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Gallacher DJ, Zhang L, Aboklaish AF, Mitchell E, Wach R, Marchesi JR, Kotecha S. Baseline azithromycin resistance in the gut microbiota of preterm born infants. Pediatr Res 2024; 95:205-212. [PMID: 37550487 PMCID: PMC10798878 DOI: 10.1038/s41390-023-02743-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 07/08/2023] [Accepted: 07/10/2023] [Indexed: 08/09/2023]
Abstract
BACKGROUND Macrolides, including azithromycin, are increasingly used in preterm-born infants to treat Ureaplasma infections. The baseline carriage of macrolide resistance genes in the preterm stool microbiota is unknown. OBJECTIVES Identify carriage of azithromycin resistant bacteria and the incidence of macrolide resistant genes. METHODS Azithromycin resistant bacteria were isolated from serial stool samples obtained from preterm infants (≤32 weeks' gestation) by culturing aerobically/anaerobically, in the presence/absence of azithromycin. Using quantitative PCR, we targeted 6 common macrolide resistance genes (erm(A), erm(B), erm(C), erm(F), mef(A/E), msr(A)) in DNA extracted from selected bacteria resistant to azithromycin. RESULTS From 89 stool samples from 37 preterm-born infants, 93.3% showed bacterial growth in aerobic or anaerobic conditions. From the 280 azithromycin resistant isolates that were identified, Staphylococcus (75%) and Enterococcus (15%) species dominated. Macrolide resistance genes were identified in 91% of resistant isolates: commonest were erm(C) (46% of isolates) and msr(A) (40%). Multiple macrolide resistance genes were identified in 18% of isolates. CONCLUSION Macrolide resistance is common in the gut microbiota of preterm-born infants early in life, most likely acquired from exposure to the maternal microbiota. It will be important to assess modulation of macrolide resistance, if macrolide treatment becomes routine in the management of preterm infants. IMPACT STATEMENT Azithromycin resistance is present in the stool microbiota in the first month of life in preterm infants 91% of azithromycin resistant bacteria carried at least one of 6 common macrolide resistant genes Increasing use of macrolides in the preterm population makes this an important area of study.
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Affiliation(s)
- David J Gallacher
- Neonatal Unit, University Hospital of Wales, Cardiff, UK
- Department of Child Health, Cardiff University School of Medicine, Cardiff, UK
| | - Lei Zhang
- Department of Child Health, Cardiff University School of Medicine, Cardiff, UK
| | - Ali F Aboklaish
- Department of Child Health, Cardiff University School of Medicine, Cardiff, UK
| | - Emma Mitchell
- Department of Child Health, Cardiff University School of Medicine, Cardiff, UK
| | | | - Julian R Marchesi
- Division of Digestive Diseases, Faculty of Medicine, Imperial College London, London, UK
| | - Sailesh Kotecha
- Department of Child Health, Cardiff University School of Medicine, Cardiff, UK.
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Laux J, Martorelli M, Strass S, Schollmeyer D, Maier F, Burnet M, Laufer SA. Inherent Fluorescence Demonstrates Immunotropic Properties for Novel Janus Kinase 3 Inhibitors. ACS Pharmacol Transl Sci 2023; 6:1433-1452. [PMID: 37854620 PMCID: PMC10580734 DOI: 10.1021/acsptsci.3c00119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Indexed: 10/20/2023]
Abstract
There is a general question in small molecule pharmacology about how apparent compound concentrations in blood, plasma, and organs actually relate to actual amounts at the target site of a compound. In this study, we used inherently fluorescent JAK3 ligands and their macrolide conjugates to investigate the relationship between physical properties, apparent bulk concentration, and organ and subcellular distribution. In vitro uptake into immune cells suggested that much of the substance was associated with granules or organelles. Samples from murine pharmacokinetic studies were analyzed by both conventional mass spectrometry and cryofluorescence microscopy methods to show the distribution of a compound within organs and cells without artifacts of fixation. These observations confirm the uptake of granules observed in vitro. Data from macrolides carrying either a coumarin fluorophore or a JAK3 inhibitor were similar, suggesting that the distribution is directed by the properties of the larger macrolide. These data show a propensity for azalide macrolides to concentrate in the lung and gut epithelia and suggest that the plasma- or whole-blood-derived estimates of drug levels almost certainly underestimate concentrations of macrolides in the mucous membranes. Thus, their apparent efficacy at sub-bacteriostatic doses may reflect their higher levels in barrier layers.
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Affiliation(s)
- Julian Laux
- Synovo GmbH,
Paul-Ehrlich-Straße 15, Tübingen 72076, Germany
- Department of Pharmaceutical/Medicinal Chemistry,
Eberhard Karls University Tübingen, Auf der
Morgenstelle 8, Tübingen 72076, Germany
| | - Mariella Martorelli
- Synovo GmbH,
Paul-Ehrlich-Straße 15, Tübingen 72076, Germany
- Department of Pharmaceutical/Medicinal Chemistry,
Eberhard Karls University Tübingen, Auf der
Morgenstelle 8, Tübingen 72076, Germany
| | - Simon Strass
- Synovo GmbH,
Paul-Ehrlich-Straße 15, Tübingen 72076, Germany
| | - Dieter Schollmeyer
- Institute for Organic Chemistry, Johannes
Gutenberg University Mainz, Duesbergweg 10-14, Mainz 55099,
Germany
| | - Florian Maier
- Synovo GmbH,
Paul-Ehrlich-Straße 15, Tübingen 72076, Germany
| | - Michael Burnet
- Synovo GmbH,
Paul-Ehrlich-Straße 15, Tübingen 72076, Germany
| | - Stefan A. Laufer
- Department of Pharmaceutical/Medicinal Chemistry,
Eberhard Karls University Tübingen, Auf der
Morgenstelle 8, Tübingen 72076, Germany
- Cluster of Excellence iFIT (EXC 2180)
“Image-Guided and Functionally Instructed Tumor Therapies”,
University of Tübingen, Tübingen 72076,
Germany
- Tübingen Center for Academic Drug
Discovery & Development (TüCAD2), Tübingen 72076,
Germany
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Gómara-Lomero M, López-Calleja AI, Rezusta A, Aínsa JA, Ramón-García S. In vitro synergy screens of FDA-approved drugs reveal novel zidovudine- and azithromycin-based combinations with last-line antibiotics against Klebsiella pneumoniae. Sci Rep 2023; 13:14429. [PMID: 37660210 PMCID: PMC10475115 DOI: 10.1038/s41598-023-39647-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 07/28/2023] [Indexed: 09/04/2023] Open
Abstract
Treatment of infections caused by multi-drug resistant (MDR) enterobacteria remains challenging due to the limited therapeutic options available. Drug repurposing could accelerate the development of new urgently needed successful interventions. This work aimed to identify and characterise novel drug combinations against Klebsiella pneumoniae based on the concepts of synergy and drug repurposing. We first performed a semi-qualitative high-throughput synergy screen (sHTSS) with tigecycline, colistin and fosfomycin (last-line antibiotics against MDR Enterobacteriaceae) against a FDA-library containing 1430 clinically approved drugs; a total of 109 compounds potentiated any of the last-line antibiotics. Selected hits were further validated by secondary checkerboard (CBA) and time-kill (TKA) assays, obtaining 15.09% and 65.85% confirmation rates, respectively. Accordingly, TKA were used for synergy classification based on determination of bactericidal activities at 8, 24 and 48 h, selecting 27 combinations against K. pneumoniae. Among them, zidovudine or azithromycin combinations with last-line antibiotics were further evaluated by TKA against a panel of 12 MDR/XDR K. pneumoniae strains, and their activities confronted with those clinical combinations currently used for MDR enterobacteria treatment; these combinations showed better bactericidal activities than usual treatments without added cytotoxicity. Our studies show that sHTSS paired to TKA are powerful tools for the identification and characterisation of novel synergistic drug combinations against K. pneumoniae. Further pre-clinical studies might support the translational potential of zidovudine- and azithromycin-based combinations for the treatment of these infections.
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Affiliation(s)
- Marta Gómara-Lomero
- Department of Microbiology. Faculty of Medicine, University of Zaragoza, C/ Domingo Miral S/N, 50009, Zaragoza, Spain.
| | | | - Antonio Rezusta
- Servicio de Microbiología, Hospital Universitario Miguel Servet, Zaragoza, Spain
| | - José Antonio Aínsa
- Department of Microbiology. Faculty of Medicine, University of Zaragoza, C/ Domingo Miral S/N, 50009, Zaragoza, Spain
- CIBER Respiratory Diseases, Carlos III Health Institute, Madrid, Spain
| | - Santiago Ramón-García
- Department of Microbiology. Faculty of Medicine, University of Zaragoza, C/ Domingo Miral S/N, 50009, Zaragoza, Spain.
- CIBER Respiratory Diseases, Carlos III Health Institute, Madrid, Spain.
- Research and Development Agency of Aragon (ARAID) Foundation, Zaragoza, Spain.
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Liu X, Tashiro S, Igarashi Y, Takemura W, Kojima N, Morita T, Hayashi M, Enoki Y, Taguchi K, Matsumoto K. Differences in Pharmacokinetic/Pharmacodynamic Parameters of Tedizolid Against VRE and MRSA. Pharm Res 2023; 40:187-196. [PMID: 36329373 DOI: 10.1007/s11095-022-03425-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Accepted: 10/25/2022] [Indexed: 11/06/2022]
Abstract
PURPOSE Vancomycin-resistant enterococci (VRE) have recently become a major cause of nosocomial infections and a global public health concern. Tedizolid exhibits powerful antibacterial activity against VRE in vitro, but its pharmacokinetic/pharmacodynamic (PK/PD) parameters remain unclear. Therefore, we aimed to determine the PK/PD indices of tedizolid action on VRE and the mechanisms underlying the PK/PD indices differences of tedizolid against VRE and methicillin-resistant Staphylococcus aureus (MRSA). METHODS Optimal PK/PD target values of tedizolid were determined in vitro, based on time-kill curves and post-antibiotic effects (PAEs), and in vivo, using mouse models of thigh infection with VRE and MRSA strains. RESULTS The tedizolid bactericidal activity on VRE and MRSA was time-dependent. Correlations were closest between fAUC24/MIC and the tedizolid PK/PD index against MRSA and VRE. To achieve 1 log10 kill tedizolid fAUC24/MIC in neutropenic mouse models of thigh infection with VRE and MRSA should be 14.2 and 138.5, respectively. The PAEs of tedizolid against VRE and MRSA were 2.39 and 0.99 h, respectively. CONCLUSION Tedizolid showed bactericidal effects against VRE even in neutropenic mice unlike MRSA, which could be attributed to its longer PAE against VRE. Hence, we hypothesize that tedizolid treatment against VRE infections is promising for achieving therapeutic success in clinical.
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Affiliation(s)
- Xiaoxi Liu
- Division of Pharmacodynamics, Faculty of Pharmacy, Keio University, 1-5-30 Shiba Koen, Minato-Ku, Tokyo, 105-8512, Japan
| | - Sho Tashiro
- Division of Pharmacodynamics, Faculty of Pharmacy, Keio University, 1-5-30 Shiba Koen, Minato-Ku, Tokyo, 105-8512, Japan
| | - Yuki Igarashi
- Division of Pharmacodynamics, Faculty of Pharmacy, Keio University, 1-5-30 Shiba Koen, Minato-Ku, Tokyo, 105-8512, Japan
| | - Wataru Takemura
- Division of Pharmacodynamics, Faculty of Pharmacy, Keio University, 1-5-30 Shiba Koen, Minato-Ku, Tokyo, 105-8512, Japan
| | - Nana Kojima
- Division of Pharmacodynamics, Faculty of Pharmacy, Keio University, 1-5-30 Shiba Koen, Minato-Ku, Tokyo, 105-8512, Japan
| | - Takumi Morita
- Division of Pharmacodynamics, Faculty of Pharmacy, Keio University, 1-5-30 Shiba Koen, Minato-Ku, Tokyo, 105-8512, Japan
| | - Marina Hayashi
- Division of Pharmacodynamics, Faculty of Pharmacy, Keio University, 1-5-30 Shiba Koen, Minato-Ku, Tokyo, 105-8512, Japan
| | - Yuki Enoki
- Division of Pharmacodynamics, Faculty of Pharmacy, Keio University, 1-5-30 Shiba Koen, Minato-Ku, Tokyo, 105-8512, Japan.
| | - Kazuaki Taguchi
- Division of Pharmacodynamics, Faculty of Pharmacy, Keio University, 1-5-30 Shiba Koen, Minato-Ku, Tokyo, 105-8512, Japan
| | - Kazuaki Matsumoto
- Division of Pharmacodynamics, Faculty of Pharmacy, Keio University, 1-5-30 Shiba Koen, Minato-Ku, Tokyo, 105-8512, Japan
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Excipient-Free Inhalable Microparticles of Azithromycin Produced by Electrospray: A Novel Approach to Direct Pulmonary Delivery of Antibiotics. Pharmaceutics 2021; 13:pharmaceutics13121988. [PMID: 34959270 PMCID: PMC8704604 DOI: 10.3390/pharmaceutics13121988] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/08/2021] [Accepted: 11/16/2021] [Indexed: 11/16/2022] Open
Abstract
Inhalation therapy offers several advantages in respiratory disease treatment. Azithromycin is a macrolide antibiotic with poor solubility and bioavailability but with a high potential to be used to fight lung infections. The main objective of this study was to generate a new inhalable dry powder azithromycin formulation. To this end, an electrospray was used, yielding a particle size around 2.5 µm, which is considered suitable to achieve total deposition in the respiratory system. The physicochemical properties and morphology of the obtained microparticles were analysed with a battery of characterization techniques. In vitro deposition assays were evaluated after aerosolization of the powder at constant flow rate (100 L/min) and the consideration of the simulation of two different realistic breathing profiles (healthy and chronic obstructive pulmonary disease (COPD) patients) into a next generation impactor (NGI). The formulation was effective in vitro against two types of bacteria, Staphylococcus aureus and Pseudomonas aeruginosa. Finally, the particles were biocompatible, as evidenced by tests on the alveolar cell line (A549) and bronchial cell line (Calu-3).
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Teymourinia H, Amiri O, Salavati-Niasari M. Synthesis and characterization of cotton-silver-graphene quantum dots (cotton/Ag/GQDs) nanocomposite as a new antibacterial nanopad. CHEMOSPHERE 2021; 267:129293. [PMID: 33348263 DOI: 10.1016/j.chemosphere.2020.129293] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 12/07/2020] [Accepted: 12/09/2020] [Indexed: 06/12/2023]
Abstract
Appearance of antibiotic resistance in bacteria is a convoluted topic, particularly in treating pestiferous immunodeficiency correlated diseases. The main objective of the current research is to fabricate antibacterial pads by utilizing of graphene quantum dots (GQDs) as a linker, stabilizing, and reduction agent of in situ synthesized Ag nanoparticles (Ag NPs) on cotton pad. Five different antibacterial pads including cotton/Ag pad, cotton/GQDs/Ag pad, cotton/Ag/GQDs pad, cotton/GQDs/Ag/GQDs pad, and cotton/Ag/GQDs/Ag were fabricated and their antibacterial activities were compared to those of as-synthesized Ag/GQDs nanocomposites. The results indicate that cotton/GQDs/Ag pad shows a very promising minimum inhibitory concentration(MIC) of 0.09 and 0.01 against S. aureus and E. coli, respectively. Using GQDs as a linker (cotton/GQDs/Ag) and as a stabilizing agent (cotton/Ag/GQDs) significantly improves the antibacterial activity of Ag NPs.
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Affiliation(s)
- Hakimeh Teymourinia
- Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P. O. Box. 87317-51167, Iran; Trita Nanomedicine Research Center (TNRC), Trita Third Millennium Pharmaceuticals, 45331-55681, Zanjan, Iran
| | - Omid Amiri
- Department of Chemistry, College of Science, University of Raparin, Rania, Kurdistan Region, Iraq; Department of Chemistry, College of Science, International University of Erbil, Iraq
| | - Masoud Salavati-Niasari
- Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P. O. Box. 87317-51167, Iran.
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Rázquin-Olazarán I, Shahrour H, Martínez-de-Tejada G. A synthetic peptide sensitizes multi-drug resistant Pseudomonas aeruginosa to antibiotics for more than two hours and permeabilizes its envelope for twenty hours. J Biomed Sci 2020; 27:85. [PMID: 32762680 PMCID: PMC7412836 DOI: 10.1186/s12929-020-00678-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 07/30/2020] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Pseudomonas aeruginosa is a Gram-negative pathogen that frequently causes life-threatening infections in immunocompromised patients. We previously showed that subinhibitory concentrations of short synthetic peptides permeabilize P. aeruginosa and enhance the lethal action of co-administered antibiotics. METHODS Long-term permeabilization caused by exposure of multidrug-resistant P. aeruginosa strains to peptide P4-9 was investigated by measuring the uptake of several antibiotics and fluorescent probes and by using confocal imaging and atomic force microscopy. RESULTS We demonstrated that P4-9, a 13-amino acid peptide, induces a growth delay (i.e. post-antibiotic effect) of 1.3 h on a multidrug-resistant P. aeruginosa clinical isolate. Remarkably, when an independently P4-9-treated culture was allowed to grow in the absence of the peptide, cells remained sensitive to subinhibitory concentrations of antibiotics such as ceftazidime, fosfomycin and erythromycin for at least 2 h. We designated this persistent sensitization to antibiotics occurring in the absence of the sensitizing agent as Post-Antibiotic Effect associated Permeabilization (PAEP). Using atomic force microscopy, we showed that exposure to P4-9 induces profound alterations on the bacterial surface and that treated cells need at least 2 h of growth to repair those lesions. During PAEP, P. aeruginosa mutants overexpressing either the efflux pump MexAB-OprM system or the AmpC β-lactamase were rendered sensitive to antibiotics that are known substrates of those mechanisms of resistance. Finally, we showed for the first time that the descendants of bacteria surviving exposure to a membrane disturbing peptide retain a significant level of permeability to hydrophobic compounds, including propidium iodide, even after 20 h of growth in the absence of the peptide. CONCLUSIONS The phenomenon of long-term sensitization to antibiotics shown here may have important therapeutic implications for a combined peptide-antibiotic treatment because the peptide would not need to be present to exert its antibiotic enhancing activity as long as the target organism retains sensitization to the antibiotic.
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Affiliation(s)
- Iosu Rázquin-Olazarán
- Department of Microbiology and Parasitology, University of Navarra, E-31008, Pamplona, Spain
| | - Hawraa Shahrour
- Department of Microbiology and Parasitology, University of Navarra, E-31008, Pamplona, Spain
- Laboratory of Microbiology, Department of Life & Earth Sciences, Faculty of Sciences I, Lebanese University, Hadat campus, Beirut, Lebanon
| | - Guillermo Martínez-de-Tejada
- Department of Microbiology and Parasitology, University of Navarra, E-31008, Pamplona, Spain.
- Navarra Institute for Health Research (IdiSNA), Pamplona, Spain.
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Ikemoto K, Kobayashi S, Haranosono Y, Kozai S, Wada T, Tokushige H, Kawamura A. Contribution of anti-inflammatory and anti-virulence effects of azithromycin in the treatment of experimental Staphylococcus aureus keratitis. BMC Ophthalmol 2020; 20:89. [PMID: 32143675 PMCID: PMC7060554 DOI: 10.1186/s12886-020-01358-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 02/27/2020] [Indexed: 12/01/2022] Open
Abstract
Background We aimed to demonstrate the contribution of anti-inflammatory and anti-virulence effects of azithromycin (AZM) in ocular surface infection treatment. Methods Staphylococcus aureus was injected into the corneal stroma of rabbits to induce keratitis. AZM at concentrations of 0.01, 0.1, and 1% was instilled into the eye twice daily. The eyes were examined using a slit lamp and scored. The viable bacteria in the cornea were counted at 48 h post infection. To evaluate the anti-inflammatory efficacy of AZM, S. aureus culture supernatant-induced anterior ocular inflammation in rabbit was examined using a slit lamp and scored. To evaluate the inhibitory effect of AZM on bacterial toxin production, S. aureus was cultured with AZM and hemolytic reaction in the culture supernatant was determined. Results In the bacterial keratitis model, AZM dose-dependently inhibited the increase in the clinical score. The viable bacterial count in the cornea treated with 1% AZM significantly decreased compared with that of the vehicle, whereas bacterial count in 0.01 and 0.1% AZM-treated corneas was similar to that of the vehicle. In the anterior ocular inflammation model, 0.1 and 1% AZM inhibited the increase in the clinical score. AZM inhibited hemolytic reaction at concentrations that did not inhibit bacterial growth. Conclusions The results demonstrated that AZM has not only anti-bacterial, but also anti-inflammatory effects, and inhibits bacterial toxin production leading to ocular surface damage in bacterial infection. Thus, the therapeutic effect of AZM against ocular infections is expected to be higher than that which could be assumed if it only had anti-bacterial activity.
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Affiliation(s)
- Kana Ikemoto
- Senju Pharmaceutical Co., Ltd., 6-4-3 Minatojima-Minamimachi, Chuo-Ku, Kobe, Hyogo, 650-0047, Japan.
| | - Shinya Kobayashi
- Senju Pharmaceutical Co., Ltd., 6-4-3 Minatojima-Minamimachi, Chuo-Ku, Kobe, Hyogo, 650-0047, Japan
| | - Yu Haranosono
- Senju Pharmaceutical Co., Ltd., 6-4-3 Minatojima-Minamimachi, Chuo-Ku, Kobe, Hyogo, 650-0047, Japan
| | - Seiko Kozai
- Senju Pharmaceutical Co., Ltd., 6-4-3 Minatojima-Minamimachi, Chuo-Ku, Kobe, Hyogo, 650-0047, Japan
| | - Tomoyuki Wada
- Senju Pharmaceutical Co., Ltd., 6-4-3 Minatojima-Minamimachi, Chuo-Ku, Kobe, Hyogo, 650-0047, Japan
| | - Hideki Tokushige
- Senju Pharmaceutical Co., Ltd., 6-4-3 Minatojima-Minamimachi, Chuo-Ku, Kobe, Hyogo, 650-0047, Japan
| | - Akio Kawamura
- Senju Pharmaceutical Co., Ltd., 6-4-3 Minatojima-Minamimachi, Chuo-Ku, Kobe, Hyogo, 650-0047, Japan
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Teymourinia H, Salavati-Niasari M, Amiri O, Yazdian F. Application of green synthesized TiO2/Sb2S3/GQDs nanocomposite as high efficient antibacterial agent against E. coli and Staphylococcus aureus. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2019; 99:296-303. [DOI: 10.1016/j.msec.2019.01.094] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 01/16/2019] [Accepted: 01/20/2019] [Indexed: 10/27/2022]
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10
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Kitamura Y, Yoshida K, Kusama M, Sugiyama Y. A proposal of a pharmacokinetic/pharmacodynamic (PK/PD) index map for selecting an optimal PK/PD index from conventional indices (AUC/MIC, Cmax/MIC, and TAM) for antibiotics. Drug Metab Pharmacokinet 2014; 29:455-62. [PMID: 25008846 DOI: 10.2133/dmpk.dmpk-14-rg-013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A pharmacokinetic/pharmacodynamic (PK/PD) analysis is important in antibiotic chemotherapy. Basically, the in vivo efficacy of antibiotics that exert concentration-dependent effects can be predicted using conventional PK/PD indices such as the ratio of the area under the curve to the minimum inhibitory concentration (AUC/MIC) and/or the ratio of the maximum plasma concentration to MIC (Cmax/MIC), whereas that of antibiotics with time-dependent effects can be determined using the period of time for which the drug concentration exceeds the MIC (time above MIC [TAM]). However, an optimal PK/PD index remains to be established for some antibiotics. Thus, a PK/PD model which describes the PK profile and effect of an antibiotic was developed, and the results obtained from this model were interpreted to form a PK/PD index map to assess the optimal PK/PD index for the antibiotic. The findings from the map were generally consistent with clinical outcomes even for the antibiotics which proved to be exceptions to the conventional classification. For example, AUC/MIC was an optimal index for azithromycin despite its time-dependent bactericidal activity, and Cmax/MIC was a poor index for arbekacin despite its concentration-dependent profile. Thus, the map would be useful for selecting the appropriate PK/PD index for an antibiotic.
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Petropoulos AD, Kouvela EC, Starosta AL, Wilson DN, Dinos GP, Kalpaxis DL. Time-resolved binding of azithromycin to Escherichia coli ribosomes. J Mol Biol 2008; 385:1179-92. [PMID: 19071138 DOI: 10.1016/j.jmb.2008.11.042] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2008] [Revised: 11/13/2008] [Accepted: 11/18/2008] [Indexed: 11/19/2022]
Abstract
Azithromycin is a semisynthetic derivative of erythromycin that inhibits bacterial protein synthesis by binding within the peptide exit tunnel of the 50S ribosomal subunit. Nevertheless, there is still debate over what localization is primarily responsible for azithromycin binding and as to how many molecules of the drug actually bind per ribosome. In the present study, kinetic methods and footprinting analysis are coupled together to provide time-resolved details of the azithromycin binding process. It is shown that azithromycin binds to Escherichia coli ribosomes in a two-step process: The first-step involves recognition of azithromycin by the ribosomal machinery and places the drug in a low-affinity site located in the upper part of the exit tunnel. The second step corresponds to the slow formation of a final complex that is both much tighter and more potent in hindering the progression of the nascent peptide through the exit tunnel. Substitution of uracil by cytosine at nucleoside 2609 of 23S rRNA, a base implicated in the high-affinity site, facilitates the shift of azithromycin to this site. In contrast, mutation U754A hardly affects the binding process. Binding of azithromycin to both sites is hindered by high concentrations of Mg(2+) ions. Unlike Mg(2+) ions, polyamines do not significantly affect drug binding to the low-affinity site but attenuate the formation of the final complex. The low- and high-affinity sites of azithromycin binding are mutually exclusive, which means that one molecule of the drug binds per E. coli ribosome at a time. In contrast, kinetic and binding data indicate that in Deinococcus radiodurans, two molecules of azithromycin bind cooperatively to the ribosome. This finding confirms previous crystallographic results and supports the notion that species-specific structural differences may primarily account for the apparent discrepancies between the antibiotic binding modes obtained for different organisms.
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Abstract
The pharmacodynamics of antibiotics have become increasingly important for the determination of optimal dosing regimens. Studies over the past decade have demonstrated marked differences in the time course of antimicrobial activity for different classes of antibiotics both in vitro, in animals and in human trials. One of the explanations for the success of intermittent dosing regimens has been the delay in regrowth after the concentration has fallen under the MIC, the so called postantibiotic effect (PAE). In addition to the PAE, the success of discontinuous dosing regimens may be attributed to both the function of a normal host defence and to the effects of subinhibitory antibiotic concentrations (sub-MICs). It has been shown that there is a difference between the effects of sub-MICs following a suprainhibitory dose (postantibiotic sub-MIC effect; PA SME) and the effects of sub-MICs (SME) alone. It seems that the PA SME is more clinically relevant compared with the PAE, since exposure to suprainhibitory concentrations will always be followed by sub-MICs in vivo. A long PA SME could indicate that longer dosing intervals may be used for that antibiotic /bacterial combination and together with the known effects of sub-MICs on bacterial virulence and the influence of the immune system, it may explain the efficacy of antibiotics with short half-lives even of they are given infrequently.
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Affiliation(s)
- I Odenholt
- Department of Infectious Diseases, University Hospital, MAS, S-20502, Malmö, Sweden.
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Abstract
Isepamicin is an aminoglycoside antibacterial with properties similar to those of amikacin, but with better activity against strains producing type I 6'-acetyltransferase. The antibacterial spectrum includes Enterobacteriaceae and staphylococci. Anaerobes, Neisseriaceae and streptococci are resistant. The lower and upper break-points are 8 and 16 mg/L. Like other aminoglycosides, isepamicin exhibits a strong concentration-dependent bactericidal effect, a long post-antibiotic effect (several hours) and induces adaptive resistance. Isepamicin is administered intravenously or intramuscularly at a dosage of 15 mg/kg once daily or 7.5 mg/kg twice daily. Isepamicin is not bound to plasma proteins, and it distributes in extracellular fluids and into some cells (outer hair cells, kidney cortex) by active transport. Isepamicin is not metabolised and is eliminated solely via the renal route with an elimination half-life (t 1/2 beta) of 2 to 3 hours in adults with normal renal function. The clearance of isepamicin is reduced in neonates, and 7.5 mg/kg once daily is recommended in children <16 days old. Clearance is also reduced in the elderly, but no dosage adjustment is required. In patients with chronic renal impairment, isepamicin clearance is proportional to creatinine clearance (CLCR); the recommended regimen is 8 mg/kg with an administration interval of 24 hours in moderate impairment, 48 hours in severe impairment, 72 hours for CL(CR) 0.6 to 1.14 L/h (10 to 19 ml/min) and 96 hours for CL(CR) 0.36 to 0.54 L/h (6 to 9 ml/min). In end-stage renal failure, isepamicin is eliminated by haemodialysis, but the administration interval should be determined by monitoring the plasma concentration. Compared with healthy volunteers, patients in the intensive care unit or with neutropenic cancer have an increased volume of distribution and a lower clearance, but the 15 mg/kg once daily regimen remains adequate. Isepamicin kinetics are linear in the range 7.5 to 25 mg/kg, so that dosage adjustments, if necessary, are straightforward. Isepamicin can induce nephro-, vestibulo- and oto-toxicity. However, animal and clinical studies show that isepamicin is one of the less toxic aminoglycosides. The usefulness of maintaining serum aminoglycoside concentrations within a therapeutic range remains controversial. With isepamicin, it is proposed to achieve a 1-hour concentration (30 minutes after a 30-minute infusion) >40 mg/L to maximise bactericidal efficacy, and a 'trough' concentration (at the end of the administration interval) <5 mg/L to minimise toxicity. These thresholds should be modified on an individual basis, considering covariates such as concomitant treatment, underlying disease, nature of bacterial strain and site of infection.
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Affiliation(s)
- M Tod
- Department of Pharmacotoxicology, Avicenne Hospital, Bobigny, France.
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14
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Champney WS, Tober CL. Molecular investigation of the postantibiotic effects of clarithromycin and erythromycin on Staphylococcus aureus cells. Antimicrob Agents Chemother 1999; 43:1324-8. [PMID: 10348746 PMCID: PMC89272 DOI: 10.1128/aac.43.6.1324] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The kinetics of recovery after inhibition of growth by erythromycin and clarithromycin were examined in Staphylococcus aureus cells. After inhibition for one mass doubling by 0.5 microg of the antibiotics/ml, a postantibiotic effect (PAE) of 3 and 4 h duration was observed for the two drugs before growth resumed. Cell viability was reduced by 25% with erythromycin and 45% with clarithromycin compared with control cells. Erythromycin and clarithromycin treatment reduced the number of 50S ribosomal subunits to 24 and 13% of the number found in untreated cells. 30S subunit formation was not affected. Ninety minutes was required for resynthesis to give the control level of 50S particles. Protein synthesis rates were diminished for up to 4 h after the removal of the macrolides. This continuing inhibition of translation was the result of prolonged binding of the antibiotics to the 50S subunit as measured by 14C-erythromycin binding to ribosomes in treated cells. The limiting factors in recovery from macrolide inhibition in these cells, reflected as a PAE, are the time required for the synthesis of new 50S subunits and the slow loss of the antibiotics from ribosomes in inhibited cells.
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Affiliation(s)
- W S Champney
- Department of Biochemistry and Molecular Biology, J. H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614, USA.
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15
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Abstract
The in vivo situation is far more complex than that of the standard in vitro susceptibility test yet in vitro tests have stood the test of time and are often good predictors of clinical outcome. Nevertheless, our understanding of the pharmacodynamics of antibiotic microbe interaction are giving us new insights into how to improve our performance and interpretation of these tests. These factors include consideration of inoculum effect, antibiotic interactions, cidal effects and the area under the inhibitory time curve (AUIC). There are however other variables which it is difficult to incorporate into in vitro tests, especially the immune status of the patient, which can be crucial to outcome. While the immune system can be boosted in certain instances, e.g. by growth factors or immunoglobulin infusions, our ability to modify the immune response to infection has been frustrated. Understanding the interaction of antibiotics with the immune system and the consequences of the differing actions of the various antibiotic classes on the immune response is another door that is opening for the future.
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Affiliation(s)
- I M Gould
- Dept. of Medical Microbiology, Aberdeen Royal Infirmary, Foresterhill, Scotland, UK.
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