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Maxwell A, Chaudhari BB, Chaudhari P, Ananthamurthy K, Aranjani J, Moorkoth S, Ghate V, Lewis S. In vitro antibacterial activity and in vivo pharmacokinetics of intravenously administered Amikacin-loaded Liposomes for the management of bacterial septicaemia. Colloids Surf B Biointerfaces 2022; 220:112892. [DOI: 10.1016/j.colsurfb.2022.112892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 09/10/2022] [Accepted: 09/28/2022] [Indexed: 10/14/2022]
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2
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Save J, Que YA, Entenza JM, Kolenda C, Laurent F, Resch G. Bacteriophages Combined With Subtherapeutic Doses of Flucloxacillin Act Synergistically Against Staphylococcus aureus Experimental Infective Endocarditis. J Am Heart Assoc 2022; 11:e023080. [PMID: 35043655 PMCID: PMC9238497 DOI: 10.1161/jaha.121.023080] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Background The potential of phage therapy for the treatment of endovascular Staphylococcus aureus infections remains to be evaluated. Methods and Results The efficacy of a phage cocktail combining Herelleviridae phage vB_SauH_2002 and Podoviriae phage 66 was evaluated against a methicillin‐sensitive S. aureus strain in vitro and in vivo in a rodent model of experimental endocarditis. Six hours after bacterial challenge, animals were treated with (1) the phage cocktail. (2) subtherapeutic flucloxacillin dosage, (3) combination of the phage cocktail and flucloxacillin, or (4) saline. Bacterial loads in cardiac vegetations at 30 hours were the primary outcome. Secondary outcomes were phage loads at 30 hours in cardiac vegetations, blood, spleen, liver, and kidneys. We evaluated phage resistance 30 hours post infection in vegetations of rats under combination treatment. In vitro, phages synergized against S. aureus planktonic cells and the cocktail synergized with flucloxacillin to eradicated biofilms. In infected animals, the phage cocktail achieved bacteriostatic effect. The addition of low‐dose flucloxacillin elevated bacterial suppression (∆ of −5.25 log10 colony forming unit/g [CFU/g] versus treatment onset, P<0.0001) and synergism was confirmed (∆ of −2.15 log10 CFU/g versus low‐dose flucloxacillin alone, P<0.01). Importantly, 9/12 rats given the combination treatment had sterile vegetations at 30 hours. In vivo phage replication was partially suppressed by the antibiotic and selection of resistance to the Podoviridae component of the phage cocktail occurred. Plasma‐mediated inhibition of phage killing activity was observed in vitro. Conclusions Combining phages with a low‐dose standard of care antibiotic represents a promising strategy for the treatment of S. aureus infective endocarditis.
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Affiliation(s)
- Jonathan Save
- Centre for Research and Innovation in Clinical Pharmaceutical Sciences Lausanne University Hospital Lausanne Switzerland.,Department of Intensive Care Medicine Inselspital, Bern University Hospital, University of Bern Bern Switzerland
| | - Yok-Ai Que
- Department of Intensive Care Medicine Inselspital, Bern University Hospital, University of Bern Bern Switzerland
| | - José M Entenza
- Department of Fundamental Microbiology University of Lausanne Lausanne Switzerland
| | - Camille Kolenda
- Bacteriology Department, Institute for Infectious Agents French National Reference Centre for Staphylococci, Croix-Rousse University Hospital Hospices Civils de Lyon, Lyon France.,National Centre of Research in Infectiology, Team "Staphylococcal Pathogenesis", INSERM U1111, CNRS UMR5308, ENS Lyon, University of Lyon Lyon France
| | - Frédéric Laurent
- Bacteriology Department, Institute for Infectious Agents French National Reference Centre for Staphylococci, Croix-Rousse University Hospital Hospices Civils de Lyon, Lyon France.,National Centre of Research in Infectiology, Team "Staphylococcal Pathogenesis", INSERM U1111, CNRS UMR5308, ENS Lyon, University of Lyon Lyon France
| | - Grégory Resch
- Centre for Research and Innovation in Clinical Pharmaceutical Sciences Lausanne University Hospital Lausanne Switzerland
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Alarfaj RE, Alkhulaifi MM, Al-Fahad AJ, Aljihani S, Yassin AEB, Alghoribi MF, Halwani MA. Antibacterial Efficacy of Liposomal Formulations Containing Tobramycin and N-Acetylcysteine against Tobramycin-Resistant Escherichia coli, Klebsiella pneumoniae, and Acinetobacter baumannii. Pharmaceutics 2022; 14:130. [PMID: 35057026 PMCID: PMC8778299 DOI: 10.3390/pharmaceutics14010130] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/23/2021] [Accepted: 12/28/2021] [Indexed: 12/13/2022] Open
Abstract
The antibacterial activity and biofilm reduction capability of liposome formulations encapsulating tobramycin (TL), and Tobramycin-N-acetylcysteine (TNL) were tested against tobramycin-resistant strains of E. coli, K. pneumoniae and A. baumannii in the presence of several resistant genes. All antibacterial activity were assessed against tobramycin-resistant bacterial clinical isolate strains, which were fully characterized by whole-genome sequencing (WGS). All isolates acquired one or more of AMEs genes, efflux pump genes, OMP genes, and biofilm formation genes. TL formulation inhibited the growth of EC_089 and KP_002 isolates from 64 mg/L and 1024 mg/L to 8 mg/L. TNL formulation reduced the MIC of the same isolates to 16 mg/L. TNL formulation was the only effective formulation against all A. baumannii strains compared with TL and conventional tobramycin (in the plektonic environment). Biofilm reduction was significantly observed when TL and TNL formulations were used against E. coli and K. pneumoniae strains. TNL formulation reduced biofilm formation at a low concentration of 16 mg/L compared with TL and conventional tobramycin. In conclusion, TL and TNL formulations particularly need to be tested on animal models, where they may pave the way to considering drug delivery for the treatment of serious infectious diseases.
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Affiliation(s)
- Reem E. Alarfaj
- Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (R.E.A.); (M.M.A.)
- Infectious Diseases Research Department, King Abdullah International Medical Research Center, King Saud bin Abdulaziz University for Health Sciences, National Guard Health Affairs, Riyadh 11481, Saudi Arabia
| | - Manal M. Alkhulaifi
- Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (R.E.A.); (M.M.A.)
| | - Ahmed J. Al-Fahad
- National Center for Biotechnology, Life Science & Environment Research Institute, King Abdulaziz City for Science and Technology (KACST), Riyadh 12354, Saudi Arabia;
| | - Shokran Aljihani
- Nanomedicine Department, King Abdullah International Medical Research Center, King Saud bin Abdulaziz University for Health Sciences, National Guard Health Affairs, Riyadh 11481, Saudi Arabia;
| | - Alaa Eldeen B. Yassin
- Pharmaceutical Sciences Department, College of Pharmacy, King Saud bin Abdulaziz University for Health Sciences, National Guard Health Affairs, Riyadh 11481, Saudi Arabia;
| | - Majed F. Alghoribi
- Infectious Diseases Research Department, King Abdullah International Medical Research Center, King Saud bin Abdulaziz University for Health Sciences, National Guard Health Affairs, Riyadh 11481, Saudi Arabia
| | - Majed A. Halwani
- Nanomedicine Department, King Abdullah International Medical Research Center, King Saud bin Abdulaziz University for Health Sciences, National Guard Health Affairs, Riyadh 11481, Saudi Arabia;
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4
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Cheung AL, Cho J, Bayer AS, Yeaman MR, Xiong YQ, Donegan NP, Mikheyeva IV, Lee GY, Yang SJ. Role of the Staphylococcus aureus Extracellular Loop of GraS in Resistance to Distinct Human Defense Peptides in PMN and Invasive Cardiovascular infections. Infect Immun 2021; 89:e0034721. [PMID: 34227840 PMCID: PMC8445198 DOI: 10.1128/iai.00347-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 06/23/2021] [Indexed: 11/20/2022] Open
Abstract
GraS is a membrane sensor in Staphylococcus aureus that induces mprF and dltABCD expression to alter the surface positive charge upon exposure to cationic human defense peptides (HDPs). The sensing domain of GraS likely resides in the 9-residue extracellular loop (EL). In this study, we assessed a hospital-acquired methicillin-resistant S. aureus (HA-MRSA) strain (COL) for the specific role of two distinct EL mutations: F38G (bulk) and D/35/37/41K (charged inversion). Activation of mprF by polymyxin B (PMB) was reduced in the D35/37/41K mutant versus the D35/37/41G mutant, correlating with reduced surface positive charge; in contrast, these effects were less prominent in the F38G mutant but still lower than those in the parent. These data indicated that both electrostatic charge and steric bulk of the EL of GraS influence induction of genes impacting HDP resistance. Using mprF expression as a readout, we confirmed GraS signaling was pH dependent, increasing as pH was lowered (from pH 7.5 down to pH 5.5). In contrast to PMB activation, reduction of mprF was comparable at pH 5.5 between the P38G and D35/37/41K point mutants, indicating a mechanistic divergence between GraS activation by acidic pH versus cationic peptides. Survival assays in human blood and purified polymorphonuclear leukocytes (PMNs) revealed lower survival of the D35/37/41K mutant versus the F38G mutant, with both being lower than that of the parent. Virulence studies in the rabbit endocarditis model mirrored whole blood and PMN killing assay data described above. Collectively, these data confirmed the importance of specific residues within the EL of GraS in conferring essential bacterial responses for MRSA survival in infections.
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Affiliation(s)
- Ambrose L. Cheung
- Department of Microbiology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Junho Cho
- Department of Microbiology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Arnold S. Bayer
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
- Department of Medicine, Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, USA
- The David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Michael R. Yeaman
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
- Department of Medicine, Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, USA
- The David Geffen School of Medicine at UCLA, Los Angeles, California, USA
- Department of Medicine, Division of Molecular Medicine, Harbor-UCLA Medical Center, Torrance, California, USA
| | - Yan Q. Xiong
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
- Department of Medicine, Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, USA
- The David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Niles P. Donegan
- Department of Microbiology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Irina V. Mikheyeva
- Department of Microbiology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Gi Yong Lee
- Department of Veterinary Microbiology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, Republic of Korea
| | - Soo-Jin Yang
- Department of Veterinary Microbiology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, Republic of Korea
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Maxwell A, Ghate V, Aranjani J, Lewis S. Breaking the barriers for the delivery of amikacin: Challenges, strategies, and opportunities. Life Sci 2021; 284:119883. [PMID: 34390724 DOI: 10.1016/j.lfs.2021.119883] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 04/30/2021] [Accepted: 07/30/2021] [Indexed: 12/14/2022]
Abstract
Hypodermic delivery of amikacin is a widely adopted treatment modality for severe infections, including bacterial septicemia, meningitis, intra-abdominal infections, burns, postoperative complications, and urinary tract infections in both paediatric and adult populations. In most instances, the course of treatment requires repeated bolus doses of amikacin, prolonged hospitalization, and the presence of a skilled healthcare worker for administration and continuous therapeutic monitoring to manage the severe adverse effects. Amikacin is hydrophilic and exhibits a short half-life, which further challenges the delivery of sufficient systemic concentrations when administered by the oral or transdermal route. In this purview, the exploitation of novel controlled and sustained release drug delivery platforms is warranted. Furthermore, it has been shown that novel delivery systems are capable of increasing the antibacterial activity of amikacin at lower doses when compared to the conventional formulations and also aid in overcoming the development of drug-resistance, which currently is a significant threat to the healthcare system worldwide. The current review presents a comprehensive overview of the developmental history of amikacin, the mechanism of action in virulent strains as well as the occurrence of resistance, and various emerging drug delivery solutions developed both by the academia and the industry. The examples outlined within the review provides significant pieces of evidence on novel amikacin formulations in the field of antimicrobial research paving the path for future therapeutic interventions that will result in improved clinical outcome.
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Affiliation(s)
- Amala Maxwell
- Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education (MAHE), Manipal 576104, Karnataka, India
| | - Vivek Ghate
- Mechatronics Lab, Department of Electronic System Engineering, Indian Institute of Science, Bengaluru 560012, Karnataka, India
| | - Jesil Aranjani
- Department of Pharmaceutical Biotechnology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education (MAHE), Manipal 576104, Karnataka, India
| | - Shaila Lewis
- Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education (MAHE), Manipal 576104, Karnataka, India.
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6
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Amikacin: Uses, Resistance, and Prospects for Inhibition. Molecules 2017; 22:molecules22122267. [PMID: 29257114 PMCID: PMC5889950 DOI: 10.3390/molecules22122267] [Citation(s) in RCA: 134] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 12/13/2017] [Accepted: 12/14/2017] [Indexed: 12/16/2022] Open
Abstract
Aminoglycosides are a group of antibiotics used since the 1940s to primarily treat a broad spectrum of bacterial infections. The primary resistance mechanism against these antibiotics is enzymatic modification by aminoglycoside-modifying enzymes that are divided into acetyl-transferases, phosphotransferases, and nucleotidyltransferases. To overcome this problem, new semisynthetic aminoglycosides were developed in the 70s. The most widely used semisynthetic aminoglycoside is amikacin, which is refractory to most aminoglycoside modifying enzymes. Amikacin was synthesized by acylation with the l-(-)-γ-amino-α-hydroxybutyryl side chain at the C-1 amino group of the deoxystreptamine moiety of kanamycin A. The main amikacin resistance mechanism found in the clinics is acetylation by the aminoglycoside 6'-N-acetyltransferase type Ib [AAC(6')-Ib], an enzyme coded for by a gene found in integrons, transposons, plasmids, and chromosomes of Gram-negative bacteria. Numerous efforts are focused on finding strategies to neutralize the action of AAC(6')-Ib and extend the useful life of amikacin. Small molecules as well as complexes ionophore-Zn+2 or Cu+2 were found to inhibit the acetylation reaction and induced phenotypic conversion to susceptibility in bacteria harboring the aac(6')-Ib gene. A new semisynthetic aminoglycoside, plazomicin, is in advance stage of development and will contribute to renewed interest in this kind of antibiotics.
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Cern A, Michael-Gayego A, Bavli Y, Koren E, Goldblum A, Moses AE, Xiong YQ, Barenholz Y. Nano-mupirocin: enabling the parenteral activity of mupirocin. EUROPEAN JOURNAL OF NANOMEDICINE 2016. [DOI: 10.1515/ejnm-2016-0006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractMupirocin is an antibiotic having a unique mode of action, not shared by any other therapeutically available antibiotic. However, due to its rapid elimination following injection and high protein binding, current therapeutic use is limited to topical administration. Computational methods have identified mupirocin as a good candidate for delivery via long-circulating nano-liposomes. Formulating mupirocin in such liposomes to form Nano-mupirocin protects the drug in the circulation, enabling therapeutic efficacy. This was demonstrated using two different animal models that served as a proof of concept: the mice
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Site-specific mutation of the sensor kinase GraS in Staphylococcus aureus alters the adaptive response to distinct cationic antimicrobial peptides. Infect Immun 2014; 82:5336-45. [PMID: 25287929 DOI: 10.1128/iai.02480-14] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Staphylococcus aureus two-component regulatory system, GraRS, is involved in resistance to killing by distinct host defense cationic antimicrobial peptides (HD-CAPs). It is believed to regulate downstream target genes such as mprF and dltABCD to modify the S. aureus surface charge. However, the detailed mechanism(s) by which the histidine kinase, GraS, senses specific HD-CAPs is not well defined. Here, we studied a well-characterized clinical methicillin-resistant S. aureus (MRSA) strain (MW2), its isogenic graS deletion mutant (ΔgraS strain), a nonameric extracellular loop mutant (ΔEL strain), and four residue-specific ΔEL mutants (D37A, P39A, P39S, and D35G D37G D41G strains). The ΔgraS and ΔEL strains were unable to induce mprF and dltA expression and, in turn, demonstrated significantly increased susceptibilities to daptomycin, polymyxin B, and two prototypical HD-CAPs (hNP-1 and RP-1). Further, P39A, P39S, and D35G-D37G-D41G ΔEL mutations correlated with moderate increases in HD-CAP susceptibility. Reductions of mprF and dltA induction by PMB were also found in the ΔEL mutants, suggesting these residues are pivotal to appropriate activation of the GraS sensor kinase. Importantly, a synthetic exogenous soluble EL mimic of GraS protected the parental MW2 strain against hNP-1- and RP-1-mediated killing, suggesting a direct interaction of the EL with HD-CAPs in GraS activation. In vivo, the ΔgraS and ΔEL strains displayed dramatic reductions in achieved target tissue MRSA counts in an endocarditis model. Taken together, our results provide new insights into potential roles of GraS in S. aureus sensing of HD-CAPs to induce adaptive survival responses to these molecules.
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Abed N, Couvreur P. Nanocarriers for antibiotics: a promising solution to treat intracellular bacterial infections. Int J Antimicrob Agents 2014; 43:485-96. [PMID: 24721232 DOI: 10.1016/j.ijantimicag.2014.02.009] [Citation(s) in RCA: 206] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 02/07/2014] [Indexed: 10/25/2022]
Abstract
In the field of antibiotherapy, intracellular infections remain difficult to eradicate mainly due to the poor intracellular penetration of most of the commonly used antibiotics. Bacteria have quickly understood that their intracellular localisation allows them to be protected from the host immune system, but also from the action of antimicrobial agents. In addition, in most cases pathogens nestle in professional phagocytic cells, and can even use them as a 'Trojan horse' to induce a secondary site of infection thereby causing persistent or recurrent infections. Thus, new strategies had to be considered in order to counteract these problems. Amongst them, nanocarriers loaded with antibiotics represent a promising approach. Nowadays, it is possible to encapsulate, incorporate or even conjugate biologically active molecules into different families of nanocarriers such as liposomes or nanoparticles in order to deliver antibiotics intracellularly and hence to treat infections. This review gives an overview of the variety of nanocarriers developed to deliver antibiotics directly into infected cells.
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Affiliation(s)
- Nadia Abed
- Faculté de Pharmacie, Institut Galien UMR CNRS 8612, Université Paris-Sud XI, 5 rue Jean-Baptiste Clément, 92296 Châtenay-Malabry Cedex, France
| | - Patrick Couvreur
- Faculté de Pharmacie, Institut Galien UMR CNRS 8612, Université Paris-Sud XI, 5 rue Jean-Baptiste Clément, 92296 Châtenay-Malabry Cedex, France.
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Anwer MK, Jamil S, Ibnouf EO, Shakeel F. Enhanced antibacterial effects of clove essential oil by nanoemulsion. J Oleo Sci 2014; 63:347-54. [PMID: 24599109 DOI: 10.5650/jos.ess13213] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The aim of present study was to develop and evaluate nanoemulsion formulations of clove essential oil (CEO) for its antibacterial effects in comparison with pure CEO and standard amikacin antibiotic (positive control). Different nanoemulsions of CEO were developed by aqueous phase titration method via construction of pseudo-ternary phase diagrams and investigated for thermodynamic stability and self-nanoemulsification tests. Selected formulations (F1-F5) were characterized for droplet size distribution, viscosity, zeta potential, transmittance and surface morphology. Based on lowest droplet size (29.1 nm), lowest PI (0.026), lowest viscosity (34.6 cp), optimal zeta potential (-31.4 mV), highest transmittance (99.4 %) and lowest concentration of Triacetin (8 % w/w), CEO nanoemulsion F1 (containing 1 % w/w of CEO, 8 % w/w of Triacetin, 15 % w/w of Tween-80, 15 % w/w of Labrasol and 61 % w/w of water) was subjected to antibacterial studies in comparison with pure oil and standard amikacin. The antibacterial effects of F1 were found to be superior over pure oil against all bacterial strains investigated. However, the antibacterial effects of F1 were highly comparable with standard amikacin against all bacterial strains. The minimum inhibitory concentrations (MICs) of F1 were observed in the range of 0.075-0.300 % w/w as compared to pure oil (MICs 0.130-0.500 % w/w) and standard amikacin (MICs 2-16 μg/ml). These results indicated the potential of nanoemulsions for enhancing the therapeutic efficacy of natural bioactive ingredients such as CEO.
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Affiliation(s)
- Md Khalid Anwer
- Department of Pharmaceutics, College of Pharmacy, Salman Bin Abdulaziz University
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11
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Role of the LytSR two-component regulatory system in adaptation to cationic antimicrobial peptides in Staphylococcus aureus. Antimicrob Agents Chemother 2013; 57:3875-82. [PMID: 23733465 DOI: 10.1128/aac.00412-13] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Many host defense cationic antimicrobial peptides (HDPs) perturb the staphylococcal cell membrane (CM) and alter transmembrane potential (ΔΨ) as key parts of their lethal mechanism. Thus, a sense-response system for detecting and mediating adaptive responses to such stresses could impact organism survival; the Staphylococcus aureus LytSR two-component regulatory system (TCRS) may serve as such a ΔΨ sensor. One well-known target of this system is the lrgAB operon, which, along with the related cidABC operon, has been shown to be a regulator in the control of programmed cell death and lysis. We used an isogenic set of S. aureus strains: (i) UAMS-1, (ii) its isogenic ΔlytS and ΔlrgAB mutants, and (iii) plasmid-complemented ΔlytSR and ΔlrgAB mutants. The ΔlytS strain displayed significantly increased in vitro susceptibilities to all HDPs tested (neutrophil-derived human neutrophil peptide 1 [hNP-1], platelet-derived thrombin-induced platelet microbicidal proteins [tPMPs], and the tPMP-mimetic peptide RP-1), as well as to calcium-daptomycin (DAP), a cationic antimicrobial peptide (CAP). In contrast, the ΔlrgAB strain exhibited no significant changes in susceptibilities to these cationic peptides, indicating that although lytSR positively regulates transcription of lrgAB, increased HDP/CAP susceptibilities in the ΔlytS mutant were lrgAB independent. Further, parental UAMS-1 (but not the ΔlytS mutant) became more resistant to hNP-1 and DAP following pretreatment with carbonyl cyanide m-chlorophenylhydrazone (CCCP) (a CM-depolarizing agent). Of note, lytSR-dependent survival against CAP/HDP killing was not associated with changes in either surface positive charge, expression of mprF and dlt, or CM fluidity. The ΔlytS strain (but not the ΔlrgAB mutant) displayed a significant reduction in target tissue survival in an endocarditis model during DAP treatment. Collectively, these results suggest that the lytSR TCRS plays an important role in adaptive responses of S. aureus to CM-perturbing HDPs/CAPs, likely by functioning as a sense-response system for detecting subtle changes in ΔΨ.
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12
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Plata KB, Riosa S, Singh CR, Rosato RR, Rosato AE. Targeting of PBP1 by β-lactams determines recA/SOS response activation in heterogeneous MRSA clinical strains. PLoS One 2013; 8:e61083. [PMID: 23637786 PMCID: PMC3634065 DOI: 10.1371/journal.pone.0061083] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 03/06/2013] [Indexed: 11/19/2022] Open
Abstract
The SOS response, a conserved regulatory network in bacteria that is induced in response to DNA damage, has been shown to be associated with the emergence of resistance to antibiotics. Previously, we demonstrated that heterogeneous (HeR) MRSA strains, when exposed to sub-inhibitory concentrations of oxacillin, were able to express a homogeneous high level of resistance (HoR). Moreover, we showed that oxacillin appeared to be the triggering factor of a β-lactam-mediated SOS response through lexA/recA regulators, responsible for an increased mutation rate and selection of a HoR derivative. In this work, we demonstrated, by selectively exposing to β-lactam and non-β-lactam cell wall inhibitors, that PBP1 plays a critical role in SOS-mediated recA activation and HeR-HoR selection. Functional analysis of PBP1 using an inducible PBP1-specific antisense construct showed that PBP1 depletion abolished both β-lactam-induced recA expression/activation and increased mutation rates during HeR/HoR selection. Furthermore, based on the observation that HeR/HoR selection is accompanied by compensatory increases in the expression of PBP1,-2, -2a, and -4, our study provides evidence that a combination of agents simultaneously targeting PBP1 and either PBP2 or PBP2a showed both in-vitro and in-vivo efficacy, thereby representing a therapeutic option for the treatment of highly resistant HoR-MRSA strains. The information gathered from these studies contributes to our understanding of β-lactam-mediated HeR/HoR selection and provides new insights, based on β-lactam synergistic combinations, that mitigate drug resistance for the treatment of MRSA infections.
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Affiliation(s)
- Konrad B. Plata
- Department of Pathology and Genomic Medicine, The Methodist Hospital, Houston, Texas, United States of America
- Center for Molecular and Translational Human Infectious Diseases Research, The Methodist Hospital Research Institute, Houston, Texas, United States of America
| | - Sarah Riosa
- Department of Pathology and Genomic Medicine, The Methodist Hospital, Houston, Texas, United States of America
- Center for Molecular and Translational Human Infectious Diseases Research, The Methodist Hospital Research Institute, Houston, Texas, United States of America
| | - Christopher R. Singh
- Department of Pathology and Genomic Medicine, The Methodist Hospital, Houston, Texas, United States of America
- Center for Molecular and Translational Human Infectious Diseases Research, The Methodist Hospital Research Institute, Houston, Texas, United States of America
| | - Roberto R. Rosato
- Department of Pathology and Genomic Medicine, The Methodist Hospital, Houston, Texas, United States of America
- Center for Molecular and Translational Human Infectious Diseases Research, The Methodist Hospital Research Institute, Houston, Texas, United States of America
| | - Adriana E. Rosato
- Department of Pathology and Genomic Medicine, The Methodist Hospital, Houston, Texas, United States of America
- Center for Molecular and Translational Human Infectious Diseases Research, The Methodist Hospital Research Institute, Houston, Texas, United States of America
- * E-mail:
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β-Lactams increase the antibacterial activity of daptomycin against clinical methicillin-resistant Staphylococcus aureus strains and prevent selection of daptomycin-resistant derivatives. Antimicrob Agents Chemother 2012; 56:6192-200. [PMID: 22985884 DOI: 10.1128/aac.01525-12] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) has emerged to be one of the most important pathogens both in health care and in community-onset infections. Daptomycin (DAP) is a cyclic anionic lipopeptide recommended for treatment of skin infections, bacteremia, and right-sided endocarditis caused by MRSA. Resistance to DAP (DAP(r)) has been reported in MRSA and is mostly accompanied by a parallel decrease in oxacillin resistance, a process known as the "seesaw effect." Our study provides evidence that the seesaw effect applies to other β-lactams and carbapenems of clinical use, including nafcillin (NAF), cefotaxime (CTX), amoxicillin-clavulanic (AMC), and imipenem (IMP), in heterogeneous DAP(r) MRSA strains but not in MRSA strains expressing homogeneous β-lactam resistance. The antibacterial efficacy of DAP in combination with β-lactams was evaluated in isogenic DAP-susceptible (DAP(s))/Dap(r) MRSA strains originally obtained from patients that failed DAP monotherapy. Both in vitro (MIC, synergy-kill curve) and in vivo (wax worm model) approaches were used. In these models, DAP and a β-lactam proved to be highly synergistic against both heterogeneous and homogeneous clinical DAP(r) MRSA strains. Mechanistically, β-lactams induced a reduction in the cell net positive surface charge, reverting the increased repulsion provoked by DAP alone, an effect that may favor the binding of DAP to the cell surface. The ease of in vitro mutant selection was observed when DAP(s) MRSA strains were exposed to DAP. Importantly, the combination of DAP and a β-lactam prevented the selection of DAP(r) variants. In summary, our data show that the DAP-β-lactam combination may significantly enhance both the in vitro and in vivo efficacy of anti-MRSA therapeutic options against DAP(r) MRSA infections and represent an option in preventing DAP(r) selection in persistent or refractory MRSA infections.
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Telavancin in therapy of experimental aortic valve endocarditis in rabbits due to daptomycin-nonsusceptible methicillin-resistant Staphylococcus aureus. Antimicrob Agents Chemother 2012; 56:5528-33. [PMID: 22890759 DOI: 10.1128/aac.00922-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
A number of cases of both methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) strains that have developed daptomycin resistance (DAP-R) have been reported. Telavancin (TLV) is a lipoglycopeptide agent with a dual mechanism of activity (cell wall synthesis inhibition plus depolarization of the bacterial cell membrane). Five recent daptomycin-susceptible (DAP-S)/DAP-R MRSA isogenic strain pairs were evaluated for in vitro TLV susceptibility. All five DAP-R strains (DAP MICs ranging from 2 to 4 μg/ml) were susceptible to TLV (MICs of ≤0.38 μg/ml). In vitro time-kill analyses also revealed that several TLV concentrations (1-, 2-, and 4-fold MICs) caused rapid killing against the DAP-R strains. Moreover, for 3 of 5 DAP-R strains (REF2145, A215, and B(2.0)), supra-MICs of TLV were effective at preventing regrowth at 24 h of incubation. Further, the combination of TLV plus oxacillin (at 0.25× or 0.50× MIC for each agent) increased killing of DAP-R MRSA strains REF2145 and A215 at 24 h (∼2-log and 5-log reductions versus TLV and oxacillin alone, respectively). Finally, using a rabbit model of aortic valve endocarditis caused by DAP-R strain REF2145, TLV therapy produced a mean reduction of >4.5 log(10) CFU/g in vegetations, kidneys, and spleen compared to untreated or DAP-treated rabbits. Moreover, TLV-treated rabbits had a significantly higher percentage of sterile tissue cultures (87% in vegetations and 100% in kidney and spleen) than all other treatment groups (P < 0.0001). Together, these results demonstrate that TLV has potent bactericidal activity in vitro and in vivo against DAP-R MRSA isolates.
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Jia Y, Joly H, Omri A. Characterization of the interaction between liposomal formulations and Pseudomonas aeruginosa. J Liposome Res 2012; 20:134-46. [PMID: 19831502 DOI: 10.3109/08982100903218892] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The interactions between three liposomal formulations and Pseudomonas aeruginosa cells were evaluated by a lipid mixing assay and electron paramagnetic resonance (EPR) spectroscopy. The effect of the bacteria on the liposomal phase characteristics, the release of the liposomes' content, and the uptake rate of gentamicin by bacteria were monitored as a function of time, using EPR spectroscopy. The [16-DSA uptake](Total) from DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) liposomes reached 93 +/- 12% over a 3-hour assay period, of which 9% crossed the bacterial inner membrane. A small amount of 16-DSA uptake from DPPC/Chol (cholesterol) vesicles was found throughout the 3-hour period of time. Although DPPC/DMPG (dimyristoylphosphatidylglycerol) vesicles showed a smaller value of [16-DSA uptake](Total) with respect to that of DPPC vesicles, they appeared to be effective in disrupting the bacterial membrane, resulting in a greater accumulation of 16-DSA inside the inner membrane. Exposure to bacteria caused the DPPC/Chol, DPPC, and DPPC/DMPG formulations to release 4.6 +/- 1.5, 17.6 +/- 1.2, and 34 +/- 3.7% of their content, respectively. Time-dependent fluid regions were developed within the vesicles when mixed with bacteria, and their growth over time depended on liposomal formulations. Incubation of gentamicin with bacteria for 3 hours resulted in 87 +/- 3% of the drug crossing the bacterial inner membrane. In conclusion, interaction between the liposome drug carriers and the bacterial cells result in vesicle fusion, disruption of the bacterial membrane, release of the liposomal content in the close vicinity of the bacteria cells, and the subsequent intracellular uptake of the released liposomal content.
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Affiliation(s)
- Yimei Jia
- Laurentian University, Sudbury, Ontario, Canada
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16
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Schroeder A, Turjeman K, Schroeder JE, Leibergall M, Barenholz Y. Using liposomes to target infection and inflammation induced by foreign body injuries or medical implants. Expert Opin Drug Deliv 2010; 7:1175-89. [DOI: 10.1517/17425247.2010.517519] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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17
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Yang SJ, Xiong YQ, Boyle-Vavra S, Daum R, Jones T, Bayer AS. Daptomycin-oxacillin combinations in treatment of experimental endocarditis caused by daptomycin-nonsusceptible strains of methicillin-resistant Staphylococcus aureus with evolving oxacillin susceptibility (the "seesaw effect"). Antimicrob Agents Chemother 2010; 54:3161-9. [PMID: 20547804 PMCID: PMC2916313 DOI: 10.1128/aac.00487-10] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Revised: 05/18/2010] [Accepted: 06/02/2010] [Indexed: 01/02/2023] Open
Abstract
In vivo development of daptomycin resistance (DAPr) among Staphylococcus aureus strains, especially methicillin-resistant S. aureus (MRSA) strains, in conjunction with clinical treatment failures, has emerged as a major problem. This has raised the question of DAP-based combination regimens to enhance efficacy against such strains. We studied five recent DAP-susceptible (DAPs)/DAPr clinical MRSA strain pairs obtained from patients who failed DAP monotherapy regimens, as well as one DAPs/DAPr MRSA strain pair in which the resistant strain was generated by in vitro passage in DAP. Of note, we identified a DAP-oxacillin (OX) "seesaw" phenomenon in vitro in which development of DAPr was accompanied by a concomitant fall in OX resistance, as demonstrated by 3- to 4-fold decreases in the OX MIC, a susceptibility shift by population analyses, and enhanced early killing by OX in time-kill assays. In addition, the combination of DAP and OX exerted modest improvement in in vitro bactericidal effects. Using an experimental model of infective endocarditis and two DAPs/DAPr strain pairs, we demonstrated that (i) OX monotherapy was ineffective at clearing DAPr strains from any target tissue in this model (heart valve, kidneys, or spleen) and (ii) DAP-OX combination therapy was highly effective in DAPr strain clearances from these organs. The mechanism(s) of the seesaw effect remains to be defined but does not appear to involve excision of the staphylococcal cassette chromosome mec (SCCmec) that carries mecA.
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Affiliation(s)
- Soo-Jin Yang
- LA Biomedical Research Institute at Harbor-UCLA, 1124 West Carson Street, RB-2, Rm. 230, Torrance, CA 90502, USA.
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18
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Drulis-Kawa Z, Dorotkiewicz-Jach A. Liposomes as delivery systems for antibiotics. Int J Pharm 2010; 387:187-98. [DOI: 10.1016/j.ijpharm.2009.11.033] [Citation(s) in RCA: 222] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Revised: 11/25/2009] [Accepted: 11/27/2009] [Indexed: 11/25/2022]
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19
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Zhu Y, Xiong YQ, Sadykov MR, Fey PD, Lei MG, Lee CY, Bayer AS, Somerville GA. Tricarboxylic acid cycle-dependent attenuation of Staphylococcus aureus in vivo virulence by selective inhibition of amino acid transport. Infect Immun 2009; 77:4256-64. [PMID: 19667045 PMCID: PMC2747957 DOI: 10.1128/iai.00195-09] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Staphylococci are the leading causes of endovascular infections worldwide. Commonly, these infections involve the formation of biofilms on the surface of biomaterials. Biofilms are a complex aggregation of bacteria commonly encapsulated by an adhesive exopolysaccharide matrix. In staphylococci, this exopolysaccharide matrix is composed of polysaccharide intercellular adhesin (PIA). PIA is synthesized when the tricarboxylic acid (TCA) cycle is repressed. The inverse correlation between PIA synthesis and TCA cycle activity led us to hypothesize that increasing TCA cycle activity would decrease PIA synthesis and biofilm formation and reduce virulence in a rabbit catheter-induced model of biofilm infection. TCA cycle activity can be induced by preventing staphylococci from exogenously acquiring a TCA cycle-derived amino acid necessary for growth. To determine if TCA cycle induction would decrease PIA synthesis in Staphylococcus aureus, the glutamine permease gene (glnP) was inactivated and TCA cycle activity, PIA accumulation, biofilm forming ability, and virulence in an experimental catheter-induced endovascular biofilm (endocarditis) model were determined. Inactivation of this major glutamine transporter increased TCA cycle activity, transiently decreased PIA synthesis, and significantly reduced in vivo virulence in the endocarditis model in terms of achievable bacterial densities in biofilm-associated cardiac vegetations, kidneys, and spleen. These data confirm the close linkage of TCA cycle activity and virulence factor production and establish that this metabolic linkage can be manipulated to alter infectious outcomes.
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Affiliation(s)
- Yefei Zhu
- Department of Veterinary and Biomedical Sciences, University of Nebraska, 155 VBS, Fair St. and East Campus Loop, Lincoln, NE 68583-0905, USA
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20
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Regulation of mprF in daptomycin-nonsusceptible Staphylococcus aureus strains. Antimicrob Agents Chemother 2009; 53:2636-7. [PMID: 19289517 DOI: 10.1128/aac.01415-08] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We used a well-characterized isogenic set of clinical bloodstream Staphylococcus aureus strains to study (i) regulation of mprF-mediated phosphatidylglycerol lysinylation in the contexts of in vitro daptomycin (DAP) nonsuceptibility and (ii) the role of mprF mutation in endovascular virulence. We observed a correlation between increased expression of a mutant mprF gene and reduced in vitro DAP susceptibility. There were no detectable fitness differences between strains in experimental infective endocarditis.
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Jia Y, Joly H, Omri A. Liposomes as a carrier for gentamicin delivery: Development and evaluation of the physicochemical properties. Int J Pharm 2008; 359:254-63. [DOI: 10.1016/j.ijpharm.2008.03.035] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Revised: 03/21/2008] [Accepted: 03/25/2008] [Indexed: 10/22/2022]
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22
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Skiadas I, Pefanis A, Papalois A, Kyroudi A, Triantafyllidi H, Tsaganos T, Giamarellou H. Dexamethasone as adjuvant therapy to moxifloxacin attenuates valve destruction in experimental aortic valve endocarditis due to Staphylococcus aureus. Antimicrob Agents Chemother 2007; 51:2848-54. [PMID: 17562794 PMCID: PMC1932528 DOI: 10.1128/aac.01376-06] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although the beneficial effects of dexamethasone have frequently been investigated in various serious-infection settings, insufficient data on valve histology and cardiac function for infective endocarditis are available. The efficacy of moxifloxacin for the treatment of experimental aortic valve endocarditis due to methicillin-susceptible Staphylococcus aureus and the long-term effects of dexamethasone were evaluated in the current study. Sixty-eight rabbits were randomly assigned to four groups: A, B, C, and D. Group A consisted of 18 animals and functioned as a control group. Groups B and C consisted of 11 and 23 subjects, respectively, which received moxifloxacin for 5 days in a human-like pharmacokinetic simulation. Group D consisted of 16 animals that were administered moxifloxacin plus dexamethasone (0.25 mg/kg of body weight twice a day intravenously). The group B animals were sacrificed a day after the completion of treatment, and group C and D animals were sacrificed after 12 days in order to monitor any possible relapse and allow microbiological, histopathological, and echocardiographic evaluation of the long-term effects of glucocorticoids. No differences in survival, sterilization rates, or inflammatory infiltration and calcification of valve tissue were observed among the treated groups. However, the degrees of valve damage and collagenization were significantly worse, the fibroblast content was higher, and fractional shortening of the left ventricle fluctuated significantly in group C compared to group D (all groups, P < 0.05). We concluded that dexamethasone treatment for experimental S. aureus endocarditis attenuates valve destruction and preserves overall cardiac function without impeding the efficacy of moxifloxacin.
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Affiliation(s)
- Ioannis Skiadas
- Cardiology Department, Hippocration General Hospital, Athens, Greece.
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23
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Schiffelers RM, Bakker-Woudenberg IAJM. Innovations in liposomal formulations for antimicrobial therapy. Expert Opin Ther Pat 2005. [DOI: 10.1517/13543776.13.8.1127] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Xiong YQ, Willard J, Kadurugamuwa JL, Yu J, Francis KP, Bayer AS. Real-time in vivo bioluminescent imaging for evaluating the efficacy of antibiotics in a rat Staphylococcus aureus endocarditis model. Antimicrob Agents Chemother 2005; 49:380-7. [PMID: 15616318 PMCID: PMC538900 DOI: 10.1128/aac.49.1.380-387.2005] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Therapeutic options for invasive Staphylococcus aureus infections have become limited due to rising antimicrobial resistance, making relevant animal model testing of new candidate agents more crucial than ever. In the present studies, a rat model of aortic infective endocarditis (IE) caused by a bioluminescently engineered, biofilm-positive S. aureus strain was used to evaluate real-time antibiotic efficacy directly. This strain was vancomycin and cefazolin susceptible but gentamicin resistant. Bioluminescence was detected and quantified daily in antibiotic-treated and control animals with IE, using a highly sensitive in vivo imaging system (IVIS). Persistent and increasing cardiac bioluminescent signals (BLS) were observed in untreated animals. Three days of vancomycin therapy caused significant reductions in both cardiac BLS (>10-fold versus control) and S. aureus densities in cardiac vegetations (P < 0.005 versus control). However, 3 days after discontinuation of vancomycin therapy, a greater than threefold increase in cardiac BLS was observed, indicating relapsing IE (which was confirmed by quantitative culture). Cefazolin resulted in modest decreases in cardiac BLS and bacterial densities. These microbiologic and cardiac BLS differences during therapy correlated with a longer time-above-MIC for vancomycin (>12 h) than for cefazolin ( approximately 4 h). Gentamicin caused neither a reduction in cardiac S. aureus densities nor a reduction in BLS. There were significant correlations between cardiac BLS and S. aureus densities in vegetations in all treatment groups. These data suggest that bioluminescent imaging provides a substantial advance in the real-time monitoring of the efficacy of therapy of invasive S. aureus infections in live animals.
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Affiliation(s)
- Yan Q Xiong
- Division of Infectious Diseases, St. John's Cardiovascular Research Center, Harbor-UCLA Research and Education Institute, 1124 W. Carson St., Torrance, CA 90502, USA.
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26
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Affiliation(s)
- G Miflin
- Department of Paediatric Haematology, Children's Day Hospital, St. James University Hospital, Beckett Street, Leeds LS9 7TF, UK
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27
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Bakker-Woudenberg IAJM. Long-circulating sterically stabilized liposomes as carriers of agents for treatment of infection or for imaging infectious foci. Int J Antimicrob Agents 2002; 19:299-311. [PMID: 11978501 DOI: 10.1016/s0924-8579(02)00021-3] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Liposomes are considered as potential carriers for biologically active compounds. One evident drawback of 'classical' liposomes is their fast elimination by cells of the mononuclear phagocyte system (MPS), primarily by liver and spleen. An important breakthrough in this respect is the development of long-circulating liposomes among which liposomes coated with polyethyleneglycol (PEG), the so-called 'sterically stabilized' liposomes (SSL). An important characteristic of SSL is that their prolonged blood residence time and infectious target localization is relatively independent of the lipid dose, particle size or lipid composition of the bilayer. SSL are applied as carriers of antimicrobial agents to achieve infectious target localization, to reduce side effects, or to serve as a micro-reservoir in the circulation. In addition, radiolabelled SSL are used to image infectious and inflammatory foci.
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Affiliation(s)
- Irma A J M Bakker-Woudenberg
- Department of Medical Microbiology & Infectious Diseases, Erasmus University Medical Center Rotterdam, P.O. Box 1738, 3000 DR, The Netherlands.
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Kupferwasser LI, Yeaman MR, Shapiro SM, Nast CC, Bayer AS. In vitro susceptibility to thrombin-induced platelet microbicidal protein is associated with reduced disease progression and complication rates in experimental Staphylococcus aureus endocarditis: microbiological, histopathologic, and echocardiographic analyses. Circulation 2002; 105:746-52. [PMID: 11839632 DOI: 10.1161/hc0602.103721] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Mammalian platelets contain small, cationic, staphylocidal peptides, termed thrombin-induced platelet-microbicidal proteins (tPMPs). Evidence suggests that tPMPs play a key role in host defense against endovascular infections, such as infective endocarditis (IE). In the present study, we evaluated the influence of differences in staphylococcal tPMP-susceptibility profiles in vitro on disease severity in experimental IE. METHODS AND RESULTS Experimental IE was induced in rabbits with either a tPMP-susceptible or an isogenic tPMP-resistant Staphylococcus aureus strain. Vegetation size, left ventricular fractional shortening, and onset of aortic valvular regurgitation were serially assessed by echocardiography over an 11-day postinfection period. In addition, blood cultures were performed daily. Parameters delineated at autopsy included vegetation weights; bacterial densities in vegetations, myocardium, and kidneys; extent of valvular and perivalvular tissue damage; and renal embolization. The following significant differences were observed in animals infected with the tPMP-susceptible versus the tPMP-resistant S aureus strain: substantially lower bacteremia rates (P=0.02); reduced vegetation growth (P<0.001) and weight (P<0.001); a later onset of aortic valvular regurgitation (P=0.0039); increased preservation of left ventricular function (P<0.001); reduced valvular tissue damage (P=0.01) and perivalvular inflammation (P=0.015); and reduced bacterial densities in vegetations (P<0.001) and kidneys (P<0.01). CONCLUSIONS The in vitro tPMP-susceptibility profile in S aureus substantially affects a number of well-defined cardiac and microbiological parameters related to disease severity and prognosis in IE. These findings underscore the likelihood that platelets mitigate the pathogenesis of endovascular infections via local secretion of antimicrobial peptides.
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Affiliation(s)
- Leon Iri Kupferwasser
- Division of Infectious Diseases, St John's Cardiovascular Research Center and the Research & Education Institute, Torrance, Calif 90502, USA.
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Siaperas P, Pefanis A, Iliopoulos D, Katsarolis I, Kyroudi-Voulgari A, Donta I, Karayiannakos P, Giamarellou H. Evidence of less severe aortic valve destruction after treatment of experimental staphylococcal endocarditis with vancomycin and dexamethasone. Antimicrob Agents Chemother 2001; 45:3531-7. [PMID: 11709335 PMCID: PMC90864 DOI: 10.1128/aac.45.12.3531-3537.2001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The beneficial effects of therapy combining an antibiotic and dexamethasone have been reported in human studies on meningitis and in experimental studies on septic arthritis, nephritis, and endophthalmitis. Since most patients with staphylococcal endocarditis need a combination of medical and surgical treatment, the purpose of this study was to determine whether the addition of dexamethasone to vancomycin has any beneficial effect regarding the degree of valve tissue damage or the course of experimental aortic valve endocarditis caused by a methicillin-resistant strain of Staphylococcus aureus. Rabbits with catheter-induced aortic valve vegetations were randomly assigned to a control group and to groups receiving dexamethasone (0.5 mg/kg of body weight, intravenously [i.v.], twice a day [b.i.d]), vancomycin (30 mg/kg, i.v., b.i.d), or dexamethasone plus vancomycin, for a total of 10 doses (two doses per day for 5 days). The severity of valve tissue damage was significantly less in groups receiving vancomycin plus dexamethasone compared with that of the group receiving vancomycin alone (P < 0.001). The severity of tissue damage was inversely correlated with the mean polymorphonuclear leukocyte number in valve tissue. No statistically significant differences were observed between the vancomycin-treated group and the vancomycin-plus-dexamethasone-treated group in survival, blood culture sterilization rate, or reduction of the microbial burden (in CFU per gram) in valvular tissue. In conclusion, treatment with a combination of vancomycin and dexamethasone for 5 days reduces the severity of valve tissue damage in experimental staphylococcal aortic valve endocarditis. These findings could have significant implications in the treatment of staphylococcal endocarditis and deserve further confirmation in clinical trials.
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Affiliation(s)
- P Siaperas
- Fourth Department of Medicine, Sismanoglion General Hospital, Athens, Greece
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30
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Schiffelers RM, Storm G, ten Kate MT, Bakker-Woudenberg IA. Therapeutic efficacy of liposome-encapsulated gentamicin in rat Klebsiella pneumoniae pneumonia in relation to impaired host defense and low bacterial susceptibility to gentamicin. Antimicrob Agents Chemother 2001; 45:464-70. [PMID: 11158742 PMCID: PMC90314 DOI: 10.1128/aac.45.2.464-470.2001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Long-circulating liposomes (LCL) may be used as targeted antimicrobial drug carriers as they localize at sites of infection. As a result, LCL-encapsulated gentamicin (LE-GEN) has demonstrated superior antibacterial activity over the free drug in a single-dose study of immunocompetent rats with Klebsiella pneumoniae pneumonia. In the present study, the therapeutic efficacy of LE-GEN was evaluated by monitoring rat survival and bacterial counts in blood and lung tissue in clinically relevant models, addressing the issue of impaired host defense and low bacterial antibiotic susceptibility. The results show that in immunocompetent rats infected with the high-GEN-susceptibility K. pneumoniae strain, a single dose of LE-GEN is clearly superior to an equivalent dose of free GEN. Yet complete survival can also be obtained with multiple doses of free GEN. In leukopenic rats infected with the high-GEN-susceptible K. pneumoniae strain, free GEN at the maximum tolerated dose (MTD) was needed to obtain survival. However, with the addition of a single dose of LE-GEN to free-GEN treatment, complete survival can be obtained using a sevenfold-lower cumulative amount of GEN than with free-GEN treatment alone. In leukopenic rats infected with low-GEN-susceptible K. pneumoniae cells, free GEN at the MTD did not result in survival. The use of LE-GEN is needed for therapeutic success. Increasing LE-GEN bilayer fluidity resulted in an increased GEN release from the liposomes and hence improved rat survival, thus showing the importance of the liposome lipid composition for therapeutic efficacy. These results warrant further clinical studies of liposomal formulations of aminoglycosides in immunocompromised patients with severe infections.
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Affiliation(s)
- R M Schiffelers
- Department of Medical Microbiology & Infectious Diseases, Erasmus University Medical Center Rotterdam, Rotterdam, The Netherlands
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Garrison AE, Bendele R, Knauer S, Wolf J, Moon-McDermott L, Gill S, Colagiovanni DB. Evaluating the efficacy of amikacin in low-clearance unilamellar liposomes in a s. Aureus local infection model. J Liposome Res 2001; 11:243-54. [PMID: 19530936 DOI: 10.1081/lpr-100108465] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Traditional therapies for Staphylococcal infections such as osteomyelitis or localized abscesses have a difficult time penetrating into tissue sites. To effectively ameliorate these infections, prolonged therapy and/or high doses of antibiotics are frequently required. Aminoglycosides, such as amikacin, are not routinely utilized for treating local infections due to poor efficacy associated with ineffective tissue penetration, toxicity, and poor penetration in an acid millieu. We postulated that a formulation of amikacin in small unilamellar liposomes might readily be engulfed by inflammatory macrophages facilitating drug delivery to the site of infection. This increased drug load to the site of bacterial infection may result in enhanced bactericidal action compared to conventional aminoglycosides. Tissue drug concentrations were determined for liposomal amikacin (L-AN) and conventional amikacin (AN). Plasma amikacin levels were determined for L-AN. The L-AN was very effective at concentrating at the site of infection compared to AN. Following confirmation of adequate tissue drug levels, a rodent subcutaneous abscess infection using S. aureus as the bacterial challenge agent was evaluated. Sprague-Dawley rats were intravenously administered L-AN every other day due to its prolonged half-life, while the comparator agent, AN, was administered daily. Abscess size, weights, severity, histology, and tissue colony counts were examined. In efficacy studies, L-AN was superior to AN in reducing colony counts.
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Affiliation(s)
- A E Garrison
- Gilead Sciences, Inc., 2860 Wilderness Place, Boulder, CO, 80301, U.S.A
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Raj PA, Antonyraj KJ, Karunakaran T. Large-scale synthesis and functional elements for the antimicrobial activity of defensins. Biochem J 2000; 347 Pt 3:633-41. [PMID: 10769165 PMCID: PMC1220998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Human neutrophil defensins, and their analogues incorporating anionic, hydrophobic or cationic residues at the N- and C-termini, were synthesized by solid-phase procedures. The synthetic defensins were examined for their microbicidal activity against Candida albicans, two Gram-negative bacteria (Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis) and two Gram-positive bacteria (Streptococcus gordonii and Streptococcus mutans). The human neutrophil peptide 1 (HNP1) and HNP2 were found to be potent candidacidal agents. HNP3, which differs by one amino acid at the N-terminus of its sequence, was totally inactive. The Gram-negative bacteria A. actinomycetemcomitans and P. gingivalis and the Gram-positive bacteria S. gordonii and S. mutans were insensitive to human defensins. However, the insertion of two basic residues, such as arginine, at both the N-terminus and the C-terminus of HNP2 significantly enhanced antifungal and antibacterial activity. The addition of anionic residues, such as aspartic acid, at the N- and C-termini rendered the molecule totally inactive. The presence of two hydrophobic amino acids, such as valine, at the N-terminus of HNP2 and of two basic arginine residues at its C-terminus resulted in molecules that were optimally active against these oral pathogens. The results suggest that the N- and C-terminal residues in defensin peptides are the crucial functional elements that determine their microbicidal potency. The three-dimensional structure of all defensins constitutes the same amphiphilic beta-sheet structure, with the polar face formed by the N- and C-terminal residues playing an important role in defining microbicidal potency and the antimicrobial spectrum. The enhanced microbicidal activity observed for defensin peptides with two basic residues at both the N- and C-termini could be due to optimization of the amphiphilicity of the structure, which could facilitate specific interactions with the microbial membranes.
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Affiliation(s)
- P A Raj
- Division of Periodontics, School of Dentistry, Marquette University, 570 North 16th Street, Milwaukee, WI 53201, USA.
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