcal antibiotics on LTA-mediated immune activation of neutrophils. METHODS Neutrophils obtained from healthy volunteers were exposed to two levels of LTA (1 and 10 μg/ml) with or without addition of antibiotics from different pharmacologic classes (vancomycin, daptomycin, ceftaroline). Neutrophil function was assessed by examining phagocytic response, activation (CD11b, CD62L expression), Toll-like receptor-2 expression, cell survival and apoptosis, and CXCL8 release. RESULTS Differential LTA-mediated antibiotic effects on neutrophil function were observed primarily at the high LTA exposure level. Ceftaroline in the presence of 10 μg/ml LTA had the most prominent effects on phagocytosis and CD11b and CD62L expression, with trends towards increased neutrophil survival and preservation of CXCL8 release when compared to daptomycin and vancomycin with the latter significantly dampening PMN CXCL8 release. CONCLUSIONS Select antimicrobial agents, such as ceftaroline, exert immunostimulatory effects on neutrophils exposed to S. aureus LTA, which when confirmed in vivo, could be leveraged for its dual immunomodulatory and antibacterial actions for the treatment of persistent SAB mediated by a dysregulated host response.
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Affiliation(s)
- Marquerita Algorri
- University of Southern California, School of Pharmacy, 1985 Zonal Avenue, Los Angeles, CA, 90089, USA
| | - Annie Wong-Beringer
- University of Southern California, School of Pharmacy, 1985 Zonal Avenue, Los Angeles, CA, 90089, USA.
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3
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Abad L, Tafani V, Tasse J, Josse J, Chidiac C, Lustig S, Ferry T, Diot A, Laurent F, Valour F. Evaluation of the ability of linezolid and tedizolid to eradicate intraosteoblastic and biofilm-embedded Staphylococcus aureus in the bone and joint infection setting. J Antimicrob Chemother 2020; 74:625-632. [PMID: 30517641 DOI: 10.1093/jac/dky473] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 10/08/2018] [Accepted: 10/16/2018] [Indexed: 12/16/2022] Open
Abstract
OBJECTIVES Prolonged use of linezolid for bone and joint infection (BJI) is limited by its long-term toxicity. The better safety profile of tedizolid, a recently developed oxazolidinone, could offer an alternative. However, its efficacy against biofilm-embedded and intracellular Staphylococcus aureus, the two main bacterial reservoirs associated with BJI chronicity, is unknown. METHODS Using three S. aureus strains (6850 and two clinical BJI isolates), linezolid and tedizolid were compared regarding their ability: (i) to target the S. aureus intracellular reservoir in an in vitro model of osteoblast infection, using three concentrations increasing from the bone concentration reached with standard therapeutic doses (Cbone = 2.5 × MIC; Cplasm = 10 × MIC; Cmax = 40 × MIC); (ii) to eradicate mature biofilm [minimal biofilm eradication concentration (MBEC)]; and (iii) to prevent biofilm formation [biofilm MIC (bMIC) and confocal microscopy]. RESULTS Linezolid and tedizolid weakly reduced the intracellular inoculum of S. aureus in a strain-dependent manner despite the similar MICs for the tested strains, but improved cell viability even in the absence of an intracellular bactericidal effect. Conversely, linezolid and tedizolid were ineffective in eradicating mature biofilm formed in vitro, with MBEC >2000 and >675 mg/L, respectively. bMICs of tedizolid were 4-fold lower than those of linezolid for all strains. CONCLUSIONS Linezolid and tedizolid alone are not optimal candidates to target bacterial phenotypes associated with chronic forms of BJI. Despite weak intracellular activity, they both reduce infection-related cytotoxicity, suggesting a role in modulating intracellular expression of staphylococcal virulence factors. Although inactive against biofilm-embedded S. aureus, both-but particularly tedizolid-are able to prevent biofilm formation.
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Affiliation(s)
- Lélia Abad
- CIRI - Centre International de Recherche en Infectiologie, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Université Lyon, Lyon, France.,Regional Reference Centre for Complex Bone and Joint Infection (CRIOAc Lyon), Hospices Civils de Lyon, Lyon, France.,Université Claude Bernard Lyon 1, Lyon, France.,Department of Bacteriology, Institute for Infectious Agents, Hospices Civils de Lyon, Lyon, France
| | - Virginie Tafani
- CIRI - Centre International de Recherche en Infectiologie, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Université Lyon, Lyon, France
| | - Jason Tasse
- CIRI - Centre International de Recherche en Infectiologie, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Université Lyon, Lyon, France
| | - Jérôme Josse
- CIRI - Centre International de Recherche en Infectiologie, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Université Lyon, Lyon, France
| | - Christian Chidiac
- CIRI - Centre International de Recherche en Infectiologie, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Université Lyon, Lyon, France.,Regional Reference Centre for Complex Bone and Joint Infection (CRIOAc Lyon), Hospices Civils de Lyon, Lyon, France.,Université Claude Bernard Lyon 1, Lyon, France.,Department of Infectious Diseases, Hospices Civils de Lyon, Lyon, France
| | - Sébastien Lustig
- Regional Reference Centre for Complex Bone and Joint Infection (CRIOAc Lyon), Hospices Civils de Lyon, Lyon, France.,Université Claude Bernard Lyon 1, Lyon, France.,Department of Orthopaedic Surgery, Hospices Civils de Lyon, Lyon, France
| | - Tristan Ferry
- CIRI - Centre International de Recherche en Infectiologie, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Université Lyon, Lyon, France.,Regional Reference Centre for Complex Bone and Joint Infection (CRIOAc Lyon), Hospices Civils de Lyon, Lyon, France.,Université Claude Bernard Lyon 1, Lyon, France.,Department of Infectious Diseases, Hospices Civils de Lyon, Lyon, France
| | - Alan Diot
- CIRI - Centre International de Recherche en Infectiologie, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Université Lyon, Lyon, France
| | - Frédéric Laurent
- CIRI - Centre International de Recherche en Infectiologie, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Université Lyon, Lyon, France.,Regional Reference Centre for Complex Bone and Joint Infection (CRIOAc Lyon), Hospices Civils de Lyon, Lyon, France.,Université Claude Bernard Lyon 1, Lyon, France.,Department of Bacteriology, Institute for Infectious Agents, Hospices Civils de Lyon, Lyon, France
| | - Florent Valour
- CIRI - Centre International de Recherche en Infectiologie, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Université Lyon, Lyon, France.,Regional Reference Centre for Complex Bone and Joint Infection (CRIOAc Lyon), Hospices Civils de Lyon, Lyon, France.,Université Claude Bernard Lyon 1, Lyon, France.,Department of Infectious Diseases, Hospices Civils de Lyon, Lyon, France
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4
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Peyrusson F, Van Wessem A, Dieppois G, Van Bambeke F, Tulkens PM. Cellular pharmacokinetics and intracellular activity of the bacterial fatty acid synthesis inhibitor, afabicin desphosphono against different resistance phenotypes of Staphylococcus aureus in models of cultured phagocytic cells. Int J Antimicrob Agents 2020; 55:105848. [DOI: 10.1016/j.ijantimicag.2019.11.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 11/06/2019] [Accepted: 11/13/2019] [Indexed: 11/30/2022]
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5
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Identification of TB-E12 as a novel FtsZ inhibitor with anti-tuberculosis activity. Tuberculosis (Edinb) 2018; 110:79-85. [DOI: 10.1016/j.tube.2018.04.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 03/28/2018] [Accepted: 04/03/2018] [Indexed: 01/15/2023]
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6
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Cellular Pharmacokinetics and Intracellular Activity of Gepotidacin against Staphylococcus aureus Isolates with Different Resistance Phenotypes in Models of Cultured Phagocytic Cells. Antimicrob Agents Chemother 2018; 62:AAC.02245-17. [PMID: 29358297 PMCID: PMC5913948 DOI: 10.1128/aac.02245-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 01/09/2018] [Indexed: 11/20/2022] Open
Abstract
Gepotidacin (GSK2140944), a novel triazaacenaphthylene bacterial topoisomerase inhibitor, is currently in clinical development for the treatment of bacterial infections. This study examined in vitro its activity against intracellular Staphylococcus aureus (involved in the persistent character of skin and skin structure infections) by use of a pharmacodynamic model and in relation to cellular pharmacokinetics in phagocytic cells. Compared to oxacillin, vancomycin, linezolid, daptomycin, azithromycin, and moxifloxacin, gepotidacin was (i) more potent intracellularly (the apparent bacteriostatic concentration [Cs] was reached at an extracellular concentration about 0.7× its MIC and was not affected by mechanisms of resistance to the comparators) and (ii) caused a maximal reduction of the intracellular burden (maximum effect) of about −1.6 log10 CFU (which was better than that caused by linezolid, macrolides, and daptomycin and similar to that caused by moxifloxacin). After 24 h of incubation of infected cells with antibiotics at 100× their MIC, the intracellular persisting fraction was <0.1% with moxifloxacin, 0.5% with gepotidacin, and >1% with the other drugs. The accumulation and efflux of gepotidacin in phagocytes were very fast (kin and kout, ∼0.3 min−1; the plateau was reached within 15 min) but modest (intracellular concentration-to-extracellular concentration ratio, ∼1.6). In cell fractionation studies, about 40 to 60% of the drug was recovered in the soluble fraction and ∼40% was associated with lysosomes in uninfected cells. In infected cells, about 20% of cell-associated gepotidacin was recovered in a sedimentable fraction that also contained bacteria. This study highlights the potential for further study of gepotidacin to fight infections where intracellular niches may play a determining role in bacterial persistence and relapses.
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7
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Buyck JM, Luyckx C, Muccioli GG, Krause KM, Nichols WW, Tulkens PM, Van Bambeke F. Pharmacodynamics of ceftazidime/avibactam against extracellular and intracellular forms of Pseudomonas aeruginosa. J Antimicrob Chemother 2018; 72:1400-1409. [PMID: 28137941 DOI: 10.1093/jac/dkw587] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 12/20/2016] [Indexed: 02/05/2023] Open
Abstract
Objectives When tested in broth, avibactam reverses ceftazidime resistance in many Pseudomonas aeruginosa that express ESBLs. We examined whether similar reversal is observed against intracellular forms of P. aeruginosa . Methods Strains: reference strains; two engineered strains with basal non-inducible expression of AmpC and their isogenic mutants with stably derepressed AmpC; and clinical isolates with complete, partial or no resistance to reversion with avibactam. Pharmacodynamic model: 24 h concentration-response to ceftazidime [0.01-200 mg/L alone or with avibactam (4 mg/L)] of bacteria in broth or bacteria phagocytosed by THP-1 monocytes, with calculation of ceftazidime relative potency ( C s : concentration yielding a static effect) and maximal relative effect [ E max : cfu decrease at infinitely large antibiotic concentrations (efficacy in the model)] using the Hill equation. Cellular content of avibactam: quantification by LC-MS/MS. Results For both extracellular and intracellular bacteria, ceftazidime C s was always close to its MIC. For ceftazidime-resistant strains, avibactam addition shifted ceftazidime C s to values close to the MIC of the combination in broth. E max was systematically below the detection limit (-5 log 10 ) for extracellular bacteria, but limited to -1.3 log 10 for intracellular bacteria (except for two isolates) with no effect of avibactam. The cellular concentration of avibactam reflected extracellular concentration and was not influenced by ceftazidime (0-160 mg/L). Conclusions The potential for avibactam to inhibit β-lactamases does not differ for extracellular and intracellular forms of P. aeruginosa , denoting an unhindered access to its target in both situations. The loss of maximal relative efficacy of ceftazidime against intracellular P. aeruginosa was unrelated to resistance via avibactam-inhibitable β-lactamases.
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Affiliation(s)
- J M Buyck
- Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - C Luyckx
- Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - G G Muccioli
- MASSMET Platform, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium.,Bioanalysis and Pharmacology of Bioactive Lipids Research Group, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | | | - W W Nichols
- AstraZeneca Pharmaceuticals, Waltham, MA, USA
| | - P M Tulkens
- Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - F Van Bambeke
- Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
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A Highly Potent Class of Halogenated Phenazine Antibacterial and Biofilm-Eradicating Agents Accessed Through a Modular Wohl-Aue Synthesis. Sci Rep 2017; 7:2003. [PMID: 28515440 PMCID: PMC5435703 DOI: 10.1038/s41598-017-01045-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 03/17/2017] [Indexed: 12/13/2022] Open
Abstract
Unlike individual, free-floating planktonic bacteria, biofilms are surface-attached communities of slow- or non-replicating bacteria encased within a protective extracellular polymeric matrix enabling persistent bacterial populations to tolerate high concentrations of antimicrobials. Our current antibacterial arsenal is composed of growth-inhibiting agents that target rapidly-dividing planktonic bacteria but not metabolically dormant biofilm cells. We report the first modular synthesis of a library of 20 halogenated phenazines (HP), utilizing the Wohl-Aue reaction, that targets both planktonic and biofilm cells. New HPs, including 6-substituted analogues, demonstrate potent antibacterial activities against MRSA, MRSE and VRE (MIC = 0.003-0.78 µM). HPs bind metal(II) cations and demonstrate interesting activity profiles when co-treated in a panel of metal(II) cations in MIC assays. HP 1 inhibited RNA and protein biosynthesis while not inhibiting DNA biosynthesis using 3H-radiolabeled precursors in macromolecular synthesis inhibition assays against MRSA. New HPs reported here demonstrate potent eradication activities (MBEC = 0.59-9.38 µM) against MRSA, MRSE and VRE biofilms while showing minimal red blood cell lysis or cytotoxicity against HeLa cells. PEG-carbonate HPs 24 and 25 were found to have potent antibacterial activities with significantly improved water solubility. HP small molecules could have a dramatic impact on persistent, biofilm-associated bacterial infection treatments.
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Buyck JM, Lemaire S, Seral C, Anantharajah A, Peyrusson F, Tulkens PM, Van Bambeke F. In Vitro Models for the Study of the Intracellular Activity of Antibiotics. Methods Mol Biol 2016; 1333:147-157. [PMID: 26468107 DOI: 10.1007/978-1-4939-2854-5_13] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Intracellular bacteria are poorly responsive to antibiotic treatment. Pharmacological studies are thus needed to determine which antibiotics are most potent or effective against intracellular bacteria as well as to explore the reasons for poor bacterial responsiveness. An in vitro pharmacodynamic model is described, consisting of (1) phagocytosis of pre-opsonized bacteria by eukaryotic cells; (2) elimination of non-internalized bacteria with gentamicin; (3) incubation of infected cells with antibiotics; and (4) determination of surviving bacteria by viable cell counting and normalization of the counts based on sample protein content.
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Affiliation(s)
- Julien M Buyck
- Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Sandrine Lemaire
- Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
- GSK Biologicals, Rixensart, Belgium
| | - Cristina Seral
- Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
- Department of Microbiology, Hospital Clínico Universitario Lozano Blesa, Zaragoza, Spain
| | - Ahalieyah Anantharajah
- Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - Frédéric Peyrusson
- Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - Paul M Tulkens
- Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - Françoise Van Bambeke
- Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium.
- Pharmacologie cellulaire et molÕculaire, Louvain Drug Research Institute, Avenue E. Mounier 73 B1.73.05, Brussels, 1200, Belgium.
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10
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Cellular pharmacokinetics and intracellular activity of the novel peptide deformylase inhibitor GSK1322322 against Staphylococcus aureus laboratory and clinical strains with various resistance phenotypes: studies with human THP-1 monocytes and J774 murine macrophages. Antimicrob Agents Chemother 2015; 59:5747-60. [PMID: 26169402 DOI: 10.1128/aac.00827-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 07/04/2015] [Indexed: 01/01/2023] Open
Abstract
GSK1322322 is a peptide deformylase inhibitor active against Staphylococcus aureus strains resistant to currently marketed antibiotics. Our aim was to assess the activity of GSK1322322 against intracellular S. aureus using an in vitro pharmacodynamic model and, in parallel, to examine its cellular pharmacokinetics and intracellular disposition. For intracellular activity analysis, we used an established model of human THP-1 monocytes and tested one fully susceptible S. aureus strain (ATCC 25923) and 8 clinical strains with resistance to oxacillin, vancomycin, daptomycin, macrolides, clindamycin, linezolid, or moxifloxacin. Uptake, accumulation, release, and subcellular distribution (cell fractionation) of [(14)C]GSK1322322 were examined in uninfected murine J774 macrophages and uninfected and infected THP-1 monocytes. GSK1322322 demonstrated a uniform activity against the intracellular forms of all S. aureus strains tested, disregarding their resistance phenotypes, with a maximal relative efficacy (E max) of a 0.5 to 1 log10 CFU decrease compared to the original inoculum within 24 h and a static concentration (C s) close to its MIC in broth. Influx and efflux were very fast (<5 min to equilibrium), and accumulation was about 4-fold, with no or a minimal effect of the broad-spectrum eukaryotic efflux transporter inhibitors gemfibrozil and verapamil. GSK1322322 was recovered in the cell-soluble fraction and was dissociated from the main subcellular organelles and from bacteria (in infected cells). The results of this study show that GSK1322322, as a typical novel deformylase inhibitor, may act against intracellular forms of S. aureus. They also suggest that GSK1322322 has the ability to freely diffuse into and out of eukaryotic cells as well as within subcellular compartments.
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11
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RX-P873, a Novel Protein Synthesis Inhibitor, Accumulates in Human THP-1 Monocytes and Is Active against Intracellular Infections by Gram-Positive (Staphylococcus aureus) and Gram-Negative (Pseudomonas aeruginosa) Bacteria. Antimicrob Agents Chemother 2015; 59:4750-8. [PMID: 26014952 DOI: 10.1128/aac.00428-15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 05/24/2015] [Indexed: 11/20/2022] Open
Abstract
The pyrrolocytosine RX-P873, a new broad-spectrum antibiotic in preclinical development, inhibits protein synthesis at the translation step. The aims of this work were to study RX-P873's ability to accumulate in eukaryotic cells, together with its activity against extracellular and intracellular forms of infection by Staphylococcus aureus and Pseudomonas aeruginosa, using a pharmacodynamic approach allowing the determination of maximal relative efficacies (Emax values) and bacteriostatic concentrations (Cs values) on the basis of Hill equations of the concentration-response curves. RX-P873's apparent concentration in human THP-1 monocytes was about 6-fold higher than the extracellular one. In broth, MICs ranged from 0.125 to 0.5 mg/liter (S. aureus) and 2 to 8 mg/liter (P. aeruginosa), with no significant shift in these values against strains resistant to currently used antibiotics being noted. In concentration-dependent experiments, the pharmacodynamic profile of RX-P873 was not influenced by the resistance phenotype of the strains. Emax values (expressed as the decrease in the number of CFU from that in the initial inoculum) against S. aureus and P. aeruginosa reached more than 4 log units and 5 log units in broth, respectively, and 0.7 log unit and 2.7 log units in infected THP-1 cells, respectively, after 24 h. Cs values remained close to the MIC in all cases, making RX-P873 more potent than antibiotics to which the strains were resistant (moxifloxacin, vancomycin, and daptomycin for S. aureus; ciprofloxacin and ceftazidime for P. aeruginosa). Kill curves in broth showed that RX-P873 was more rapidly bactericidal against P. aeruginosa than against S. aureus. Taken together, these data suggest that RX-P873 may constitute a useful alternative for infections involving intracellular bacteria, especially Gram-negative species.
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Stryjewski ME, Jones RN, Corey GR. Ceftaroline: clinical and microbiology experience with focus on methicillin-resistant Staphylococcus aureus after regulatory approval in the USA. Diagn Microbiol Infect Dis 2015; 81:183-8. [PMID: 25583130 DOI: 10.1016/j.diagmicrobio.2014.11.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 10/24/2014] [Accepted: 11/23/2014] [Indexed: 01/12/2023]
Abstract
Ceftaroline fosamil was approved in 2010 by the United States Food and Drug Administration (USA-FDA) for the treatment of patients with acute bacterial skin and skin structure infections (ABSSSIs) and community-acquired bacterial pneumonia (CABP). After approval, several studies and case reports have described the postmarketing clinical experience with ceftaroline in ABSSSIs and CABP and in patients with invasive methicillin-resistant Staphylococcus aureus (MRSA) infections, many of whom had failed prior antibiotics. Successful clinical outcomes observed among the majority of these patients were supported by preapproval and postapproval in vitro surveillance of ceftaroline activity using breakpoint criteria that have been harmonized between the USA-FDA and CLSI. MIC90 values/percentage of strains susceptible to ceftaroline has remained stable over the period 2009-2012. Taken together, these postapproval studies support the use of ceftaroline for ABSSSI as well as CABP. Importantly, these data also suggest that ceftaroline can be effective in patients with serious invasive MRSA infections who have failed other therapies.
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Affiliation(s)
- Martin E Stryjewski
- Department of Medicine and Division of Infectious Diseases, Centro de Educación Médica e Investigaciones Clínicas (CEMIC), Buenos Aires, Argentina.
| | | | - G Ralph Corey
- Division of Infectious Diseases, Duke Clinical Research Institute, Durham, NC, USA; Duke University Medical Center, Durham, NC, USA.
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13
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Antimicrobial activity against intraosteoblastic Staphylococcus aureus. Antimicrob Agents Chemother 2015; 59:2029-36. [PMID: 25605365 DOI: 10.1128/aac.04359-14] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Although Staphylococcus aureus persistence in osteoblasts, partly as small-colony variants (SCVs), can contribute to bone and joint infection (BJI) relapses, the intracellular activity of antimicrobials is not currently considered in the choice of treatment strategies for BJI. Here, antistaphylococcal antimicrobials were evaluated for their intraosteoblastic activity and their impact on the intracellular emergence of SCVs in an ex vivo osteoblast infection model. Osteoblastic MG63 cells were infected for 2 h with HG001 S. aureus. After killing the remaining extracellular bacteria with lysostaphin, infected cells were incubated for 24 h with antimicrobials at the intraosseous concentrations reached with standard therapeutic doses. Intracellular bacteria and SCVs were then quantified by plating cell lysates. A bactericidal effect was observed with fosfomycin, linezolid, tigecycline, oxacillin, rifampin, ofloxacin, and clindamycin, with reductions in the intracellular inocula of -2.5, -3.1, -3.9, -4.2, -4.9, -4.9, and -5.2 log10 CFU/100,000 cells, respectively (P < 10(-4)). Conversely, a bacteriostatic effect was observed with ceftaroline and teicoplanin, whereas vancomycin and daptomycin had no significant impact on intracellular bacterial growth. Ofloxacin, daptomycin, and vancomycin significantly limited intracellular SCV emergence. Overall, ofloxacin was the only molecule to combine an excellent intracellular activity while limiting the emergence of SCVs. These data provide a basis for refining the choice of antibiotics to prioritise in the management of BJI, justifying the combination of a fluoroquinolone for its intracellular activity with an anti-biofilm molecule, such as rifampin.
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Development of LC-MS methods for quantitation of hepcidin and demonstration of siRNA-mediated hepcidin suppression in serum. J Pharmacol Toxicol Methods 2014; 71:110-9. [PMID: 25281793 DOI: 10.1016/j.vascn.2014.09.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 09/07/2014] [Accepted: 09/24/2014] [Indexed: 11/22/2022]
Abstract
INTRODUCTION A requisite step in developing a therapeutic to modulate the levels of hepcidin is the development of a quantitative method for measuring the concentration of serum hepcidin. METHODS To this end, an LC-MS method, based on selected reaction monitoring (SRM) with a triple quadrupole MS and an isotopically labeled hepcidin as internal standard, was developed to measure hepcidin in mouse and monkey sera. RESULTS Initially, 40 normal cynomolgus monkeys and 40 normal mice were studied to determine the normal endogenous levels of hepcidin, and an average of 50ng/mL was found in the monkeys and 46ng/mL in the mice. Next, experiments were conducted where an siRNA, targeting hepcidin, was administered to cynomolgus monkeys, resulting in effective hepcidin reduction (inhibition rate) of 87% after 24h and 74% after 48h, demonstrating to effectively reduce serume level of hepcidin. CONCLUSIONS For better sensitivity, especially for the low volumes available for mouse sera, a second LC-MS method, based on parallel reaction monitoring (PRM) using a Orbitrap MS was developed and shown to be at least 10 fold lower in detection limits (or consumption of serum volume) than the SRM approach.
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High doses of daptomycin (10 mg/kg/d) plus rifampin for the treatment of staphylococcal prosthetic joint infection managed with implant retention: a comparative study. Diagn Microbiol Infect Dis 2014; 80:66-71. [DOI: 10.1016/j.diagmicrobio.2014.05.022] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 05/26/2014] [Accepted: 05/27/2014] [Indexed: 11/19/2022]
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Edwards B, Andini R, Esposito S, Grossi P, Lew D, Mazzei T, Novelli A, Soriano A, Gould IM. Treatment options for methicillin-resistant Staphylococcus aureus (MRSA) infection: Where are we now? J Glob Antimicrob Resist 2014; 2:133-140. [PMID: 27873719 DOI: 10.1016/j.jgar.2014.03.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 03/28/2014] [Accepted: 03/31/2014] [Indexed: 01/05/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) infection continues to be a substantial global problem with significant associated morbidity and mortality. This review summarises the discussions that took place at the 4th MRSA Consensus Conference in relation to the current treatment options for serious MRSA infections and how to optimise whichever therapy is embarked upon. It highlights the many challenges faced by both the laboratory and clinicians in the diagnosis and treatment of MRSA infections.
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Affiliation(s)
- B Edwards
- Medical Microbiology Department, Royal Infirmary of Edinburgh, 51 Little France Crescent, Dalkeith Road, Edinburgh EH16 4SA, UK.
| | - R Andini
- Second University of Naples, UOC Transplant and Infectious Disease Medicine, AORN Monaldi, Naples, Italy
| | - S Esposito
- Department of Medicine, University of Salerno, Salerno, Italy
| | - P Grossi
- Department of Surgical and Morphological Studies, University of Unisubria, Varese, Italy
| | - D Lew
- Chief Infectious Diseases Division, Chief Department of Specialties of Internal Medicine, Geneva University Hospital, Geneva, Switzerland
| | - T Mazzei
- Department of Health Sciences, Clinical Pharmacology and Oncology Section, University of Firenze, Firenze, Italy
| | - A Novelli
- Department of Health Sciences, Clinical Pharmacology and Oncology Section, University of Firenze, Firenze, Italy
| | - A Soriano
- Department of Infectious Diseases, IDIBAPS, Hospital Clinic of Barcelona, Spain
| | - I M Gould
- Medical Microbiology Department, Aberdeen Royal Infirmary, Aberdeen, UK
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