1
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Rafiei E, Shahini Shams Abadi M, Zamanzad B, Gholipour A. The frequency of efflux pump genes expression in Acinetobacter baumannii isolates from pulmonary secretions. AMB Express 2022; 12:103. [PMID: 35925415 PMCID: PMC9352836 DOI: 10.1186/s13568-022-01444-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Accepted: 07/28/2022] [Indexed: 11/24/2022] Open
Abstract
Acinetobacter baumannii is an important opportunistic pathogen, and the cause of nosocomial infections worldwide in recent decades. Efflux pumps are considered as the important causes of multidrug resistance of A. baumannii. The aim of this study was to determine the frequency of efflux pump genes, and evaluate the antibiotic effect of Tigecycline on the expression of adeB gene in isolates of multidrug-resistant. A. baumannii. 70 isolates of A. baumannii were collected and confirmed by biochemical and molecular tests. Antibiotic resistance (Ciprofloxacin, Trimethoprim-sulfamethoxazole, and Tigecycline) was performed based on the minimum inhibitory concentration (MIC) method. Then, the effect of Carbonyl cyanide m-chlorophenyl hydrazone inhibitor (CCCP) on isolates was investigated and the frequency of adeB, adeG, adeJ and abeM genes were examined by PCR for isolates with reduced in MIC titer. Also, the antibiotic effect of Tigecycline on adeB gene expression in A. baumannii isolates was analyzed by Real-Time PCR. The antibiotic resistance for Ciprofloxacin, Trimethoprim-sulfamethoxazole, and Tigecycline was 97.1%, 95.8% and 37.2%, respectively. Following CCCP inhibitor use, the MIC titer had a decrease in MIC titer containing CCCP inhibitor was 64.3% for Ciprofloxacin, 51.5% for Trimethoprim-sulfamethoxazole and 50% for Tigecycline. The frequencies of genes associated with adeB, adeG, adeJ and abeM efflux pump were 100%, 92.8%, 86% and 98.5%, respectively. Real-Time PCR results showed a correlation between the antibiotic effects of Tigecycline on adeB gene expression. The antibiotic resistance of the isolates was relatively high. The isolates were resistant to Ciprofloxacin and Trimethoprim-sulfamethoxazole antibiotics, while more sensitive to Tigecycline. Also, efflux pump genes, which are the antibiotic resistance factors of A. baumannii, are frequently high in the isolates but it seems that isolates use other effluxe pumps than RND family to exit tigecycline. The frequencies of genes associated with adeB, adeG, adeJ and abeM efflux pump were 100%, 92.8%, 86% and 98.5%, respectively. Real-Time PCR results showed a correlation between the antibiotic effects of Tigecycline on adeB gene expression. The antibiotic resistance of the isolates was relatively high. Also, efflux pump genes, which are the antibiotic resistance factors of A. baumannii, are frequently high in the isolates but it seems that isolates use other effluxe pumps than RND family to exit tigecycline.
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Affiliation(s)
- Ebrahim Rafiei
- Cellular and Molecular Research Center, Faculty of Medicine, Shahrekord University of Medical Sciences, Shahrekord, Iran.,Department of Microbiology and Immunology, School of Medicine, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Milad Shahini Shams Abadi
- Cellular and Molecular Research Center, Faculty of Medicine, Shahrekord University of Medical Sciences, Shahrekord, Iran.,Department of Microbiology and Immunology, School of Medicine, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Behnam Zamanzad
- Cellular and Molecular Research Center, Faculty of Medicine, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Abolfazl Gholipour
- Cellular and Molecular Research Center, Faculty of Medicine, Shahrekord University of Medical Sciences, Shahrekord, Iran. .,Department of Microbiology and Immunology, School of Medicine, Shahrekord University of Medical Sciences, Shahrekord, Iran.
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2
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Holland M, Bjanes E, Nizet V, Dillon N. Bicarbonate modulates delafloxacin activity against MDR Staphylococcus aureus and Pseudomonas aeruginosa. J Antimicrob Chemother 2022; 77:433-442. [PMID: 34893834 PMCID: PMC8809187 DOI: 10.1093/jac/dkab421] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 10/13/2021] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES To investigate the utility of recently approved delafloxacin and other fluoroquinolones against leading MDR bacterial pathogens under physiologically relevant conditions. METHODS MIC and MBC assays were conducted for MDR strains of Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae in the standard antibiotic susceptibility testing medium CAMHB, amended Roswell-Park Memorial Institute tissue culture medium (RPMI+) or 20% fresh human whole blood. In vivo correlation of in vitro findings was performed in a murine P. aeruginosa pneumonia model. Mechanistic bases for the findings were explored by altering media conditions and with established fluoroquinolone accumulation assays. RESULTS Fluoroquinolone MICs were increased in RPMI+ compared with CAMHB for all four MDR pathogens. Specifically, delafloxacin MICs were increased 32-fold versus MDR S. aureus and 8-fold versus MDR P. aeruginosa. MBC assays in 20% human whole blood and a murine MDR P. aeruginosa pneumonia model both confirmed that delafloxacin activity was reduced under physiological conditions. Bicarbonate (HCO3-), a key component of host physiology found in RPMI+ but absent from CAMHB, dictated delafloxacin susceptibility in CAMHB and RPMI+ by impairing its intracellular accumulation. CONCLUSIONS Standard in vitro antibiotic susceptibility testing conditions overpredicted the effectiveness of delafloxacin against MDR pathogens by failing to capture the role of the biological buffer HCO3- to impair delafloxacin accumulation. This work showcases limitations of our current antibiotic susceptibility testing paradigm and highlights the importance of understanding host microenvironmental conditions that impact true clinical efficacy.
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Affiliation(s)
- Mische Holland
- Department of Pediatrics, UC San Diego, La Jolla, CA 92093, USA
| | - Elisabet Bjanes
- Department of Pediatrics, UC San Diego, La Jolla, CA 92093, USA
- Collaborative to Halt Antibiotic-Resistant Microbes (CHARM), UC San Diego, La Jolla, CA 92093, USA
| | - Victor Nizet
- Department of Pediatrics, UC San Diego, La Jolla, CA 92093, USA
- Collaborative to Halt Antibiotic-Resistant Microbes (CHARM), UC San Diego, La Jolla, CA 92093, USA
- Skaggs School of Pharmacy and Pharmaceutical Sciences, UC San Diego, La Jolla, CA 92093, USA
| | - Nicholas Dillon
- Collaborative to Halt Antibiotic-Resistant Microbes (CHARM), UC San Diego, La Jolla, CA 92093, USA
- Department of Biological Sciences, UT Dallas, Richardson, TX 75080, USA
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3
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López Y, Muñoz L, Gargallo-Viola D, Cantón R, Vila J, Zsolt I. Uptake of Ozenoxacin and Other Quinolones in Gram-Positive Bacteria. Int J Mol Sci 2021; 22:13363. [PMID: 34948159 PMCID: PMC8708121 DOI: 10.3390/ijms222413363] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 12/07/2021] [Accepted: 12/09/2021] [Indexed: 12/22/2022] Open
Abstract
The big problem of antimicrobial resistance is that it requires great efforts in the design of improved drugs which can quickly reach their target of action. Studies of antibiotic uptake and interaction with their target it is a key factor in this important challenge. We investigated the accumulation of ozenoxacin (OZN), moxifloxacin (MOX), levofloxacin (LVX), and ciprofloxacin (CIP) into the bacterial cells of 5 species, including Staphylococcus aureus (SA4-149), Staphylococcus epidermidis (SEP7602), Streptococcus pyogenes (SPY165), Streptococcus agalactiae (SAG146), and Enterococcus faecium (EF897) previously characterized.The concentration of quinolone uptake was estimated by agar disc-diffusion bioassay. Furthermore, we determined the inhibitory concentrations 50 (IC50) of OZN, MOX, LVX, and CIP against type II topoisomerases from S. aureus.The accumulation of OZN inside the bacterial cell was superior in comparison to MOX, LVX, and CIP in all tested species. The accumulation of OZN inside the bacterial cell was superior in comparison to MOX, LVX, and CIP in all tested species. The rapid penetration of OZN into the cell was reflected during the first minute of exposure with antibiotic values between 190 and 447 ng/mg (dry weight) of bacteria in all strains. Moreover, OZN showed the greatest inhibitory activity among the quinolones tested for both DNA gyrase and topoisomerase IV isolated from S. aureus with IC50 values of 10 and 0.5 mg/L, respectively. OZN intracellular concentration was significantly higher than that of MOX, LVX and CIP. All of these features may explain the higher in vitro activity of OZN compared to the other tested quinolones.
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Affiliation(s)
- Yuly López
- Institute of Global Health of Barcelona, 08036 Barcelona, Spain;
| | - Laura Muñoz
- Institute of Global Health of Barcelona, 08036 Barcelona, Spain;
| | | | - Rafael Cantón
- Department of Clinical Microbiology, Hospital Universitario Ramón y Cajal & Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain;
- CIBER Enfermedades Infecciosas, ISCIII, 28029 Madrid, Spain
| | - Jordi Vila
- Institute of Global Health of Barcelona, 08036 Barcelona, Spain;
- CIBER Enfermedades Infecciosas, ISCIII, 28029 Madrid, Spain
- Department of Clinical Microbiology, Hospital Clinic, School of Medicine, University of Barcelona, 08007 Barcelona, Spain
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4
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Pandeya A, Alegun O, Cai Y, Wei Y. Distribution of fluoroquinolones in the two aqueous compartments of Escherichia coli. Biochem Biophys Rep 2020; 24:100849. [PMID: 33235925 PMCID: PMC7670238 DOI: 10.1016/j.bbrep.2020.100849] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 10/10/2020] [Accepted: 10/23/2020] [Indexed: 12/31/2022] Open
Abstract
The double-layered cell envelope of Gram-negative bacteria and active drug efflux present a formidable barrier for antimicrobial compounds to penetrate. Fluoroquinolones are among the few classes of antimicrobials that are clinically useful in the treatment of Gram-negative bacterial infection. Previous studies on fluoroquinolone accumulation measured total bacteria associated compounds, rather than the cytoplasmic accumulation. Fluoroquinolones target the type II topoisomerases in the cytoplasm. Thus, the cytoplasmic accumulation is expected to be more relevant to the potency of the drugs. Here, we fractionated and measured the concentration of nine fluoroquinolone compounds in the periplasm and the cytoplasm of two strains of E. coli cells, a parent strain and its isogenic efflux-deficient tolC knockout strain. The potency of the drugs was determined using the minimum inhibitory concentration (MIC) assay. We found that all fluoroquinolones tested accumulated at much higher concentrations in the periplasm than in the cytoplasm. The periplasmic concentrations were 2–15 folds higher than the cytoplasmic concentration, while the actual distribution ratio varies drastically among the compounds tested. Good correlation between the MIC and the cytoplasmic accumulation, but not whole cell accumulation, was observed using a pair of isogenic wild type and drug-efflux deficient strains. Fluoroquinolones accumulate to high concentration in the periplasm of E. coli Periplasmic concentrations are higher than the cytoplasmic and exterior media concentration. Good correlation was observed for the cytoplasmic drug concentration and the antimicrobial potency. Disruption of active efflux has a larger impact on the periplasmic than the cytoplasmic accumulation.
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Affiliation(s)
- Ankit Pandeya
- Department of Chemistry, University of Kentucky, Lexington, KY, 40506, USA
| | - Olaniyi Alegun
- Department of Chemistry, University of Kentucky, Lexington, KY, 40506, USA
| | - Yuguang Cai
- Department of Chemistry, University of Kentucky, Lexington, KY, 40506, USA
| | - Yinan Wei
- Department of Chemistry, University of Kentucky, Lexington, KY, 40506, USA
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5
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Cama J, Voliotis M, Metz J, Smith A, Iannucci J, Keyser UF, Tsaneva-Atanasova K, Pagliara S. Single-cell microfluidics facilitates the rapid quantification of antibiotic accumulation in Gram-negative bacteria. LAB ON A CHIP 2020; 20:2765-2775. [PMID: 32613221 PMCID: PMC7953842 DOI: 10.1039/d0lc00242a] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 06/15/2020] [Indexed: 06/01/2023]
Abstract
The double-membrane cell envelope of Gram-negative bacteria is a formidable barrier to intracellular antibiotic accumulation. A quantitative understanding of antibiotic transport in these cells is crucial for drug development, but this has proved elusive due to a dearth of suitable investigative techniques. Here we combine microfluidics and time-lapse auto-fluorescence microscopy to rapidly quantify antibiotic accumulation in hundreds of individual Escherichia coli cells. By serially manipulating the microfluidic environment, we demonstrated that stationary phase Escherichia coli, traditionally more refractory to antibiotics than growing cells, display reduced accumulation of the antibiotic ofloxacin compared to actively growing cells. Our novel microfluidic method facilitates the quantitative comparison of the role of the microenvironment versus that of the absence of key membrane transport pathways in cellular drug accumulation. Unlike traditional techniques, our assay is rapid, studying accumulation as the cells are dosed with the drug. This platform provides a powerful new tool for studying antibiotic accumulation in bacteria, which will be critical for the rational development of the next generation of antibiotics.
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Affiliation(s)
- Jehangir Cama
- Living Systems Institute
, University of Exeter
,
Exeter EX4 4QD
, UK
.
- College of Engineering
, Mathematics and Physical Sciences
, University of Exeter
,
Exeter EX4 4QF
, UK
- Cavendish Laboratory
, Department of Physics
, University of Cambridge
,
JJ Thomson Avenue
, Cambridge CB3 0HE
, UK
| | - Margaritis Voliotis
- Living Systems Institute
, University of Exeter
,
Exeter EX4 4QD
, UK
.
- College of Engineering
, Mathematics and Physical Sciences
, University of Exeter
,
Exeter EX4 4QF
, UK
| | - Jeremy Metz
- Living Systems Institute
, University of Exeter
,
Exeter EX4 4QD
, UK
.
- School of Biosciences
, College of Life and Environmental Sciences
, University of Exeter
,
Exeter EX4 4QD
, UK
.
| | - Ashley Smith
- Living Systems Institute
, University of Exeter
,
Exeter EX4 4QD
, UK
.
- School of Biosciences
, College of Life and Environmental Sciences
, University of Exeter
,
Exeter EX4 4QD
, UK
.
| | - Jari Iannucci
- Living Systems Institute
, University of Exeter
,
Exeter EX4 4QD
, UK
.
- School of Biosciences
, College of Life and Environmental Sciences
, University of Exeter
,
Exeter EX4 4QD
, UK
.
| | - Ulrich F. Keyser
- Cavendish Laboratory
, Department of Physics
, University of Cambridge
,
JJ Thomson Avenue
, Cambridge CB3 0HE
, UK
| | - Krasimira Tsaneva-Atanasova
- Living Systems Institute
, University of Exeter
,
Exeter EX4 4QD
, UK
.
- College of Engineering
, Mathematics and Physical Sciences
, University of Exeter
,
Exeter EX4 4QF
, UK
| | - Stefano Pagliara
- Living Systems Institute
, University of Exeter
,
Exeter EX4 4QD
, UK
.
- School of Biosciences
, College of Life and Environmental Sciences
, University of Exeter
,
Exeter EX4 4QD
, UK
.
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6
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Zgurskaya HI, Rybenkov VV. Permeability barriers of Gram-negative pathogens. Ann N Y Acad Sci 2020; 1459:5-18. [PMID: 31165502 PMCID: PMC6940542 DOI: 10.1111/nyas.14134] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/06/2019] [Accepted: 05/13/2019] [Indexed: 12/13/2022]
Abstract
Most clinical antibiotics do not have efficacy against Gram-negative pathogens, mainly because these cells are protected by the permeability barrier comprising the two membranes with active efflux. The emergence of multidrug-resistant Gram-negative strains threatens the utility even of last resort therapeutic treatments. Significant efforts at different levels of resolution are currently focused on finding a solution to this nonpermeation problem and developing new approaches to the optimization of drug activities against multidrug-resistant pathogens. The exceptional efficiency of the Gram-negative permeability barrier is the result of a complex interplay between the two opposing fluxes of drugs across the two membranes. In this review, we describe the current state of understanding of the problem and the recent advances in theoretical and empirical approaches to characterization of drug permeation and active efflux in Gram-negative bacteria.
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Affiliation(s)
- Helen I Zgurskaya
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma
| | - Valentin V Rybenkov
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma
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7
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Spectrofluorimetric quantification of antibiotic drug concentration in bacterial cells for the characterization of translocation across bacterial membranes. Nat Protoc 2018; 13:1348-1361. [DOI: 10.1038/nprot.2018.036] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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8
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Richter MF, Hergenrother PJ. The challenge of converting Gram-positive-only compounds into broad-spectrum antibiotics. Ann N Y Acad Sci 2018; 1435:18-38. [PMID: 29446459 DOI: 10.1111/nyas.13598] [Citation(s) in RCA: 131] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 12/07/2017] [Accepted: 12/14/2017] [Indexed: 12/14/2022]
Abstract
Multidrug resistant Gram-negative bacterial infections are on the rise, and there is a lack of new classes of drugs to treat these pathogens. This drug shortage is largely due to the challenge of finding antibiotics that can permeate and persist inside Gram-negative species. Efforts to understand the molecular properties that enable certain compounds to accumulate in Gram-negative bacteria based on retrospective studies of known antibiotics have not been generally actionable in the development of new antibiotics. A recent assessment of the ability of >180 diverse small molecules to accumulate in Escherichia coli led to predictive guidelines for compound accumulation in E. coli. These "eNTRy rules" state that compounds are most likely to accumulate if they contain a nonsterically encumbered ionizable Nitrogen (primary amines are the best), have low Three-dimensionality (globularity ≤ 0.25), and are relatively Rigid (rotatable bonds ≤ 5). In this review, we look back through 50+ years of antibacterial research and 1000s of derivatives and assess this historical data set through the lens of these predictive guidelines. The results are consistent with the eNTRy rules, suggesting that the eNTRy rules may provide an actionable and general roadmap for the conversion of Gram-positive-only compounds into broad-spectrum antibiotics.
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Affiliation(s)
- Michelle F Richter
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Paul J Hergenrother
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois
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9
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Tamburrino G, Llabrés S, Vickery ON, Pitt SJ, Zachariae U. Modulation of the Neisseria gonorrhoeae drug efflux conduit MtrE. Sci Rep 2017; 7:17091. [PMID: 29213101 PMCID: PMC5719041 DOI: 10.1038/s41598-017-16995-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 11/21/2017] [Indexed: 11/09/2022] Open
Abstract
Widespread antibiotic resistance, especially of Gram-negative bacteria, has become a severe concern for human health. Tripartite efflux pumps are one of the major contributors to resistance in Gram-negative pathogens, by efficiently expelling a broad spectrum of antibiotics from the organism. In Neisseria gonorrhoeae, one of the first bacteria for which pan-resistance has been reported, the most expressed efflux complex is MtrCDE. Here we present the electrophysiological characterisation of the outer membrane component MtrE and the membrane fusion protein MtrC, obtained by a combination of planar lipid bilayer recordings and in silico techniques. Our in vitro results show that MtrE can be regulated by periplasmic binding events and that the interaction between MtrE and MtrC is sufficient to stabilize this complex in an open state. In contrast to other efflux conduits, the open complex only displays a slight preference for cations. The maximum conductance we obtain in the in vitro recordings is comparable to that seen in our computational electrophysiology simulations conducted on the MtrE crystal structure, indicating that this state may reflect a physiologically relevant open conformation of MtrE. Our results suggest that the MtrC/E binding interface is an important modulator of MtrE function, which could potentially be targeted by new efflux inhibitors.
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Affiliation(s)
- Giulia Tamburrino
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
- Physics, School of Science and Engineering, University of Dundee, Dundee, DD1 4NH, UK
| | - Salomé Llabrés
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
- Physics, School of Science and Engineering, University of Dundee, Dundee, DD1 4NH, UK
| | - Owen N Vickery
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
- Physics, School of Science and Engineering, University of Dundee, Dundee, DD1 4NH, UK
| | - Samantha J Pitt
- School of Medicine, University of St Andrews, St Andrews, KY16 9TF, UK.
| | - Ulrich Zachariae
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK.
- Physics, School of Science and Engineering, University of Dundee, Dundee, DD1 4NH, UK.
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10
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Brito L, Wilton J, Ferrándiz MJ, Gómez-Sanz A, de la Campa AG, Amblar M. Absence of tmRNA Has a Protective Effect against Fluoroquinolones in Streptococcus pneumoniae. Front Microbiol 2017; 7:2164. [PMID: 28119681 PMCID: PMC5222879 DOI: 10.3389/fmicb.2016.02164] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 12/23/2016] [Indexed: 11/13/2022] Open
Abstract
The transfer messenger RNA (tmRNA), encoded by the ssrA gene, is a small non-coding RNA involved in trans-translation that contributes to the recycling of ribosomes stalled on aberrant mRNAs. In most bacteria, its inactivation has been related to a decreased ability to respond to and recover from a variety of stress conditions. In this report, we investigated the role of tmRNA in stress adaptation in the human pathogen Streptococcus pneumoniae. We constructed a tmRNA deletion mutant and analyzed its response to several lethal stresses. The ΔssrA strain grew slower than the wild type, indicating that, although not essential, tmRNA is important for normal pneumococcal growth. Moreover, deletion of tmRNA increased susceptibility to UV irradiation, to exogenous hydrogen peroxide and to antibiotics that inhibit protein synthesis and transcription. However, the ΔssrA strain was more resistant to fluoroquinolones, showing twofold higher MIC values and up to 1000-fold higher survival rates than the wild type. Deletion of SmpB, the other partner in trans-translation, also reduced survival to levofloxacin in a similar extent. Accumulation of intracellular reactive oxygen species associated to moxifloxacin and levofloxacin treatment was also highly reduced (∼100-fold). Nevertheless, the ΔssrA strain showed higher intracellular accumulation of ethidium bromide and levofloxacin than the wild type, suggesting that tmRNA deficiency protects pneumococcal cells from fluoroquinolone-mediated killing. In fact, analysis of chromosome integrity revealed that deletion of tmRNA prevented the fragmentation of the chromosome associated to levofloxacin treatment. Moreover, such protective effect appears to relay mainly on inhibition of protein synthesis, since a similar effect was observed with antibiotics that inhibit that process. The emergence and spread of drug-resistant pneumococci is a matter of concern and these results contribute to a better comprehension of the mechanisms underlying fluoroquinolones action.
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Affiliation(s)
- Liliana Brito
- Unidad de Patología Molecular del Neumococo, Centro Nacional de Microbiología, Instituto de Salud Carlos III Madrid, Spain
| | - Joana Wilton
- Unidad de Patología Molecular del Neumococo, Centro Nacional de Microbiología, Instituto de Salud Carlos III Madrid, Spain
| | - María J Ferrándiz
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III Madrid, Spain
| | - Alicia Gómez-Sanz
- Unidad de Patología Molecular del Neumococo, Centro Nacional de Microbiología, Instituto de Salud Carlos III Madrid, Spain
| | - Adela G de la Campa
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos IIIMadrid, Spain; Presidencia, Consejo Superior de Investigaciones CientíficasMadrid, Spain
| | - Mónica Amblar
- Unidad de Patología Molecular del Neumococo, Centro Nacional de Microbiología, Instituto de Salud Carlos III Madrid, Spain
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11
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Rubinstein E, Lagacé-Wiens P. Quinolones. Infect Dis (Lond) 2017. [DOI: 10.1016/b978-0-7020-6285-8.00144-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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12
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Phetsang W, Pelingon R, Butler MS, KC S, Pitt ME, Kaeslin G, Cooper MA, Blaskovich MAT. Fluorescent Trimethoprim Conjugate Probes To Assess Drug Accumulation in Wild Type and Mutant Escherichia coli. ACS Infect Dis 2016; 2:688-701. [PMID: 27737551 PMCID: PMC5067704 DOI: 10.1021/acsinfecdis.6b00080] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
![]()
Reduced
susceptibility to antimicrobials in Gram-negative bacteria may result
from multiple resistance mechanisms, including increased efflux pump
activity or reduced porin protein expression. Up-regulation of the
efflux pump system is closely associated with multidrug resistance
(MDR). To help investigate the role of efflux pumps on compound accumulation,
a fluorescence-based assay was developed using fluorescent derivatives
of trimethoprim (TMP), a broad-spectrum synthetic antibiotic that
inhibits an intracellular target, dihydrofolate reductase (DHFR).
Novel fluorescent TMP probes inhibited eDHFR activity
with comparable potency to TMP, but did not kill or inhibit growth
of wild type Escherichia coli. However,
bactericidal activity was observed against an efflux pump deficient E. coli mutant strain (ΔtolC). A simple and quick fluorescence assay was developed to measure
cellular accumulation of the TMP probe using either fluorescence spectroscopy
or flow cytometry, with validation by LC-MS/MS. This fluorescence
assay may provide a simple method to assess efflux pump activity with
standard laboratory equipment.
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Affiliation(s)
- Wanida Phetsang
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Ruby Pelingon
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Mark S. Butler
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Sanjaya KC
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Miranda E. Pitt
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Geraldine Kaeslin
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Matthew A. Cooper
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Mark A. T. Blaskovich
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
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13
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Abstract
Bacterial multidrug resistance (MDR) efflux pumps are an important mechanism of antibiotic resistance and are required for many pathogens to cause infection. They are also being harnessed to improve microbial biotechnological processes, including biofuel production. Therefore, scientists of many specialties must be able to accurately measure efflux activity. However, myriad methodologies have been described and the most appropriate method is not always clear. Within the scientific literature, many methods are misused or data arising are misinterpreted. The methods for measuring efflux activity can be split into two groups, (i) those that directly measure efflux and (ii) those that measure the intracellular accumulation of a substrate, which is then used to infer efflux activity. Here, we review the methods for measuring efflux and explore the most recent advances in this field, including single-cell or cell-free technologies and mass spectrometry, that are being used to provide more detailed information about efflux pump activity.
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Hernando-Amado S, Blanco P, Alcalde-Rico M, Corona F, Reales-Calderón JA, Sánchez MB, Martínez JL. Multidrug efflux pumps as main players in intrinsic and acquired resistance to antimicrobials. Drug Resist Updat 2016; 28:13-27. [PMID: 27620952 DOI: 10.1016/j.drup.2016.06.007] [Citation(s) in RCA: 117] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 05/31/2016] [Accepted: 06/23/2016] [Indexed: 12/31/2022]
Abstract
Multidrug efflux pumps constitute a group of transporters that are ubiquitously found in any organism. In addition to other functions with relevance for the cell physiology, efflux pumps contribute to the resistance to compounds used for treating different diseases, including resistance to anticancer drugs, antibiotics or antifungal compounds. In the case of antimicrobials, efflux pumps are major players in both intrinsic and acquired resistance to drugs currently in use for the treatment of infectious diseases. One important aspect not fully explored of efflux pumps consists on the identification of effectors able to induce their expression. Indeed, whereas the analysis of clinical isolates have shown that mutants overexpressing these resistance elements are frequently found, less is known on the conditions that may trigger expression of efflux pumps, hence leading to transient induction of resistance in vivo, a situation that is barely detectable using classical susceptibility tests. In the current article we review the structure and mechanisms of regulation of the expression of bacterial and fungal efflux pumps, with a particular focus in those for which a role in clinically relevant resistance has been reported.
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Affiliation(s)
- Sara Hernando-Amado
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Darwin 3, Cantoblanco, 28049 Madrid, Spain
| | - Paula Blanco
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Darwin 3, Cantoblanco, 28049 Madrid, Spain
| | - Manuel Alcalde-Rico
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Darwin 3, Cantoblanco, 28049 Madrid, Spain
| | - Fernando Corona
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Darwin 3, Cantoblanco, 28049 Madrid, Spain
| | - Jose A Reales-Calderón
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Darwin 3, Cantoblanco, 28049 Madrid, Spain
| | - María B Sánchez
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Darwin 3, Cantoblanco, 28049 Madrid, Spain
| | - José L Martínez
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Darwin 3, Cantoblanco, 28049 Madrid, Spain.
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Davis TD, Gerry CJ, Tan DS. General platform for systematic quantitative evaluation of small-molecule permeability in bacteria. ACS Chem Biol 2014; 9:2535-44. [PMID: 25198656 PMCID: PMC4245172 DOI: 10.1021/cb5003015] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The chemical features that impact small-molecule permeability across bacterial membranes are poorly understood, and the resulting lack of tools to predict permeability presents a major obstacle to the discovery and development of novel antibiotics. Antibacterials are known to have vastly different structural and physicochemical properties compared to nonantiinfective drugs, as illustrated herein by principal component analysis (PCA). To understand how these properties influence bacterial permeability, we have developed a systematic approach to evaluate the penetration of diverse compounds into bacteria with distinct cellular envelopes. Intracellular compound accumulation is quantitated using LC-MS/MS, then PCA and Pearson pairwise correlations are used to identify structural and physicochemical parameters that correlate with accumulation. An initial study using 10 sulfonyladenosines in Escherichia coli, Bacillus subtilis, and Mycobacterium smegmatis has identified nonobvious correlations between chemical structure and permeability that differ among the various bacteria. Effects of cotreatment with efflux pump inhibitors were also investigated. This sets the stage for use of this platform in larger prospective analyses of diverse chemotypes to identify global relationships between chemical structure and bacterial permeability that would enable the development of predictive tools to accelerate antibiotic drug discovery.
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Affiliation(s)
- Tony D. Davis
- Pharmacology Program−Weill Cornell Graduate School of Medical Sciences, ‡Gerstner Sloan Kettering Summer Undergraduate Research Program, §Molecular Pharmacology & Chemistry Program and Tri-Institutional Research Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, Box 422, New York, New York 10065, United States
| | - Christopher J. Gerry
- Pharmacology Program−Weill Cornell Graduate School of Medical Sciences, ‡Gerstner Sloan Kettering Summer Undergraduate Research Program, §Molecular Pharmacology & Chemistry Program and Tri-Institutional Research Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, Box 422, New York, New York 10065, United States
| | - Derek S. Tan
- Pharmacology Program−Weill Cornell Graduate School of Medical Sciences, ‡Gerstner Sloan Kettering Summer Undergraduate Research Program, §Molecular Pharmacology & Chemistry Program and Tri-Institutional Research Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, Box 422, New York, New York 10065, United States
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Bhat J, Narayan A, Venkatraman J, Chatterji M. LC-MS based assay to measure intracellular compound levels in Mycobacterium smegmatis: linking compound levels to cellular potency. J Microbiol Methods 2013; 94:152-158. [PMID: 23747411 DOI: 10.1016/j.mimet.2013.05.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 05/07/2013] [Accepted: 05/14/2013] [Indexed: 11/18/2022]
Abstract
Dihydrofolate reductase (DHFR) plays a central role in maintaining cellular pool of tetrahydrofolic acid, a cofactor necessary for DNA, RNA and protein synthesis. The clinical validation of DHFR as antibacterial target was established by the success of trimethoprim (TMP). DHFR is also an attractive target for identifying anti-tuberculosis molecules however, due to observed weak cellular potency, no DHFR inhibitors have been developed as drugs so far. TMP and its analogs have poor cellular potency on Mycobacterium tuberculosis and Mycobacterium smegmatis cells. We found a mutant strain of M. smegmatis, mc²155 to be sensitive to TMP whereas wild type strain was not inhibited by TMP. We utilized this system to probe if poor or lack of activity of TMP is a consequence of poor intracellular compound levels. An LC-MS based method was developed for measuring TMP and rifampicin (RIF) in M. smegmatis. Using the assay, equivalent RIF levels were observed in both strains however, TMP was detected only in mc²155 cells, hence proving a positive correlation between potency and compound levels. To the best of our knowledge this is the first time LC-MS method has been used to measure compound levels in mycobacterial cells. We propose it to be a valuable tool to understand the lack of potency or resistance mechanisms in antimycobacterial drug development.
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Affiliation(s)
- Jyothi Bhat
- AstraZeneca India Pvt Ltd., Bellary Road, Hebbal, Bangalore 560024, India
| | - Ashwini Narayan
- AstraZeneca India Pvt Ltd., Bellary Road, Hebbal, Bangalore 560024, India
| | - Janani Venkatraman
- AstraZeneca India Pvt Ltd., Bellary Road, Hebbal, Bangalore 560024, India
| | - Monalisa Chatterji
- AstraZeneca India Pvt Ltd., Bellary Road, Hebbal, Bangalore 560024, India.
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El Garch F, Lismond A, Piddock LJV, Courvalin P, Tulkens PM, Van Bambeke F. Fluoroquinolones induce the expression of patA and patB, which encode ABC efflux pumps in Streptococcus pneumoniae. J Antimicrob Chemother 2010; 65:2076-82. [DOI: 10.1093/jac/dkq287] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Howe R, Williams E. Quinolones. Infect Dis (Lond) 2010. [DOI: 10.1016/b978-0-323-04579-7.00139-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Abdi-Ali A, Rahmani-Badi A, Falsafi T, Nikname V. Study of antibiotic resistance by efflux in clinical isolates of Pseudomonas aeruginosa. Pak J Biol Sci 2009; 10:924-7. [PMID: 19069890 DOI: 10.3923/pjbs.2007.924.927] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Twenty three multidrug resistant (MDR) strains were selected from 104 clinical isolates of P. aeruginosa and screened for resistance to ceftazidim, ceftriaxone, ciprofloxacin, ofloxacin and ethidium bromide by determining MICs. The MICs of EtBr and antibiotics were also measured in presence of proton conductor, carbonyl cyanide m-chlorophenyl hydrazone (CCCP). The presence of proton gradient-dependent efflux mechanism was assessed using ethidium bromide accumulation assays. Drug accumulation studies for these antibiotics were performed to determine the drug specificity of efflux. PCR was used to identify the mexAB-oprM gene as a major factor in MDR intrinsic resistance of clinical isolates of P. aeruginosa. In absence of CCCP, the MICs of these antimicrobial agents were > or = 4 microg L(-1). CCCP reduced the MICs of them at least in 1 dilution. Ethidium bromide accumulation assays confirmed the presence of proton gradient-dependent efflux mechanism in clinical isolates of P. aeruginosa and results of accumulation assays of drugs demonstrate that, active efflux in this bacterium are due to broadly-specific multidrug efflux system(s). PCR products demonstrate the presence of mexAB-oprM operon in 4 strains from 23 clinical isolates. These results confirmed the presence of proton gradient-dependent efflux mechanism in all of the clinical isolates of P. aeruginosa and demonstrate that, efflux pumps in this bacterium are broadly-specific multidrug efflux systems. In this study we show that MexAB-OprM multidrug efflux system was expressed in only 17% of clinical isolates of P. aeruginosa. These results confirmed the presence of other multidrug efflux pumps in clinical isolates of P. aeruginosa.
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Affiliation(s)
- A Abdi-Ali
- Department of Biology, Alzahra University, Tehran, Iran
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Cai H, Rose K, Liang LH, Dunham S, Stover C. Development of a liquid chromatography/mass spectrometry-based drug accumulation assay in Pseudomonas aeruginosa. Anal Biochem 2008; 385:321-5. [PMID: 19032927 DOI: 10.1016/j.ab.2008.10.041] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Revised: 10/23/2008] [Accepted: 10/28/2008] [Indexed: 10/21/2022]
Abstract
Bacterial resistance to antibiotic therapy remains a worldwide problem. In Pseudomonasaeruginosa, rates of efflux confer inherent resistance to many antimicrobial agents, including fluoroquinolones, due to a high level of expression and a relatively high turnover number of the efflux pumps in gram-negative bacteria. To understand the roles of efflux pumps in both the influx and efflux of compounds in P. aeruginosa and to aid the chemistry compound design by bridging in vitro enzymatic binding data (IC(50) values) with whole cell results (MIC numbers), a collaborative effort was put forward to validate a series of bacterial penetration/accumulation assays for assessment of intracellular drug concentration. Initially, using 2-(4-dimethylaminostyryl)-1-ethylpyridinium cation (DMP) as the tracer, a 96-well fluorescence assay was established to measure the time-dependent accumulation of DMP in wild-type (PAO1), MexABOprM deletion (PAO200), and MexABOprM-MexCDOprJ-MexJKL:FRT deletion mutants (PAO314). At steady state, the order of DMP accumulation was PAO314>PAO200>PAO1. Subsequently, the established assay conditions were applied to a radiolabeled assay format using (3)H-labeled ciprofloxacin. At the concentration tested, the accumulation of [(3)H]ciprofloxacin approached a plateau after 15 min and the amount of accumulation in PAO314 was higher (~2- to 10-fold) than that in PAO1. Finally, with an additional step of cell lysis, a liquid chromatography/mass spectrometry-based assay was established with ciprofloxacin with (i) superior sensitivity (the detection limit can be as low as 0.24 ng/ml for ciprofloxacin) and (ii) the ability to monitor cold or nonfluorescent compounds in a drug discovery setting.
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Affiliation(s)
- Hongliang Cai
- Department of Pharmacokinetics, Dynamics, and Metabolism, Pfizer Global Research and Development, Michigan Laboratories, Ann Arbor, MI 48105, USA.
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Okumura R, Hirata T, Onodera Y, Hoshino K, Otani T, Yamamoto T. Dual-targeting properties of the 3-aminopyrrolidyl quinolones, DC-159a and sitafloxacin, against DNA gyrase and topoisomerase IV: contribution to reducing in vitro emergence of quinolone-resistant Streptococcus pneumoniae. J Antimicrob Chemother 2008; 62:98-104. [PMID: 18390884 DOI: 10.1093/jac/dkn136] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES DC-159a (a novel quinolone) and sitafloxacin (DU-6859a) are structurally related quinolones, bearing a 3-aminopyrrolidyl substitution. We investigated the relationship between the target preferences of these 3-aminopyrrolidyl quinolones, in vitro potencies and emergence of quinolone-resistant mutants in Streptococcus pneumoniae, compared with other quinolones. METHODS MICs, resistance frequencies and mutant prevention concentrations (MPCs) were determined using quinolone-susceptible strains and first-step parC mutant strains of S. pneumoniae. Target preferences were tested by the following two methods: antibacterial activities against gyrA or parC mutants and in vitro enzyme assays for the determination of 50% inhibition (IC(50)) values. RESULTS DC-159a and sitafloxacin exhibited potent antibacterial activities, low frequencies of mutant selection, low MPCs and narrow mutant selection windows against both quinolone-susceptible strains and first-step parC mutants of S. pneumoniae, compared with gatifloxacin, moxifloxacin and other quinolones tested. DC-159a and sitafloxacin showed relatively low MIC ratios against single gyrA or parC mutants relative to the wild-type strain and low IC(50) ratios against DNA gyrase and topoisomerase IV. CONCLUSIONS DC-159a and sitafloxacin demonstrated a more balanced dual-targeting activity than gatifloxacin, moxifloxacin and other quinolones tested. In addition, DC-159a and sitafloxacin have a lower propensity for selecting first- and second-step resistant mutants.
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Affiliation(s)
- Ryo Okumura
- Biological Research Laboratories IV, Daiichi Sankyo Co., Ltd, 1-16-13 Kitakasai, Edogawa-ku, Tokyo 134-8630, Japan.
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The efflux pump inhibitor reserpine selects multidrug-resistant Streptococcus pneumoniae strains that overexpress the ABC transporters PatA and PatB. Antimicrob Agents Chemother 2008; 52:1677-85. [PMID: 18362193 DOI: 10.1128/aac.01644-07] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
One way to combat multidrug-resistant microorganisms is the use of efflux pump inhibitors (EPIs). Spontaneous mutants resistant to the EPI reserpine selected from Streptococcus pneumoniae NCTC 7465 and R6 at a frequency suggestive of a single mutational event were also multidrug resistant. No mutations in pmrA (which encodes the efflux protein PmrA) were detected, and the expression of pmrA was unaltered in all mutants. In the reserpine-resistant multidrug-resistant mutants, the overexpression of both patA and patB, which encode ABC transporters, was associated with accumulation of low concentrations of antibiotics and dyes. The addition of sodium orthovanadate, an inhibitor of ABC efflux pumps, or the insertional inactivation of either gene restored wild-type antibiotic susceptibility and wild-type levels of accumulation. Only when patA was insertionally inactivated were both multidrug resistance and reserpine resistance lost. Strains in which patA was insertionally inactivated grew significantly more slowly than the wild type. These data indicate that the overexpression of both patA and patB confers multidrug resistance in S. pneumoniae but that only patA is involved in reserpine resistance. The selection of reserpine-resistant multidrug-resistant pneumococci has implications for analogous systems in other bacteria or in cancer.
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Razek TMA, El‐Baqary RI, Ramadan AE. Fluorimetric Determination of Gatifloxacin in Aqueous, Pure and Pharmaceutical Formulations. ANAL LETT 2008. [DOI: 10.1080/00032710701746816] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Lubelski J, Konings WN, Driessen AJM. Distribution and physiology of ABC-type transporters contributing to multidrug resistance in bacteria. Microbiol Mol Biol Rev 2007; 71:463-76. [PMID: 17804667 PMCID: PMC2168643 DOI: 10.1128/mmbr.00001-07] [Citation(s) in RCA: 210] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Membrane proteins responsible for the active efflux of structurally and functionally unrelated drugs were first characterized in higher eukaryotes. To date, a vast number of transporters contributing to multidrug resistance (MDR transporters) have been reported for a large variety of organisms. Predictions about the functions of genes in the growing number of sequenced genomes indicate that MDR transporters are ubiquitous in nature. The majority of described MDR transporters in bacteria use ion motive force, while only a few systems have been shown to rely on ATP hydrolysis. However, recent reports on MDR proteins from gram-positive organisms, as well as genome analysis, indicate that the role of ABC-type MDR transporters in bacterial drug resistance might be underestimated. Detailed structural and mechanistic analyses of these proteins can help to understand their molecular mode of action and may eventually lead to the development of new strategies to counteract their actions, thereby increasing the effectiveness of drug-based therapies. This review focuses on recent advances in the analysis of ABC-type MDR transporters in bacteria.
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Affiliation(s)
- Jacek Lubelski
- Department of Molecular Microbiology, University of Groningen, Kerklaan 30, NL-9751 NN Haren, The Netherlands
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Louie A, Brown DL, Liu W, Kulawy RW, Deziel MR, Drusano GL. In vitro infection model characterizing the effect of efflux pump inhibition on prevention of resistance to levofloxacin and ciprofloxacin in Streptococcus pneumoniae. Antimicrob Agents Chemother 2007; 51:3988-4000. [PMID: 17846144 PMCID: PMC2151412 DOI: 10.1128/aac.00391-07] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The prevalence of fluoroquinolone-resistant Streptococcus pneumoniae is slowly rising as a consequence of the increased use of fluoroquinolone antibiotics to treat community-acquired pneumonia. We tested the hypothesis that increased efflux pump (EP) expression by S. pneumoniae may facilitate the emergence of fluoroquinolone resistance. By using an in vitro pharmacodynamic infection system, a wild-type S. pneumoniae strain (Spn-058) and an isogenic strain with EP overexpression (Spn-RC2) were treated for 10 days with ciprofloxacin or levofloxacin in the presence or absence of the EP inhibitor reserpine to evaluate the effect of EP inhibition on the emergence of resistance. Cultures of Spn-058 and Spn-RC2 were exposed to concentration-time profiles simulating those in humans treated with a regimen of ciprofloxacin at 750 mg orally once every 12 h and with regimens of levofloxacin at 500 and 750 mg orally once daily (QD; with or without continuous infusions of 20 microg of reserpine/ml). The MICs of ciprofloxacin and levofloxacin for Spn-058 were both 1 microg/ml when susceptibility testing was conducted with each antibiotic alone and with each antibiotic in the presence of reserpine. For Spn-RC2, the MIC of levofloxacin alone and with reserpine was also 1 mug/ml; the MICs of ciprofloxacin were 2 and 1 microg/ml, respectively, when determined with ciprofloxacin alone and in combination with reserpine. Reserpine, alone, had no effect on the growth of Spn-058 and Spn-RC2. For Spn-058, simulated regimens of ciprofloxacin at 750 mg every 12 h or levofloxacin at 500 mg QD were associated with the emergence of fluoroquinolone resistance. However, the use of ciprofloxacin at 750 mg every 12 h and levofloxacin at 500 mg QD in combination with reserpine rapidly killed Spn-058 and prevented the emergence of resistance. For Spn-RC2, levofloxacin at 500 mg QD was associated with the emergence of resistance, but again, the resistance was prevented when this levofloxacin regimen was combined with reserpine. Ciprofloxacin at 750 mg every 12 h also rapidly selected for ciprofloxacin-resistant mutants of Spn-RC2. However, the addition of reserpine to ciprofloxacin therapy only delayed the emergence of resistance. Levofloxacin at 750 mg QD, with and without reserpine, effectively eradicated Spn-058 and Spn-RC2 without selecting for fluoroquinolone resistance. Ethidium bromide uptake and efflux studies demonstrated that, at the baseline, Spn-RC2 had greater EP expression than Spn-058. These studies also showed that ciprofloxacin was a better inducer of EP expression than levofloxacin in both Spn-058 and Spn-RC2. However, in these isolates, the increase in EP expression by short-term exposure to ciprofloxacin and levofloxacin was transient. Mutants of Spn-058 and Spn-RC2 that emerged under suboptimal antibiotic regimens had a stable increase in EP expression. Levofloxacin at 500 mg QD in combination with reserpine, an EP inhibitor, or at 750 mg QD alone killed wild-type S. pneumoniae and strains that overexpressed reserpine-inhibitable EPs and was highly effective in preventing the emergence of fluoroquinolone resistance in S. pneumoniae during therapy. Ciprofloxacin at 750 mg every 12 h, as monotherapy, was ineffective for the treatment of Spn-058 and Spn-RC2. Ciprofloxacin in combination with reserpine prevented the emergence of resistance in Spn-058 but not in Spn-RC2, the EP-overexpressing strain.
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Affiliation(s)
- Arnold Louie
- Emerging Infection and Host Defense Theme, Ordway Research Institute, 150 New Scotland Ave., Albany, NY 12208, USA.
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Association of MexAB-OprM with intrinsic resistance ofPseudomonas aeruginosa to aminoglycosides. ANN MICROBIOL 2007. [DOI: 10.1007/bf03175084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Stavri M, Piddock LJV, Gibbons S. Bacterial efflux pump inhibitors from natural sources. J Antimicrob Chemother 2006; 59:1247-60. [PMID: 17145734 DOI: 10.1093/jac/dkl460] [Citation(s) in RCA: 327] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The rapid spread of bacteria expressing multidrug resistance (MDR) has necessitated the discovery of new antibacterials and resistance-modifying agents. Since the initial discovery of bacterial efflux pumps in the 1980s, many have been characterized in community- and hospital-acquired Gram-positive and Gram-negative pathogens, such as Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and, more recently, in mycobacteria. Efflux pumps are able to extrude structurally diverse compounds, including antibiotics used in a clinical setting; the latter are rendered therapeutically ineffective. Antibiotic resistance can develop rapidly through changes in the expression of efflux pumps, including changes to some antibiotics considered to be drugs of last resort. It is therefore imperative that new antibiotics, resistance-modifying agents and, more specifically, efflux pump inhibitors (EPIs) are characterized. The use of bacterial resistance modifiers such as EPIs could facilitate the re-introduction of therapeutically ineffective antibiotics back into clinical use such as ciprofloxacin and might even suppress the emergence of MDR strains. Here we review the literature on bacterial EPIs derived from natural sources, primarily those from plants. The resistance-modifying activities of many new chemical classes of EPIs warrant further studies to assess their potential as leads for clinical development.
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Affiliation(s)
- Michael Stavri
- Centre for Pharmacognosy and Phytotherapy, The School of Pharmacy, University of London 29-39 Brunswick Square, London, UK
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Le Carrou J, Laurentie M, Kobisch M, Gautier-Bouchardon AV. Persistence of Mycoplasma hyopneumoniae in experimentally infected pigs after marbofloxacin treatment and detection of mutations in the parC gene. Antimicrob Agents Chemother 2006; 50:1959-66. [PMID: 16723552 PMCID: PMC1479153 DOI: 10.1128/aac.01527-05] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The ability of Mycoplasma hyopneumoniae to persist despite fluoroquinolone treatments was investigated with pigs. Groups of specific-pathogen-free pigs were experimentally infected with M. hyopneumoniae strain 116 and treated with marbofloxacin at the therapeutic dose (TD) or half of the therapeutic dose (TD/2) for 3 days. Results showed that, despite tissue penetration of marbofloxacin, particularly in the trachea and the tracheal secretions, the treatments did not have any influence on M. hyopneumoniae recovery from tracheal swabs. Mycoplasmas were also isolated from inner organs and tissues such as liver, spleen, kidneys, and bronchial lymph nodes. Recontamination of pigs via environment could not explain mycoplasma persistence after medication, as decontamination of pigs and allocation to a new disinfected environment did not have any significant effect on the phenomenon. A significant decrease in the susceptibility level to marbofloxacin of 12 mycoplasma clones reisolated after the treatments (TD/2 and TD) was observed. Two point mutations were found in the ParC quinolone resistance-determining region (QRDR) of DNA topoisomerase IV (Ser80-->Phe and Asp84-->Asn), and one point mutation was observed just behind the QRDR of ParC (Ala116-->Glu). This is the first time that mutations in a gene coding for topoisomerase IV have been described for M. hyopneumoniae after in vivo marbofloxacin treatments in experimentally infected pigs. However, development of resistance is not sufficient to explain M. hyopneumoniae persistence in vivo since (i) marbofloxacin concentrations were above the marbofloxacin MIC of the wild-type strain and (ii) mycoplasmas reisolated after a single injection of marbofloxacin did not display an increased marbofloxacin MIC.
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Affiliation(s)
- J Le Carrou
- Agence Française de Sécurité Sanitaire des Aliments, Laboratoire d'Etudes et de Recherches Avicoles et Porcines, Unité de Mycoplasmologie-Bactériologie, Ploufragan, France
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Decousser JW, Methlouthi I, Pina P, Collignon A, Allouch P. New real-time PCR assay using locked nucleic acid probes to assess prevalence of ParC mutations in fluoroquinolone-susceptible Streptococcus pneumoniae isolates from France. Antimicrob Agents Chemother 2006; 50:1594-8. [PMID: 16569894 PMCID: PMC1426917 DOI: 10.1128/aac.50.4.1594-1598.2006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A real-time PCR assay with locked nucleic acid probes was developed to screen mutations at codons 79 and 83 of the Streptococcus pneumoniae parC gene. Only silent mutations were detected among 236 French invasive fluoroquinolone-susceptible strains. This test could be useful for some high-risk patients or in national surveys.
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Affiliation(s)
- Jean-Winoc Decousser
- Laboratoire de Biologie, Centre Hospitalier de Dourdan, 2 Rue du Potelet, 91415 Dourdan, France.
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Piddock LJV. Clinically relevant chromosomally encoded multidrug resistance efflux pumps in bacteria. Clin Microbiol Rev 2006; 19:382-402. [PMID: 16614254 PMCID: PMC1471989 DOI: 10.1128/cmr.19.2.382-402.2006] [Citation(s) in RCA: 751] [Impact Index Per Article: 41.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Efflux pump genes and proteins are present in both antibiotic-susceptible and antibiotic-resistant bacteria. Pumps may be specific for one substrate or may transport a range of structurally dissimilar compounds (including antibiotics of multiple classes); such pumps can be associated with multiple drug (antibiotic) resistance (MDR). However, the clinical relevance of efflux-mediated resistance is species, drug, and infection dependent. This review focuses on chromosomally encoded pumps in bacteria that cause infections in humans. Recent structural data provide valuable insights into the mechanisms of drug transport. MDR efflux pumps contribute to antibiotic resistance in bacteria in several ways: (i) inherent resistance to an entire class of agents, (ii) inherent resistance to specific agents, and (iii) resistance conferred by overexpression of an efflux pump. Enhanced efflux can be mediated by mutations in (i) the local repressor gene, (ii) a global regulatory gene, (iii) the promoter region of the transporter gene, or (iv) insertion elements upstream of the transporter gene. Some data suggest that resistance nodulation division systems are important in pathogenicity and/or survival in a particular ecological niche. Inhibitors of various efflux pump systems have been described; typically these are plant alkaloids, but as yet no product has been marketed.
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Affiliation(s)
- Laura J V Piddock
- Antimicrobial Agents Research Group, Division of Immunity and Infection, The Medical School, University of Birmingham, Birmingham, United Kingdom, B15 2TT.
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Marrer E, Satoh AT, Johnson MM, Piddock LJV, Page MGP. Global transcriptome analysis of the responses of a fluoroquinolone-resistant Streptococcus pneumoniae mutant and its parent to ciprofloxacin. Antimicrob Agents Chemother 2006; 50:269-78. [PMID: 16377697 PMCID: PMC1346767 DOI: 10.1128/aac.50.1.269-278.2006] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus pneumoniae M22 is a multidrug-resistant mutant selected after exposure of capsulated wild-type S. pneumoniae NCTC 7465 (strain M4) to ciprofloxacin. DNA microarray analysis comparing the gene expression profiles of strain M22 with those of strain M4 showed that strain M22 constitutively expressed 22 genes at levels higher than those observed in strain M4 under all conditions studied. These included the genes encoding the enzymes involved in branched-chain amino acid biosynthesis and two genes (patA and patB) with sequences suggestive of ABC transporter proteins. Expression of the patA and patB genes was induced by ciprofloxacin in both strains, but in strain M4 it only reached the levels observed in strain M22 after long incubation with high concentrations of ciprofloxacin. The altered expression profile observed with strain M22 suggested that the mutation or mutations acquired during resistance selection bring the cell into a state in which the expression of critical genes is preemptively altered to correct for the potential effects of ciprofloxacin on gene expression in the parent strain.
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Affiliation(s)
- Estelle Marrer
- The University of Texas Health Science Center at San Antonio, Texas 78229-3900, USA
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Marrer E, Schad K, Satoh AT, Page MGP, Johnson MM, Piddock LJV. Involvement of the putative ATP-dependent efflux proteins PatA and PatB in fluoroquinolone resistance of a multidrug-resistant mutant of Streptococcus pneumoniae. Antimicrob Agents Chemother 2006; 50:685-93. [PMID: 16436727 PMCID: PMC1366865 DOI: 10.1128/aac.50.2.685-693.2006] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The multidrug-resistant mutant Streptococcus pneumoniae M22 constitutively overexpresses two genes (patA and patB) that encode proteins homologous to known efflux proteins belonging to the ABC transporter family. It is shown here that PatA and PatB were strongly induced by quinolone antibiotics and distamycin in fluoroquinolone-sensitive strains. PatA was very important for growth of S. pneumoniae, and it could not be disrupted in strain M22. PatB appeared to control metabolic activity, particularly in amino acid biosynthesis, and it may have a pivotal role in coordination of the response to quinolone antibiotics. The induction of PatA and PatB by antibiotics showed a pattern similar to that exhibited by SP1861, a homologue of ABC-type transporters of choline and other osmoprotectants. A second group of quinolone-induced transporter genes comprising SP1587 and SP0287, which are homologues of, respectively, oxalate/formate antiporters and xanthine or uracil permeases belonging to the major facilitator family, showed a different pattern of induction by other antibiotics. There was no evidence for the involvement of PmrA, the putative proton-dependent multidrug transporter that has been implicated in norfloxacin resistance, in the response to quinolone antibiotics in either the resistant mutant or the fluoroquinolone-sensitive strains.
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Affiliation(s)
- Estelle Marrer
- Basilea Pharmaceutica Ltd., P.O. Box 3255, CH-4005 Basel, Switzerland
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Hiyama L, Tang A, Miller LG. Levofloxacin Penetration Into a Renal Cyst in a Patient With Autosomal Dominant Polycystic Kidney Disease. Am J Kidney Dis 2006; 47:e9-13. [PMID: 16377378 DOI: 10.1053/j.ajkd.2005.09.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2005] [Accepted: 09/19/2005] [Indexed: 11/11/2022]
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is a common inherited disorder often complicated by cyst infection. Treatment becomes particularly challenging when the culprit organism is resistant to antibiotics known to sufficiently penetrate cysts. We present the case of a patient with ADPKD and suspected cyst infection caused by group B streptococcus who was treated successfully with levofloxacin and ampicillin. Although data support excellent cyst penetration with ciprofloxacin, its gram-positive antimicrobial activity is marginal. The newer quinolones have added gram-positive activity, but little is known about cyst penetration by these antibiotics. We simultaneously measured cyst and serum levels of levofloxacin and ampicillin and found levofloxacin to penetrate cysts well. Therefore, levofloxacin may be useful in the management of renal cyst infection, particularly for the treatment of gram-positive organisms.
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Cottagnoud P, Johnson M, Cottagnoud M, Piddock L. Preincubation of pneumococci with beta-lactams alone or combined with levofloxacin prevents quinolone-induced resistance without increasing intracellular levels of levofloxacin. Antimicrob Agents Chemother 2005; 49:3517-9. [PMID: 16048972 PMCID: PMC1196276 DOI: 10.1128/aac.49.8.3517-3519.2005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Preincubation of pneumococci with sub-MIC concentrations of ceftriaxone (1/16x MIC), cefotaxime (1/8x MIC), and meropenem (1/4x MIC) alone or combined with levofloxacin (1/8x MIC) over 6 h prevents the emergence of levofloxacin-resistant mutants after 96 h of incubation but does not affect the intracellular accumulation of levofloxacin in two penicillin-resistant pneumococcal strains, suggesting a link between the mechanism of action of beta-lactams and the emergence of quinolone-induced resistance in pneumococci.
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Affiliation(s)
- Philippe Cottagnoud
- Department of Internal Medicine, Inselspital, Freiburgstrasse, 3010 Bern, Switzerland.
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Sierra JM, Cabeza JG, Ruiz Chaler M, Montero T, Hernandez J, Mensa J, Llagostera M, Vila J. The selection of resistance to and the mutagenicity of different fluoroquinolones in Staphylococcus aureus and Streptococcus pneumoniae. Clin Microbiol Infect 2005; 11:750-8. [PMID: 16104991 DOI: 10.1111/j.1469-0691.2005.01211.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Two quinolone-susceptible Staphylococcus aureus and five quinolone-susceptible Streptococcus pneumoniae isolates were used to obtain in-vitro quinolone-resistant mutants in a multistep resistance selection process. The fluoroquinolones used were ciprofloxacin, moxifloxacin, levofloxacin, gemifloxacin, trovafloxacin and clinafloxacin. The mutagenicity of these quinolones was determined by the Salmonella and the Escherichia coli retromutation assays. All quinolone-resistant Staph. aureus mutants had at least one mutation in the grlA gene, while 86.6% of quinolone-resistant Strep. pneumoniae mutants had mutations in either or both the gyrA and parC genes. Moxifloxacin and levofloxacin selected resistant mutants later than the other quinolones, but this difference was more obvious in Staph. aureus. Accumulation of the fluoroquinolones by Staph. aureus did not explain these differences, since levofloxacin and moxifloxacin accumulated inside bacteria to the same extent as clinafloxacin and trovafloxacin. The results also showed that moxifloxacin and levofloxacin had less mutagenic potency in both mutagenicity assays, suggesting a possible relationship between the selection of resistance to quinolones and the mutagenic potency of the molecule. Furthermore, gemifloxacin selected efflux mutants more frequently than the other quinolones used. Thus, the risk of developing quinolone resistance may depend on the density of the microorganism at the infection site and the concentration of the fluoroquinolone, and also on the mutagenicity of the quinolone used, with moxifloxacin and levofloxacin being the least mutagenic.
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Affiliation(s)
- J M Sierra
- Departament de Microbiologia, Centre de Diagnòstic Biomèdic, IDIBAPS, Hospital Clínic Barcelona, and Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Spain
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Zhanel GG, Hoban DJ, Schurek K, Karlowsky JA. Role of efflux mechanisms on fluoroquinolone resistance in Streptococcus pneumoniae and Pseudomonas aeruginosa. Int J Antimicrob Agents 2005; 24:529-35. [PMID: 15555873 DOI: 10.1016/j.ijantimicag.2004.08.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Prokaryotic efflux mechanisms can effectively increase the intrinsic resistance of bacteria by actively transporting antibiotics out of cells, thus reducing the effective concentration of these agents. The fluoroquinolones, similar to most other antimicrobial classes, are susceptible to efflux mechanisms, particularly in Gram-negative organisms, such as Pseudomonas aeruginosa. Resistant P. aeruginosa clones isolated after fluoroquinolone therapy frequently over express at least one of the multiple efflux pump mechanisms found in this organism. Gram-positive bacteria, such as Streptococcus pneumoniae, also possess efflux mechanisms, though their effect on fluoroquinolone resistance seems to be more limited and selective. In the future, efflux pump inhibitors may offer effective adjunctive therapy to antibiotics for the treatment of difficult infections by efflux mutants. In the meantime, appropriate antibiotic selection and optimal dosing strategies should aim to eradicate the causative pathogen before a resistant efflux mutant can emerge.
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Affiliation(s)
- George G Zhanel
- Department of Medical Microbiology, Faculty of Medicine, University of Manitoba, Manitoba, Canada.
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Cattoir V. [Efflux-mediated antibiotics resistance in bacteria]. ACTA ACUST UNITED AC 2005; 52:607-16. [PMID: 15596311 DOI: 10.1016/j.patbio.2004.09.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2004] [Accepted: 09/07/2004] [Indexed: 11/17/2022]
Abstract
Bacteria can resist to antibiotics by active exportation mediated by membrane transporters called efflux pumps. These proteins can be specific of a class of antibiotics or responsible for multidrug resistance (MDR). Energy required by efflux pumps can be provided by transmembrane electrochemical gradient of protons (MFS, RND, SMR families) or sodium ions (MATE family) or by ATP hydrolysis (ABC family). Several physiological functions have been described in prokaryotes, such as protection from environmental toxics and regulation of cell homeostasis, which can indirectly contributes to bacterial virulence. In Gram-negative bacteria, efflux transporters usually are organized as multicomponent systems in which the efflux pump located in the inner membrane works in conjunction with a periplasmic fusion protein and an outer membrane factor. The most frequently encountered pumps are of the RND-type such as AcrB in Escherichia coli or MexB in Pseudomonas aeruginosa. In Gram-positive bacteria, efflux is solely mediated by the pump protein, so described with MFS pumps such as NorA or QacA in Staphylococcus aureus and PmrA in Streptococcus pneumoniae. Efflux transporters have also been described in mycobacteria. Although numerous bacterial pumps have been characterized, the clinical consequences of efflux-mediated resistance are mostly unknown because of variable levels of expression and of the lack of specific markers in laboratory practice. Finally, associating pump-specific inhibitors to efflux-sensitive antibiotics might prove an interesting therapeutic perspective. However, inhibitors that are not toxic to eukaryotic cells remain to be identified.
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Affiliation(s)
- Vincent Cattoir
- Laboratoire de bactériologie-virologie, faculté de médecine de Rennes, 2, avenue du Professeur-Léon-Bernard, 35043 Rennes cedex, France.
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Woodford N. Biological counterstrike: antibiotic resistance mechanisms of Gram-positive cocci. Clin Microbiol Infect 2005; 11 Suppl 3:2-21. [PMID: 15811020 DOI: 10.1111/j.1469-0691.2005.01140.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The development of antibiotic resistance by bacteria is an evolutionary inevitability, a convincing demonstration of their ability to adapt to adverse environmental conditions. Since the emergence of penicillinase-producing Staphylococcus aureus in the 1940s, staphylococci, enterococci and streptococci have proved themselves adept at developing or acquiring mechanisms that confer resistance to all clinically available antibacterial classes. The increasing problems of methicillin-resistant S. aureus and coagulase-negative staphylococci (MRSA and MRCoNS), glycopeptide-resistant enterococci and penicillin-resistant pneumococci in the 1980s, and recognition of glycopeptide-intermediate S. aureus in the 1990s and, most recently, of fully vancomycin-resistant isolates of S. aureus have emphasised our need for new anti-Gram-positive agents. Antibiotic resistance is one of the major public health concerns for the beginning of the 21st century. The pharmaceutical industry has responded with the development of oxazolidinones, lipopeptides, injectable streptogramins, ketolides, glycylcyclines, second-generation glycopeptides and novel fluoroquinolones. However, clinical use of these novel agents will cause new selective pressures and will continue to drive the development of resistance. This review describes the various antibiotic resistance mechanisms identified in isolates of staphylococci, enterococci and streptococci, including mechanisms of resistance to recently introduced anti-Gram-positive agents.
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Affiliation(s)
- N Woodford
- Antibiotic Resistance Monitoring and Reference Laboratory, Centre for Infections, Health Protection Agency, London NW9 5HT, UK.
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Abstract
Drug resistance in bacteria, and especially resistance to multiple antibacterials, has attracted much attention in recent years. In addition to the well known mechanisms, such as inactivation of drugs and alteration of targets, active efflux is now known to play a major role in the resistance of many species to antibacterials. Drug-specific efflux (e.g. that of tetracycline) has been recognised as the major mechanism of resistance to this drug in Gram-negative bacteria. In addition, we now recognise that multidrug efflux pumps are becoming increasingly important. Such pumps play major roles in the antiseptic resistance of Staphylococcus aureus, and fluoroquinolone resistance of S. aureus and Streptococcus pneumoniae. Multidrug pumps, often with very wide substrate specificity, are not only essential for the intrinsic resistance of many Gram-negative bacteria but also produce elevated levels of resistance when overexpressed. Paradoxically, 'advanced' agents for which resistance is unlikely to be caused by traditional mechanisms, such as fluoroquinolones and beta-lactams of the latest generations, are likely to select for overproduction mutants of these pumps and make the bacteria resistant in one step to practically all classes of antibacterial agents. Such overproduction mutants are also selected for by the use of antiseptics and biocides, increasingly incorporated into consumer products, and this is also of major concern. We can consider efflux pumps as potentially effective antibacterial targets. Inhibition of efflux pumps by an efflux pump inhibitor would restore the activity of an agent subject to efflux. An alternative approach is to develop antibacterials that would bypass the action of efflux pumps.
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Affiliation(s)
- Xian-Zhi Li
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3202, USA
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Piddock LJV, Jin YF, Webber MA, Everett MJ. Novel ciprofloxacin-resistant, nalidixic acid-susceptible mutant of Staphylococcus aureus. Antimicrob Agents Chemother 2002; 46:2276-8. [PMID: 12069989 PMCID: PMC127307 DOI: 10.1128/aac.46.7.2276-2278.2002] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A ciprofloxacin-resistant, nalidixic acid-susceptible mutant of Staphylococcus aureus (F145) contained no mutations within gyrA, gyrB, grlA, and grlB or within norA or its promoter region. MICs and accumulation studies suggest the role of a novel multidrug efflux pump.
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Affiliation(s)
- Laura J V Piddock
- Antimicrobial Agents Research Group, Division of Immunity & Infection, University of Birmingham, Birmingham B15 2TT, United Kingdom.
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