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Darby EM, Moran RA, Holden E, Morris T, Harrison F, Clough B, McInnes RS, Schneider L, Frickel EM, Webber MA, Blair JMA. Differential development of antibiotic resistance and virulence between Acinetobacter species. mSphere 2024; 9:e0010924. [PMID: 38578105 DOI: 10.1128/msphere.00109-24] [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: 02/10/2024] [Accepted: 03/13/2024] [Indexed: 04/06/2024] Open
Abstract
The two species that account for most cases of Acinetobacter-associated bacteremia in the United Kingdom are Acinetobacter lwoffii, often a commensal but also an emerging pathogen, and Acinetobacter baumannii, a well-known antibiotic-resistant species. While these species both cause similar types of human infection and occupy the same niche, A. lwoffii (unlike A. baumannii) has thus far remained susceptible to antibiotics. Comparatively little is known about the biology of A. lwoffii, and this is the largest study on it conducted to date, providing valuable insights into its behaviour and potential threat to human health. This study aimed to explain the antibiotic susceptibility, virulence, and fundamental biological differences between these two species. The relative susceptibility of A. lwoffii was explained as it encoded fewer antibiotic resistance and efflux pump genes than A. baumannii (9 and 30, respectively). While both species had markers of horizontal gene transfer, A. lwoffii encoded more DNA defense systems and harbored a far more restricted range of plasmids. Furthermore, A. lwoffii displayed a reduced ability to select for antibiotic resistance mutations, form biofilm, and infect both in vivo and in in vitro models of infection. This study suggests that the emerging pathogen A. lwoffii has remained susceptible to antibiotics because mechanisms exist to make it highly selective about the DNA it acquires, and we hypothesize that the fact that it only harbors a single RND system restricts the ability to select for resistance mutations. This provides valuable insights into how development of resistance can be constrained in Gram-negative bacteria. IMPORTANCE Acinetobacter lwoffii is often a harmless commensal but is also an emerging pathogen and is the most common cause of Acinetobacter-derived bloodstream infections in England and Wales. In contrast to the well-studied and often highly drug-resistant A. baumannii, A. lwoffii has remained susceptible to antibiotics. This study explains why this organism has not evolved resistance to antibiotics. These new insights are important to understand why and how some species develop antibiotic resistance, while others do not, and could inform future novel treatment strategies.
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Affiliation(s)
- Elizabeth M Darby
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Robert A Moran
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Emma Holden
- Quadram Institute Bioscience, Norwich Research Park, Norwich, Norfolk, United Kingdom
| | - Theresa Morris
- Centre for Electron Microscopy, University of Birmingham, Birmingham, United Kingdom
| | - Freya Harrison
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Barbara Clough
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Ross S McInnes
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Ludwig Schneider
- Centre for Electron Microscopy, University of Birmingham, Birmingham, United Kingdom
| | - Eva M Frickel
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Mark A Webber
- Quadram Institute Bioscience, Norwich Research Park, Norwich, Norfolk, United Kingdom
- Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich, Norfolk, United Kingdom
| | - Jessica M A Blair
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
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Dai H, Hu Y, Zhang Y, Zhu Q, Xu T, Cui P, Fan R, He Q. Identification of CH 2-linked quinolone-aminopyrimidine hybrids as potent anti-MRSA agents: Low resistance potential and lack of cross-resistance with fluoroquinolone antibiotics. Eur J Med Chem 2024; 271:116399. [PMID: 38640868 DOI: 10.1016/j.ejmech.2024.116399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Revised: 04/03/2024] [Accepted: 04/06/2024] [Indexed: 04/21/2024]
Abstract
The structural optimization of B14, an antibacterial agent we previously obtained, has led to the discovery of a new class of CH2-linked quinolone-aminopyrimidine hybrids with potent anti-MRSA activities. Surprisingly, the hybrids lacking a C-6 fluoro atom at the quinolone nucleus showed equal or even stronger anti-MRSA activities than their corresponding 6-fluoro counterparts, despite the well-established structure-activity relationships (SARs) indicating that the 6-fluoro substituent enhances the antibacterial activity in conventional fluoroquinolone antibiotics. Moreover, these new hybrids, albeit structurally related to conventional fluoroquinolones, showed no cross-resistance with fluoroquinolone drugs. The most active compound, 15m, exhibited excellent activities with a MIC value of 0.39 μg/mL against both fluoroquinolone-sensitive strain USA500 and -resistant MRSA isolate Mu50. Further resistance development studies indicated MRSA is unlikely to acquire resistance against 15m. Moreover, 15m displayed favorable in vivo half-life and safety profiles. These findings suggest a rationale for further evolution of quinolone antibiotics with a high barrier to resistance.
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Affiliation(s)
- Hongxue Dai
- Department of Chemistry, Fudan University, 2005 Songhu Road, Yangpu District, Shanghai, China
| | - Yue Hu
- Department of Chemistry, Fudan University, 2005 Songhu Road, Yangpu District, Shanghai, China
| | - Yiwen Zhang
- Department of Chemistry, Fudan University, 2005 Songhu Road, Yangpu District, Shanghai, China
| | - Qi Zhu
- Department of Chemistry, Fudan University, 2005 Songhu Road, Yangpu District, Shanghai, China
| | - Tao Xu
- Department of Infectious Diseases, National Medical Center for Infectious Diseases, Huashan Hospital, Shanghai Medical College, Fudan University, 525 Wulumuqizhong Road, Jing'an District, Shanghai, China
| | - Peng Cui
- Department of Infectious Diseases, National Medical Center for Infectious Diseases, Huashan Hospital, Shanghai Medical College, Fudan University, 525 Wulumuqizhong Road, Jing'an District, Shanghai, China.
| | - Renhua Fan
- Department of Chemistry, Fudan University, 2005 Songhu Road, Yangpu District, Shanghai, China.
| | - Qiuqin He
- Department of Chemistry, Fudan University, 2005 Songhu Road, Yangpu District, Shanghai, China.
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3
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Collins J, Osheroff N. Gyrase and Topoisomerase IV: Recycling Old Targets for New Antibacterials to Combat Fluoroquinolone Resistance. ACS Infect Dis 2024; 10:1097-1115. [PMID: 38564341 PMCID: PMC11019561 DOI: 10.1021/acsinfecdis.4c00128] [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: 02/16/2024] [Revised: 03/14/2024] [Accepted: 03/18/2024] [Indexed: 04/04/2024]
Abstract
Beyond their requisite functions in many critical DNA processes, the bacterial type II topoisomerases, gyrase and topoisomerase IV, are the targets of fluoroquinolone antibacterials. These drugs act by stabilizing gyrase/topoisomerase IV-generated DNA strand breaks and by robbing the cell of the catalytic activities of these essential enzymes. Since their clinical approval in the mid-1980s, fluoroquinolones have been used to treat a broad spectrum of infectious diseases and are listed among the five "highest priority" critically important antimicrobial classes by the World Health Organization. Unfortunately, the widespread use of fluoroquinolones has been accompanied by a rise in target-mediated resistance caused by specific mutations in gyrase and topoisomerase IV, which has curtailed the medical efficacy of this drug class. As a result, efforts are underway to identify novel antibacterials that target the bacterial type II topoisomerases. Several new classes of gyrase/topoisomerase IV-targeted antibacterials have emerged, including novel bacterial topoisomerase inhibitors, Mycobacterium tuberculosis gyrase inhibitors, triazaacenaphthylenes, spiropyrimidinetriones, and thiophenes. Phase III clinical trials that utilized two members of these classes, gepotidacin (triazaacenaphthylene) and zoliflodacin (spiropyrimidinetrione), have been completed with positive outcomes, underscoring the potential of these compounds to become the first new classes of antibacterials introduced into the clinic in decades. Because gyrase and topoisomerase IV are validated targets for established and emerging antibacterials, this review will describe the catalytic mechanism and cellular activities of the bacterial type II topoisomerases, their interactions with fluoroquinolones, the mechanism of target-mediated fluoroquinolone resistance, and the actions of novel antibacterials against wild-type and fluoroquinolone-resistant gyrase and topoisomerase IV.
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Affiliation(s)
- Jessica
A. Collins
- Department
of Biochemistry, Vanderbilt University School
of Medicine, Nashville, Tennessee 37232, United States
| | - Neil Osheroff
- Department
of Biochemistry, Vanderbilt University School
of Medicine, Nashville, Tennessee 37232, United States
- Department
of Medicine (Hematology/Oncology), Vanderbilt
University School of Medicine, Nashville, Tennessee 37232, United States
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4
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Dao TH, Echlin H, McKnight A, Marr ES, Junker J, Jia Q, Hayden R, van Opijnen T, Isberg RR, Cooper VS, Rosch JW. Streptococcus pneumoniae favors tolerance via metabolic adaptation over resistance to circumvent fluoroquinolones. mBio 2024; 15:e0282823. [PMID: 38193698 PMCID: PMC10865975 DOI: 10.1128/mbio.02828-23] [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: 10/17/2023] [Accepted: 12/01/2023] [Indexed: 01/10/2024] Open
Abstract
Streptococcus pneumoniae is a major human pathogen of global health concern and the rapid emergence of antibiotic resistance poses a serious public health problem worldwide. Fluoroquinolone resistance in S. pneumoniae is an intriguing case because the prevalence of fluoroquinolone resistance does not correlate with increasing usage and has remained rare. Our data indicate that deleterious fitness costs in the mammalian host constrain the emergence of fluoroquinolone resistance both by de novo mutation and recombination. S. pneumoniae was able to circumvent such deleterious fitness costs via the development of antibiotic tolerance through metabolic adaptation that reduced the production of reactive oxygen species, resulting in a fitness benefit during infection of mice treated with fluoroquinolones. These data suggest that the emergence of fluoroquinolone resistance is tightly constrained in S. pneumoniae by fitness tradeoffs and that mutational pathways involving metabolic networks to enable tolerance phenotypes are an important contributor to the evasion of antibiotic-mediated killing.IMPORTANCEThe increasing prevalence of antibiotic resistant bacteria is a major global health concern. While many species have the potential to develop antibiotic resistance, understanding the barriers to resistance emergence in the clinic remains poorly understood. A prime example of this is fluroquinolone resistance in Streptococcus pneumoniae, whereby, despite continued utilization, resistance to this class of antibiotic remains rare. In this study, we found that the predominant pathways for developing resistance to this antibiotic class severely compromised the infectious capacity of the pneumococcus, providing a key impediment for the emergence of resistance. Using in vivo models of experimental evolution, we found that S. pneumoniae responds to repeated fluoroquinolone exposure by modulating key metabolic pathways involved in the generation of redox molecules, which leads to antibiotic treatment failure in the absence of appreciable shifts in resistance levels. These data underscore the complex pathways available to pathogens to evade antibiotic mediating killing via antibiotic tolerance.
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Affiliation(s)
- Tina H. Dao
- Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Haley Echlin
- Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Abigail McKnight
- Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Enolia S. Marr
- Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Julia Junker
- Nationales Referenzzentrum für Streptokokken Abteilung Medizinische Mikrobiologie, Universitätsklinikum RWTH Aachen, Aachen, Germany
| | - Qidong Jia
- Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Randall Hayden
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Tim van Opijnen
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Ralph R. Isberg
- Deptartment of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Vaughn S. Cooper
- Center for Evolutionary Biology and Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Jason W. Rosch
- Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
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Kasza K, Richards B, Jones S, Romero M, Robertson SN, Hardie KR, Gurnani P, Cámara M, Alexander C. Ciprofloxacin Poly(β-amino ester) Conjugates Enhance Antibiofilm Activity and Slow the Development of Resistance. ACS APPLIED MATERIALS & INTERFACES 2024; 16:5412-5425. [PMID: 38289032 PMCID: PMC10859900 DOI: 10.1021/acsami.3c14357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 12/17/2023] [Accepted: 01/05/2024] [Indexed: 02/09/2024]
Abstract
To tackle the emerging antibiotic resistance crisis, novel antimicrobial approaches are urgently needed. Bacterial biofilms are a particular concern in this context as they are responsible for over 80% of bacterial infections and are inherently more recalcitrant toward antimicrobial treatments. The high tolerance of biofilms to conventional antibiotics has been attributed to several factors, including reduced drug diffusion through the dense exopolymeric matrix and the upregulation of antimicrobial resistance machinery with successful biofilm eradication requiring prolonged high doses of multidrug treatments. A promising approach to tackle bacterial infections involves the use of polymer drug conjugates, shown to improve upon free drug toxicity and bioavailability, enhance drug penetration through the thick biofilm matrix, and evade common resistance mechanisms. In the following study, we conjugated the antibiotic ciprofloxacin (CIP) to a small library of biodegradable and biocompatible poly(β-amino ester) (PBAE) polymers with varying central amine functionality. The suitability of the polymers as antibiotic conjugates was then verified in a series of assays including testing of efficacy and resistance response in planktonic Gram-positive and Gram-negative bacteria and the reduction of viability in mono- and multispecies biofilm models. The most active polymer within the prepared PBAE-CIP library was shown to achieve an over 2-fold increase in the reduction of biofilm viability in a Pseudomonas aeruginosa monospecies biofilm and superior elimination of all the species present within the multispecies biofilm model. Hence, we demonstrate that CIP conjugation to PBAEs can be employed to achieve improved antibiotic efficacy against clinically relevant biofilm models.
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Affiliation(s)
- Karolina Kasza
- Division
of Molecular Therapeutics and Formulation, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, U.K.
- National
Biofilms Innovation Centre, School of Life Sciences, Biodiscovery
Institute, University Park, University of
Nottingham, Nottingham NG7 2RD, U.K.
| | - Brogan Richards
- National
Biofilms Innovation Centre, School of Life Sciences, Biodiscovery
Institute, University Park, University of
Nottingham, Nottingham NG7 2RD, U.K.
| | - Sal Jones
- Division
of Molecular Therapeutics and Formulation, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, U.K.
| | - Manuel Romero
- National
Biofilms Innovation Centre, School of Life Sciences, Biodiscovery
Institute, University Park, University of
Nottingham, Nottingham NG7 2RD, U.K.
- Department
of Microbiology and Parasitology, Faculty of Biology-CIBUS, Universidade de Santiago de Compostela, Santiago de Compostela 15782, Spain
| | - Shaun N. Robertson
- National
Biofilms Innovation Centre, School of Life Sciences, Biodiscovery
Institute, University Park, University of
Nottingham, Nottingham NG7 2RD, U.K.
| | - Kim R. Hardie
- National
Biofilms Innovation Centre, School of Life Sciences, Biodiscovery
Institute, University Park, University of
Nottingham, Nottingham NG7 2RD, U.K.
| | - Pratik Gurnani
- UCL
School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, U.K.
| | - Miguel Cámara
- National
Biofilms Innovation Centre, School of Life Sciences, Biodiscovery
Institute, University Park, University of
Nottingham, Nottingham NG7 2RD, U.K.
| | - Cameron Alexander
- Division
of Molecular Therapeutics and Formulation, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, U.K.
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6
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Aris P, Mohamadzadeh M, Zarei M, Xia X. Computational Design of Novel Griseofulvin Derivatives Demonstrating Potential Antibacterial Activity: Insights from Molecular Docking and Molecular Dynamics Simulation. Int J Mol Sci 2024; 25:1039. [PMID: 38256112 PMCID: PMC10816260 DOI: 10.3390/ijms25021039] [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: 11/17/2023] [Revised: 01/11/2024] [Accepted: 01/13/2024] [Indexed: 01/24/2024] Open
Abstract
In response to the urgent demand for innovative antibiotics, theoretical investigations have been employed to design novel analogs. Because griseofulvin is a potential antibacterial agent, we have designed novel derivatives of griseofulvin to enhance its antibacterial efficacy and to evaluate their interactions with bacterial targets using in silico analysis. The results of this study reveal that the newly designed derivatives displayed the most robust binding affinities towards PBP2, tyrosine phosphatase, and FtsZ proteins. Additionally, molecular dynamics (MD) simulations underscored the notable stability of these derivatives when engaged with the FtsZ protein, as evidenced by root mean square deviation (RMSD), root mean square fluctuation (RMSF), radius of gyration (Rg), and solvent-accessible surface area (SASA). Importantly, this observation aligns with expectations, considering that griseofulvin primarily targets microtubules in eukaryotic cells, and FtsZ functions as the prokaryotic counterpart to microtubules. These findings collectively suggest the promising potential of griseofulvin and its designed derivatives as effective antibacterial agents, particularly concerning their interaction with the FtsZ protein. This research contributes to the ongoing exploration of novel antibiotics and may serve as a foundation for future drug development efforts.
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Affiliation(s)
- Parisa Aris
- Department of Biology, University of Ottawa, 30 Marie Curie, P.O. Box 450, Ottawa, ON K1N 6N5, Canada
| | - Masoud Mohamadzadeh
- Department of Chemistry, Faculty of Sciences, University of Hormozgan, Bandar Abbas 71961, Iran; (M.M.); (M.Z.)
| | - Maaroof Zarei
- Department of Chemistry, Faculty of Sciences, University of Hormozgan, Bandar Abbas 71961, Iran; (M.M.); (M.Z.)
- Nanoscience, Nanotechnology and Advanced Materials Research Center, University of Hormozgan, Bandar Abbas 71961, Iran
| | - Xuhua Xia
- Department of Biology, University of Ottawa, 30 Marie Curie, P.O. Box 450, Ottawa, ON K1N 6N5, Canada
- Ottawa Institute of Systems Biology, Ottawa, ON K1H 8M5, Canada
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Yokota SI, Tsukamoto N, Sato T, Ohkoshi Y, Yamamoto S, Ogasawara N. Serotype replacement and an increase in non-encapsulated isolates among community-acquired infections of Streptococcus pneumoniae during post-vaccine era in Japan. IJID REGIONS 2023; 8:105-110. [PMID: 37554357 PMCID: PMC10404989 DOI: 10.1016/j.ijregi.2023.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 07/05/2023] [Accepted: 07/06/2023] [Indexed: 08/10/2023]
Abstract
OBJECTIVES It is feared that the serotype replacement of Streptococcus pneumoniae occurred by the introduction of pneumococcal vaccines as periodical inoculation leads to reduced efficacy of the approved vaccines and altered antimicrobial susceptibility. METHODS We determined serotypes of 351 S. pneumoniae isolates collected at a commercial clinical laboratory in Hokkaido prefecture, Japan, from December 2018 to February 2019 by using the polymerase chain reaction procedure of the US Centers for Disease Control and Prevention. Antimicrobial susceptibility and resistance gene profiles were also examined. RESULTS Vaccine coverage rates were 7.9% for 13-valent conjugate vaccine, and 32.5% for 23-valent polysaccharide vaccine, respectively. Non-typable strains were 19.7%. cpsA-positive isolates (group I), and null capsule clade (NCC)1, NCC2 and NCC3 (group II) comprised 31.3%, 28.4%, 32.8%, and 7.5% of the 69 non-typable strains, respectively. No penicillin-resistant/intermediate isolates were found; however, serotypes 35B and 15A/F showed low susceptibility to β-lactams. Only five strains (1.4%) were levofloxacin-resistant, and all were from the older persons, and three strains were serotype 35B. CONCLUSION The progression of serotype replacement in non-invasive pneumococcal infections has occurred during the post-vaccine era in Japan, and non-encapsulated isolates, such as NCC, have increased. Antimicrobial susceptibility is not worsened.
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Affiliation(s)
- Shin-ichi Yokota
- Department of Microbiology, Sapporo Medical University School of Medicine, Sapporo, Japan
| | | | - Toyotaka Sato
- Laboratory of Veterinary Hygiene, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan
- Graduate School of Infectious Diseases, Hokkaido University, Sapporo, Japan
- One Health Research Center, Hokkaido University, Sapporo, Japan
| | - Yasuo Ohkoshi
- Department of Microbiology, Sapporo Medical University School of Medicine, Sapporo, Japan
- Department of Clinical Laboratory, NTT Medical Center Sapporo, Sapporo, Japan
| | - Soh Yamamoto
- Department of Microbiology, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Noriko Ogasawara
- Department of Microbiology, Sapporo Medical University School of Medicine, Sapporo, Japan
- Department of Otolaryngology-Head and Neck Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan
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8
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Barik K, Arya PK, Singh AK, Kumar A. Potential therapeutic targets for combating Mycoplasma genitalium. 3 Biotech 2023; 13:9. [PMID: 36532859 PMCID: PMC9755450 DOI: 10.1007/s13205-022-03423-9] [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: 06/22/2022] [Accepted: 12/05/2022] [Indexed: 12/23/2022] Open
Abstract
Mycoplasma genitalium (M. genitalium) has emerged as a sexually transmitted infection (STI) all over the world in the last three decades. It has been identified as a cause of male urethritis, and there is now evidence that it also causes cervicitis and pelvic inflammatory disease in women. However, the precise role of M. genitalium in diseases such as pelvic inflammatory disease, and infertility is unknown, and more research is required. It is a slow-growing organism, and with the advent of the nucleic acid amplification test (NAAT), more studies are being conducted and knowledge about the pathogenicity of this organism is being elucidated. The accumulation of data has improved our understanding of the pathogen and its role in disease transmission. Despite the widespread use of single-dose azithromycin in the sexual health field, M. genitalium is known to rapidly develop antibiotic resistance. As a result, the media frequently refer to this pathogen as the "new STI superbug." Despite their rarity, antibiotics available today have serious side effects. As the cure rates for first-line antimicrobials have decreased, it is now a challenge to determine the effective antimicrobial therapy. In this review, we summarise recent M. genitalium research and investigate potential therapeutic targets for combating this pathogen.
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Affiliation(s)
- Krishnendu Barik
- Department of Bioinformatics, Central University of South Bihar, Gaya, 824236 India
| | - Praffulla Kumar Arya
- Department of Bioinformatics, Central University of South Bihar, Gaya, 824236 India
| | - Ajay Kumar Singh
- Department of Bioinformatics, Central University of South Bihar, Gaya, 824236 India
| | - Anil Kumar
- Department of Bioinformatics, Central University of South Bihar, Gaya, 824236 India
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Characterization of ampicillin-resistant genes in Vibrio parahaemolyticus. Microb Pathog 2022; 168:105573. [PMID: 35588966 DOI: 10.1016/j.micpath.2022.105573] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 04/28/2022] [Accepted: 05/07/2022] [Indexed: 12/29/2022]
Abstract
Vibrio parahaemolyticus is strongly resistant to ampicillin (AMP). In this study, AMP-resistant genes in V. parahaemolyticus ATCC33846 were characterized. Transcriptomic analysis of V. parahaemolyticus exposed to AMP revealed 4608 differentially transcribed genes, including 670 significantly up-regulated genes and 655 significantly down-regulated genes. Based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, significantly modulated genes in ATCC33846 under AMP stimulation were observed in the following categories: microbial metabolism in diverse environments, metabolic pathways, bacterial secretion system, citrate cycle, biofilm formation, oxidative phosphorylation, ribosome, citrate cycle, pyruvate metabolism, carbon metabolism, nitrogen metabolism, fatty acid metabolism and tryptophan metabolism. The genes VPA0510, VPA0252, VPA0699, VPA0768, VPA0320, VP0636, VPA1096, VPA0947 and VP1775 were significantly up-regulated at the similar level to blaA in V. parahaemolyticus under AMP stimulation, and their overexpression in V. parahaemolyticus could increase its resistance to AMP. These results indicate that AMP has a global influence on V. parahaemolyticus cells. The findings would provide new insights into the resistant mechanism of V. parahaemolyticus to AMP, which would be helpful for developing novel drugs for treating V. parahaemolyticus infection.
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10
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Huang F, Xu X, Dong H, Li N, Zhong B, Lu H, Liu Q, Feng Y. Catalytic properties and biological function of a PIWI-RE nuclease from Pseudomonas stutzeri. BIORESOUR BIOPROCESS 2022; 9:57. [PMID: 38647609 PMCID: PMC10991935 DOI: 10.1186/s40643-022-00539-x] [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: 02/17/2022] [Accepted: 04/22/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Prokaryotic Argonaute (pAgo) proteins are well-known oligonucleotide-directed endonucleases, which contain a conserved PIWI domain required for endonuclease activity. Distantly related to pAgos, PIWI-RE family, which is defined as PIWI with conserved R and E residues, has been suggested to exhibit divergent activities. The distinctive biochemical properties and physiological functions of PIWI-RE family members need to be elucidated to explore their applications in gene editing. RESULTS Here, we describe the catalytic performance and cellular functions of a PIWI-RE family protein from Pseudomonas stutzeri (PsPIWI-RE). Structural modelling suggests that the protein possesses a PIWI structure similar to that of pAgo, but with different PAZ-like and N-terminal domains. Unlike previously reported pAgos, recombinant PsPIWI-RE acts as an RNA-guided DNA nuclease, as well as a DNA-guided RNA nuclease. It cleaves single-stranded DNA at temperatures ranging from 20 to 65 °C, with an optimum temperature of 45 °C. Mutation at D525 or D610 significantly reduced its endonuclease activity, confirming that both residues are key for catalysis. Comparing with wild-type, mutant with PIWI-RE knockout is more sensitive to ciprofloxacin as DNA replication inhibitor, suggesting PIWI-RE may potentially be involved in DNA replication. CONCLUSION Our study provides the first insights into the programmable nuclease activity and biological function of the unknown PIWI-RE family of proteins, emphasizing their important role in vivo and potential application in genomic DNA modification.
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Affiliation(s)
- Fei Huang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xiaoyi Xu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Huarong Dong
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Nuolan Li
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Bozitao Zhong
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Hui Lu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Qian Liu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Yan Feng
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.
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Lv J, Liu G, Ju Y, Sun Y, Guo W. Prediction of Synergistic Antibiotic Combinations by Graph Learning. Front Pharmacol 2022; 13:849006. [PMID: 35350764 PMCID: PMC8958015 DOI: 10.3389/fphar.2022.849006] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 02/14/2022] [Indexed: 12/31/2022] Open
Abstract
Antibiotic resistance is a major public health concern. Antibiotic combinations, offering better efficacy at lower doses, are a useful way to handle this problem. However, it is difficult for us to find effective antibiotic combinations in the vast chemical space. Herein, we propose a graph learning framework to predict synergistic antibiotic combinations. In this model, a network proximity method combined with network propagation was used to quantify the relationships of drug pairs, and we found that synergistic antibiotic combinations tend to have smaller network proximity. Therefore, network proximity can be used for building an affinity matrix. Subsequently, the affinity matrix was fed into a graph regularization model to predict potential synergistic antibiotic combinations. Compared with existing methods, our model shows a better performance in the prediction of synergistic antibiotic combinations and interpretability.
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Affiliation(s)
- Ji Lv
- College of Computer Science and Technology, Jilin University, Changchun, China.,Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of Education, Jilin University, Changchun, China
| | - Guixia Liu
- College of Computer Science and Technology, Jilin University, Changchun, China.,Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of Education, Jilin University, Changchun, China
| | - Yuan Ju
- Sichuan University Library, Sichuan University, Chengdu, China
| | - Ying Sun
- Department of Respiratory Medicine, The First Hospital of Jilin University, Changchun, China
| | - Weiying Guo
- The First Hospital of Jilin University, Changchun, China
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12
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Tuft S, Somerville TF, Li JPO, Neal T, De S, Horsburgh MJ, Fothergill JL, Foulkes D, Kaye S. Bacterial keratitis: identifying the areas of clinical uncertainty. Prog Retin Eye Res 2021; 89:101031. [PMID: 34915112 DOI: 10.1016/j.preteyeres.2021.101031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 11/24/2021] [Accepted: 11/29/2021] [Indexed: 12/12/2022]
Abstract
Bacterial keratitis is a common corneal infection that is treated with topical antimicrobials. By the time of presentation there may already be severe visual loss from corneal ulceration and opacity, which may persist despite treatment. There are significant differences in the associated risk factors and the bacterial isolates between high income and low- or middle-income countries, so that general management guidelines may not be appropriate. Although the diagnosis of bacterial keratitis may seem intuitive there are multiple uncertainties about the criteria that are used, which impacts the interpretation of investigations and recruitment to clinical studies. Importantly, the concept that bacterial keratitis can only be confirmed by culture ignores the approximately 50% of cases clinically consistent with bacterial keratitis in which investigations are negative. The aetiology of these culture-negative cases is unknown. Currently, the estimation of bacterial susceptibility to antimicrobials is based on data from systemic administration and achievable serum or tissue concentrations, rather than relevant corneal concentrations and biological activity in the cornea. The provision to the clinician of minimum inhibitory concentrations of the antimicrobials for the isolated bacteria would be an important step forward. An increase in the prevalence of antimicrobial resistance is a concern, but the effect this has on disease outcomes is yet unclear. Virulence factors are not routinely assessed although they may affect the pathogenicity of bacteria within species and affect outcomes. New technologies have been developed to detect and kill bacteria, and their application to bacterial keratitis is discussed. In this review we present the multiple areas of clinical uncertainty that hamper research and the clinical management of bacterial keratitis, and we address some of the assumptions and dogma that have become established in the literature.
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Affiliation(s)
- Stephen Tuft
- Moorfields Eye Hospital NHS Foundation Trust, 162 City Road, London, EC1V 2PD, UK.
| | - Tobi F Somerville
- Department of Eye and Vision Sciences, University of Liverpool, 6 West Derby Street, Liverpool, L7 8TX, UK.
| | - Ji-Peng Olivia Li
- Moorfields Eye Hospital NHS Foundation Trust, 162 City Road, London, EC1V 2PD, UK.
| | - Timothy Neal
- Department of Clinical Microbiology, Liverpool Clinical Laboratories, Liverpool University Hospital NHS Foundation Trust, Prescot Street, Liverpool, L7 8XP, UK.
| | - Surjo De
- Department of Clinical Microbiology, University College London Hospitals NHS Foundation Trust, 250 Euston Road, London, NW1 2PG, UK.
| | - Malcolm J Horsburgh
- Department of Infection and Microbiomes, University of Liverpool, Crown Street, Liverpool, L69 7BX, UK.
| | - Joanne L Fothergill
- Department of Eye and Vision Sciences, University of Liverpool, 6 West Derby Street, Liverpool, L7 8TX, UK.
| | - Daniel Foulkes
- Department of Eye and Vision Sciences, University of Liverpool, 6 West Derby Street, Liverpool, L7 8TX, UK.
| | - Stephen Kaye
- Department of Eye and Vision Sciences, University of Liverpool, 6 West Derby Street, Liverpool, L7 8TX, UK.
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13
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Millanao AR, Mora AY, Villagra NA, Bucarey SA, Hidalgo AA. Biological Effects of Quinolones: A Family of Broad-Spectrum Antimicrobial Agents. Molecules 2021; 26:7153. [PMID: 34885734 PMCID: PMC8658791 DOI: 10.3390/molecules26237153] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 10/28/2021] [Accepted: 11/05/2021] [Indexed: 11/28/2022] Open
Abstract
Broad antibacterial spectrum, high oral bioavailability and excellent tissue penetration combined with safety and few, yet rare, unwanted effects, have made the quinolones class of antimicrobials one of the most used in inpatients and outpatients. Initially discovered during the search for improved chloroquine-derivative molecules with increased anti-malarial activity, today the quinolones, intended as antimicrobials, comprehend four generations that progressively have been extending antimicrobial spectrum and clinical use. The quinolone class of antimicrobials exerts its antimicrobial actions through inhibiting DNA gyrase and Topoisomerase IV that in turn inhibits synthesis of DNA and RNA. Good distribution through different tissues and organs to treat Gram-positive and Gram-negative bacteria have made quinolones a good choice to treat disease in both humans and animals. The extensive use of quinolones, in both human health and in the veterinary field, has induced a rise of resistance and menace with leaving the quinolones family ineffective to treat infections. This review revises the evolution of quinolones structures, biological activity, and the clinical importance of this evolving family. Next, updated information regarding the mechanism of antimicrobial activity is revised. The veterinary use of quinolones in animal productions is also considered for its environmental role in spreading resistance. Finally, considerations for the use of quinolones in human and veterinary medicine are discussed.
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Affiliation(s)
- Ana R. Millanao
- Facultad de Ciencias, Instituto de Farmacia, Universidad Austral de Chile, Valdivia 5090000, Chile;
| | - Aracely Y. Mora
- Programa de Doctorado en Bioquímica, Universidad de Chile, Santiago 8380544, Chile;
| | - Nicolás A. Villagra
- Escuela de Tecnología Médica, Universidad Andres Bello, Santiago 8370071, Chile;
| | - Sergio A. Bucarey
- Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago 8820808, Chile;
| | - Alejandro A. Hidalgo
- Escuela de Química y Farmacia, Universidad Andres Bello, Santiago 8370071, Chile
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14
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Alegun O, Pandeya A, Cui J, Ojo I, Wei Y. Donnan Potential across the Outer Membrane of Gram-Negative Bacteria and Its Effect on the Permeability of Antibiotics. Antibiotics (Basel) 2021; 10:antibiotics10060701. [PMID: 34208097 PMCID: PMC8230823 DOI: 10.3390/antibiotics10060701] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 06/01/2021] [Accepted: 06/07/2021] [Indexed: 11/16/2022] Open
Abstract
The cell envelope structure of Gram-negative bacteria is unique, composed of two lipid bilayer membranes and an aqueous periplasmic space sandwiched in between. The outer membrane constitutes an extra barrier to limit the exchange of molecules between the cells and the exterior environment. Donnan potential is a membrane potential across the outer membrane, resulted from the selective permeability of the membrane, which plays a pivotal role in the permeability of many antibiotics. In this review, we discussed factors that affect the intensity of the Donnan potential, including the osmotic strength and pH of the external media, the osmoregulated periplasmic glucans trapped in the periplasmic space, and the displacement of cell surface charges. The focus of our discussion is the impact of Donnan potential on the cellular permeability of selected antibiotics including fluoroquinolones, tetracyclines, β-lactams, and trimethoprim.
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Affiliation(s)
| | | | | | | | - Yinan Wei
- Correspondence: ; Tel.: +1-8592577085
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15
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Meidanchi A. Cobalt ferrite nanoparticles supported on reduced graphene oxide sheets: optical, magnetic and magneto-antibacterial studies. NANOTECHNOLOGY 2020; 31:445704. [PMID: 32693389 DOI: 10.1088/1361-6528/aba7e2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The development of antibacterial nanomaterials has emerged as a strategy to control bacterial activity, due to the growth and spread of antibiotic-resistant pathogen microorganisms. Graphene-based nanocarbons, as one of the most attractive materials, given their extraordinary physical and chemical properties, are promising candidate nanomaterials for biomedical applications. In this study, cobalt ferrite nanoparticles (NPs) supported on reduced graphene oxide (rGO) sheets to form metal nanocomposites (MNCs) known as CoFe2O4@rGO MNCs with different rGO contents (0, 10, 25 and 40 wt%) have been synthesized by a one-step process. The structures, morphology, optical, magnetic and antibacterial properties of the CoFe2O4@rGO were investigated by x-ray diffraction patterns, scanning electron microscopy and transmission electron microscopy images, Raman, Fourier transform infrared (FTIR) and UV-Vis spectroscopies, vibration sample magnetometry and antibacterial tests as a function of rGO content. The particle sizes of the CoFe2O4 NPs supported on the different rGO contents were below 10 nm. The band gap energy of the samples decreased from about 3.1 to 1.7 eV with reducing rGO content. The results prove the effective reduction of graphene oxide to rGO and also the support of CoFe2O4 on rGO sheets by a one-step hydrothermal reaction. The increase in rGO content in the samples reduced their saturated magnetization from about 15 to 7 emu g-1. The CoFe2O4@rGO MNCs have shown magneto-antibacterial activity against gram-negative bacteria (Escherichia coli), whose efficacy depends on the value of the rGO content. In contrast, the CoFe2O4@rGO MNC (25 wt% rGO) which was synthesized by the one-step hydrothermal method not only has a narrow band gap energy (for photocatalytic applications), but also significant magneto-antibacterial activity was observed.
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Affiliation(s)
- Alireza Meidanchi
- Department of Physics, Payame Noor University (PNU), 19395-3697, Tehran, Iran
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16
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Song R, Wang Y, Wang M, Gao R, Yang T, Yang S, Yang CG, Jin Y, Zou S, Cai J, Fan R, He Q. Design and synthesis of novel desfluoroquinolone-aminopyrimidine hybrids as potent anti-MRSA agents with low hERG activity. Bioorg Chem 2020; 103:104176. [PMID: 32891858 DOI: 10.1016/j.bioorg.2020.104176] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 08/04/2020] [Accepted: 08/11/2020] [Indexed: 01/05/2023]
Abstract
Despite the fact that the introduction of a fluorine atom at the C-6 position has resulted in the evolution of fluoroquinolones, fluoroquinolone-induced cardiac toxicity has drawn considerable attention. In this context, desfluoroquinolone-based hybrids with involvement of C-7 aminopyrimidine functional group were designed and synthesized. The biological results showed majority of these hybrids still demonstrated potent anti-MRSA activity with MIC values between 0.38 and 1.5 μg/mL, despite the lack of the typical C-6 fluorine atom. Particularly, the most active B14 exhibited activities at submicromolar concentrations against a panel of MRSA strains including vancomycin-intermediate strains, levofloxacin-resistant isolates, and linezolid-resistant isolates, etc. As expected, it also displayed highly selective toxicity toward bacterial cells and low hERG inhibition. Further resistance development study indicated MRSA is unlikely to acquire resistance against B14. The docking study revealed that two hydrogen bonds were formed between the C-7 substituent and the surrounding DNA bases, which might contribute to overcome resistance by reducing the dependence on the magnesium-water bridge interactions with topoisomerase IV. These results indicate a promising strategy for developing new antibiotic quinolones to combat multidrug resistance and cardiotoxicity.
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Affiliation(s)
- Runzhe Song
- Department of Chemistry, Fudan University, 2005 Songhu Road, Yangpu District, Shanghai 200438, China
| | - Yue Wang
- Department of Chemistry, Fudan University, 2005 Songhu Road, Yangpu District, Shanghai 200438, China
| | - Minghui Wang
- Department of Chemistry, University of South Florida, Tampa, FL 33620, United States
| | - Ruixuan Gao
- Department of Chemistry, University of South Florida, Tampa, FL 33620, United States
| | - Teng Yang
- State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals, Guizhou University, Guiyang 550025, China; State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Song Yang
- State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals, Guizhou University, Guiyang 550025, China
| | - Cai-Guang Yang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Yongsheng Jin
- School of Pharmacy, The Second Military Medical University, Shanghai 200433, China
| | - Siyuan Zou
- Department of Chemistry, Fudan University, 2005 Songhu Road, Yangpu District, Shanghai 200438, China
| | - Jianfeng Cai
- Department of Chemistry, University of South Florida, Tampa, FL 33620, United States.
| | - Renhua Fan
- Department of Chemistry, Fudan University, 2005 Songhu Road, Yangpu District, Shanghai 200438, China.
| | - Qiuqin He
- Department of Chemistry, Fudan University, 2005 Songhu Road, Yangpu District, Shanghai 200438, China.
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17
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Pham TDM, Ziora ZM, Blaskovich MAT. Quinolone antibiotics. MEDCHEMCOMM 2019; 10:1719-1739. [PMID: 31803393 PMCID: PMC6836748 DOI: 10.1039/c9md00120d] [Citation(s) in RCA: 304] [Impact Index Per Article: 60.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 06/09/2019] [Indexed: 12/12/2022]
Abstract
The quinolone antibiotics arose in the early 1960s, with the first examples possessing a narrow-spectrum of activity with unfavorable pharmacokinetic properties. Over time, the development of new quinolone antibiotics has led to improved analogues with an expanded spectrum and high efficacy. Nowadays, quinolones are widely used for treating a variety of infections. Quinolones are broad-spectrum antibiotics that are active against both Gram-positive and Gram-negative bacteria, including mycobacteria, and anaerobes. They exert their actions by inhibiting bacterial nucleic acid synthesis through disrupting the enzymes topoisomerase IV and DNA gyrase, and by causing breakage of bacterial chromosomes. However, bacteria have acquired resistance to quinolones, similar to other antibacterial agents, due to the overuse of these drugs. Mechanisms contributing to quinolone resistance are mediated by chromosomal mutations and/or plasmid gene uptake that alter the topoisomerase targets, modify the quinolone, and/or reduce drug accumulation by either decreased uptake or increased efflux. This review discusses the development of this class of antibiotics in terms of potency, pharmacokinetics and toxicity, along with the resistance mechanisms which reduce the quinolones' activity against pathogens. Potential strategies for future generations of quinolone antibiotics with enhanced activity against resistant strains are suggested.
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Affiliation(s)
- Thu D M Pham
- School of Chemistry & Molecular Biosciences , The University of Queensland , Brisbane , QLD 4072 , Australia
| | - Zyta M Ziora
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , QLD 4072 , Australia .
| | - Mark A T Blaskovich
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , QLD 4072 , Australia .
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18
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Prevalence of Various Vaccine Candidate Proteins in Clinical Isolates of Streptococcus pneumoniae: Characterization of the Novel Pht Fusion Proteins PhtA/B and PhtA/D. Pathogens 2019; 8:pathogens8040162. [PMID: 31554325 PMCID: PMC6963846 DOI: 10.3390/pathogens8040162] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 09/09/2019] [Accepted: 09/23/2019] [Indexed: 12/14/2022] Open
Abstract
Pneumococcal proteins unrelated to serotypes are considered to be candidates of antigens in next-generation vaccines. In the present study, the prevalence of vaccine candidate protein genes, along with serotypes and antimicrobial resistance determinants, was investigated in a total of 57 isolates obtained from a tertiary care hospital in Japan. All of the pediatric isolates and 76.6% of the adult isolates did not belong to PCV13 (a 13-valent pneumococcal conjugate vaccine) serotypes, and 70.2% of all isolates showed multidrug resistance. All of the isolates had ply, pavA, nanA, and nanB, and high prevalence was noted for the pspA and pspC genes (96.5% and 78.9%, respectively). Detection rates for the pneumococcal histidine triad protein (Pht) genes phtA, phtB, phtD, and phtE were 49.1%, 26.3%, 61.4%, and 100%, respectively. Two fusion-type genes, phtA/B and phtA/D, were identified, with a prevalence of 36.9% and 14.0%, respectively. These fusion types showed 78.1–90.0% nucleotide sequence identity with phtA, phtB, and phtD. The most prevalent pht profile was phtA + phtD + phtE (26.3%), followed by phtA/B + phtE (19.3%) and phtA/B + phtD + phtE (17.5%), while pht profiles including phtD and/or phtA/phtD were found in 71.9% of isolates. The present study revealed the presence of two fusion types of Pht and their unexpectedly high prevalence. These fusion types, as well as PhtA and PhtB, contained sequences similar to the B cell epitopes that have been previously reported for PhtD.
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19
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Mohamed NM, Zakaria AS, Edward EA, Abdel-Bary A. In Vitro and In Vivo Activity of Zabofloxacin and Other Fluoroquinolones Against MRSA Isolates from A University Hospital in Egypt. Pol J Microbiol 2019; 68:59-69. [PMID: 31050254 PMCID: PMC7256792 DOI: 10.21307/pjm-2019-007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/09/2018] [Indexed: 11/30/2022] Open
Abstract
The widespread of infections caused by methicillin-resistant Staphylococcus aureus (MRSA), has necessitated the search for alternative therapies; introduction of new agents being a suggestion. This study compares the in vitro and in vivo activities of zabofloxacin, a novel fluoroquinolone, with moxifloxacin, levofloxacin and ciprofloxacin against clinical isolates of MRSA from patients hospitalized in the Alexandria Main University hospital; a tertiary hospital in Alexandria, Egypt, where zabofloxacin has not been yet introduced. The strains tested showed the highest percentage of susceptibility to zabofloxacin (61.2%) among the tested fluoroquinolones with the most effective MIC50 and MIC90 (0.25 and 2 µg/ml, respectively). Time-kill curve analysis revealed a rapid bactericidal activity of zabofloxacin after 6 h of incubation with a quinolone-resistant isolate and complete killing when tested against a quinolone-sensitive isolate with inhibition of regrowth in both cases. PCR amplification and sequencing of QRDRs in selected strains revealed the following amino acid substitutions: Ser-84→Leu in GyrA, Ser-80→Phe in GrlA and Pro-451→Ser in GrlB. The in vivo studies demonstrated that zabofloxacin possessed the most potent protective effect against systemic infection in mice (ED50: 29.05 mg/kg) with lowest count in the dissected lungs (3.66 log10 CFU/ml). The histopathological examination of lung specimens of mice treated with zabofloxacin displayed least congestion, inflammation, oedema and necrosis with clear alveolar spaces and normal vessels. In conclusion, zabofloxacin was proved to possess high in vitro and in vivo efficacy encompassing its comparators and could be considered as a possible candidate for the treatment of infections caused by MRSA. To our knowledge, this is the first study evaluating the in vitro and in vivo activity of zabofloxacin against Egyptian MRSA clinical isolates.
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Affiliation(s)
- Nelly M Mohamed
- Department of Microbiology and Immunology, Faculty of Pharmacy, Alexandria University , Alexandria , Egypt
| | - Azza S Zakaria
- Department of Microbiology and Immunology, Faculty of Pharmacy, Alexandria University , Alexandria , Egypt
| | - Eva A Edward
- Department of Microbiology and Immunology, Faculty of Pharmacy, Alexandria University , Alexandria , Egypt
| | - Amany Abdel-Bary
- Department of Pathology, Faculty of Medicine, Alexandria University , Alexandria , Egypt
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20
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Regulatory Effect of DNA Topoisomerase I on T3SS Activity, Antibiotic Susceptibility and Quorum- Sensing-Independent Pyocyanin Synthesis in Pseudomonas aeruginosa. Int J Mol Sci 2019; 20:ijms20051116. [PMID: 30841529 PMCID: PMC6429228 DOI: 10.3390/ijms20051116] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 02/22/2019] [Accepted: 02/28/2019] [Indexed: 02/04/2023] Open
Abstract
Topoisomerases are required for alleviating supercoiling of DNA during transcription and replication. Recent evidence suggests that supercoiling of bacterial DNA can affect bacterial pathogenicity. To understand the potential regulatory role of a topoisomerase I (TopA) in Pseudomonas aeruginosa, we investigated a previously isolated topA mutation using genetic approaches. We here report the effects of the altered topoisomerase in P. aeruginosa on type III secretion system, antibiotic susceptibility, biofilm initiation, and pyocyanin production. We found that topA was essential in P. aeruginosa, but a transposon mutant lacking the 13 amino acid residues at the C-terminal of the TopA and a mutant, named topA-RM, in which topA was split into three fragments were viable. The reduced T3SS expression in topA-RM seemed to be directly related to TopA functionality, but not to DNA supercoiling. The drastically increased pyocyanin production in the mutant was a result of up-regulation of the pyocyanin related genes, and the regulation was mediated through the transcriptional regulator PrtN, which is known to regulate bacteriocin. The well-established regulatory pathway, quorum sensing, was unexpectedly not involved in the increased pyocyanin synthesis. Our results demonstrated the unique roles of TopA in T3SS activity, antibiotic susceptibility, initial biofilm formation, and secondary metabolite production, and revealed previously unknown regulatory pathways.
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21
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Kawaguchiya M, Urushibara N, Aung MS, Habadera S, Ito M, Kudo K, Kobayashi N. Association Between Pneumococcal Surface Protein A Family and Genetic/Antimicrobial Resistance Traits of Non-Invasive Pneumococcal Isolates from Adults in Northern Japan. Microb Drug Resist 2019; 25:744-751. [PMID: 30676875 DOI: 10.1089/mdr.2018.0267] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Pneumococcal isolates from adult patients in northern Japan in 2016 were subjected to molecular investigation related to pneumococcal surface protein A (PspA) and drug resistance determinants. Of the 51 isolates, serotype 3/ST180 was the most prevalent (17.6%), followed by 35B (ST2755/ST558) (11.8%) and 15A (ST63/ST7874/ST13068/ST13785) (9.8%). Coverage of serotypes by 13-valent conjugate vaccine and 23-valent polysaccharide vaccine was 27.5% and 49%, respectively. All the isolates expressed PspA family 1 or 2 (51% and 49%, respectively). Each serotype was associated with either of the PspA families (e.g., serotype 3, PspA family 1; serotypes 35B and 15A, PspA family 2). Multidrug resistance (MDR) was found in 84.3% of the isolates. Minimum of one altered penicillin-binding protein gene was detected in 82.4% of isolates, indicating 25.5% non-susceptibility to penicillin. Serotypes 15A and 35B were predominant and demonstrated MDR. An isolate of serotype 15A/ST13785 (single-locus variant of ST242) was resistant to fluoroquinolones associated with double mutation in the quinolone resistance-determining regions of gyrA and parC. The present study indicates the spread of MDR pneumococci represented by isolates of serotypes 3, 15A, and 35B, and prevalence of both PspA family 1 and 2 in isolates obtained from adult patients.
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Affiliation(s)
- Mitsuyo Kawaguchiya
- 1 Department of Hygiene, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Noriko Urushibara
- 1 Department of Hygiene, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Meiji Soe Aung
- 1 Department of Hygiene, Sapporo Medical University School of Medicine, Sapporo, Japan
| | | | - Masahiko Ito
- 2 Sapporo Clinical Laboratory, Inc., Sapporo, Japan
| | - Kenji Kudo
- 2 Sapporo Clinical Laboratory, Inc., Sapporo, Japan
| | - Nobumichi Kobayashi
- 1 Department of Hygiene, Sapporo Medical University School of Medicine, Sapporo, Japan
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22
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Ostrer L, Khodursky RF, Johnson JR, Hiasa H, Khodursky A. Analysis of mutational patterns in quinolone resistance-determining regions of GyrA and ParC of clinical isolates. Int J Antimicrob Agents 2018; 53:318-324. [PMID: 30582984 DOI: 10.1016/j.ijantimicag.2018.12.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 12/15/2018] [Indexed: 01/03/2023]
Abstract
Fluoroquinolone (FQ)-resistant bacteria pose a major global health threat. Unanalysed genomic data from thousands of sequenced microbes likely contain important hints regarding the evolution of FQ resistance, yet this information lies fallow. Here we analysed the co-occurrence patterns of quinolone resistance mutations in genes encoding the FQ drug targets DNA gyrase (gyrase) and topoisomerase IV (topo-IV) from 36,402 bacterial genomes, representing 10 Gram-positive and 10 Gram-negative species. For 19 species, the likeliest routes toward resistance mutations in both targets were determined, and for 5 species those mutations necessary and sufficient to predict FQ resistance were also determined. Target mutation hierarchy was fixed in all examined Gram-negative species, with gyrase being the primary and topo-IV the secondary quinolone target, as well as in six of nine Gram-positive species, with topo-IV being the primary and gyrase the secondary target. By contrast, in three Gram-positive species (Staphylococcus haemolyticus, Streptococcus pneumoniae and Streptococcus suis), under some conditions gyrase became the primary and topo-IV the secondary target. The path through individual resistance mutations varied by species. Both linear and branched paths were identified in Gram-positive and Gram-negative organisms alike. Finally, FQ resistance could be predicted based solely on target gene quinolone resistance mutations for Acinetobacter baumannii, Escherichia coli and Staphylococcus aureus, but not Klebsiella pneumoniae or Pseudomonas aeruginosa. These findings have important implications both for sequence-based diagnostics and for understanding the emergence of FQ resistance.
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Affiliation(s)
- Lev Ostrer
- Department of Biochemistry, Molecular Biology and Biophysics, Biotechnology Institute, University of Minnesota, St Paul, MN, USA
| | - Rachel F Khodursky
- Department of Biochemistry, Molecular Biology and Biophysics, Biotechnology Institute, University of Minnesota, St Paul, MN, USA
| | | | - Hiroshi Hiasa
- Department of Pharmacology, University of Minnesota Medical School, 6-120 Jackson Hall, 321 Church Street SE, Minneapolis, MN, USA
| | - Arkady Khodursky
- Department of Biochemistry, Molecular Biology and Biophysics, Biotechnology Institute, University of Minnesota, St Paul, MN, USA.
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23
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Ktari S, Ben Ayed NEH, Jmal I, Mnif B, Mezghani S, Rhimi F, Hammami A. Clinical levofloxacin-resistant Streptococcus pneumoniae isolates in North Africa. J Glob Antimicrob Resist 2018; 12:181-182. [PMID: 29425693 DOI: 10.1016/j.jgar.2018.01.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 01/29/2018] [Accepted: 01/30/2018] [Indexed: 10/18/2022] Open
Affiliation(s)
- Sonia Ktari
- University of Sfax, Faculty of Medicine of Sfax, Sfax, Tunisia; Laboratory of Microbiology, Habib Bourguiba University Hospital, Sfax, MPH LR03SP03, Tunisia.
| | - Nour El Houda Ben Ayed
- University of Sfax, Faculty of Medicine of Sfax, Sfax, Tunisia; Laboratory of Microbiology, Habib Bourguiba University Hospital, Sfax, MPH LR03SP03, Tunisia.
| | - Ikram Jmal
- University of Sfax, Faculty of Medicine of Sfax, Sfax, Tunisia; Laboratory of Microbiology, Habib Bourguiba University Hospital, Sfax, MPH LR03SP03, Tunisia.
| | - Basma Mnif
- University of Sfax, Faculty of Medicine of Sfax, Sfax, Tunisia; Laboratory of Microbiology, Habib Bourguiba University Hospital, Sfax, MPH LR03SP03, Tunisia.
| | - Sonda Mezghani
- University of Sfax, Faculty of Medicine of Sfax, Sfax, Tunisia; Laboratory of Microbiology, Habib Bourguiba University Hospital, Sfax, MPH LR03SP03, Tunisia.
| | - Faouzia Rhimi
- University of Sfax, Faculty of Medicine of Sfax, Sfax, Tunisia; Laboratory of Microbiology, Habib Bourguiba University Hospital, Sfax, MPH LR03SP03, Tunisia.
| | - Adnene Hammami
- University of Sfax, Faculty of Medicine of Sfax, Sfax, Tunisia; Laboratory of Microbiology, Habib Bourguiba University Hospital, Sfax, MPH LR03SP03, Tunisia.
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24
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Park M, Kim HS, Kim HS, Park JY, Song W, Cho HC, Kim JS. Novel Levofloxacin-Resistant Multidrug-Resistant Streptococcus pneumoniae Serotype 11A Isolates, South Korea. Emerg Infect Dis 2018; 22:1978-1980. [PMID: 27767906 PMCID: PMC5088008 DOI: 10.3201/eid2211.151450] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Of 608 Streptococcus pneumoniae clinical strains isolated at a hospital in South Korea during 2009–2014, sixteen (2.6%) were identified as levofloxacin resistant. The predominant serotype was 11A (9 isolates). Two novel sequence types of multidrug-resistant S. pneumoniae with serotype 11A were identified, indicating continuous diversification of resistant strains.
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25
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Mutant selection window of four quinolone antibiotics against clinical isolates of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. J Infect Chemother 2017; 24:83-87. [PMID: 29290527 DOI: 10.1016/j.jiac.2017.08.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 07/18/2017] [Accepted: 08/16/2017] [Indexed: 11/23/2022]
Abstract
Community-acquired pneumonia and otitis media are caused by several bacterial species, including Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. For the treatment of these diseases, various quinolones are frequently used. We determined the mutant prevention concentration (MPC) of four quinolones, levofloxacin, sitafloxacin, tosufloxacin, and garenoxacin, using 92 clinical isolates and evaluated each mutant selection window (MSW). Furthermore, the DNA sequence of the quinolone resistance-determining region (QRDR) for the resistant mutant selected based on the MSW was determined. The MIC90 and MPC90 of levofloxacin were 0.781 μg/mL and 6.250 μg/mL for S. pneumoniae and 0.049 μg/mL and 1.563 μg/mL for M. catarrhalis and were higher than those for the other three quinolones. In addition, 5 strains of 30 S. pneumoniae (16.7%) selected based on the MSW of levofloxacin acquired resistance to only levofloxacin. In these 5 strains, a mutation of gyrA and/or parC was detected. In this study, no resistant mutant was selected in the MSW of any of the other three quinolones. On the other hand, clinical isolates of H. influenzae showed no resistance by all quinolone exposure. Finally, The MIC value and the mutation status in the QRDR did not change after 14 passages in antibiotic-free medium. In conclusion, our findings suggest that the increased use of levofloxacin may contribute to the increased quinolone-resistance of S. pneumoniae and M. catarrhalis.
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26
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Ashley RE, Dittmore A, McPherson SA, Turnbough CL, Neuman KC, Osheroff N. Activities of gyrase and topoisomerase IV on positively supercoiled DNA. Nucleic Acids Res 2017; 45:9611-9624. [PMID: 28934496 PMCID: PMC5766186 DOI: 10.1093/nar/gkx649] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 07/14/2017] [Indexed: 11/12/2022] Open
Abstract
Although bacterial gyrase and topoisomerase IV have critical interactions with positively supercoiled DNA, little is known about the actions of these enzymes on overwound substrates. Therefore, the abilities of Bacillus anthracis and Escherichia coli gyrase and topoisomerase IV to relax and cleave positively supercoiled DNA were analyzed. Gyrase removed positive supercoils ∼10-fold more rapidly and more processively than it introduced negative supercoils into relaxed DNA. In time-resolved single-molecule measurements, gyrase relaxed overwound DNA with burst rates of ∼100 supercoils per second (average burst size was 6.2 supercoils). Efficient positive supercoil removal required the GyrA-box, which is necessary for DNA wrapping. Topoisomerase IV also was able to distinguish DNA geometry during strand passage and relaxed positively supercoiled substrates ∼3-fold faster than negatively supercoiled molecules. Gyrase maintained lower levels of cleavage complexes with positively supercoiled (compared with negatively supercoiled) DNA, whereas topoisomerase IV generated similar levels with both substrates. Results indicate that gyrase is better suited than topoisomerase IV to safely remove positive supercoils that accumulate ahead of replication forks. They also suggest that the wrapping mechanism of gyrase may have evolved to promote rapid removal of positive supercoils, rather than induction of negative supercoils.
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Affiliation(s)
- Rachel E Ashley
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA
| | - Andrew Dittmore
- Laboratory of Single Molecule Biophysics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20982, USA
| | - Sylvia A McPherson
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Charles L Turnbough
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Keir C Neuman
- Laboratory of Single Molecule Biophysics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20982, USA
| | - Neil Osheroff
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA.,VA Tennessee Valley Healthcare System, Nashville, TN 37212, USA.,Department of Medicine (Hematology/Oncology), Vanderbilt University School of Medicine, Nashville, TN 37232-6307, USA
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27
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Simoni S, Vincenzi C, Brenciani A, Morroni G, Bagnarelli P, Giovanetti E, Varaldo PE, Mingoia M. Molecular Characterization of Italian Isolates of Fluoroquinolone-Resistant Streptococcus agalactiae and Relationships with Chloramphenicol Resistance. Microb Drug Resist 2017; 24:225-231. [PMID: 28783417 DOI: 10.1089/mdr.2017.0139] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A total number of 368 clinical isolates of Streptococcus agalactiae (group B Streptococcus, GBS) were collected in 2010-2016 from three hospitals in a region of central Italy. Fluoroquinolone (FQ)-resistant isolates were selected using levofloxacin. Levofloxacin-resistant (LR) strains (11/368, 2.99%) were characterized for several features, and their FQ resistance was analyzed phenotypically and genotypically using seven additional FQs. Their gyrA and parC quinolone resistance-determining regions were sequenced. Of the 11 LR isolates, 10 showed high-level and 1 low-level resistance. The former isolates exhibited higher minimal inhibitory concentrations also of the other FQs and all shared one amino acid substitution in ParC (Ser79Phe) and one in GyrA (Ser81Leu); only Ser79Phe in ParC was detected in the low-level LR isolate. The 11 LR strains exhibited distinctive relationships between their susceptibilities to non-FQ antibiotics and typing data. Remarkably, despite the very rare occurrence of chloramphenicol resistance in S. agalactiae, no <4 of the 11 LR isolates were chloramphenicol-resistant. Studies of GBS resistance to FQs in Europe remain scarce, notwithstanding the emergence of multidrug-resistant isolates. The incidence of LR GBS isolates is still limited in Italy, consistent with the moderate (though growing) rates reported in Europe, and much lower than the very high rates reported in East Asia. The intriguing relationships between FQ and chloramphenicol resistance deserve further investigation.
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Affiliation(s)
- Serena Simoni
- 1 Department of Biomedical Sciences and Public Health, Polytechnic University of Marche Medical School , Ancona, Italy
| | - Chiara Vincenzi
- 1 Department of Biomedical Sciences and Public Health, Polytechnic University of Marche Medical School , Ancona, Italy .,2 Clinical Microbiology Laboratory, Torrette Regional Hospital , Ancona, Italy
| | - Andrea Brenciani
- 1 Department of Biomedical Sciences and Public Health, Polytechnic University of Marche Medical School , Ancona, Italy
| | - Gianluca Morroni
- 1 Department of Biomedical Sciences and Public Health, Polytechnic University of Marche Medical School , Ancona, Italy
| | - Patrizia Bagnarelli
- 1 Department of Biomedical Sciences and Public Health, Polytechnic University of Marche Medical School , Ancona, Italy
| | - Eleonora Giovanetti
- 3 Department of Life and Environmental Sciences, Polytechnic University of Marche , Ancona, Italy
| | - Pietro E Varaldo
- 1 Department of Biomedical Sciences and Public Health, Polytechnic University of Marche Medical School , Ancona, Italy
| | - Marina Mingoia
- 1 Department of Biomedical Sciences and Public Health, Polytechnic University of Marche Medical School , Ancona, Italy
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28
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Sang Q, Williams GR, Wu H, Liu K, Li H, Zhu LM. Electrospun gelatin/sodium bicarbonate and poly(lactide-co-ε-caprolactone)/sodium bicarbonate nanofibers as drug delivery systems. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2017; 81:359-365. [PMID: 28887984 DOI: 10.1016/j.msec.2017.08.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 07/20/2017] [Accepted: 08/02/2017] [Indexed: 12/17/2022]
Abstract
In this work, we report electrospun nanofibers made of model hydrophobic (poly(lactide-co-ε-caprolactone); PLCL) and hydrophilic (gelatin) polymers. We explored the effect on drug release of the incorporation of sodium bicarbonate (SB) into these fibers, using the potent antibacterial agent ciprofloxacin as a model drug. The fibers prepared are smooth and have relatively uniform diameters lying between ca. 600 and 850nm. The presence of ciprofloxacin in the fibers was confirmed using IR spectroscopy. X-ray diffraction showed the drug to be incorporated into the fibers in the amorphous form. In vitro drug release studies revealed that, as expected, more rapid drug release was seen with gelatin fibers than those made of PLCL, and a greater final release percentage was obtained. The inclusion of SB in the gelatin fibers imparts them with pH sensitivity: gelatin/SB fibers showed faster release at pH5 than pH7.4, while fibers without SB gave the same release profiles at both pHs. The PLCL fibers have no pH sensitivity, even when SB was included, as a result of their hydrophobic structure precluding the ingress of solvent. In vitro cell culture studies showed that all the fibers are able to promote cell proliferation. The ciprofloxacin loaded fibers are effective in inhibiting Escherichia coli and Staphylococcus aureus growth in antibacterial tests. Thus, the gelatin-based fibers can be used as pH-responsive drug delivery systems, with potential applications for instance in the treatment of tumor resection sites. Should these become infected, the pH would drop, resulting in ciprofloxacin being released and the infection halted.
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Affiliation(s)
- Qingqing Sang
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China
| | - Gareth R Williams
- UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Huanling Wu
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China
| | - Kailin Liu
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China
| | - Heyu Li
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China
| | - Li-Min Zhu
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China; Key Laboratory of Science & Technology of Eco-Textiles, Ministry of Education, Donghua University, Shanghai 201620, China.
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29
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Ashley RE, Lindsey RH, McPherson SA, Turnbough CL, Kerns RJ, Osheroff N. Interactions between Quinolones and Bacillus anthracis Gyrase and the Basis of Drug Resistance. Biochemistry 2017; 56:4191-4200. [PMID: 28708938 PMCID: PMC5560241 DOI: 10.1021/acs.biochem.7b00203] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
![]()
Gyrase appears to
be the primary cellular target for quinolone
antibacterials in multiple pathogenic bacteria, including Bacillus anthracis, the causative agent of anthrax. Given
the significance of this type II topoisomerase as a drug target, it
is critical to understand how quinolones interact with gyrase and
how specific mutations lead to resistance. However, these important
issues have yet to be addressed for a canonical gyrase. Therefore,
we utilized a mechanistic approach to characterize interactions of
quinolones with wild-type B. anthracis gyrase and
enzymes containing the most common quinolone resistance mutations.
Results indicate that clinically relevant quinolones interact with
the enzyme through a water–metal ion bridge in which a noncatalytic
divalent metal ion is chelated by the C3/C4 keto acid of the drug.
In contrast to other bacterial type II topoisomerases that have been
examined, the bridge is anchored to gyrase primarily through a single
residue (Ser85). Substitution of groups at the quinolone C7 and C8
positions generated drugs that were less dependent on the water–metal
ion bridge and overcame resistance. Thus, by analyzing the interactions
of drugs with type II topoisomerases from individual bacteria, it
may be possible to identify specific quinolone derivatives that can
overcome target-mediated resistance in important pathogenic species.
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Affiliation(s)
| | | | - Sylvia A McPherson
- Department of Microbiology, University of Alabama at Birmingham , Birmingham, Alabama 35294, United States
| | - Charles L Turnbough
- Department of Microbiology, University of Alabama at Birmingham , Birmingham, Alabama 35294, United States
| | - Robert J Kerns
- Department of Pharmaceutical Sciences and Experimental Therapeutics, University of Iowa College of Pharmacy , Iowa City, Iowa 52242, United States
| | - Neil Osheroff
- VA Tennessee Valley Healthcare System , Nashville, Tennessee 37212, United States
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30
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Schmitz J, van der Linden M, Al-Lahham A, Levina N, Pletz MW, Imöhl M. Fluoroquinolone resistance in Streptococcus pneumoniae isolates in Germany from 2004-2005 to 2014-2015. Int J Med Microbiol 2017; 307:216-222. [PMID: 28506425 DOI: 10.1016/j.ijmm.2017.04.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 04/11/2017] [Accepted: 04/16/2017] [Indexed: 11/18/2022] Open
Abstract
Streptococcus pneumoniae is a major cause of bacterial pneumonia, sepsis and meningitis worldwide. Prevalence of levofloxacin-resistant S. pneumoniae isolates in Germany and associated mutations in the quinolone resistance determining regions (QRDRs), as well as serotype distribution and multi locus sequence types (MLST) are shown. 21,764 invasive S. pneumoniae isolates from Germany, isolated in the epidemiological seasons from 2004/05 to 2014/15 were analyzed at the German National Reference Centre for Streptococci (GNRCS) for their levofloxacin resistance by micro broth dilution method. All resistant (minimal inhibitory concentration (MIC) ≥8μg/ml) and intermediate (MIC >2μg/ml and <8μg/ml) isolates were selected for the present study. Additionally, 29 susceptible isolates were randomly selected. A total of ninety isolates were tested for their levofloxacin-MIC by Etest, their serotype and sequence type, as well as for point-mutations at the QRDRs in the genes parC, parE, gyrA and gyrB. Twenty-five isolates exhibited levofloxacin MICs <2μg/ml (Etest) and no mutations in the QRDRs. Four isolates with MICs=2μg/ml had one mutation in parC; isolates with MICs >2μg/ml all had one or more mutations in the QRDRs. Four of nine intermediate isolates had a mutation in either parC or gyrA, and four isolates had mutations in both parC and gyrB. One isolate had mutations in both parC and gyrA. All isolates with MICs ≥8μg/ml (52) had mutations in both topoisomerase IV and gyrase. Serotypes associated with levofloxacin resistance shifted from a majority of PCV13 serotypes before the introduction of the PCV13 vaccine towards non-PCV serotypes. Resistant isolates were almost exclusively found among adults (98.1%).
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Affiliation(s)
- Julia Schmitz
- Institute of Medical Microbiology, National Reference Center for Streptococci, University Hospital (RWTH), Aachen, Germany.
| | - Mark van der Linden
- Institute of Medical Microbiology, National Reference Center for Streptococci, University Hospital (RWTH), Aachen, Germany
| | - Adnan Al-Lahham
- School of Applied Medical Sciences, German Jordanian University, Amman, Jordan
| | - Natalia Levina
- Institute of Medical Microbiology, National Reference Center for Streptococci, University Hospital (RWTH), Aachen, Germany
| | - Mathias W Pletz
- Center for Infectious Diseases and Infection Control, Jena University Hospital, Jena, Germany
| | - Matthias Imöhl
- Institute of Medical Microbiology, National Reference Center for Streptococci, University Hospital (RWTH), Aachen, Germany
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31
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Takeuchi N, Ohkusu M, Hoshino T, Naito S, Takaya A, Yamamoto T, Ishiwada N. Emergence of quinolone-resistant strains in Streptococcus pneumoniae isolated from paediatric patients since the approval of oral fluoroquinolones in Japan. J Infect Chemother 2017; 23:218-223. [PMID: 28159338 DOI: 10.1016/j.jiac.2016.12.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 11/17/2016] [Accepted: 12/19/2016] [Indexed: 11/30/2022]
Abstract
Tosufloxacin (TFLX) is a fluoroquinolone antimicrobial agent. TFLX granules for children were initially released in Japan in 2010 to treat otitis media and pneumonia caused by drug-resistant bacteria, e.g. penicillin-resistant Streptococcus pneumoniae and beta-lactamase-negative, ampicillin-resistant Haemophilus influenzae. The evolution of bacterial resistance since TFLX approval is not known. To clarify the influence of quinolones administered to children since their approval, we examined the resistance mechanism of TFLX-resistant S. pneumoniae isolated from paediatric patients as well as patient clinical characteristics. TFLX-resistant strains (MIC ≥ 2 mg/L) were detected among clinical isolates of S. pneumoniae derived from children (≤15 years old) between 2010 and 2014. These strains were characterised based on quinolone resistance-determining regions (QRDRs), i.e. gyrA, gyrB, parC, and parE. In addition, the antimicrobial susceptibility, serotype, and multilocus sequence type of strains were determined, pulsed-field gel electrophoresis was performed, and patient clinical characteristics based on medical records were assessed for cases with underling TFLX-resistant strains. Among 1168 S. pneumoniae isolates, two TFLX-resistant strains were detected from respiratory specimens obtained from paediatric patients with frequent exposure to TFLX. Both strains had mutations in the QRDRs of gyrA and parC. One case exhibited gradual changes in the QRDR during the clinical course. This is the first study of quinolone-resistant S. pneumoniae isolated from children, including clinical data, in Japan. These data may help prevent increases in infections of quinolone-resistant S. pneumoniae in children; specifically, the results emphasise the importance of administering fluoroquinolones only in appropriate cases.
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Affiliation(s)
- Noriko Takeuchi
- Department of Infectious Diseases, Medical Mycology Research Center, Chiba University, Chiba, Japan.
| | - Misako Ohkusu
- Department of Infectious Diseases, Medical Mycology Research Center, Chiba University, Chiba, Japan
| | - Tadashi Hoshino
- Division of Infectious Diseases, Chiba Children's Hospital, Chiba, Japan
| | - Sachiko Naito
- Department of Pediatrics, Chiba University Hospital, Chiba, Japan
| | - Akiko Takaya
- Department of Microbiology and Molecular Genetics, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan
| | - Tomoko Yamamoto
- Department of Infectious Diseases, Medical Mycology Research Center, Chiba University, Chiba, Japan
| | - Naruhiko Ishiwada
- Department of Infectious Diseases, Medical Mycology Research Center, Chiba University, Chiba, Japan
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32
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Laponogov I, Pan XS, Veselkov DA, Cirz RT, Wagman A, Moser HE, Fisher LM, Sanderson MR. Exploring the active site of the Streptococcus pneumoniae topoisomerase IV-DNA cleavage complex with novel 7,8-bridged fluoroquinolones. Open Biol 2016; 6:rsob.160157. [PMID: 27655731 PMCID: PMC5043579 DOI: 10.1098/rsob.160157] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 08/26/2016] [Indexed: 12/16/2022] Open
Abstract
As part of a programme of synthesizing and investigating the biological properties of new fluoroquinolone antibacterials and their targeting of topoisomerase IV from Streptococcus pneumoniae, we have solved the X-ray structure of the complexes of two new 7,8-bridged fluoroquinolones (with restricted C7 group rotation favouring tight binding) in complex with the topoisomerase IV from S. pneumoniae and an 18-base-pair DNA binding site—the E-site—found by our DNA mapping studies to bind drug strongly in the presence of topoisomerase IV (Leo et al. 2005 J. Biol. Chem.280, 14 252–14 263, doi:10.1074/jbc.M500156200). Although the degree of antibiotic resistance towards fluoroquinolones is much lower than that of β-lactams and a range of ribosome-bound antibiotics, there is a pressing need to increase the diversity of members of this successful clinically used class of drugs. The quinolone moiety of the new 7,8-bridged agents ACHN-245 and ACHN-454 binds similarly to that of clinafloxocin, levofloxacin, moxifloxacin and trovofloxacin but the cyclic scaffold offers the possibility of chemical modification to produce interactions with other topoisomerase residues at the active site.
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Affiliation(s)
- Ivan Laponogov
- Randall Division of Cell and Molecular Biophysics, King's College, Guy's Campus, London Bridge, London SE1 1UL, UK Molecular and Clinical Sciences Research Institute, St George's, University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Xiao-Su Pan
- Molecular and Clinical Sciences Research Institute, St George's, University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Dennis A Veselkov
- Randall Division of Cell and Molecular Biophysics, King's College, Guy's Campus, London Bridge, London SE1 1UL, UK
| | - Ryan T Cirz
- Achaogen, 7000 Shoreline Ct. No. 371, San Francisco, CA 94080, USA
| | - Allan Wagman
- Achaogen, 7000 Shoreline Ct. No. 371, San Francisco, CA 94080, USA
| | - Heinz E Moser
- Achaogen, 7000 Shoreline Ct. No. 371, San Francisco, CA 94080, USA
| | - L Mark Fisher
- Molecular and Clinical Sciences Research Institute, St George's, University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Mark R Sanderson
- Randall Division of Cell and Molecular Biophysics, King's College, Guy's Campus, London Bridge, London SE1 1UL, UK
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33
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Yan Y, Hu H, Lu T, Fan H, Hu Y, Li G, Zhang X, Shi Y, Xia R. Investigation of serotype distribution and resistance genes profile in group B Streptococcus isolated from pregnant women: a Chinese multicenter cohort study. APMIS 2016; 124:794-9. [PMID: 27452669 DOI: 10.1111/apm.12570] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 05/20/2016] [Indexed: 11/29/2022]
Abstract
We surveyed the group B Streptococcus (GBS) strains isolated from four teaching hospitals during 1-year period to investigate the current serotypes and antimicrobial resistance status of these strains. A total of 231 non-duplicate colonizing GBS isolates were collected from pregnant women. Antimicrobial susceptibility of these isolates was tested by the disk diffusion method. Serotype was performed by a multiplex polymerase chain reaction (PCR) method. Analysis of the resistance mechanisms was performed by PCR amplification and DNA sequencing. Seven serotypes (Ia, Ib, II, III, V, VI, and VIII) were identified, and the prevalence ranged from 0.9 to 35.9%. All isolates were susceptible to the penicillin, ceftriaxone, and vancomycin. The resistance of all the isolates to erythromycin, clindamycin, and levofloxacin was 61.5, 51.9, and 35.5%, respectively. The erythromycin resistance was mainly associated with the genes ermB and ermB-mef(A/E) (69.8%). The most predominant phenotype was cMLSB (77.5%). Five gene panels, including gyrA, parC, parE, gyrA-parC, and gyrA-parC-parE, were detected. The most predominant genotype was gyrA-parC-parE triple mutation (69.5%). The S81L in gyrA gene, S79Y mutation in parC gene, and H225Y mutation in parE gene were discovered. The isolates with serotype III, V, and Ia were the most important clone concerning the prevalence and resistance.
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Affiliation(s)
- Yuzhong Yan
- Department of Transfusion Medicine, Shanghai Huashan Hospital, Fudan University, Shanghai, China.,Department of Clinical Laboratory, Shanghai Pudong Hospital, Fudan University, Shanghai, China
| | - Hua Hu
- Department of Gynaecology and Obstetrics, Shanghai Pudong Hospital, Fudan University, Shanghai, China
| | - Tingyan Lu
- Department of Clinical Laboratory, Shanghai International Peace Maternity & Child Health Hospital, Jiaotong University, Shanghai, China
| | - Huiqing Fan
- Department of Clinical Laboratory, Shanghai Pudong Hospital, Fudan University, Shanghai, China
| | - Yan Hu
- Department of Clinical Laboratory, Shanghai Pudong Hospital, Fudan University, Shanghai, China
| | - Gang Li
- Department of Clinical Laboratory, Shanghai Huashan Hospital, Fudan University, Shanghai, China
| | - Xianhua Zhang
- Department of Clinical Laboratory, Shanghai First Maternity & Infant Hospital, Tongji University, Shanghai, China
| | - Yi Shi
- Department of Clinical Laboratory, Shanghai Pudong Hospital, Fudan University, Shanghai, China
| | - Rong Xia
- Department of Transfusion Medicine, Shanghai Huashan Hospital, Fudan University, Shanghai, China
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34
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Tan L, Zhang Z, Gao D, Luo J, Tu ZC, Li Z, Peng L, Ren X, Ding K. 4-Oxo-1,4-dihydroquinoline-3-carboxamide Derivatives as New Axl Kinase Inhibitors. J Med Chem 2016; 59:6807-25. [PMID: 27379978 DOI: 10.1021/acs.jmedchem.6b00608] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Li Tan
- State
Key Laboratory of Respiratory Diseases, Guangzhou Institutes of Biomedicine
and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Guangzhou 510530, China
- University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China
| | - Zhang Zhang
- State
Key Laboratory of Respiratory Diseases, Guangzhou Institutes of Biomedicine
and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Guangzhou 510530, China
- School
of Pharmacy, Jinan University, 601 Huangpu Avenue West, Guangzhou 510632, China
| | - Donglin Gao
- State
Key Laboratory of Respiratory Diseases, Guangzhou Institutes of Biomedicine
and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Guangzhou 510530, China
- University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China
| | - Jinfeng Luo
- State
Key Laboratory of Respiratory Diseases, Guangzhou Institutes of Biomedicine
and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Guangzhou 510530, China
| | - Zheng-Chao Tu
- State
Key Laboratory of Respiratory Diseases, Guangzhou Institutes of Biomedicine
and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Guangzhou 510530, China
| | - Zhengqiu Li
- School
of Pharmacy, Jinan University, 601 Huangpu Avenue West, Guangzhou 510632, China
| | - Lijie Peng
- School
of Pharmacy, Jinan University, 601 Huangpu Avenue West, Guangzhou 510632, China
| | - Xiaomei Ren
- State
Key Laboratory of Respiratory Diseases, Guangzhou Institutes of Biomedicine
and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Guangzhou 510530, China
- School
of Pharmacy, Jinan University, 601 Huangpu Avenue West, Guangzhou 510632, China
| | - Ke Ding
- State
Key Laboratory of Respiratory Diseases, Guangzhou Institutes of Biomedicine
and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Guangzhou 510530, China
- School
of Pharmacy, Jinan University, 601 Huangpu Avenue West, Guangzhou 510632, China
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35
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Abstract
DNA gyrase and topoisomerase IV are type IIA bacterial topoisomerases that are targeted by highly effective antibiotics. However, resistance via multiple mechanisms arises to limit the efficacies of these drugs. Continued research on type IIA bacterial topoisomerases has provided novel approaches to counter the most common resistance mechanism for utilization of these proven targets in antibacterial therapy. Bacterial topoisomerase I is being explored as an alternative target that is not expected to show cross-resistance. Dual targeting or combination therapy could be strategies for circumventing the development of resistance to topoisomerase-targeting antibiotics. Bacterial topoisomerases are high-value bactericidal targets that could continue to be exploited for antibacterial therapy, if new tactics to counter resistance can be adopted.
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Roychoudhury S, Makin K, Twinem T, Leunk R, Hsu MC. In Vitro Resistance Development to Nemonoxacin in Streptococcus pneumoniae: A Unique Profile for a Novel Nonfluorinated Quinolone. Microb Drug Resist 2016; 22:578-584. [PMID: 27267788 PMCID: PMC5073217 DOI: 10.1089/mdr.2016.0021] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Selection of resistant strains in Streptococcus pneumoniae was studied in vitro with nemonoxacin, a novel nonfluorinated quinolone (NFQ), in comparison with quinolone benchmarks, ciprofloxacin, garenoxacin, and gatifloxacin. In stepwise resistance selection studies, a 256-fold loss of potency was observed after three to four steps of exposure to ciprofloxacin or garenoxacin. In contrast, the loss of potency was limited to eightfold after three steps of exposure to nemonoxacin and repeated attempts to isolate highly resistant organisms after four steps of exposure yielded isolates that could not be subcultured in liquid medium. The quinolone resistance-determining regions of the target genes, parC, parE, gyrA, and gyrB, were analyzed through DNA sequencing. Known mutations, especially in the hotspots of parC and gyrA, were selected with exposure to garenoxacin, ciprofloxacin, and gatifloxacin. In contrast, mutations selected with nemonoxacin were limited to GyrA, GyrB, and ParE, sparing ParC, which is known as a key driver of resistance in clinical isolates of S. pneumoniae. This observation is consistent with previous data using other NFQs, which showed no loss of potency due to ParC mutations in clinical isolates. This apparently unique feature of nemonoxacin is potentially attributable to the structural uniqueness of the NFQs, distinguishing them from the fluoroquinolones that are commonly prescribed for infections by S. pneumoniae.
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Affiliation(s)
| | | | | | | | - Ming Chu Hsu
- 2 TaiGen Biotechnology Co., Ltd. , Taipei, Taiwan
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37
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Ubukata K, Chiba N, Hanada S, Morozumi M, Wajima T, Shouji M, Iwata S. Serotype Changes and Drug Resistance in Invasive Pneumococcal Diseases in Adults after Vaccinations in Children, Japan, 2010-2013. Emerg Infect Dis 2016; 21:1956-65. [PMID: 26485679 PMCID: PMC4622236 DOI: 10.3201/eid2111.142029] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Pneumococcal conjugate vaccination of children is associated with penicillin-resistant Streptococcus pneumoniae in adults. After 7-valent pneumococcal conjugate vaccine (PCV) for children was introduced in Japan in November 2010, we examined changes in Streptococcus pneumoniae serotypes and in genetic antimicrobial drug resistance of isolates from adults with invasive pneumococcal diseases. During April 2010–March 2013, a total of 715 isolates were collected from adults with invasive pneumococcal diseases. Seven-valent PCV serotypes in adults decreased from 43.3% to 23.8%, most noticeably for serotype 6B. Concomitantly, 23-valent pneumococcal polysaccharide vaccine (PPSV23) serotypes decreased from 82.2% to 72.2%; non-PPSV23 serotypes increased from 13.8% to 25.1%. Parallel with serotype changes, genotypic penicillin-resistant S. pneumoniae decreased from 32.4% to 21.1%, and 6 non-PPSV23 serotypes emerged (6D, 15A, 15C, 16F, 23A, and 35B). Respective vaccine coverage rates for 13-valent PCV and PPSV23 differed by disease: 73.9% and 84.3% for patients with pneumonia, 56.4% and 69.2% for patients with bacteremia and sepsis, and 45.7% and 69.3% for patients with meningitis.
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38
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Preethi B, Ramanathan K. Molecular level understanding of resistance to nalidixic acid in Salmonella enteric serovar typhimurium associates with the S83F sequence type. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2015; 45:35-44. [PMID: 26329667 DOI: 10.1007/s00249-015-1073-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 07/15/2015] [Accepted: 08/12/2015] [Indexed: 02/04/2023]
Abstract
Nalidixic acid is an antibiotic drug used for treatment of Salmonellosis, a gastrointestinal infection. DNA gyrase subunit A (GyrA) of Salmonella typhimurium is the drug target for nalidixic acid. Resistance of GyrA to nalidixic acid, because of a point mutation in S. typhimurium, was recently reported. Substitution of Phe in place of Ser at locus 83 in GyrA of S. typhimurium has been experimentally associated with nalidixic acid resistance. Despite recent efforts, the mechanism of this resistance is not well understood. In this investigation we used computational techniques to address this shortcoming. Our results showed that contact with residue Arg 91 is certainly important for efficient binding of nalidixic acid to the target protein, and that mutation of this residue results in 180° rotation of the antibiotic in its binding pocket, around its own long axis. It is hoped these findings may enable development of new antibiotics against resistant forms of Salmonella.
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Affiliation(s)
- B Preethi
- Industrial Biotechnology Division, School of Bio Sciences and Technology, VIT University, Vellore, 632014, Tamil Nadu, India
| | - K Ramanathan
- Industrial Biotechnology Division, School of Bio Sciences and Technology, VIT University, Vellore, 632014, Tamil Nadu, India.
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39
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Huang X, Bao Y, Zhu S, Zhang X, Lan S, Wang T. Synthesis and biological evaluation of levofloxacin core-based derivatives with potent antibacterial activity against resistant Gram-positive pathogens. Bioorg Med Chem Lett 2015; 25:3928-32. [PMID: 26238324 DOI: 10.1016/j.bmcl.2015.07.044] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2015] [Revised: 06/29/2015] [Accepted: 07/16/2015] [Indexed: 12/30/2022]
Abstract
A series of C10 non-basic building block-substituted, levofloxacin core-based derivatives were synthesized in 43-86% yield. The antibacterial activity of these new fluoroquinolones was evaluated using a standard broth microdilution technique. The quinolone (S)-9-fluoro-10-(4-hydroxypiperidin-1-yl)-3-methyl-7-oxo-3,7-dihydro-2H-[1,4]oxazino[2,3,4-ij]quinoline-6-carboxylic acid L-arginine tetrahydrate exhibited superior antibacterial activity against quinolone-susceptible and resistant strains compared with the clinically used fluoroquinolones ciprofloxacin, levofloxacin, moxifloxacin, penicillin, and vancomycin, especially to the methicillin-resistant Staphylococcus aureus clinical isolates, penicillin-resistant Streptococcus pneumoniae clinical isolates, and Streptococcus pyogenes.
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Affiliation(s)
- Xiaoguang Huang
- Department of Medicinal Chemistry, Guangzhou Baiyunshan Pharmaceutical General Factory, Guangzhou 510515, China.
| | - Yingxia Bao
- Department of Medicinal Chemistry, Guangzhou Baiyunshan Pharmaceutical General Factory, Guangzhou 510515, China
| | - Shaoxuan Zhu
- Department of Medicinal Chemistry, Guangzhou Baiyunshan Pharmaceutical General Factory, Guangzhou 510515, China
| | - Xiaona Zhang
- Department of Medicinal Chemistry, Guangzhou Baiyunshan Pharmaceutical General Factory, Guangzhou 510515, China
| | - Shilong Lan
- Department of Medicinal Chemistry, Guangzhou Baiyunshan Pharmaceutical General Factory, Guangzhou 510515, China
| | - Ting Wang
- Department of Medicinal Chemistry, Guangzhou Baiyunshan Pharmaceutical General Factory, Guangzhou 510515, China
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40
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Ardanuy C, de la Campa AG, García E, Fenoll A, Calatayud L, Cercenado E, Pérez-Trallero E, Bouza E, Liñares J. Spread of Streptococcus pneumoniae serotype 8-ST63 multidrug-resistant recombinant Clone, Spain. Emerg Infect Dis 2015; 20:1848-56. [PMID: 25340616 PMCID: PMC4214286 DOI: 10.3201/eid2011.131215] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
This clone has spread throughout this country and caused invasive pneumococcal disease. Since 2004, a total of 131 isolates of Streptococcus pneumoniae multidrug-resistant invasive serotype 8 have been detected in Spain. These isolates showed resistance to erythromycin, clindamycin, tetracycline, and ciprofloxacin. All isolates were obtained from adult patients and shared a common genotype (sequence type [ST]63; penicillin-binding protein 1a [pbp1a], pbp2b, and pbp2x gene profiles; ermB and tetM genes; and a ParC-S79F change). Sixty-eight isolates that required a ciprofloxacin MIC ≥16 μg/mL had additional gyrA gene changes. Serotype 8-ST63 pbp2x sequences were identical with those of antimicrobial drug–susceptible serotype 8-ST53 isolates. Serotype 8-ST63 pbp2b sequences were identical with those of the multidrug-resistant Sweden 15A-ST63 clone. Recombination between the capsular locus and flanking regions of an ST53 isolate (donor) and an ST63 pneumococcus (recipient) generated the novel 15A-ST63 clone. One recombination point was upstream of pbp2x and another was within pbp1a. A serotype 8-ST63 clone was identified as a cause of invasive disease in Spain.
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41
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El-Kawy OA, Farah K. Radiocomplexation and biological evaluation of nemonoxacin in mice infected with multiresistant Staphylococcus aureus and penicillin-resistant Streptococci. J Radioanal Nucl Chem 2015. [DOI: 10.1007/s10967-015-4069-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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42
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Baylay AJ, Piddock LJV. Clinically relevant fluoroquinolone resistance due to constitutive overexpression of the PatAB ABC transporter in Streptococcus pneumoniae is conferred by disruption of a transcriptional attenuator. J Antimicrob Chemother 2014; 70:670-9. [PMID: 25411187 PMCID: PMC4319486 DOI: 10.1093/jac/dku449] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Constitutive overexpression of patAB has been observed in several unrelated fluoroquinolone-resistant laboratory mutants and clinical isolates; therefore, we sought to identify the cause of this overexpression. METHODS Constitutive patAB overexpression in two clinical isolates and a laboratory-selected mutant was investigated using a whole-genome transformation approach. To determine the effect of the detected terminator mutations, the WT and mutated patA leader sequences were cloned upstream of a GFP reporter. Finally, mutation of the opposing base in the stem-loop structure was carried out. RESULTS We identified three novel mutations causing up-regulation of patAB. All three of these were located in the upstream region of patA and affected the same Rho-independent transcriptional terminator structure. Each mutation was predicted to destabilize the terminator stem-loop to a different degree, and there was a strong correlation between predicted terminator stability and patAB expression level. Using a GFP reporter of patA transcription, these terminator mutations led to increased transcription of a downstream gene. For one mutant sequence, terminator stability could be restored by mutation of the opposing base in the stem-loop structure, demonstrating that transcriptional suppression of patAB is mediated by the terminator stem-loop structure. CONCLUSIONS This study showed that a mutation in a Rho-independent transcriptional terminator structure confers overexpression of patAB and fluoroquinolone resistance. Understanding how levels of the PatAB efflux pump are regulated increases our knowledge of pneumococcal biology and how the pneumococcus can respond to various stresses, including antimicrobials.
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Affiliation(s)
- Alison J Baylay
- Antimicrobials Research Group, School of Immunity and Infection, Institute of Microbiology and Infection and College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Laura J V Piddock
- Antimicrobials Research Group, School of Immunity and Infection, Institute of Microbiology and Infection and College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
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43
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Target-based resistance in Pseudomonas aeruginosa and Escherichia coli to NBTI 5463, a novel bacterial type II topoisomerase inhibitor. Antimicrob Agents Chemother 2014; 59:331-7. [PMID: 25348539 DOI: 10.1128/aac.04077-14] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
In a previous report (T. J. Dougherty, A. Nayar, J. V. Newman, S. Hopkins, G. G. Stone, M. Johnstone, A. B. Shapiro, M. Cronin, F. Reck, and D. E. Ehmann, Antimicrob Agents Chemother 58:2657-2664, 2014), a novel bacterial type II topoisomerase inhibitor, NBTI 5463, with activity against Gram-negative pathogens was described. First-step resistance mutations in Pseudomonas aeruginosa arose exclusively in the nfxB gene, a regulator of the MexCD-OprJ efflux pump system. The present report describes further resistance studies with NBTI 5463 in both Pseudomonas aeruginosa and Escherichia coli. Second-step mutations in P. aeruginosa arose at aspartate 82 of the gyrase A subunit and led to 4- to 8-fold increases in the MIC over those seen in the parental strain with a first-step nfxB efflux mutation. A third-step mutant showed additional GyrA changes, with no changes in topoisomerase IV. Despite repeated efforts, resistance mutations could not be selected in E. coli. Genetic introduction of the Asp82 mutations observed in P. aeruginosa did not significantly increase the NBTI MIC in E. coli. However, with the aspartate 82 mutation present, it was possible to select second-step mutations in topoisomerase IV that did lead to MIC increases of 16- and 128-fold. As with the gyrase aspartate 82 mutation, the mutations in topoisomerase IV did not by themselves raise the NBTI MIC in E. coli. Only the presence of mutations in both targets of E. coli led to an increase in NBTI MIC values. This represents a demonstration of the value of balanced dual-target activity in mitigating resistance development.
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44
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In vitro selection of resistance to pradofloxacin and ciprofloxacin in canine uropathogenic Escherichia coli isolates. Vet Microbiol 2014; 174:514-522. [PMID: 25465666 DOI: 10.1016/j.vetmic.2014.10.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 10/15/2014] [Accepted: 10/16/2014] [Indexed: 11/20/2022]
Abstract
This study explored and compared the mechanisms and selective concentration of resistance between a 3rd (pradofloxacin) and 2nd (ciprofloxacin) generation fluoroquinolone. Pradofloxacin- and ciprofloxacin-resistant mutants were selected by stepwise exposure of Escherichia coli (E. coli) to escalating concentrations of pradofloxacin and ciprofloxacin. The sequence of the quinolone resistance determining region (QRDR) and the transcriptional regulator soxS were analyzed, and efflux pump AcrAB-TolC activity was measured by quantitative real-time reverse transcription-PCR (qRT-PCR). First-step mutants reduced the fluoroquinolone sensitivity and one mutant bore a single substitution in gyrA. Four of six second-step mutants expressed ciprofloxacin resistance, and displayed additional mutations in gyrA and/or parC, while these mutants retained susceptibility to pradofloxacin. All the third-step mutants were fluoroquinolone resistant, and each expressed multidrug resistance (MDR) phenotypes. Further, they displayed resistance to all antibacterials tested except cefotaxime, ceftazidime and meropenem. The number of mutations in QRDR of gyrA and parC correlated with fluoroquinolone MICs. Mutations in parC were not common in pradofloxacin-associated mutants. Moreover, one second- and one third-step ciprofloxacin-associated mutants bore both mutations at position 12 (Ala12Ser) and 78 (Met78Leu) in the soxS gene, yet no mutations in the soxS gene were detected in the pradofloxacin-selected mutants. Altogether, these results demonstrated that resistance emerged relatively more rapidly in 2nd compared to 3rd generation fluoroquinolones. Point mutations in gyrA were a key mechanism of resistance to pradofloxacin, and overexpression of efflux pump gene acrB played a potential role in the emergence of MDR phenotypes identified in this study.
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45
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Dana S, Prusty D, Dhayal D, Gupta MK, Dar A, Sen S, Mukhopadhyay P, Adak T, Dhar SK. Potent antimalarial activity of acriflavine in vitro and in vivo. ACS Chem Biol 2014; 9:2366-73. [PMID: 25089658 PMCID: PMC4201339 DOI: 10.1021/cb500476q] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Malaria continues to be a major health
problem globally. There
is an urgent need to find new antimalarials. Acriflavine (ACF) is
known as an antibacterial agent and more recently as an anticancer
agent. Here, we report that ACF inhibits the growth of asexual stages
of both chloroquine (CQ) sensitive and resistant strains of human
malarial parasite, Plasmodium falciparum in vitro at nanomolar concentration. ACF clears the malaria infection in vivo from the bloodstreams of mice infected with Plasmodium berghei. Interestingly, ACF is accumulated only
in the parasitized red blood cells (RBCs) and parasite specific transporters
may have role in this specific drug accumulation. We further show
that ACF impairs DNA replication foci formation in the parasites and
affects the enzymatic activities of apicoplast specific Gyrase protein.
We thus establish ACF as a potential antimalarial amidst the widespread
incidences of drug resistant Plasmodium strains.
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Affiliation(s)
- Srikanta Dana
- Special
Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi 110067, India
- Supramolecular
and Material Chemistry Lab, School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Dhaneswar Prusty
- Special
Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi 110067, India
| | - Devender Dhayal
- National Institute of Malaria Research, New Delhi 110077, India
| | - Mohit Kumar Gupta
- Special
Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi 110067, India
| | - Ashraf Dar
- Special
Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi 110067, India
| | - Sobhan Sen
- Spectroscopy
Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New
Delhi 110067, India
| | - Pritam Mukhopadhyay
- Supramolecular
and Material Chemistry Lab, School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Tridibesh Adak
- National Institute of Malaria Research, New Delhi 110077, India
| | - Suman Kumar Dhar
- Special
Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi 110067, India
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46
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Bacillus anthracis GrlAV96A topoisomerase IV, a quinolone resistance mutation that does not affect the water-metal ion bridge. Antimicrob Agents Chemother 2014; 58:7182-7. [PMID: 25246407 DOI: 10.1128/aac.03734-14] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The rise in quinolone resistance is threatening the clinical use of this important class of broad-spectrum antibacterials. Quinolones kill bacteria by increasing the level of DNA strand breaks generated by the type II topoisomerases gyrase and topoisomerase IV. Most commonly, resistance is caused by mutations in the serine and acidic amino acid residues that anchor a water-metal ion bridge that facilitates quinolone-enzyme interactions. Although other mutations in gyrase and topoisomerase IV have been reported in quinolone-resistant strains, little is known regarding their contributions to cellular quinolone resistance. To address this issue, we characterized the effects of the V96A mutation in the A subunit of Bacillus anthracis topoisomerase IV on quinolone activity. The results indicate that this mutation causes an ∼ 3-fold decrease in quinolone potency and reduces the stability of covalent topoisomerase IV-cleaved DNA complexes. However, based on metal ion usage, the V96A mutation does not disrupt the function of the water-metal ion bridge. A similar level of resistance to quinazolinediones (which do not use the bridge) was seen. V96A is the first topoisomerase IV mutation distal to the water-metal ion bridge demonstrated to decrease quinolone activity. It also represents the first A subunit mutation reported to cause resistance to quinazolinediones. This cross-resistance suggests that the V96A change has a global effect on the structure of the drug-binding pocket of topoisomerase IV.
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47
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Mahdi LK, Deihimi T, Zamansani F, Fruzangohar M, Adelson DL, Paton JC, Ogunniyi AD, Ebrahimie E. A functional genomics catalogue of activated transcription factors during pathogenesis of pneumococcal disease. BMC Genomics 2014; 15:769. [PMID: 25196724 PMCID: PMC4171566 DOI: 10.1186/1471-2164-15-769] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 09/03/2014] [Indexed: 11/11/2022] Open
Abstract
Background Streptococcus pneumoniae (the pneumococcus) is the world’s foremost microbial pathogen, killing more people each year than HIV, TB or malaria. The capacity to penetrate deeper host tissues contributes substantially to the ability of this organism to cause disease. Here we investigated, for the first time, functional genomics modulation of 3 pneumococcal strains (serotype 2 [D39], serotype 4 [WCH43] and serotype 6A [WCH16]) during transition from the nasopharynx to lungs to blood and to brain of mice at both promoter and domain activation levels. Results We found 7 highly activated transcription factors (TFs) [argR, codY, hup, rpoD, rr02, scrR and smrC] capable of binding to a large number of up-regulated genes, potentially constituting the regulatory backbone of pneumococcal pathogenesis. Strain D39 showed a distinct profile in employing a large number of TFs during blood infection. Interestingly, the same highly activated TFs used by D39 in blood are also used by WCH16 and WCH43 during brain infection. This indicates that different pneumococcal strains might activate a similar set of TFs and regulatory elements depending on the final site of infection. Hierarchical clustering analysis showed that all the highly activated TFs, except rpoD, clustered together with a high level of similarity in all 3 strains, which might suggest redundancy in the regulatory roles of these TFs during infection. Discriminant function analysis of the TFs in various niches highlights differential regulatory backgrounds of the 3 strains, and pathogenesis data confirms codY as the most significant predictor discriminating between these strains in various niches, particularly in the blood. Moreover, the predicted TF and domain activation profiles of the 3 strains correspond with their distinct pathogenicity characteristics. Conclusions Our findings suggest that the pneumococcus changes the short binding sites in the promoter regions of genes in a niche-specific manner to enhance its ability to disseminate from one host niche to another. This study provides a framework for an improved understanding of the dynamics of pneumococcal pathogenesis, and opens a new avenue into similar investigations in other pathogenic bacteria. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-769) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | | | - Abiodun D Ogunniyi
- Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, The University of Adelaide, Adelaide, South Australia, Australia.
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48
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Wang H, Zou D, Xie K, Xie M. Antibacterial mechanism of fraxetin against Staphylococcus aureus. Mol Med Rep 2014; 10:2341-5. [PMID: 25189268 PMCID: PMC4214354 DOI: 10.3892/mmr.2014.2529] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 06/24/2014] [Indexed: 11/05/2022] Open
Abstract
Fraxetin is one of the main constituents of the traditional medicinal plant Fraxinus rhynchophylla. The inhibitory effect of fraxetin on various bacterial strains has been extensively reported, however, its mechanism of action on bacterial cells remains to be elucidated. In the present study, the antibacterial mechanism of fraxetin on Staphylococcus aureus was systematically investigated by examining its effect on cell membranes, protein synthesis, nucleic acid content and topoisomerase activity. The results indicated that fraxetin increased the permeability of the cell membrane but did not render it permeable to macromolecules, such as DNA and RNA. Additionally, the quantity of protein, DNA and RNA decreased to 55.74, 33.86 and 48.96%, respectively following treatment with fraxetin for 16 h. The activity of topoisomerase I and topoisomerase II were also markedly inhibited as fraxetin concentration increased. The result of the ultraviolet‑visible spectrophotometry demonstrated that the DNA characteristics exhibited a blue shift and hypochromic effect following treatment with fraxetin. These results indicated that fraxetin had a marked inhibitory effect on S.aureus proliferation. Further mechanistic studies showed that fraxetin could disrupt nucleic acid and protein synthesis by preventing topoisomerase from binding to DNA.
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Affiliation(s)
- Haiting Wang
- Liaoning Provincial Key Laboratory of Biotechnology and Drug Discovery, College of Life Science, Liaoning Normal University, Dalian, Liaoning 116000, P.R. China
| | - Dan Zou
- Liaoning Provincial Key Laboratory of Biotechnology and Drug Discovery, College of Life Science, Liaoning Normal University, Dalian, Liaoning 116000, P.R. China
| | - Kunpeing Xie
- Liaoning Provincial Key Laboratory of Biotechnology and Drug Discovery, College of Life Science, Liaoning Normal University, Dalian, Liaoning 116000, P.R. China
| | - Mingjie Xie
- Liaoning Provincial Key Laboratory of Biotechnology and Drug Discovery, College of Life Science, Liaoning Normal University, Dalian, Liaoning 116000, P.R. China
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49
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Aldred KJ, Breland EJ, Vlčková V, Strub MP, Neuman KC, Kerns RJ, Osheroff N. Role of the water-metal ion bridge in mediating interactions between quinolones and Escherichia coli topoisomerase IV. Biochemistry 2014; 53:5558-67. [PMID: 25115926 PMCID: PMC4151693 DOI: 10.1021/bi500682e] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
![]()
Although
quinolones have been in clinical use for decades, the
mechanism underlying drug activity and resistance has remained elusive.
However, recent studies indicate that clinically relevant quinolones
interact with Bacillus anthracis (Gram-positive)
topoisomerase IV through a critical water–metal ion bridge
and that the most common quinolone resistance mutations decrease drug
activity by disrupting this bridge. As a first step toward determining
whether the water–metal ion bridge is a general mechanism of
quinolone–topoisomerase interaction, we characterized drug
interactions with wild-type Escherichia coli (Gram-negative)
topoisomerase IV and a series of ParC enzymes with mutations (S80L,
S80I, S80F, and E84K) in the predicted bridge-anchoring residues.
Results strongly suggest that the water–metal ion bridge is
essential for quinolone activity against E. coli topoisomerase
IV. Although the bridge represents a common and critical mechanism
that underlies broad-spectrum quinolone function, it appears to play
different roles in B. anthracis and E. coli topoisomerase IV. The water–metal ion bridge is the most
important binding contact of clinically relevant quinolones with the
Gram-positive enzyme. However, it primarily acts to properly align
clinically relevant quinolones with E. coli topoisomerase
IV. Finally, even though ciprofloxacin is unable to increase levels
of DNA cleavage mediated by several of the Ser80 and Glu84 mutant E. coli enzymes, the drug still retains the ability to inhibit
the overall catalytic activity of these topoisomerase IV proteins.
Inhibition parallels drug binding, suggesting that the presence of
the drug in the active site is sufficient to diminish DNA relaxation
rates.
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Affiliation(s)
- Katie J Aldred
- Department of Biochemistry and ‡Department of Medicine (Hematology/Oncology), Vanderbilt University School of Medicine , Nashville, Tennessee 37232-0146, United States
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Abstract
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Quinolones
are one of the most commonly prescribed classes of antibacterials
in the world and are used to treat a variety of bacterial infections
in humans. Because of the wide use (and overuse) of these drugs, the
number of quinolone-resistant bacterial strains has been growing steadily
since the 1990s. As is the case with other antibacterial agents, the
rise in quinolone resistance threatens the clinical utility of this
important drug class. Quinolones act by converting their targets,
gyrase and topoisomerase IV, into toxic enzymes that fragment the
bacterial chromosome. This review describes the development of the
quinolones as antibacterials, the structure and function of gyrase
and topoisomerase IV, and the mechanistic basis for quinolone action
against their enzyme targets. It will then discuss the following three
mechanisms that decrease the sensitivity of bacterial cells to quinolones.
Target-mediated resistance is the most common and clinically significant
form of resistance. It is caused by specific mutations in gyrase and
topoisomerase IV that weaken interactions between quinolones and these
enzymes. Plasmid-mediated resistance results from extrachromosomal
elements that encode proteins that disrupt quinolone–enzyme
interactions, alter drug metabolism, or increase quinolone efflux.
Chromosome-mediated resistance results from the underexpression of
porins or the overexpression of cellular efflux pumps, both of which
decrease cellular concentrations of quinolones. Finally, this review
will discuss recent advancements in our understanding of how quinolones
interact with gyrase and topoisomerase IV and how mutations in these
enzymes cause resistance. These last findings suggest approaches to
designing new drugs that display improved activity against resistant
strains.
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Affiliation(s)
- Katie J Aldred
- Department of Biochemistry and ‡Department of Medicine (Hematology/Oncology), Vanderbilt University School of Medicine , Nashville, Tennessee 37232-0146, United States
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