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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
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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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53
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In vitro activity of nemonoxacin, a novel nonfluorinated quinolone antibiotic, against Chlamydia trachomatis and Chlamydia pneumoniae. Antimicrob Agents Chemother 2013; 58:1800-1. [PMID: 24366753 DOI: 10.1128/aac.02263-13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The in vitro activities of nemonoxacin, levofloxacin, azithromycin, and doxycycline were tested against 10 isolates each of Chlamydia trachomatis and Chlamydia pneumoniae. The MICs at which 90% of the isolates of both C. trachomatis and C. pneumoniae were inhibited (MIC90s) were 0.06 μg/ml (range, 0.03 to 0.13 μg/ml). The minimal bactericidal concentrations at which 90% of the isolates were killed by nemonoxacin (MBC90s) were 0.06 μg/ml for C. trachomatis (range, 0.03 to 0.125 μg/ml) and 0.25 for C. pneumoniae (range, 0.015 to 0.5 μg/ml).
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Ciesielczuk H, Hornsey M, Choi V, Woodford N, Wareham DW. Development and evaluation of a multiplex PCR for eight plasmid-mediated quinolone-resistance determinants. J Med Microbiol 2013; 62:1823-1827. [DOI: 10.1099/jmm.0.064428-0] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The objective of this study was to develop and validate an expanded multiplex PCR assay for the simultaneous detection of eight plasmid-mediated quinolone-resistance determinants in Enterobacteriaceae. Primers were designed to amplify conserved fragments of qnrABCDS, qepA, oqxAB and aac(6′)-Ib-cr genes and were optimized in uniplex and multiplex PCR assays with control template DNA. The assay was used to determine the prevalence of plasmid-mediated quinolone resistance (PMQR) genes in 174 ciprofloxacin-resistant and 43 ciprofloxacin-susceptible extraintestinal pathogenic Escherichia coli isolates. Each resistance gene could be detected alone and in combination. PMQR determinants were detected in 65 ciprofloxacin-resistant isolates (37 %) and one ciprofloxacin-susceptible isolate (2 %). Prevalences of the identified determinants were: aac(6′)-Ib-cr, 34.5 %; qnrS, 1.1 %; qepA, 1.1 %; and oqxAB, 0.6 %. In conclusion, we developed an eight-target multiplex PCR for the accurate detection of PMQR genes and confirmed that PMQR prevalence remains low among human Escherichia coli clinical isolates in the UK.
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Affiliation(s)
- H. Ciesielczuk
- Antimicrobial Resistance and Healthcare Associated Infections Reference Laboratory, Public Health England, London NW9 5EQ, UK
- Antimicrobial Research Group, Centre for Immunology and Infectious Disease, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary, University of London, London E1 2AT, UK
| | - M. Hornsey
- Department of Life Sciences, Whitelands College, University of Roehampton, Holybourne Avenue, London SW15 4JD, UK
- Antimicrobial Research Group, Centre for Immunology and Infectious Disease, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary, University of London, London E1 2AT, UK
| | - V. Choi
- Singapore General Hospital, Singapore 169037, Singapore
- Antimicrobial Research Group, Centre for Immunology and Infectious Disease, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary, University of London, London E1 2AT, UK
| | - N. Woodford
- Antimicrobial Resistance and Healthcare Associated Infections Reference Laboratory, Public Health England, London NW9 5EQ, UK
- Antimicrobial Research Group, Centre for Immunology and Infectious Disease, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary, University of London, London E1 2AT, UK
| | - D. W. Wareham
- Antimicrobial Research Group, Centre for Immunology and Infectious Disease, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary, University of London, London E1 2AT, UK
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55
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Guo Q, Zhuo C, Xu Y, Huang W, Wang C, Zhang S, Huang J, Hu F, Zhu D, Yang F, Wang M. Genetic diversity of fluoroquinolone-nonsusceptible Streptococcus pneumoniae clinical isolates and the first identification of serotype 20B in China. Eur J Clin Microbiol Infect Dis 2013; 33:465-70. [PMID: 24091745 DOI: 10.1007/s10096-013-1979-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 09/04/2013] [Indexed: 11/26/2022]
Abstract
The purpose of this study was to investigate the genetic characteristics of fluoroquinolone-nonsusceptible Streptococcus pneumoniae clinical isolates in China. A total of 377 S. pneumoniae clinical isolates, including 307 pediatric strains and 70 adult strains, were collected from eight centers in China. The minimal inhibitory concentrations (MICs) of 10 antimicrobial agents were determined by agar dilution. Multilocus sequence typing (MLST), serotyping, and quinolone resistance-determining region (QRDR) variations were conducted in levofloxacin-nonsusceptible isolates by polymerase chain reaction (PCR)-based methods. Seven levofloxacin-nonsusceptible isolates were found, with an overall resistance rate of 1.9 % (7/377) and 8.6 % (6/70) in adults. Sequence analyses of parC, gyrA, and parE QRDRs in levofloxacin-resistant isolates demonstrated mutations in dual target sites at the hot spots. These seven strains represented multiple clones: two strains were serotype 19F (Taiwan(19F)-14) and MLST clonal complex (CC) 271/320, two were typed as 23F (Spain(23F)-1) and CC81, two were determined as serotype 20B and a new sequence type of ST6935, and one non-serotypeable pediatric strain belonged to a new sequence type of ST6946. Two serotype 19F strains possessed a variety of characteristic alterations of viridans group streptococci in gyrA (Ser114Gly) or parC (Ser52Gly, Asn91Asp). Fluoroquinolone-nonsusceptible S. pneumoniae isolates showed a substantial degree of genetic diversity and belonged to pre-existing epidemic clones together with native clones. S. pneumoniae strains with serotype 20B was recovered for the first time to be associated with levofloxacin resistance in China.
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Affiliation(s)
- Q Guo
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, 200040, China
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56
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Laponogov I, Veselkov DA, Crevel IMT, Pan XS, Fisher LM, Sanderson MR. Structure of an 'open' clamp type II topoisomerase-DNA complex provides a mechanism for DNA capture and transport. Nucleic Acids Res 2013; 41:9911-23. [PMID: 23965305 PMCID: PMC3834822 DOI: 10.1093/nar/gkt749] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Type II topoisomerases regulate DNA supercoiling and chromosome segregation. They act as ATP-operated clamps that capture a DNA duplex and pass it through a transient DNA break in a second DNA segment via the sequential opening and closure of ATPase-, G-DNA- and C-gates. Here, we present the first ‘open clamp’ structures of a 3-gate topoisomerase II-DNA complex, the seminal complex engaged in DNA recognition and capture. A high-resolution structure was solved for a (full-length ParE-ParC55)2 dimer of Streptococcus pneumoniae topoisomerase IV bound to two DNA molecules: a closed DNA gate in a B-A-B form double-helical conformation and a second B-form duplex associated with closed C-gate helices at a novel site neighbouring the catalytically important β-pinwheel DNA-binding domain. The protein N gate is present in an ‘arms-wide-open’ state with the undimerized N-terminal ParE ATPase domains connected to TOPRIM domains via a flexible joint and folded back allowing ready access both for gate and transported DNA segments and cleavage-stabilizing antibacterial drugs. The structure shows the molecular conformations of all three gates at 3.7 Å, the highest resolution achieved for the full complex to date, and illuminates the mechanism of DNA capture and transport by a type II topoisomerase.
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Affiliation(s)
- Ivan Laponogov
- Randall Division of Cell and Molecular Biophysics, 3rd floor New Hunt's House, Guy's Campus, King's College London, London, SE1 1UL, UK and Division of Biomedical Sciences, St. George's, University of London, Cranmer Terrace, London, SW17 0RE, UK
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57
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Arnoldi E, Pan XS, Fisher LM. Functional determinants of gate-DNA selection and cleavage by bacterial type II topoisomerases. Nucleic Acids Res 2013; 41:9411-23. [PMID: 23939623 PMCID: PMC3814380 DOI: 10.1093/nar/gkt696] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Antibacterial fluoroquinolones trap a cleavage complex of gyrase and topoisomerase (topo) IV inducing site-specific DNA breakage within a bent DNA gate engaged in DNA transport. Despite its importance for drug action and in revealing potential sites of topoisomerase catalysis, the mechanism of DNA selectivity is poorly understood. To explore its functional basis, we generated mutant versions of the strongly cleaved E-site and used a novel competitive assay to examine their gemifloxacin-mediated DNA breakage by Streptococcus pneumoniae topo IV and gyrase. Parallel studies of Ca2+-induced cleavage distinguished ‘intrinsic recognition’ of DNA cleavage sites by topo IV from drug-induced preferences. Analysis revealed strong enzyme-determined requirements for −4G, −2A and −1T bases preceding the breakage site (between −1 and +1) and enzyme-unique or degenerate determinants at −3, plus drug-specific preferences at +2/+3 and for +1 purines associated with drug intercalation. Similar cleavage rules were seen additionally at the novel V-site identified here in ColE1-derived plasmids. In concert with DNA binding data, our results provide functional evidence for DNA, enzyme and drug contributions to DNA cleavage at the gate, suggest a mechanism for DNA discrimination involving enzyme-induced DNA bending/helix distortion and cleavage complex stabilization and advance understanding of fluoroquinolones as important cleavage-enhancing therapeutics.
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Affiliation(s)
- Elisa Arnoldi
- Division of Biomedical Sciences, St.George's, University of London, London SW17 0RE, UK
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58
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Cheng G, Hao H, Dai M, Liu Z, Yuan Z. Antibacterial action of quinolones: From target to network. Eur J Med Chem 2013; 66:555-62. [DOI: 10.1016/j.ejmech.2013.01.057] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2012] [Revised: 01/23/2013] [Accepted: 01/26/2013] [Indexed: 11/27/2022]
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Genomic characterization of ciprofloxacin resistance in a laboratory-derived mutant and a clinical isolate of Streptococcus pneumoniae. Antimicrob Agents Chemother 2013; 57:4911-9. [PMID: 23877698 DOI: 10.1128/aac.00418-13] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The broad-spectrum fluoroquinolone ciprofloxacin is a bactericidal antibiotic targeting DNA topoisomerase IV and DNA gyrase encoded by the parC and gyrA genes. Resistance to ciprofloxacin in Streptococcus pneumoniae mainly occurs through the acquisition of mutations in the quinolone resistance-determining region (QRDR) of the ParC and GyrA targets. A role in low-level ciprofloxacin resistance has also been attributed to efflux systems. To look into ciprofloxacin resistance at a genome-wide scale and to discover additional mutations implicated in resistance, we performed whole-genome sequencing of an S. pneumoniae isolate selected for resistance to ciprofloxacin in vitro (128 μg/ml) and of a clinical isolate displaying low-level ciprofloxacin resistance (2 μg/ml). Gene disruption and DNA transformation experiments with PCR fragments harboring the mutations identified in the in vitro S. pneumoniae mutant revealed that resistance is mainly due to QRDR mutations in parC and gyrA and to the overexpression of the ABC transporters PatA and PatB. In contrast, no QRDR mutations were identified in the genome of the S. pneumoniae clinical isolate with low-level resistance to ciprofloxacin. Assays performed in the presence of the efflux pump inhibitor reserpine suggested that resistance is likely mediated by efflux. Interestingly, the genome sequence of this clinical isolate also revealed mutations in the coding region of patA and patB that we implicated in resistance. Finally, a mutation in the NAD(P)H-dependent glycerol-3-phosphate dehydrogenase identified in the S. pneumoniae clinical strain was shown to protect against ciprofloxacin-mediated reactive oxygen species.
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60
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Bast DJ, Dresser L, Duncan CL, Walker SE, Mandell LA, Low DE, de Azavedo JCS. Short-Course Therapy of Gemifloxacin Effective Against Pneumococcal Pneumonia in Mice. J Chemother 2013; 18:634-40. [PMID: 17267342 DOI: 10.1179/joc.2006.18.6.634] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Standard 7-14 day (d) courses of antimicrobial therapy for community-acquired pneumonia (CAP) are thought to have contributed to the emergence of resistant pneumoccoci. Consequently, short-course fluoroquinolone regimens have been proposed to minimize resistance. To test this, we examined 2-day versus 5-day regimens of gemifloxacin and levofloxacin for treatment of pneumonia in a murine model. In doing so, we also investigated whether the enhanced potency of gemifloxacin would influence outcomes. CD1 Swiss mice were infected intratracheally with 10(5)-CFU of a virulent Streptococcus pneumoniae strain. Drugs were administered every 8 h for 2 d and 5 d, starting at 24 h postinfection. Temperature was used to assess disease progression. Gemifloxacin remained effective for 2 d and 5 d, with survival rates of 100%-83% compared with 40%-58% for levofloxacin. Eighty-nine to 100% of gemifloxacin-treated mice were clear of pulmonary bacteria compared with only 0%-20% for levofloxacin. For levofloxacin-treated mice, 2 of 7 (29%) isolates with a levofloxacin minimum inhibitory concentration (MIC) 4 times that of the infecting parent strain had ParC mutations. By contrast, no isolates recovered from gemifloxacin-treated mice were reduced in susceptibility. Gemifloxacin could be effective in shortening duration of therapy for CAP treatment as well as minimize resistance development.
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Affiliation(s)
- D J Bast
- Department of Microbiology, Mount Sinai Hospital, Toronto, Ontario, Canada
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61
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Dobay O, Rozgonyi F, Ghidán A, Matuz M, Nagy K, Amyes SGB. The First Steps Towards Fluoroquinolone Resistance in Hungarian Pneumococci. J Chemother 2013; 18:624-7. [PMID: 17267340 DOI: 10.1179/joc.2006.18.6.624] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
The incidence of fluoroquinolone resistance among Hungarian routine laboratory Streptococcus pneumoniae isolates, collected in 2000-2002, in common with other European countries, was very low; only 5/304 strains (1.64%) were resistant to ciprofloxacin (MIC = 4 microg/ml), and the other fluoroquinolones showed full efficacy. However, we could identify the Lys-137-Asp amino acid change, caused by a point mutation in the QRDR of the parC gene, in five strains. Additionally, we observed a definite shift in the minimum inhibitory concentrations (MICs) of all fluoroquinolones towards higher values throughout the study period. These two findings, coupled with the increasing consumption figures of fluoroquinolones, suggest that pneumococcal resistance looks poised to develop in Hungary.
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Affiliation(s)
- O Dobay
- University of Edinburgh, Scotland, UK
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62
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High prevalence of multiresistance in levofloxacin-nonsusceptible Streptococcus pneumoniae isolates in Korea. Diagn Microbiol Infect Dis 2013; 76:227-31. [PMID: 23623384 DOI: 10.1016/j.diagmicrobio.2013.02.032] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 02/18/2013] [Accepted: 02/26/2013] [Indexed: 11/22/2022]
Abstract
Korea exhibits the highest rates of multidrug resistance among Streptococcus pneumoniae. The increasing use of levofloxacin has raised concern about the dissemination of levofloxacin resistance in dominant multidrug-resistant (MDR) clones of our pneumococcal population. A total of 50 levofloxacin-nonsusceptible S. pneumoniae (MIC, ≥4 μg/mL) collected from a multihospital network from 1996 to 2006 were analyzed for serotype, antibiotic resistance profile, quinolone resistance-determining region mutation, and multilocus sequence type. Most levofloxacin-nonsusceptible S. pneumoniae (94.0%) exhibited an MDR phenotype. This phenotype was closely associated with a limited number of epidemic MDR clones that are well-known key agents of the global spread of antimicrobial resistance in S. pneumoniae. However, the clonal dissemination of levofloxacin-nonsusceptible S. pneumoniae was rare. Levofloxacin-nonsusceptible clones with nonvaccine serotypes increased during the post-vaccine era in this study. This result suggests that Korean clinicians must be aware of the levofloxacin resistance trend and need to be more prudent for the first choice of fluoroquinolone for empiric treatment of respiratory tract infections in clinical setting. Moreover, the emergence of new clones and their variations may be more frequently associated with resistance under this selective pressure, such as the introduction of a 7-valent pneumococcal conjugate vaccine into our community.
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63
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Molecular characterization of acquired enrofloxacin resistance in Mycoplasma synoviae field isolates. Antimicrob Agents Chemother 2013; 57:3072-7. [PMID: 23612192 DOI: 10.1128/aac.00203-13] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The in vitro activity of enrofloxacin against 73 Mycoplasma synoviae field strains isolated in Israel and Europe was determined by broth microdilution. Decreased susceptibility to enrofloxacin was identified in 59% of strains, with the MICs ranging from 1 to >16 μg/ml. The estimated MIC50 and MIC90 values for enrofloxacin were 2 and 8 μg/ml, respectively. Moreover, this study showed that 92% of recent Israeli field isolates (2009 to 2011) of M. synoviae have MICs of ≥ 2 μg/ml to enrofloxacin. Comparison of the quinolone resistance-determining regions (QRDRs) in M. synoviae isolates revealed a clear correlation between the presence of one of the amino acid substitutions Asp79-Asn, Thr80-Ala/Ile, Ser81-Pro, and Asp84-Asn/Tyr/His of the ParC QRDR and decreased susceptibility to enrofloxacin (MIC, ≥ 1 μg/ml). Amino acid substitutions at positions GyrA 87, GyrB 401/402, and ParE 420/454 were also identified, but there was no clear-cut correlation with susceptibility to enrofloxacin. Comparison of vlhA molecular profiles revealed the presence of 9 different genotypes in the Israeli M. synoviae field isolates and 10 genotypes in the European isolates; only one vlhA genotype (type 4) was identified in both cohorts. Based on results of vlhA molecular typing, several mechanisms for emergence and dissemination of Israeli enrofloxacin-resistant M. synoviae isolates are suggested.
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64
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Pletz MW, Michaylov N, Schumacher U, van der Linden M, Duesberg CB, Fuehner T, Klugman KP, Welte T, Makarewicz O. Antihypertensives suppress the emergence of fluoroquinolone-resistant mutants in pneumococci: an in vitro study. Int J Med Microbiol 2013; 303:176-81. [PMID: 23545281 DOI: 10.1016/j.ijmm.2013.02.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 02/01/2013] [Accepted: 02/03/2013] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND The antihypertensives reserpine and verapamil are also inhibitors of pneumococcal efflux pumps. We addressed the following questions: (i) Do verapamil and reserpine influence the mutation ratio of pneumococci in the presence of ciprofloxacin? (ii) At which concentrations does this occur? (iii) Is this limited to isolates with efflux phenotype? METHODS 14 clinical isolates, nested in 6 genetically similar clusters, were used, 7 strains with efflux and 7 without. The mutation ratio in the presence of ciprofloxacin (3 × MIC) and increasing concentrations of reserpine and verapamil was determined and the quinolone-resistance determining regions (QRDR) of selected mutants were sequenced. Analysis of the efficacy was performed using a mixed linear model, supported by descriptive statistics. RESULTS Reserpine and verapamil reduced the mutation ratio of QRDR in the presence of ciprofloxacin with the required concentration for a reduction ≥ 50% of 1mg/l for reserpine and 50mg/l for verapamil. The mutation prevention effect is not limited to, but is more pronounced in efflux positive phenotypes. CONCLUSION Reserpine and verapamil can prevent the selection of ciprofloxacin resistant isolates by reduction of the mutation ratio, particularly in strain with an efflux phenotype. However, the required concentrations are too toxic for clinical use.
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Affiliation(s)
- Mathias W Pletz
- Center for Infectious Diseases and Infection Control, Jena University Hospital, Jena, Germany.
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65
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Aldred KJ, McPherson SA, Turnbough CL, Kerns RJ, Osheroff N. Topoisomerase IV-quinolone interactions are mediated through a water-metal ion bridge: mechanistic basis of quinolone resistance. Nucleic Acids Res 2013; 41:4628-39. [PMID: 23460203 PMCID: PMC3632122 DOI: 10.1093/nar/gkt124] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although quinolones are the most commonly prescribed antibacterials, their use is threatened by an increasing prevalence of resistance. The most common causes of quinolone resistance are mutations of a specific serine or acidic residue in the A subunit of gyrase or topoisomerase IV. These amino acids are proposed to serve as a critical enzyme-quinolone interaction site by anchoring a water-metal ion bridge that coordinates drug binding. To probe the role of the proposed water-metal ion bridge, we characterized wild-type, GrlAE85K, GrlAS81F/E85K, GrlAE85A, GrlAS81F/E85A and GrlAS81FBacillus anthracis topoisomerase IV, their sensitivity to quinolones and related drugs and their use of metal ions. Mutations increased the Mg2+ concentration required to produce maximal quinolone-induced DNA cleavage and restricted the divalent metal ions that could support quinolone activity. Individual mutation of Ser81 or Glu85 partially disrupted bridge function, whereas simultaneous mutation of both residues abrogated protein–quinolone interactions. Results provide functional evidence for the existence of the water-metal ion bridge, confirm that the serine and glutamic acid residues anchor the bridge, demonstrate that the bridge is the primary conduit for interactions between clinically relevant quinolones and topoisomerase IV and provide a likely mechanism for the most common causes of quinolone resistance.
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Affiliation(s)
- Katie J Aldred
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA
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66
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Bowker KE, Garvey MI, Noel AR, Tomaselli SG, Macgowan AP. Comparative antibacterial effects of moxifloxacin and levofloxacin on Streptococcus pneumoniae strains with defined mechanisms of resistance: impact of bacterial inoculum. J Antimicrob Chemother 2013; 68:1130-8. [PMID: 23361641 DOI: 10.1093/jac/dks537] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVES We aim to further define the impact of the mechanism of fluoroquinolone resistance and inoculum load on the pharmacodynamic effects of levofloxacin and moxifloxacin on Streptococcus pneumoniae. METHODS The antibacterial effects of and emergence of resistance (EoR) to moxifloxacin (400 mg once daily) or levofloxacin (750 mg once daily or 500 mg twice daily) were compared using five S. pneumoniae strains containing no known resistance mechanisms, efflux resistance mechanisms, a parC mutation or parC and gyrA mutations, at high (10(8) cfu/mL) and low (10(6) cfu/mL) inocula. An in vitro pharmacokinetic model was used and simulations were performed over 96 h. After drug exposure, isolates were tested for the presence of efflux pumps and mutations in the quinolone resistance-determining regions. RESULTS A high inoculum diminished the antibacterial effect of moxifloxacin and levofloxacin. Levofloxacin at both dosages produced EoR with all strains. Levofloxacin regimens with AUC/MIC ratios <100 produced EoR. Moxifloxacin produced EoR with the parC strain only. CONCLUSIONS Levofloxacin dosing regimens with low AUC/MIC ratios select for efflux pump overexpression, leading to fluoroquinolone resistance. Levofloxacin dosing may select for gyrA mutations, inducing moxifloxacin resistance. These data confirm that a fluoroquinolone AUC/MIC ratio of >100 is required for prevention of EoR.
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Affiliation(s)
- K E Bowker
- Bristol Centre for Antimicrobial Research and Evaluation, North Bristol NHS Trust and University of Bristol, Department of Microbiology, Lime Walk Building, Southmead Hospital, Westbury-on-Trym, Bristol BS10 5NB, UK.
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67
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Contribution of topoisomerase IV mutation to quinolone resistance in Mycoplasma genitalium. Antimicrob Agents Chemother 2013; 57:1772-6. [PMID: 23357772 DOI: 10.1128/aac.01956-12] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mechanism of quinolone resistance in Mycoplasma genitalium remains poorly understood due to difficulties with in vitro culture, especially of clinical isolates. In this study, to confirm the association between mutations in topoisomerases and antimicrobial susceptibilities to quinolones, ciprofloxacin-resistant mutant strains were selected using the cultivable type strain ATCC 33530. Sequence analysis revealed that the mutant strains harbored mutations in topoisomerase IV: Gly81Cys in ParC, Pro261Thr in ParC, or Asn466Lys in ParE. The MICs of all quinolones tested against the mutant strains were 2- to 16-fold higher than those against the wild-type strain. No cross-resistance was observed with macrolides or tetracyclines. We determined the inhibitory activities of quinolones against DNA gyrase and topoisomerase IV in order to investigate the correlation between antimicrobial susceptibility and inhibitory activity against the target enzymes, considered the primary targets of quinolones. Furthermore, using enzymatic analysis, we confirmed that Gly81Cys in the ParC quinolone resistance-determining region (QRDR) contributed to quinolone resistance. This is the first study to isolate quinolone-resistant mutant strains of M. genitalium harboring substitutions in the parC or parE gene in vitro and to measure the inhibitory activities against the purified topoisomerases of M. genitalium.
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68
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Karkare S, Chung TTH, Collin F, Mitchenall LA, McKay AR, Greive SJ, Meyer JJM, Lall N, Maxwell A. The naphthoquinone diospyrin is an inhibitor of DNA gyrase with a novel mechanism of action. J Biol Chem 2012; 288:5149-56. [PMID: 23275348 PMCID: PMC3576119 DOI: 10.1074/jbc.m112.419069] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Tuberculosis and other bacterial diseases represent a significant threat to human health. The DNA topoisomerases are excellent targets for chemotherapy, and DNA gyrase in particular is a well-validated target for antibacterial agents. Naphthoquinones (e.g. diospyrin and 7-methyljuglone) have been shown to have therapeutic potential, particularly against Mycobacterium tuberculosis. We have found that these compounds are inhibitors of the supercoiling reaction catalyzed by M. tuberculosis gyrase and other gyrases. Our evidence strongly suggests that the compounds bind to the N-terminal domain of GyrB, which contains the ATPase active site, but are not competitive inhibitors of the ATPase reaction. We propose that naphthoquinones bind to GyrB at a novel site close to the ATPase site. This novel mode of action could be exploited to develop new antibacterial agents.
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Affiliation(s)
- Shantanu Karkare
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
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69
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Functional analysis of pneumococcal drug efflux pumps associates the MATE DinF transporter with quinolone susceptibility. Antimicrob Agents Chemother 2012; 57:248-53. [PMID: 23114782 DOI: 10.1128/aac.01298-12] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The pneumococcal chromosome encodes about 140 transporters, many of which are predicted to be involved in efflux. In order to critically evaluate pneumococcal efflux, a series of transporter mutants were constructed, and their phenotypes were assayed by disk diffusion, microdilution drug susceptibility testing (MIC testing), growth of cultures at sub-MIC concentrations, and phenotype microarray analysis. Mutants with mutations in seven ATP binding cassette (ABC) transporters, three multiantimicrobial extrusion (MATE) family efflux pumps, and one major facilitator superfamily (MFS) transporter were obtained in Streptococcus pneumoniae strain DP1004. The susceptibility of these 11 mutants to over 250 different substances was compared to that of the parent strain. Of the tested transporters, only the ABC transporter PatAB (SP2073-5) presented a clear multidrug resistance (MDR) profile, as the mutant showed significantly increased susceptibility to ethidium bromide, acriflavine, and berberine. Among the other transporters analyzed, the mutants devoid of the MATE efflux pump SP2065 exhibited reduced susceptibility to novobiocin, and those with mutations of the MATE family DinF transport system (SP1939) exhibited increased susceptibility to moxifloxacin, ciprofloxacin, and levofloxacin. This change in quinolone MIC was found to be independent from the competence-mediated effect of quinolones on the cinA-recA-dinF operon. Furthermore, the dinF mutant, in contrast to the parental strain, allowed selection for quinolone-resistant mutants when exposed to moxifloxacin. These data confirm the clear MDR profile of the PatAB ABC transporter and suggest for the MATE DinF a phenotype associated with quinolone susceptibility, particularly for moxifloxacin.
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70
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Pneumococci can persistently colonize adult patients with chronic respiratory disease. J Clin Microbiol 2012; 50:4047-53. [PMID: 23052300 DOI: 10.1128/jcm.02056-12] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus pneumoniae plays an important role in causing acute exacerbations in patients with chronic respiratory disease. However, few data are available regarding pneumococcal persistence in adult patients with chronic respiratory diseases. Fifty pneumococci recovered from sputum samples (1995 to 2010) from 13 adult patients with ≥ 3 episodes of acute exacerbation or pneumonia, with the same serotype and pulsed-field gel electrophoresis (PFGE) pattern, were studied. Multilocus sequence typing (MLST) loci, penicillin-binding protein (PBP) genes (pbp2x, pbp1a, pbp2b), and the quinolone-resistant determining regions (QRDRs) of parC, parE, and gyrA were PCR amplified and sequenced. The average time between the first and last episode was 582 days (standard deviation [SD], ± 362). All but two patients received multiple courses of β-lactam treatment, and all persistent strains were resistant to penicillin; however, the PBP sequences were stable over time apart from one variable nucleotide in pbp2x, observed among pneumococci isolated from three patients. In contrast, 7/11 patients treated with fluoroquinolones had fluoroquinolone-resistant pneumococci. In three patients, the initially fluoroquinolone-susceptible strain developed resistance after fluoroquinolone therapy, and in the remaining four patients, the persistent strain was fluoroquinolone resistant from the first episode. QRDR changes involved in fluoroquinolone resistance were frequently observed in persistent strains after fluoroquinolone treatment; however, the PBP sequences and MLST genotypes of these strains were stable over time.
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71
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Remy JM, Tow-Keogh CA, McConnell TS, Dalton JM, DeVito JA. Activity of delafloxacin against methicillin-resistant Staphylococcus aureus: resistance selection and characterization. J Antimicrob Chemother 2012; 67:2814-20. [DOI: 10.1093/jac/dks307] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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72
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Woodhead M, Blasi F, Ewig S, Garau J, Huchon G, Ieven M, Ortqvist A, Schaberg T, Torres A, van der Heijden G, Read R, Verheij TJM. Guidelines for the management of adult lower respiratory tract infections--summary. Clin Microbiol Infect 2012; 17 Suppl 6:1-24. [PMID: 21951384 DOI: 10.1111/j.1469-0691.2011.03602.x] [Citation(s) in RCA: 195] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This document is an update of Guidelines published in 2005 and now includes scientific publications through to May 2010. It provides evidence-based recommendations for the most common management questions occurring in routine clinical practice in the management of adult patients with LRTI. Topics include management outside hospital, management inside hospital (including community-acquired pneumonia (CAP), acute exacerbations of COPD (AECOPD), acute exacerbations of bronchiectasis) and prevention. The target audience for the Guideline is thus all those whose routine practice includes the management of adult LRTI.
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Affiliation(s)
- M Woodhead
- Department of Respiratory Medicine, Manchester Royal Infirmary, Oxford Road, Manchester, UK.
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73
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Aldred KJ, McPherson SA, Wang P, Kerns RJ, Graves DE, Turnbough CL, Osheroff N. Drug interactions with Bacillus anthracis topoisomerase IV: biochemical basis for quinolone action and resistance. Biochemistry 2011; 51:370-81. [PMID: 22126453 DOI: 10.1021/bi2013905] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Bacillus anthracis, the causative agent of anthrax, is considered a serious threat as a bioweapon. The drugs most commonly used to treat anthrax are quinolones, which act by increasing the levels of DNA cleavage mediated by topoisomerase IV and gyrase. Quinolone resistance most often is associated with specific serine mutations in these enzymes. Therefore, to determine the basis for quinolone action and resistance, we characterized wild-type B. anthracis topoisomerase IV, the GrlA(S81F) and GrlA(S81Y) quinolone-resistant mutants, and the effects of quinolones and a related quinazolinedione on these enzymes. Ser81 is believed to anchor a water-Mg(2+) bridge that coordinates quinolones to the enzyme through the C3/C4 keto acid. Consistent with this hypothesized bridge, ciprofloxacin required increased Mg(2+) concentrations to support DNA cleavage by GrlA(S81F) topoisomerase IV. The three enzymes displayed similar catalytic activities in the absence of drugs. However, the resistance mutations decreased the affinity of topoisomerase IV for ciprofloxacin and other quinolones, diminished quinolone-induced inhibition of DNA religation, and reduced the stability of the enzyme-quinolone-DNA ternary complex. Wild-type DNA cleavage levels were generated by mutant enzymes at high quinolone concentrations, suggesting that increased drug potency could overcome resistance. 8-Methyl-quinazoline-2,4-dione, which lacks the quinolone keto acid (and presumably does not require the water-Mg(2+) bridge to mediate protein interactions), was more potent than quinolones against wild-type topoisomerase IV and was equally efficacious. Moreover, it maintained high potency and efficacy against the mutant enzymes, effectively inhibited DNA religation, and formed stable ternary complexes. Our findings provide an underlying biochemical basis for the ability of quinazolinediones to overcome clinically relevant quinolone resistance mutations in bacterial type II topoisomerases.
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Affiliation(s)
- Katie J Aldred
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, United States
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74
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Fukuda Y, Takahata M, Sugiura Y, Shinmura Y, Nomura N. In vitro pharmacodynamic evaluation of garenoxacin against quinolone-resistant Streptococcus pneumoniae. Int J Antimicrob Agents 2011; 39:163-7. [PMID: 22088660 DOI: 10.1016/j.ijantimicag.2011.09.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 09/22/2011] [Accepted: 09/23/2011] [Indexed: 10/15/2022]
Abstract
The bactericidal activity and resistance selectivity of garenoxacin against Streptococcus pneumoniae with mutations in ParC (S79F) or both GyrA (S81F) and ParC (D83Y and K137N) were investigated using in vitro pharmacokinetic models simulating plasma concentrations for a standard clinical regimen [400mg once daily (q.d.)]. The efficacy of garenoxacin was compared with that of levofloxacin (500 mg q.d.) and moxifloxacin (400mg q.d.). Garenoxacin showed excellent bactericidal activity against S. pneumoniae, including quinolone-resistant S. pneumoniae (QRSP), achieving ratios of area under the plasma concentration-time curve over 24h to minimum inhibitory concentration (AUC(0-24)/MIC) ≥ 26.3, without emerging resistant subpopulations. The area above the killing curves was greater and the time to achieve 99.9% killing was shorter for garenoxacin than the corresponding values for levofloxacin and moxifloxacin. No resistant subpopulations and no additional substitution of amino acids in GyrA or ParC emerged following treatment with garenoxacin. On the other hand, in the parC mutant strain, levofloxacin and moxifloxacin treatment caused an increase in the frequency of the resistant population and an additional substitution of amino acids in GyrA (levofloxacin, S81Y/F/C; moxifloxacin, S81Y or E85K). In QRSP with mutations in GyrA and ParC, levofloxacin had no bactericidal activity, whilst the bactericidal activity of moxifloxacin was less than that of garenoxacin; moreover, an additional substitution of amino acids in ParC (S79Y) was noted. In conclusion, garenoxacin corresponding to an oral dose of 400mg showed excellent bactericidal activity against S. pneumoniae, including QRSP, without the emergence of resistant mutants.
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Affiliation(s)
- Yoshiko Fukuda
- Research Laboratories, Toyama Chemical Co. Ltd., 2-4-1 Shimookui, Toyama 930-8508, Japan. yoshiko
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75
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Woodhead M, Blasi F, Ewig S, Garau J, Huchon G, Ieven M, Ortqvist A, Schaberg T, Torres A, van der Heijden G, Read R, Verheij TJM. Guidelines for the management of adult lower respiratory tract infections--full version. Clin Microbiol Infect 2011; 17 Suppl 6:E1-59. [PMID: 21951385 PMCID: PMC7128977 DOI: 10.1111/j.1469-0691.2011.03672.x] [Citation(s) in RCA: 592] [Impact Index Per Article: 45.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
This document is an update of Guidelines published in 2005 and now includes scientific publications through to May 2010. It provides evidence-based recommendations for the most common management questions occurring in routine clinical practice in the management of adult patients with LRTI. Topics include management outside hospital, management inside hospital (including community-acquired pneumonia (CAP), acute exacerbations of COPD (AECOPD), acute exacerbations of bronchiectasis) and prevention. Background sections and graded evidence tables are also included. The target audience for the Guideline is thus all those whose routine practice includes the management of adult LRTI.
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Affiliation(s)
- M Woodhead
- Department of Respiratory Medicine, Manchester Royal Infirmary, Oxford Road, Manchester, UK.
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76
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Spectroscopic and Photophysical Properties of Protonated Forms of Some Fluoroquinolones in Solutions. J Fluoresc 2011; 22:373-9. [DOI: 10.1007/s10895-011-0969-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Accepted: 09/02/2011] [Indexed: 10/17/2022]
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77
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de Moura VCN, da Silva MG, Gomes KM, Coelho FS, Sampaio JLM, Mello FCDQ, Lourenço MCDS, Amorim EDLT, Duarte RS. Phenotypic and molecular characterization of quinolone resistance in Mycobacterium abscessus subsp. bolletii recovered from postsurgical infections. J Med Microbiol 2011; 61:115-125. [PMID: 21903825 DOI: 10.1099/jmm.0.034942-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Several outbreaks of infections caused by rapidly growing mycobacteria (RGM) were reported in many Brazilian states (2032 notified cases) from 2004 to 2010. Most of the confirmed cases were mainly associated with Mycobacterium massiliense (recently renamed as Mycobacterium abscessus subsp. bolletii) BRA100 clone, recovered from patients who had undergone invasive procedures in which medical instruments had not been properly sterilized and/or disinfected. Since quinolones have been an option for the treatment of general RGM infections and have been suggested for therapeutic schemes for these outbreaks, we evaluated the in vitro activities of all generations of quinolones for clinical and reference RGM by broth microdilution, and analysed the peptide sequences of the quinolone resistance determining regions (QRDRs) of GyrA and GyrB after DNA sequencing followed by amino acid translation. Fifty-four isolates of M. abscessus subsp. bolletii, including clone BRA100, recovered in different states of Brazil, and 19 reference strains of RGM species were characterized. All 54 M. abscessus subsp. bolletii isolates were resistant to all generations of quinolones and showed the same amino acids in the QRDRs, including the Ala-83 in GyrA, and Arg-447 and Asp-464 in GyrB, described as being responsible for an intrinsic low level of resistance to quinolones in mycobacteria. However, other RGM species showed distinct susceptibilities to this class of antimicrobials and patterns of mutations contrary to what has been traditionally defined, suggesting that other mechanisms of resistance, different from gyrA or gyrB mutations, may also be involved in resistance to high levels of quinolones.
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Affiliation(s)
- Vinicius Calado Nogueira de Moura
- Departamento de Microbiologia, Imunologia e Parasitologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Marlei Gomes da Silva
- Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Karen Machado Gomes
- Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | | | | | | | | | | | - Rafael Silva Duarte
- Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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78
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Abstract
Clinicians have enthusiastically used fluoroquinolones owing to their good safety profile and wide range of indications. This article reviews fluoroquinolone pharmacology, pharmacodynamic principles, and fluoroquinolone resistance mechanisms, highlighting recent trends in the epidemiology of fluoroquinolone resistance among gram-negative organisms and Streptococcus pneumonia. Important fluoroquinolone safety concerns are discussed, along with indications for the most commonly used fluoroquinolones--ciprofloxacin, levofloxacin, and moxifloxacin.
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Affiliation(s)
- Maureen K Bolon
- Division of Infectious Diseases, Department of Medicine, Northwestern University Feinberg School of Medicine, 645 North Michigan Avenue, Suite 900, Chicago, IL 60611, USA.
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79
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Detection of Antimicrobial Resistance Genes and Mutations Associated with Antimicrobial Resistance in Bacteria. Mol Microbiol 2011. [DOI: 10.1128/9781555816834.ch32] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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80
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Rolo D, Fenoll A, Ardanuy C, Calatayud L, Cubero M, de la Campa AG, Linares J. Trends of invasive serotype 6C pneumococci in Spain: emergence of a new lineage. J Antimicrob Chemother 2011; 66:1712-8. [DOI: 10.1093/jac/dkr193] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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81
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Clonal spread of levofloxacin-resistant streptococcus pneumoniae invasive isolates in Madrid, Spain, 2007 to 2009. Antimicrob Agents Chemother 2011; 55:2469-71. [PMID: 21383091 DOI: 10.1128/aac.01380-10] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Among 1,349 Streptococcus pneumoniae invasive isolates, 45 (3.3%) were levofloxacin resistant. Serotype distribution was as follows: 8 (n=32 isolates), 19A (n=4 isolates), 7F (n=3 isolates), 9V (n=2 isolates), 10A (n=1 isolate), 19F (n=1 isolate), 6B (n=1 isolate), and nontypeable (n=1 isolate). Levofloxacin-resistant isolates had dual mutations in the gyrA and parC genes. Serotype 8 strains corresponded to a capsular switching of the Sweden(15A)-25 clone. Levofloxacin resistance was also detected among multiresistant (ST276(19A), Spain9V-ST156, ST88(19F), and ST1542(6B)) and among usually antibiotic-susceptible (Netherlands7F-ST191, ST1201(19A), and ST2639(10A)) clones.
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82
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Low prevalence of fluoroquinolone resistant strains and resistance precursor strains in Streptococcus pneumoniae from patients with community-acquired pneumonia despite high fluoroquinolone usage. Int J Med Microbiol 2011; 301:53-7. [DOI: 10.1016/j.ijmm.2010.05.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Revised: 05/25/2010] [Accepted: 05/30/2010] [Indexed: 11/20/2022] Open
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83
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Maeda Y, Murayama M, Goldsmith CE, Coulter WA, Mason C, Millar BC, Dooley JSG, Lowery CJ, Matsuda M, Rendall JC, Elborn JS, Moore JE. Molecular characterization and phylogenetic analysis of quinolone resistance-determining regions (QRDRs) of gyrA, gyrB, parC and parE gene loci in viridans group streptococci isolated from adult patients with cystic fibrosis. J Antimicrob Chemother 2010; 66:476-86. [DOI: 10.1093/jac/dkq485] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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84
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Nonoptimal DNA topoisomerases allow maintenance of supercoiling levels and improve fitness of Streptococcus pneumoniae. Antimicrob Agents Chemother 2010; 55:1097-105. [PMID: 21173181 DOI: 10.1128/aac.00783-10] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fluoroquinolones, which target gyrase and topoisomerase IV, are used for treating Streptococcus pneumoniae infections. Fluoroquinolone resistance in this bacterium can arise via point mutation or interspecific recombination with genetically related streptococci. Our previous study on the fitness cost of resistance mutations and recombinant topoisomerases identified GyrAE85K as a high-cost change. However, this cost was compensated for by the presence of a recombinant topoisomerase IV (parC and parE recombinant genes) in strain T14. In this study, we purified wild-type and mutant topoisomerases and compared their enzymatic activities. In strain T14, both gyrase carrying GyrAE85K and recombinant topoisomerase IV showed lower activities (from 2.0- to 3.7-fold) than the wild-type enzymes. These variations of in vitro activity corresponded to changes of in vivo supercoiling levels that were analyzed by two-dimensional electrophoresis of an internal plasmid. Strains carrying GyrAE85K and nonrecombinant topoisomerases had lower (11.1% to 14.3%) supercoiling density (σ) values than the wild type. Those carrying GyrAE85K and recombinant topoisomerases showed either partial or total supercoiling level restoration, with σ values being 7.9% (recombinant ParC) and 1.6% (recombinant ParC and recombinant ParE) lower than those for the wild type. These data suggested that changes acquired by interspecific recombination might be selected because they reduce the fitness cost associated with fluoroquinolone resistance mutations. An increase in the incidence of fluoroquinolone resistance, even in the absence of further antibiotic exposure, is envisaged.
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85
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Wang Q, Wang H, Xie M. Antibacterial mechanism of soybean isoflavone on Staphylococcus aureus. Arch Microbiol 2010; 192:893-8. [PMID: 20734190 DOI: 10.1007/s00203-010-0617-1] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2009] [Revised: 06/23/2010] [Accepted: 08/04/2010] [Indexed: 11/29/2022]
Abstract
Effects of different flavonoids on various bacterial strains have been extensively reported; however, the mechanism(s) of their action on bacterial cells remain largely elusive. In this study, the antibacterial mechanism of soybean isoflavone (SI) on Staphylococcus aureus is systematically investigated using 4'6-diamidino-2-phenylindole (DAPI) staining, pBR322DNA decatenation experiment mediated by topoisomerase and agarose gel electrophoresis for direct decatenation. The results of fluorescence microscopy and fluorescence spectrophotometer indicated that DAPI was integrated in Staphylococcus aureus. Additionally, the quantity of both DNA and RNA reduced to 66.47 and 60.18%, respectively, after treated with SI for 28 h. Effects of SI on topoisomerase I and II were also investigated. SI completely inhibited the pBR322DNA unwinding mediated by topoisomerase I and topoisomerase II at the concentration of 6.4 mg/ml and could denature the plasmid DNA at the concentration of 12.8 mg/ml. These results indicate that topoisomerase I and II are the most important targets by SI to restrain bacterial cell division.
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Affiliation(s)
- Qian Wang
- College of Life Science, Liaoning Normal University, 116029, Dalian, People's Republic of China
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86
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Park HS, Jung SJ, Choi DR, Kwak JH. Antimicrobial activity of DW286 against Streptococcus pneumoniae. Int J Antimicrob Agents 2010; 36:230-3. [PMID: 20627463 DOI: 10.1016/j.ijantimicag.2010.04.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 04/01/2010] [Accepted: 04/07/2010] [Indexed: 11/27/2022]
Abstract
DW286 is a novel broad-spectrum fluoroquinolone with excellent antipneumococcal activity. The in vitro activity of DW286 was evaluated against quinolone-susceptible and -resistant Streptococcus pneumoniae and was compared with the activities of reference compounds. Among the tested agents, DW286 showed the most potent antibacterial activity against 94 quinolone-susceptible strains [minimum inhibitory concentration (MIC) 0.008-0.03 mg/L]. Against 23 quinolone-resistant S. pneumoniae with known resistance mechanisms, DW286 also had the lowest MICs of all the tested quinolones [MIC at which 90% of isolates were inhibited (MIC(90))=0.5mg/L], followed by ciprofloxacin, sparfloxacin, moxifloxacin and gemifloxacin. The in vivo activity of DW286 against penicillin-susceptible and -resistant S. pneumoniae was more effective than that of gemifloxacin.
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Affiliation(s)
- Hee Soo Park
- School of Life Sciences, Handong Global University, Puk-ku, Pohang City, Kyungbuk 791-708, South Korea
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87
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Overexpression of patA and patB, which encode ABC transporters, is associated with fluoroquinolone resistance in clinical isolates of Streptococcus pneumoniae. Antimicrob Agents Chemother 2010; 55:190-6. [PMID: 20937787 DOI: 10.1128/aac.00672-10] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fifty-seven clinical isolates of Streptococcus pneumoniae were divided into four groups based on their susceptibilities to the fluoroquinolones ciprofloxacin and norfloxacin and the dyes ethidium bromide and acriflavine. Comparative reverse transcription-PCR was used to determine the level of expression of the genes patA and patB, which encode putative ABC transporters. Overexpression was observed in 14 of the 15 isolates that were resistant to both fluoroquinolones and dyes and in only 3 of 24 of those resistant to fluoroquinolones only. Isolates overexpressing patA and patB accumulated significantly less of the fluorescent dye Hoechst 33342 than wild-type isolates, suggesting that PatA and PatB are involved in efflux. Inactivation of patA and patB by in vitro mariner mutagenesis conferred hypersusceptibility to ethidium bromide and acriflavine in all isolates tested and lowered the MICs of ciprofloxacin in the patAB-overproducing and/or fluoroquinolone-resistant isolates. These data represent the first observation of overexpression of patA and patB in clinical isolates and show that PatA and PatB play a clinically relevant role in fluoroquinolone resistance.
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88
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van Rensburg DJJ, Perng RP, Mitha IH, Bester AJ, Kasumba J, Wu RG, Ho ML, Chang LW, Chung DT, Chang YT, King CHR, Hsu MC. Efficacy and safety of nemonoxacin versus levofloxacin for community-acquired pneumonia. Antimicrob Agents Chemother 2010; 54:4098-106. [PMID: 20660689 PMCID: PMC2944601 DOI: 10.1128/aac.00295-10] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 05/10/2010] [Accepted: 07/17/2010] [Indexed: 01/12/2023] Open
Abstract
Nemonoxacin, a novel nonfluorinated quinolone, exhibits potent in vitro and in vivo activities against community-acquired pneumonia (CAP) pathogens, including multidrug-resistant Streptococcus pneumoniae. Patients with mild to moderate CAP (n = 265) were randomized to receive oral nemonoxacin (750 mg or 500 mg) or levofloxacin (500 mg) once daily for 7 days. Clinical responses were determined at the test-of-cure visit in intent-to-treat (ITT), clinical per protocol (PPc), evaluable-ITT, and evaluable-PPc populations. The clinical cure rates for 750 mg nemonoxacin, 500 mg nemonoxacin, and levofloxacin were 89.9%, 87.0%, and 91.1%, respectively, in the evaluable-ITT population; 91.7%, 87.7%, and 90.3%, respectively, in the evaluable-PPc population; 82.6%, 75.3%, and 80.0%, respectively, in the ITT population; and 83.5%, 78.0%, and 82.3%, respectively, in the PPc population. Noninferiority to levofloxacin was demonstrated in both the 750-mg and 500-mg nemonoxacin groups for the evaluable-ITT and evaluable-PPc populations, and also in the 750 mg nemonoxacin group for the ITT and PPc populations. Overall bacteriological success rates were high for all treatment groups in the evaluable-bacteriological ITT population (90.2% in the 750 mg nemonoxacin group, 84.8% in the 500 mg nemonoxacin group, and 92.0% in the levofloxacin group). All three treatments were well tolerated, and no drug-related serious adverse events were observed. Overall, oral nemonoxacin (both 750 mg and 500 mg) administered for 7 days resulted in high clinical and bacteriological success rates in CAP patients. Further, good tolerability and excellent activity against common causative pathogens were demonstrated. Nemonoxacin (750 mg and 500 mg) once daily is as effective and safe as levofloxacin (500 mg) once daily for the treatment of CAP.
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Affiliation(s)
- Dirkie J. J. van Rensburg
- Park Medical Center, Witbank, Mpumalanga, South Africa, Taipei Veterans General Hospital, Taipei, Taiwan, Benmed/Pentagon Hospital, Benoni, South Africa, Jubilee Hospital, Temba, South Africa, Josha Research, Bloemfontien, South Africa, Cheng Ching Hospital, Taichung, Taiwan, Changhua Christian Hospital, Changhua, Taiwan, TaiGen Biotechnology Co. Ltd., Taipei, Taiwan
| | - Reury-Perng Perng
- Park Medical Center, Witbank, Mpumalanga, South Africa, Taipei Veterans General Hospital, Taipei, Taiwan, Benmed/Pentagon Hospital, Benoni, South Africa, Jubilee Hospital, Temba, South Africa, Josha Research, Bloemfontien, South Africa, Cheng Ching Hospital, Taichung, Taiwan, Changhua Christian Hospital, Changhua, Taiwan, TaiGen Biotechnology Co. Ltd., Taipei, Taiwan
| | - Ismail H. Mitha
- Park Medical Center, Witbank, Mpumalanga, South Africa, Taipei Veterans General Hospital, Taipei, Taiwan, Benmed/Pentagon Hospital, Benoni, South Africa, Jubilee Hospital, Temba, South Africa, Josha Research, Bloemfontien, South Africa, Cheng Ching Hospital, Taichung, Taiwan, Changhua Christian Hospital, Changhua, Taiwan, TaiGen Biotechnology Co. Ltd., Taipei, Taiwan
| | - Andrè J. Bester
- Park Medical Center, Witbank, Mpumalanga, South Africa, Taipei Veterans General Hospital, Taipei, Taiwan, Benmed/Pentagon Hospital, Benoni, South Africa, Jubilee Hospital, Temba, South Africa, Josha Research, Bloemfontien, South Africa, Cheng Ching Hospital, Taichung, Taiwan, Changhua Christian Hospital, Changhua, Taiwan, TaiGen Biotechnology Co. Ltd., Taipei, Taiwan
| | - Joseph Kasumba
- Park Medical Center, Witbank, Mpumalanga, South Africa, Taipei Veterans General Hospital, Taipei, Taiwan, Benmed/Pentagon Hospital, Benoni, South Africa, Jubilee Hospital, Temba, South Africa, Josha Research, Bloemfontien, South Africa, Cheng Ching Hospital, Taichung, Taiwan, Changhua Christian Hospital, Changhua, Taiwan, TaiGen Biotechnology Co. Ltd., Taipei, Taiwan
| | - Ren-Guang Wu
- Park Medical Center, Witbank, Mpumalanga, South Africa, Taipei Veterans General Hospital, Taipei, Taiwan, Benmed/Pentagon Hospital, Benoni, South Africa, Jubilee Hospital, Temba, South Africa, Josha Research, Bloemfontien, South Africa, Cheng Ching Hospital, Taichung, Taiwan, Changhua Christian Hospital, Changhua, Taiwan, TaiGen Biotechnology Co. Ltd., Taipei, Taiwan
| | - Ming-Lin Ho
- Park Medical Center, Witbank, Mpumalanga, South Africa, Taipei Veterans General Hospital, Taipei, Taiwan, Benmed/Pentagon Hospital, Benoni, South Africa, Jubilee Hospital, Temba, South Africa, Josha Research, Bloemfontien, South Africa, Cheng Ching Hospital, Taichung, Taiwan, Changhua Christian Hospital, Changhua, Taiwan, TaiGen Biotechnology Co. Ltd., Taipei, Taiwan
| | - Li-Wen Chang
- Park Medical Center, Witbank, Mpumalanga, South Africa, Taipei Veterans General Hospital, Taipei, Taiwan, Benmed/Pentagon Hospital, Benoni, South Africa, Jubilee Hospital, Temba, South Africa, Josha Research, Bloemfontien, South Africa, Cheng Ching Hospital, Taichung, Taiwan, Changhua Christian Hospital, Changhua, Taiwan, TaiGen Biotechnology Co. Ltd., Taipei, Taiwan
| | - David T. Chung
- Park Medical Center, Witbank, Mpumalanga, South Africa, Taipei Veterans General Hospital, Taipei, Taiwan, Benmed/Pentagon Hospital, Benoni, South Africa, Jubilee Hospital, Temba, South Africa, Josha Research, Bloemfontien, South Africa, Cheng Ching Hospital, Taichung, Taiwan, Changhua Christian Hospital, Changhua, Taiwan, TaiGen Biotechnology Co. Ltd., Taipei, Taiwan
| | - Yu-Ting Chang
- Park Medical Center, Witbank, Mpumalanga, South Africa, Taipei Veterans General Hospital, Taipei, Taiwan, Benmed/Pentagon Hospital, Benoni, South Africa, Jubilee Hospital, Temba, South Africa, Josha Research, Bloemfontien, South Africa, Cheng Ching Hospital, Taichung, Taiwan, Changhua Christian Hospital, Changhua, Taiwan, TaiGen Biotechnology Co. Ltd., Taipei, Taiwan
| | - Chi-Hsin R. King
- Park Medical Center, Witbank, Mpumalanga, South Africa, Taipei Veterans General Hospital, Taipei, Taiwan, Benmed/Pentagon Hospital, Benoni, South Africa, Jubilee Hospital, Temba, South Africa, Josha Research, Bloemfontien, South Africa, Cheng Ching Hospital, Taichung, Taiwan, Changhua Christian Hospital, Changhua, Taiwan, TaiGen Biotechnology Co. Ltd., Taipei, Taiwan
| | - Ming-Chu Hsu
- Park Medical Center, Witbank, Mpumalanga, South Africa, Taipei Veterans General Hospital, Taipei, Taiwan, Benmed/Pentagon Hospital, Benoni, South Africa, Jubilee Hospital, Temba, South Africa, Josha Research, Bloemfontien, South Africa, Cheng Ching Hospital, Taichung, Taiwan, Changhua Christian Hospital, Changhua, Taiwan, TaiGen Biotechnology Co. Ltd., Taipei, Taiwan
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89
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Hsieh YC, Chang LY, Huang YC, Lin HC, Huang LM, Hsueh PR. Circulation of international clones of levofloxacin non-susceptible Streptococcus pneumoniae in Taiwan. Clin Microbiol Infect 2010; 16:973-8. [DOI: 10.1111/j.1469-0691.2009.02951.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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90
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Laponogov I, Pan XS, Veselkov DA, McAuley KE, Fisher LM, Sanderson MR. Structural basis of gate-DNA breakage and resealing by type II topoisomerases. PLoS One 2010; 5:e11338. [PMID: 20596531 PMCID: PMC2893164 DOI: 10.1371/journal.pone.0011338] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Accepted: 06/07/2010] [Indexed: 11/23/2022] Open
Abstract
Type II DNA topoisomerases are ubiquitous enzymes with essential functions in DNA replication, recombination and transcription. They change DNA topology by forming a transient covalent cleavage complex with a gate-DNA duplex that allows transport of a second duplex though the gate. Despite its biological importance and targeting by anticancer and antibacterial drugs, cleavage complex formation and reversal is not understood for any type II enzyme. To address the mechanism, we have used X-ray crystallography to study sequential states in the formation and reversal of a DNA cleavage complex by topoisomerase IV from Streptococcus pneumoniae, the bacterial type II enzyme involved in chromosome segregation. A high resolution structure of the complex captured by a novel antibacterial dione reveals two drug molecules intercalated at a cleaved B-form DNA gate and anchored by drug-specific protein contacts. Dione release generated drug-free cleaved and resealed DNA complexes in which the DNA gate instead adopts an unusual A/B-form helical conformation with a Mg2+ ion repositioned to coordinate each scissile phosphodiester group and promote reversible cleavage by active-site tyrosines. These structures, the first for putative reaction intermediates of a type II topoisomerase, suggest how a type II enzyme reseals DNA during its normal reaction cycle and illuminate aspects of drug arrest important for the development of new topoisomerase-targeting therapeutics.
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Affiliation(s)
- Ivan Laponogov
- Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom
- Division of Basic Medical Sciences, St George's University of London, London, United Kingdom
| | - Xiao-Su Pan
- Division of Basic Medical Sciences, St George's University of London, London, United Kingdom
| | - Dennis A. Veselkov
- Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | | | - L. Mark Fisher
- Division of Basic Medical Sciences, St George's University of London, London, United Kingdom
- * E-mail: (LMF); (MRS)
| | - Mark R. Sanderson
- Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom
- * E-mail: (LMF); (MRS)
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91
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Loveless BM, Yermakova A, Christensen DR, Kondig JP, Heine HS, Wasieloski LP, Kulesh DA. Identification of ciprofloxacin resistance by SimpleProbe™, High Resolution Melt and Pyrosequencing™ nucleic acid analysis in biothreat agents: Bacillus anthracis, Yersinia pestis and Francisella tularensis. Mol Cell Probes 2010; 24:154-60. [DOI: 10.1016/j.mcp.2010.01.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 01/11/2010] [Accepted: 01/12/2010] [Indexed: 10/19/2022]
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92
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Abstract
Clinicians have enthusiastically used fluoroquinolones owing to their good safety profile and wide range of indications. This article reviews fluoroquinolone pharmacology, pharmacodynamic principles, and fluoroquinolone resistance mechanisms, highlighting recent trends in the epidemiology of fluoroquinolone resistance among gram-negative organisms and Streptococcus pneumonia. Important fluoroquinolone safety concerns are discussed, along with indications for the most commonly used fluoroquinolones-ciprofloxacin, levofloxacin, and moxifloxacin.
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Affiliation(s)
- Maureen K Bolon
- Department of Medicine, Division of Infectious Diseases, Northwestern University Feinberg School of Medicine, 645 N. Michigan Avenue, Suite 900, Chicago, IL 60611, USA.
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93
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Fluoroquinolone resistance in Streptococcus dysgalactiae subsp. equisimilis and evidence for a shared global gene pool with Streptococcus pyogenes. Antimicrob Agents Chemother 2010; 54:1769-77. [PMID: 20145082 DOI: 10.1128/aac.01377-09] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Quinolone resistance is an emerging problem in Streptococcus pyogenes, and recombination with Streptococcus dysgalactiae DNA has been implicated as a frequent mechanism leading to resistance. We have characterized a collection of S. dysgalactiae subsp. equisimilis isolates responsible for infections in humans (n = 314) and found a high proportion of levofloxacin-resistant isolates (12%). Resistance was associated with multiple emm types and genetic lineages, as determined by pulsed-field gel electrophoretic profiling. Since we could not find evidence for a role of efflux pumps in resistance, we sequenced the quinolone resistance-determining regions of the gyrA and parC genes of representative resistant and susceptible isolates. We found much greater diversity among the parC genes (19 alleles) than among the gyrA genes (5 alleles). While single mutations in either GyrA or ParC were sufficient to raise the MIC so that the strains were classified as intermediately resistant, higher-level resistance was associated with mutations in both GyrA and ParC. Evidence for recombination with S. pyogenes DNA was found in some parC alleles, but this was not exclusively associated with resistance. Our data support the existence of a common reservoir of genes conferring quinolone resistance shared between S. dysgalactiae subsp. equisimilis and S. pyogenes, while no recombination with the animal pathogen S. dysgalactiae subsp. dysgalactiae could be found.
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94
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Comparative study of the mutant prevention concentrations of moxifloxacin, levofloxacin, and gemifloxacin against pneumococci. Antimicrob Agents Chemother 2009; 54:673-7. [PMID: 20008781 DOI: 10.1128/aac.01353-09] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We tested the propensity of three quinolones to select for resistant Streptococcus pneumoniae mutants by determining the mutant prevention concentration (MPC) against 100 clinical strains, some of which harbored mutations in type II topoisomerases. Compared with levofloxacin and gemifloxacin, moxifloxacin had the lowest number of strains with MPCs above the susceptibility breakpoint (P<0.001), thus representing a lower selective pressure for proliferation of resistant mutants. Only moxifloxacin gave a 50% MPC (MPC50) value (1 microg/ml) within the susceptible range.
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95
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Molecular characterization of quinolone resistance-determining regions and their correlation with serotypes and genotypes among Streptococcus pneumoniae isolates in Japan. Eur J Clin Microbiol Infect Dis 2009; 29:245-8. [DOI: 10.1007/s10096-009-0832-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2009] [Accepted: 10/17/2009] [Indexed: 10/20/2022]
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96
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Prevalence and clonal characterization of Streptococcus pyogenes clinical isolates with reduced fluoroquinolone susceptibility in Spain. Antimicrob Agents Chemother 2009; 54:93-7. [PMID: 19805559 DOI: 10.1128/aac.00780-09] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The aim of this study was to determine the prevalence and characteristics of non-fluoroquinolone (FQ)-susceptible Streptococcus pyogenes isolates and to study their mechanisms of resistance. We performed a prospective prevalence study with 468 isolates collected from 2005 to 2007 and a retrospective study that was based on the examination of existing data collected from 1999 to 2008. The retrospective study included data for isolates with high-level resistance (HR) to ciprofloxacin (MIC >or= 32 microg/ml) (HR isolates) and isolates with the same emm types as those reported in the literature with low-level resistance (LR) to ciprofloxacin (MICs, 2 to 8 microg/ml) (LR isolates, n = 205). Genetic characterization of the isolates was performed by means of emm typing and multilocus sequence typing. The prevalence of LR ranged from 1.9% in 2005 to 30.8% in 2007. This increase was mainly due to the circulation of an emm6 subtype (emm6.4) that represented 77.1% of the LR isolates in 2007. Notably, another emm6 subtype, also detected in 2007 (emm6.37), showed coresistance to 14- and 15-membered macrolides mediated by the mefA gene. Only three HR isolates were detected (isolates emm68.1/ST247/T3,13,B3264, emm77/ST399/T28, and emm28/ST52/T28), and all were identified in the retrospective study. Overall, the 673 isolates represented 25 emm types. All LR isolates were clustered into two emm types: emm6 (six emm6 subtypes) and emm75. All the 156 emm6 isolates had LR, harbored the Ser79/Ala mutation in the parC gene product, and had the same sequence type (ST), ST382. Most (21/33) of the emm75 isolates had LR, showed the Ser79/Phe plus Asp91/Asn double mutation in the parC gene product, and were ST150. The Asp91/Asn mutation by itself did not confer resistance to FQs.
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97
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The synthesis and biological evaluation of a novel series of C7 non-basic substituted fluoroquinolones as antibacterial agents. Bioorg Med Chem Lett 2009; 19:4130-3. [DOI: 10.1016/j.bmcl.2009.06.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2009] [Revised: 05/20/2009] [Accepted: 06/01/2009] [Indexed: 11/18/2022]
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98
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Probing the differential interactions of quinazolinedione PD 0305970 and quinolones with gyrase and topoisomerase IV. Antimicrob Agents Chemother 2009; 53:3822-31. [PMID: 19564360 DOI: 10.1128/aac.00113-09] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Quinazoline-2,4-diones, such as PD 0305970, are new DNA gyrase and topoisomerase IV (topo IV) inhibitors with potent activity against gram-positive pathogens, including quinolone-resistant isolates. The mechanistic basis of dione activity vis-à-vis quinolones is not understood. We present evidence for Streptococcus pneumoniae gyrase and topo IV that PD 0305970 and quinolones interact differently with the enzyme breakage-reunion and Toprim domains, DNA, and Mg2+-four components that are juxtaposed in the topoisomerase cleavage complex to effect DNA scission. First, PD 0305970 targets primarily gyrase in Streptococcus pneumoniae. However, unlike quinolones, which select predominantly for gyrA (or topo IV parC) mutations in the breakage-reunion domain, unusually the dione selected for novel mutants with alterations that map to a region of the Toprim domain of GyrB (R456H and E474A or E474D) or ParE (D435H and E475A). This "dione resistance-determining region" overlaps the GyrB quinolone resistance-determining region and the region that binds essential Mg2+ ions, each function involving conserved EGDSA and PLRGK motifs. Second, dione-resistant gyrase and topo IV were inhibited by ciprofloxacin, whereas quinolone-resistant enzymes (GyrA S81F and ParC S79F) remained susceptible to PD 0305970. Third, dione-promoted DNA cleavage by gyrase occurred at a distinct repertoire of sites, implying that structural differences with quinolones are sensed at the DNA level. Fourth, unlike the situation with quinolones, the Mg2+ chelator EDTA did not reverse dione-induced gyrase cleavage nor did the dione promote Mg2+-dependent DNA unwinding. It appears that PD 0305970 interacts uniquely to stabilize the cleavage complex of gyrase/topo IV perhaps via an altered orientation directed by the bidentate 3-amino-2,4-dione moiety.
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99
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de la Campa AG, Ardanuy C, Balsalobre L, Pérez-Trallero E, Marimón JM, Fenoll A, Liñares J. Changes in fluoroquinolone-resistant Streptococcus pneumoniae after 7-valent conjugate vaccination, Spain. Emerg Infect Dis 2009; 15:905-11. [PMID: 19523289 PMCID: PMC2727337 DOI: 10.3201/eid1506.080684] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Among 4,215 Streptococcus pneumoniae isolates obtained in Spain during 2006, 98 (2.3%) were ciprofloxacin resistant (3.6% from adults and 0.14% from children). In comparison with findings from a 2002 study, global resistance remained stable. Low-level resistance (30 isolates with MIC 4-8 microg/mL) was caused by a reserpine-sensitive efflux phenotype (n = 4) or single topoisomerase IV (parC [n = 24] or parE [n = 1]) changes. One isolate did not show reserpine-sensitive efflux or mutations. High-level resistance (68 isolates with MIC >or=16 microg/mL) was caused by changes in gyrase (gyrA) and parC or parE. New changes in parC (S80P) and gyrA (S81V, E85G) were shown to be involved in resistance by genetic transformation. Although 49 genotypes were observed, clones Spain9V-ST156 and Sweden15A-ST63 accounted for 34.7% of drug-resistant isolates. In comparison with findings from the 2002 study, clones Spain14-ST17, Spain23F-ST81, and ST8819F decreased and 4 new genotypes (ST9710A, ST57016, ST43322, and ST71733) appeared in 2006.
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100
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Molecular characterization of emerging non-levofloxacin-susceptible pneumococci isolated from children in South Africa. J Clin Microbiol 2009; 47:1319-24. [PMID: 19261799 DOI: 10.1128/jcm.02280-08] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fluoroquinolones are not indicated for use for the treatment of pneumonia in children; however, non-levofloxacin-susceptible Streptococcus pneumoniae (NLSSP) has emerged in South Africa among children receiving treatment for multidrug-resistant tuberculosis. This study aimed to genotypically characterize NLSSP isolates. Invasive isolates were collected through active national laboratory-based surveillance for invasive pneumococcal disease (IPD) from 2000 through 2006 (n = 19,404). Carriage studies were conducted at two hospitals for patients with tuberculosis in two provinces. Phenotypic characterization was performed by determination of MICs and serotyping. Fluoroquinolone resistance mutations were identified, and clonality was investigated by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing. Twelve non-levofloxacin-susceptible cases of IPD were identified, and all were in children <15 years of age. Ten isolates were serotype 19F and formed two clusters according to their PFGE profiles, antibiogram types, and fluoroquinolone resistance-conferring mutations. All nine carriage isolates from children in hospital A were NLSSP, serotype 19F, were indistinguishable by PFGE, and were related to invasive isolates in cluster 2. Of 26 child carriers in hospital B, 22 (85%) were colonized with NLSSP. The isolates were indistinguishable by PFGE, although they displayed two serotypes, serotypes 19F and 23F. The isolates were related to invasive isolates in cluster 1; however, higher levofloxacin MICs and different fluoroquinolone resistance mutations were suggestive of horizontal gene transfer. A serotype 23F carriage isolate displayed increased fitness compared with the fitness of an otherwise indistinguishable serotype 19F carriage isolate. These data suggest that a low-level non-levofloxacin-susceptible strain transformed into a highly resistant strain under antibiotic pressure and underwent capsular switching in order to have increased fitness.
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