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Sato T, Ito R, Kawamura M, Fujimura S. The Drug-Specific Propensity Regarding the Acquisition of Fluoroquinolone Resistance in Escherichia coli: An in vitro Challenge and DNA Mutation Analysis. Infect Drug Resist 2023; 16:6357-6366. [PMID: 37789839 PMCID: PMC10543074 DOI: 10.2147/idr.s428383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 09/21/2023] [Indexed: 10/05/2023] Open
Abstract
Objective Many fluoroquinolones, such as ciprofloxacin, are used clinically. We investigated the relationship between resistance acquisition and exposure duration in each drug through the exposure of fluoroquinolone to Escherichia coli clinical isolates in vitro. Methods Eleven E. coli clinical isolates were exposed to each fluoroquinolone, ie, ciprofloxacin, levofloxacin, sitafloxacin, garenoxacin, and lascufloxacin, with the concentration of the mutant selection window for 5 days; these procedures were repeated 5-times. In addition, the DNA sequence in the quinolone-resistance determining region (QRDR) and the expression level in the drug efflux pump acrA were analyzed to determine the resistance mechanism. Results Although resistant strains were not detected after 5 to 10 days of exposure to fluoroquinolone, after 25 days of exposure to ciprofloxacin and levofloxacin, 100% and 45% of isolates acquired resistance, respectively. Due to 25 days of exposure to sitafloxacin, garenoxacin, and lascufloxacin, MIC measurement was elevated 2- to 4096-fold for those of the parental strain, and the cross-resistance rate to levofloxacin was 72%, 54%, and 27%, respectively. In strains with high fluoroquinolone resistance, acrA overexpression was observed in addition to QRDR mutation. Conclusion In our findings, fluoroquinolone resistance was not observed in the E. coli strain after 5- to 10-days of exposure. However, resistance acquisition was detected frequently after 15- to 25-days of exposure. Among fluoroquinolones, lascufloxacn had the least impact on the resistance acquisition in E. coli.
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Affiliation(s)
- Takumi Sato
- Division of Clinical Infectious Diseases & Chemotherapy, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Ryota Ito
- Division of Clinical Infectious Diseases & Chemotherapy, Tohoku Medical and Pharmaceutical University, Sendai, Japan
- Department of Pharmacy, Japan Labor Health and Welfare Organization Tohoku Rosai Hospital, Sendai, Japan
| | - Masato Kawamura
- Division of Clinical Infectious Diseases & Chemotherapy, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Shigeru Fujimura
- Division of Clinical Infectious Diseases & Chemotherapy, Tohoku Medical and Pharmaceutical University, Sendai, Japan
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2
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Tønnessen R, García I, Debech N, Lindstrøm JC, Wester AL, Skaare D. Molecular epidemiology and antibiotic resistance profiles of invasive Haemophilus influenzae from Norway 2017–2021. Front Microbiol 2022; 13:973257. [PMID: 36106084 PMCID: PMC9467436 DOI: 10.3389/fmicb.2022.973257] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 08/01/2022] [Indexed: 11/13/2022] Open
Abstract
Invasive Haemophilus influenzae (Hi) disease has decreased in countries that included Hi type b (Hib) vaccination in their childhood immunization programs in the 1990s. Non-typeable (NT) and non-b strains are now the leading causes of invasive Hi disease in Europe, with most cases reported in young children and the elderly. Concerningly, no vaccines toward such strains are available and beta-lactam resistance is increasing. We describe the epidemiology of invasive Hi disease reported to the Norwegian Surveillance System for Communicable Diseases (MSIS) (2017–2021, n = 407). Whole-genome sequencing (WGS) was performed on 245 isolates. We investigated the molecular epidemiology (core genome phylogeny) and the presence of antibiotic resistance markers (including chromosomal mutations associated with beta-lactam or quinolone resistance). For isolates characterized with both WGS and phenotypic antibiotic susceptibility testing (AST) (n = 113) we assessed correlation between resistance markers and susceptibility categorization by calculation of sensitivity, specificity, and predictive values. Incidence rates of invasive Hi disease in Norway ranged from 0.7 to 2.3 per 100,000 inhabitants/year (mean 1.5 per 100,000) and declined during the COVID-19 pandemic. The bacterial population consisted of two major phylogenetic groups with subclustering by serotype and multi-locus sequence type (ST). NTHi accounted for 71.8% (176). The distribution of STs was in line with previous European reports. We identified 13 clusters, including four encapsulated and three previously described international NTHi clones with blaTEM–1 (ST103) or altered PBP3 (rPBP3) (ST14/IIA and ST367/IIA). Resistance markers were detected in 25.3% (62/245) of the isolates, with blaTEM–1 (31, 50.0%) and rPBP3 (28, 45.2%) being the most frequent. All isolates categorized as resistant to aminopenicillins, tetracycline or chloramphenicol possessed relevant resistance markers, and the absence of relevant substitutions in PBP3 and GyrA/ParC predicted susceptibility to cefotaxime, ceftriaxone, meropenem and quinolones. Among the 132 WGS-only isolates, one isolate had PBP3 substitutions associated with resistance to third-generation cephalosporins, and one isolate had GyrA/ParC alterations associated with quinolone resistance. The detection of international virulent and resistant NTHi clones underlines the need for a global molecular surveillance system. WGS is a useful supplement to AST and should be performed on all invasive isolates.
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Affiliation(s)
- Ragnhild Tønnessen
- Department of Infection Control and Vaccines, Norwegian Institute of Public Health, Oslo, Norway
- European Public Health Microbiology Training Program (EUPHEM), European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden
- *Correspondence: Ragnhild Tønnessen,
| | - Ignacio García
- Department of Bacteriology, Norwegian Institute of Public Health, Oslo, Norway
| | - Nadia Debech
- Department of Bacteriology, Norwegian Institute of Public Health, Oslo, Norway
| | | | | | - Dagfinn Skaare
- Department of Microbiology, Vestfold Hospital Trust, Tønsberg, Norway
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3
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Quinolone resistance is transferred horizontally via uptake signal sequence recognition in Haemophilus influenzae. Antimicrob Agents Chemother 2021; 66:e0196721. [PMID: 34930025 DOI: 10.1128/aac.01967-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The presence of Haemophilus influenzae strains with low susceptibility to quinolones has been reported worldwide. However, the emergence and dissemination mechanisms remain unclear. In this study, a total of 14 quinolone-low-susceptible H. influenzae isolates were investigated phylogenetically and in vitro resistance transfer assay in order to elucidate the emergence and dissemination mechanisms. The phylogenetic analysis based on gyrA sequences showed that strains with the same sequence type determined by multilocus sequence typing were classified into different clusters, suggesting that H. influenzae quinolone resistance emerges not only by point mutation, but also by the horizontal transfer of mutated gyrA. Moreover, the in vitro resistance transfer assay confirmed the horizontal transfer of quinolone resistance and indicated an active role of extracellular DNA in the resistance transfer. Interestingly, the horizontal transfer of parC only occurred in those cells that harbored a GyrA with amino acid substitutions, suggesting a possible mechanism of quinolone resistance in clinical settings. Moreover, the uptake signal and uptake-signal-like sequences located downstream of the quinolone resistant-determining regions of gyrA and parC, respectively, contributed to the horizontal transfer of resistance in H. influenzae. Our study demonstrates that the quinolone resistance of H. influenzae could emerge due to the horizontal transfer of gyrA and parC via recognition of an uptake signal sequence or uptake-signal-like sequence. Since the presence of quinolone-low-susceptible H. influenzae with amino acid substitutions in GyrA have been increasing in recent years, it is necessary to focus our attention to the acquisition of further drug resistance in these isolates.
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4
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Evaluation of Fluoroquinolone Resistance in Clinical Avian Pathogenic Escherichia coli Isolates from Flanders (Belgium). Antibiotics (Basel) 2020; 9:antibiotics9110800. [PMID: 33198103 PMCID: PMC7696922 DOI: 10.3390/antibiotics9110800] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 11/06/2020] [Accepted: 11/11/2020] [Indexed: 11/16/2022] Open
Abstract
Fluoroquinolones are frequently used antimicrobials for the treatment of avian pathogenic Escherichia coli (APEC) infections. However, rapid development and selection of resistance to this class of antimicrobial drugs is a significant problem. The aim of this study was to investigate the occurrence and mechanisms of antimicrobial resistance against enrofloxacin (ENRO) in APEC strains in Flanders, Belgium. One hundred and twenty-five APEC strains from broilers with clinical colibacillosis were collected in Flanders from November 2017 to June 2018. The minimum inhibitory concentration (MIC) of all strains and the mutant prevention concentration (MPC) of a sample of sensitive isolates were determined using a commercial gradient strip test and via the agar dilution method, respectively. Non-wild type (NWT) isolates were further characterized using polymerase chain reaction (PCR), gel electrophoresis and gene sequencing. Forty percent of the APEC strains were NWT according to the epidemiological cut-off (ECOFF) measure (MIC > 0.125 μg/mL). With respect to clinical breakpoints, 21% were clinically intermediate (0.5 ≤ MIC ≤ 1 μg/mL) and 10% were clinically resistant (MIC ≥ 2). The MPC values of the tested strains ranged from 0.064 to 1 μg/mL, resulting in MPC/MIC ratios varying from 4 to 32. The majority (92%) of the NWT strains carried one or two mutations in gyrA. Less than a quarter (22%) manifested amino acid substitutions in the topoisomerase IV parC subunit. Only three of the NWT strains carried a mutation in parE. Plasmid mediated quinolone resistance (PMQR) associated genes were detected in 18% of the NWT strains. In contrast to the relatively large number of NWT strains, only a small percentage of APEC isolates was considered clinically resistant. The most common MPC value for sensitive strains was 0.125 μg/mL. Some isolates showed higher values, producing wide mutant selection windows (MSW). Chromosomal mutations in DNA gyrase and topoisomerase IV were confirmed as the main source of decreased antimicrobial fluoroquinolone susceptibility, de-emphasizing the role of PMQR mechanisms.
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5
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Chang CM, Shih HI, Wu CJ, Lauderdale TL, Lee NY, Lee CC, Chen YC, Huang CC, Ko WC. Fluoroquinolone resistance in Haemophilus influenzae from nursing home residents in Taiwan: correlation of MICs and mutations in QRDRs. J Appl Microbiol 2020; 128:1624-1633. [PMID: 31951091 DOI: 10.1111/jam.14580] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Revised: 01/09/2020] [Accepted: 01/10/2020] [Indexed: 11/28/2022]
Abstract
AIMS To study the association between number and positions of mutations with MICs of fluoroquinolone non-susceptible Haemophilus influenzae. METHODS AND RESULTS More than 40% of 48 H. influenzae isolated from nursing home residents were not susceptible to fluoroquinolone. Amino acid changes in the quinolone resistance determining regions, and correlation with MICs and inhibition zone diameters were analysed. All isolates with reduced susceptibility to fluoroquinolones (MIC ≥0·125 µg ml-1 ) had at least one mutation in gyrA at position 84 and were resistant to nalidixic acid. Compared to isolates with reduced susceptibility, resistant isolates were associated with mutations in gyrA at positions 88 and 134, and in parC at position 88 (P < 0·001). Inhibition zone diameter for nalidixic acid disk ≥23 mm may detect susceptible isolates. CONCLUSIONS Reduced susceptibility to fluoroquinolones was associated with mutations at position 84 in gyrA. A further increase in fluoroquinolone MIC was associated with mutations in gyrA at positions 88 and 134, and parC at position 88. SIGNIFICANCE AND IMPACT OF THE STUDY Due to limited resistant H. influenzae strains, prior studies on association between positions of mutations and fluoroquinolone MICs were inconclusive. The comparison of mutations between isolates with susceptibility, reduced susceptibility and high resistance supported the importance of the present study.
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Affiliation(s)
- C-M Chang
- Division of Infectious Diseases, Department of Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.,Division of Geriatrics and Gerontology, Department of Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.,Center of Infection Control, National Cheng Kung University Hospital, Tainan, Taiwan.,Department of Medicine, National Cheng Kung University Medical College, Tainan, Taiwan
| | - H-I Shih
- Department of Emergency Medicine, National Cheng Kung University Hospital, Tainan, Taiwan
| | - C-J Wu
- Division of Infectious Diseases, National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Tainan, Taiwan
| | - T-L Lauderdale
- Division of Infectious Diseases, National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Zhunan, Taiwan
| | - N-Y Lee
- Division of Infectious Diseases, Department of Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.,Center of Infection Control, National Cheng Kung University Hospital, Tainan, Taiwan
| | - C-C Lee
- Division of Infectious Diseases, Department of Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.,Center of Infection Control, National Cheng Kung University Hospital, Tainan, Taiwan
| | - Y-C Chen
- Division of Infectious Diseases, National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Zhunan, Taiwan
| | - C-C Huang
- Division of Infectious Diseases, Department of Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.,Division of Geriatrics and Gerontology, Department of Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan
| | - W-C Ko
- Division of Infectious Diseases, Department of Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.,Center of Infection Control, National Cheng Kung University Hospital, Tainan, Taiwan.,Department of Medicine, National Cheng Kung University Medical College, Tainan, Taiwan
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6
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Xie X, Lv R, Yang C, Song Y, Yan Y, Cui Y, Yang R. Soft sweep development of resistance in Escherichia coli under fluoroquinolone stress. J Microbiol 2019; 57:1056-1064. [PMID: 31555989 DOI: 10.1007/s12275-019-9177-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 08/05/2019] [Accepted: 08/13/2019] [Indexed: 11/30/2022]
Abstract
We employed a stepwise selection model for investigating the dynamics of antibiotic-resistant variants in Escherichia coli K-12 treated with increasing concentrations of ciprofloxacin (CIP). Firstly, we used Sanger sequencing to screen the variations in the fluoquinolone target genes, then, employed Illumina NGS sequencing for amplicons targeted regions with variations. The results demonstrated that variations G81C in gyrA and K276N and K277L in parC are standing resistance variations (SRVs), while S83A and S83L in gyrA and G78C in parC were emerging resistance variations (ERVs). The variants containing SRVs and/or ERVs were selected successively based on their sensitivities to CIP. Variant strain 1, containing substitution G81C in gyrA, was immediately selected following ciprofloxacin exposure, with obvious increases in the parC SRV, and parC and gyrA ERV allele frequencies. Variant strain 2, containing the SRVs, then dominated the population following a 20× increase in ciprofloxacin concentration, with other associated allele frequencies also elevated. Variant strains 3 and 4, containing ERVs in gyrA and parC, respectively, were then selected at 40× and 160× antibiotic concentrations. Two variants, strains 5 and 6, generated in the selection procedure, were lost because of higher fitness costs or a lower level of resistance compared with variants 3 and 4. For the second induction, all variations/indels were already present as SRVs and selected out step by step at different passages. Whatever the first induction or second induction, our results confirmed the soft selective sweep hypothesis and provided critical information for guiding clinical treatment of pathogens containing SRVs.
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Affiliation(s)
- Xianxing Xie
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P. R. China
| | - Ruichen Lv
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P. R. China.,Huadong Research Institute for Medicine and Biotechnics, Nanjing, P. R. China
| | - Chao Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P. R. China
| | - Yajun Song
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P. R. China
| | - Yanfeng Yan
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P. R. China
| | - Yujun Cui
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P. R. China
| | - Ruifu Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P. R. China.
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7
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Gianvecchio C, Lozano NA, Henderson C, Kalhori P, Bullivant A, Valencia A, Su L, Bello G, Wong M, Cook E, Fuller L, Neal JB, Yeh PJ. Variation in Mutant Prevention Concentrations. Front Microbiol 2019; 10:42. [PMID: 30766517 PMCID: PMC6365975 DOI: 10.3389/fmicb.2019.00042] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 01/11/2019] [Indexed: 12/12/2022] Open
Abstract
Objectives:Understanding how phenotypic traits vary has been a longstanding goal of evolutionary biologists. When examining antibiotic-resistance in bacteria, it is generally understood that the minimum inhibitory concentration (MIC) has minimal variation specific to each bacterial strain-antibiotic combination. However, there is a less studied resistance trait, the mutant prevention concentration (MPC), which measures the MIC of the most resistant sub-population. Whether and how MPC varies has been poorly understood. Here, we ask a simple, yet important question: How much does the MPC vary, within a single strain-antibiotic association? Using a Staphylococcus species and five antibiotics from five different antibiotic classes—ciprofloxacin, doxycycline, gentamicin, nitrofurantoin, and oxacillin—we examined the frequency of resistance for a wide range of concentrations per antibiotic, and measured the repeatability of the MPC, the lowest amount of antibiotic that would ensure no surviving cells in a 1010 population of bacteria. Results: We found a wide variation within the MPC and distributions that were rarely normal. When antibiotic resistance evolved, the distribution of the MPC changed, with all distributions becoming wider and some multi-modal. Conclusion: Unlike the MIC, there is high variability in the MPC for a given bacterial strain-antibiotic combination.
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Affiliation(s)
- Crystal Gianvecchio
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Natalie Ann Lozano
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Claire Henderson
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Pooneh Kalhori
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Austin Bullivant
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Alondra Valencia
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Lauren Su
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Gladys Bello
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Michele Wong
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Emoni Cook
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Lakhia Fuller
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Jerome B Neal
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Pamela J Yeh
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, United States.,Santa Fe Institute, Santa Fe, NM, United States
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8
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Ostrer L, Khodursky RF, Johnson JR, Hiasa H, Khodursky A. Analysis of mutational patterns in quinolone resistance-determining regions of GyrA and ParC of clinical isolates. Int J Antimicrob Agents 2018; 53:318-324. [PMID: 30582984 DOI: 10.1016/j.ijantimicag.2018.12.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 12/15/2018] [Indexed: 01/03/2023]
Abstract
Fluoroquinolone (FQ)-resistant bacteria pose a major global health threat. Unanalysed genomic data from thousands of sequenced microbes likely contain important hints regarding the evolution of FQ resistance, yet this information lies fallow. Here we analysed the co-occurrence patterns of quinolone resistance mutations in genes encoding the FQ drug targets DNA gyrase (gyrase) and topoisomerase IV (topo-IV) from 36,402 bacterial genomes, representing 10 Gram-positive and 10 Gram-negative species. For 19 species, the likeliest routes toward resistance mutations in both targets were determined, and for 5 species those mutations necessary and sufficient to predict FQ resistance were also determined. Target mutation hierarchy was fixed in all examined Gram-negative species, with gyrase being the primary and topo-IV the secondary quinolone target, as well as in six of nine Gram-positive species, with topo-IV being the primary and gyrase the secondary target. By contrast, in three Gram-positive species (Staphylococcus haemolyticus, Streptococcus pneumoniae and Streptococcus suis), under some conditions gyrase became the primary and topo-IV the secondary target. The path through individual resistance mutations varied by species. Both linear and branched paths were identified in Gram-positive and Gram-negative organisms alike. Finally, FQ resistance could be predicted based solely on target gene quinolone resistance mutations for Acinetobacter baumannii, Escherichia coli and Staphylococcus aureus, but not Klebsiella pneumoniae or Pseudomonas aeruginosa. These findings have important implications both for sequence-based diagnostics and for understanding the emergence of FQ resistance.
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Affiliation(s)
- Lev Ostrer
- Department of Biochemistry, Molecular Biology and Biophysics, Biotechnology Institute, University of Minnesota, St Paul, MN, USA
| | - Rachel F Khodursky
- Department of Biochemistry, Molecular Biology and Biophysics, Biotechnology Institute, University of Minnesota, St Paul, MN, USA
| | | | - Hiroshi Hiasa
- Department of Pharmacology, University of Minnesota Medical School, 6-120 Jackson Hall, 321 Church Street SE, Minneapolis, MN, USA
| | - Arkady Khodursky
- Department of Biochemistry, Molecular Biology and Biophysics, Biotechnology Institute, University of Minnesota, St Paul, MN, USA.
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9
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Microbial virulence, molecular epidemiology and pathogenic factors of fluoroquinolone-resistant Haemophilus influenzae infections in Guangzhou, China. Ann Clin Microbiol Antimicrob 2018; 17:41. [PMID: 30470228 PMCID: PMC6251178 DOI: 10.1186/s12941-018-0290-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Accepted: 10/09/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Fluoroquinolone-resistant Haemophilus influenzae (FRHI) has been reported worldwide but remain unclear in China. METHODS A total of 402 H. influenzae isolates collected from 2016 to 2017 were included. Antimicrobial susceptibility on 10 antibiotics was performed, and minimum inhibitory concentration of ciprofloxacin- and nalidixic acid-resistant strains were further determined by E-test strips, with risk factors also evaluated. Strains with resistance or reduced susceptibility to ciprofloxacin were subjected to sequencing of the quinolone resistance-determining regions (QRDR) and plasmid-mediated quinolone resistance genes by sequencing, with multi-locus sequence typing. RESULTS 2.2% of H. influenzae strains were non-susceptible (7/402, 1.7%) or susceptible (2/402, 0.5%) to ciprofloxacin but NAL-resistant by E-test, and multidrug resistance was more common in fluoroquinolones non-susceptible H. influenzae group (p = 0.000). Infection risk factors included invasive procedure (p = 0.011), catching cold/previous contact with someone who had a cold (p = 0.019), fluoroquinolones use during previous 3 months (p = 0.003). With none of mutations obtained in gyrB, parE and other plasmid-mediated quinolone resistance genes, 7 and 4 strains were found for Ser-84-Leu substitutions in gyrA and one amino acid substitution in the QRDR of gyrA linked with one amino acid substitution in the QRDR of parC, respectively. In addition, five sequence types (ST) were identified, with ST1719 firstly found. CONCLUSIONS For the first time, this study has reported the incidence, risk factors, molecular determinants on fluoroquinolones resistance and ST of FRHI strains in mainland China, representing the first evidence of mutation of gyrA and parC in China and the new ST1719 worldwide.
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10
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Podnecky NL, Fredheim EGA, Kloos J, Sørum V, Primicerio R, Roberts AP, Rozen DE, Samuelsen Ø, Johnsen PJ. Conserved collateral antibiotic susceptibility networks in diverse clinical strains of Escherichia coli. Nat Commun 2018; 9:3673. [PMID: 30202004 PMCID: PMC6131505 DOI: 10.1038/s41467-018-06143-y] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 08/16/2018] [Indexed: 01/09/2023] Open
Abstract
There is urgent need to develop novel treatment strategies to reduce antimicrobial resistance. Collateral sensitivity (CS), where resistance to one antimicrobial increases susceptibility to other drugs, might enable selection against resistance during treatment. However, the success of this approach would depend on the conservation of CS networks across genetically diverse bacterial strains. Here, we examine CS conservation across diverse Escherichia coli strains isolated from urinary tract infections. We determine collateral susceptibilities of mutants resistant to relevant antimicrobials against 16 antibiotics. Multivariate statistical analyses show that resistance mechanisms, in particular efflux-related mutations, as well as the relative fitness of resistant strains, are principal contributors to collateral responses. Moreover, collateral responses shift the mutant selection window, suggesting that CS-informed therapies may affect evolutionary trajectories of antimicrobial resistance. Our data allow optimism for CS-informed therapy and further suggest that rapid detection of resistance mechanisms is important to accurately predict collateral responses.
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Affiliation(s)
- Nicole L Podnecky
- Department of Pharmacy, Faculty of Health Sciences, UiT The Arctic University of Norway, 9037, Tromsø, Norway.
| | - Elizabeth G A Fredheim
- Department of Pharmacy, Faculty of Health Sciences, UiT The Arctic University of Norway, 9037, Tromsø, Norway
| | - Julia Kloos
- Department of Pharmacy, Faculty of Health Sciences, UiT The Arctic University of Norway, 9037, Tromsø, Norway
| | - Vidar Sørum
- Department of Pharmacy, Faculty of Health Sciences, UiT The Arctic University of Norway, 9037, Tromsø, Norway
| | - Raul Primicerio
- Department of Pharmacy, Faculty of Health Sciences, UiT The Arctic University of Norway, 9037, Tromsø, Norway
| | - Adam P Roberts
- Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
- Research Centre for Drugs and Diagnostics, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Daniel E Rozen
- Institute of Biology, Leiden University, Sylviusweg 72, PO Box 9505, 2300 RA, Leiden, The Netherlands
| | - Ørjan Samuelsen
- Department of Pharmacy, Faculty of Health Sciences, UiT The Arctic University of Norway, 9037, Tromsø, Norway
- Norwegian National Advisory Unit on Detection of Antimicrobial Resistance, Department of Microbiology and Infection Control, University Hospital of North Norway, 9037, Tromsø, Norway
| | - Pål J Johnsen
- Department of Pharmacy, Faculty of Health Sciences, UiT The Arctic University of Norway, 9037, Tromsø, Norway.
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11
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Affiliation(s)
- Zachary C. Conley
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Truston J. Bodine
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
- Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, Texas, United States of America
- Medical Scientist Training Program, Baylor College of Medicine, Houston, Texas, United States of America
| | - Andrew Chou
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
- Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas, United States of America
| | - Lynn Zechiedrich
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
- Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, Texas, United States of America
- Medical Scientist Training Program, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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12
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Effect of Fluoroquinolones and Macrolides on Eradication and Resistance of Haemophilus influenzae in Chronic Obstructive Pulmonary Disease. Antimicrob Agents Chemother 2016; 60:4151-8. [PMID: 27139476 DOI: 10.1128/aac.00301-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 04/24/2016] [Indexed: 11/20/2022] Open
Abstract
Little is known about the effect of antibiotics on eradication of carriage and development of resistance in Haemophilus influenzae in individuals with chronic obstructive pulmonary disease (COPD). Our goals were to assess antibiotic susceptibilities, prevalence of resistance genes, and development of resistance in H. influenzae and to evaluate the effect of macrolide and fluoroquinolone administration on H. influenzae eradication. Data were from a 15-year longitudinal study of COPD. Genome sequence data were used to determine genotype and identify resistance genes. MICs of antibiotics were determined by reference broth microdilution. Generalized linear mixed models were used to evaluate associations between antibiotic use and H. influenzae eradication. We examined 267 H. influenzae isolates from 77 individuals. All newly acquired H. influenzae isolates were susceptible to azithromycin. Five of 27 (19%) strains developed 4-fold increases in azithromycin MICs and reached or exceeded the susceptibility breakpoint (≤4 μg/ml) during exposure. H. influenzae isolates were uniformly susceptible to ciprofloxacin, levofloxacin, and moxifloxacin (MIC90s of 0.015, 0.015, and 0.06, respectively); there were no mutations in quinolone resistance-determining regions. Fluoroquinolone administration was associated with increased H. influenzae eradication compared to macrolides (odds ratio [OR], 16.67; 95% confidence interval [CI], 2.67 to 104.09). There was no difference in H. influenzae eradication when comparing macrolide administration to no antibiotic (OR, 1.89; 95% CI, 0.43 to 8.30). Fluoroquinolones are effective in eradicating H. influenzae in individuals with COPD. Macrolides are ineffective in eradicating H. influenzae, and their use in COPD patients may lead to decreased macrolide susceptibility and resistance.
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Fuursted K, Hartmeyer GN, Stegger M, Andersen PS, Justesen US. Molecular characterisation of the clonal emergence of high-level ciprofloxacin-monoresistant Haemophilus influenzae in the Region of Southern Denmark. J Glob Antimicrob Resist 2016; 5:67-70. [PMID: 27436470 DOI: 10.1016/j.jgar.2015.12.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 12/09/2015] [Accepted: 12/19/2015] [Indexed: 11/15/2022] Open
Abstract
Haemophilus influenzae is an important human pathogen usually susceptible to quinolones. Here we report the emergence of high-level ciprofloxacin-monoresistant H. influenzae in the Region of Southern Denmark. Four isolates were collected for phenotypic and molecular characterisation using whole-genome sequencing (WGS). During an 18-month period, the occurrence of high-level ciprofloxacin-monoresistant H. influenzae in patients aged 1-77 years from sputum, ear and eye samples was detected. An epidemiological link between the patients could not be identified. The isolates were non-encapsulated, biotype III and were demonstrated by WGS to be clonal belonging to a single clade with an unknown multilocus sequence type (double-locus variant of ST196). The antibiogram demonstrated that they were all monoresistant to ciprofloxacin with a minimum inhibitory concentration (MIC) >32mg/L. In silico resistome analysis revealed identical, both previously characterised and novel, putative resistance-related mutations in gyrA (S84L and D88N), parC (K20R, S84I, D356A or T356A, and M481I) and parE (E151K, I159A, D420N and S599A) in all isolates. The isolates were otherwise negative for any resistance genes. This is the first description of the clonal emergence of high-level monoresistant H. influenzae due to amino acid substitutions in gyrA, parC and parE.
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Affiliation(s)
- Kurt Fuursted
- Department of Microbiology & Infection Control, Statens Serum Institut, Artillerivej 5, DK-2300 Copenhagen S, Denmark.
| | - Gitte Nyvang Hartmeyer
- Department of Clinical Microbiology, Odense University Hospital, DK-5000 Odense C, Denmark
| | - Marc Stegger
- Department of Microbiology & Infection Control, Statens Serum Institut, Artillerivej 5, DK-2300 Copenhagen S, Denmark
| | - Paal Skytt Andersen
- Department of Microbiology & Infection Control, Statens Serum Institut, Artillerivej 5, DK-2300 Copenhagen S, Denmark
| | - Ulrik Stenz Justesen
- Department of Clinical Microbiology, Odense University Hospital, DK-5000 Odense C, Denmark
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Molecular characterization of fluoroquinolone resistance in nontypeable Haemophilus influenzae clinical isolates. Antimicrob Agents Chemother 2014; 59:461-6. [PMID: 25385097 DOI: 10.1128/aac.04005-14] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nontypeable Haemophilus influenzae (NTHi) is a common cause of respiratory infections in adults, who are frequently treated with fluoroquinolones. The aims of this study were to characterize the genotypes of fluoroquinolone-resistant NTHi isolates and their mechanisms of resistance. Among 7,267 H. influenzae isolates collected from adult patients from 2000 to 2013, 28 (0.39%) were ciprofloxacin resistant according to Clinical and Laboratory Standards Institute (CLSI) criteria. In addition, a nalidixic acid screening during 2010 to 2013 detected five (0.23%) isolates that were ciprofloxacin susceptible but nalidixic acid resistant. Sequencing of their quinolone resistance-determining regions and genotyping by pulse-field gel electrophoresis and multilocus sequence typing of the 25 ciprofloxacin-resistant isolates available and all 5 nalidixic acid-resistant isolates were performed. In the NTHi isolates studied, two mutations producing changes in two GyrA residues (Ser84, Asp88) and/or two ParC residues (Ser84, Glu88) were associated with increased fluoroquinolone MICs. Strains with one or two mutations (n = 15) had ciprofloxacin and levofloxacin MICs of 0.12 to 2 μg/ml, while those with three or more mutations (n = 15) had MICs of 4 to 16 μg/ml. Long persistence of fluoroquinolone-resistant strains was observed in three chronic obstructive pulmonary disease patients. High genetic diversity was observed among fluoroquinolone-resistant NTHi isolates. Although fluoroquinolones are commonly used to treat respiratory infections, the proportion of resistant NTHi isolates remains low. The nalidixic acid disk test is useful for detecting the first changes in GyrA or in GyrA plus ParC among fluoroquinolone-susceptible strains that are at a potential risk for the development of resistance under selective pressure by fluoroquinolone treatment.
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15
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Quantitative contributions of target alteration and decreased drug accumulation to Pseudomonas aeruginosa fluoroquinolone resistance. Antimicrob Agents Chemother 2012; 57:1361-8. [PMID: 23274661 DOI: 10.1128/aac.01581-12] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Quinolone antibiotics constitute a clinically successful and widely used class of broad-spectrum antibiotics; however, the emergence and spread of resistance increasingly limits the use of fluoroquinolones in the treatment and management of microbial disease. In this study, we evaluated the quantitative contributions of quinolone target alteration and efflux pump expression to fluoroquinolone resistance in Pseudomonas aeruginosa. We generated isogenic mutations in hot spots of the quinolone resistance-determining regions (QRDRs) of gyrA, gyrB, and parC and inactivated the efflux regulator genes so as to overexpress the corresponding multidrug resistance (MDR) efflux pumps. We then introduced the respective mutations into the reference strain PA14 singly and in various combinations. Whereas the combined inactivation of two efflux regulator-encoding genes did not lead to resistance levels higher than those obtained by inactivation of only one efflux regulator-encoding gene, the combination of mutations leading to increased efflux and target alteration clearly exhibited an additive effect. This combination of target alteration and overexpression of efflux pumps was commonly observed in clinical P. aeruginosa isolates; however, these two mechanisms were frequently found not to be sufficient to explain the level of fluoroquinolone resistance. Our results suggest that there are additional mechanisms, independent of the expression of the MexAB-OprM, MexCD-OprJ, MexEF-OprN, and/or MexXY-OprM efflux pump, that increase ciprofloxacin resistance in isolates with mutations in the QRDRs.
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The Inactivation of intrinsic antibiotic resistance determinants widens the mutant selection window for quinolones in Stenotrophomonas maltophilia. Antimicrob Agents Chemother 2012; 56:6397-9. [PMID: 23006759 DOI: 10.1128/aac.01558-12] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
We have determined that the mutational inactivation of the SmeDEF efflux pump and the SmQnr quinolone resistance protein widens the mutant selection windows for ofloxacin and ciprofloxacin of Stenotrophomonas maltophilia by reducing their MICs. Resistant mutants arising from a strain lacking SmeDEF and SmQnr presented levels of susceptibility similar to those of the wild-type strain. This indicates that inactivation of intrinsic resistance determinants might increase the chances for selecting resistant mutants at low antibiotic concentrations.
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Zhu YL, Mei Q, Hu LF, Cheng J, Ye Y, Li JB. Vancomycin MICs of the resistant mutants of S. aureus ATCC43300 vary based on the susceptibility test methods used. J Antibiot (Tokyo) 2012; 65:307-10. [PMID: 22491134 DOI: 10.1038/ja.2012.18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Clinical failures with vancomycin against meticillin-resistant Staphylococcus aureus (MRSA) infections have challenged vancomycin's standing as a first-line antimicrobial for these infections. Conventional MIC tests were not predictive of the in vivo therapeutic effect of vancomycin. Thus, we tested the susceptibility for the resistant mutants in the mutant selection window of S. aureus ATCC43300 (a MRSA strain) by three different MIC-testing methods in this paper. The MIC of vancomycin was estimated at 2 μg ml⁻¹ on the Mueller-Hinton agar (MHA) plate only for the resistant mutant that was selected from the plate of vancomycin concentration 12 μg ml⁻¹. The obvious changes of susceptibility testing were found between the resistant mutants and S. aureus ATCC43300 on the Brain-Heart Infusion Agar (BHIA) plates. There were subtle changes in the MIC trend within the susceptible range with the result of Etest for the resistant mutants. The susceptibility for the subcultures of resistant mutants would fall back when the external drug environment disappeared. In comparison with the S. aureus ATCC43300, sequence analysis revealed that there were no mutations in the staphylococcal protein A (spa) sequencing of the resistant mutants. The spa tape is t421 for all isolates.
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Affiliation(s)
- Yu-lin Zhu
- Department of Infectious Diseases, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China
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Optimal dose finding of garenoxacin based on population pharmacokinetics/pharmacodynamics and Monte Carlo simulation. Eur J Clin Pharmacol 2011; 68:39-53. [PMID: 21796376 PMCID: PMC3249185 DOI: 10.1007/s00228-011-1095-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Accepted: 06/28/2011] [Indexed: 12/04/2022]
Abstract
Purpose Garenoxacin, a novel des-F(6)-quinolone, possesses potent antibacterial activity against infectious pathogens in the respiratory tract. Population pharmacokinetic/pharmacodynamic (PK/PD) modeling and Monte Carlo simulations were used to optimize garenoxacin dosage regimens. Methods At the end of phase II stage, the clinical dose of garenoxacin was predicted to be 400 mg once daily by the interim PK/PD analysis using phase I and phase II clinical data. The criteria used to determine an optimal dose were (1) the target attainment of the area under the unbound concentration–time curve divided by the minimum inhibitory concentration (fAUC0−24/MIC ratio) and (2) the maintenance of a trough concentration above the mutant prevention concentration. In a confirmatory phase III study, garenoxacin was administered 400 mg once daily to 136 patients infected with mild or moderate chronic respiratory diseases. Results Logistic regression analysis showed that fAUC0−24/MIC ratio was a significant variable that predicted clinical response (p = 0.0164). Of all subjects, 92.4% reached the target value of fAUC0−24/MIC ratio > 30 h, and the clinical efficacy rate of this population was 91.8%. On the other hand, there was no significant relationship between exposure values (AUC0−24 and maximum concentration) and the incidence of adverse events by the Mann–Whitney test. Conclusions The antimicrobial efficacy of the actual phase III study was consistent with the expectation from the Monte Carlo PD simulation. We were able to show that the optimal garenoxacin dosage regimens were successfully determined using prospective population PK/PD analysis and clinical trial simulations. Electronic supplementary material The online version of this article (doi:10.1007/s00228-011-1095-3) contains supplementary material, which is available to authorized users.
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Kim IS, Lee NY, Kim S, Ki CS, Kim SH. Reduced levofloxacin susceptibility in clinical respiratory isolates of Haemophilus influenzae is not yet associated with mutations in the DNA gyrase and topoisomerase II genes in Korea. Yonsei Med J 2011; 52:188-91. [PMID: 21155053 PMCID: PMC3017696 DOI: 10.3349/ymj.2011.52.1.188] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Among 155 clinical respiratory isolates of Haemophilus influenzae in Korea, 6 (3.9%) isolates had reduced levofloxacin susceptibility (MICs ≥ 0.5 μg/mL). These six isolates had no significant quinolone resistance-determining region (QRDR) mutations in gyrA, gyrB, parC, or parE. This phenomenon suggests that neither evolution nor spread of any significant QRDRs mutations in clinical isolates occurred in Korea. Therefore, continued surveillance is necessary to observe the evolution of antibiotic-resistance and take measures to avoid the spread of drug-resistant clones.
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Affiliation(s)
- In-Suk Kim
- Department of Laboratory Medicine, Gyeongsang National University College of Medicine, Jinju, Korea
| | - Nam Yong Lee
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Sunjoo Kim
- Department of Laboratory Medicine, Gyeongsang National University College of Medicine, Jinju, Korea
| | - Chang-Seok Ki
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Sun-Hee Kim
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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Abstract
Large-scale, systems biology approaches now allow us to systematically map synergistic and antagonistic interactions between drugs. Consequently, drug antagonism is emerging as a powerful tool to study biological function and relatedness between cellular components as well as to uncover mechanisms of drug action. Furthermore, theoretical models and new experiments suggest that antagonistic interactions between antibiotics can counteract the evolution of drug resistance.
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Almahmoud I, Kay E, Schneider D, Maurin M. Mutational paths towards increased fluoroquinolone resistance in Legionella pneumophila. J Antimicrob Chemother 2009; 64:284-93. [PMID: 19474069 DOI: 10.1093/jac/dkp173] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Fluoroquinolone resistance has been poorly studied in Legionella pneumophila, an intracellular pathogen responsible for legionellosis. Our goal was to further characterize molecular mechanisms involved in fluoroquinolone resistance in this species. METHODS Eight independent lineages were founded from a common fluoroquinolone-susceptible L. pneumophila ancestor and propagated by serial passages in moxifloxacin-containing culture medium. We identified the substituted mutations that affected the DNA topoisomerase II-encoding genes, determined the order of substitution of the mutations leading to the stepwise MIC increases of moxifloxacin over evolutionary time and demonstrated their direct involvement in the resistance process. RESULTS Adaptation occurred through parallel stepwise increases in the moxifloxacin MICs up to 512-fold the MIC for the parental strain. Mutations affected the topoisomerase II-encoding genes gyrA, parC and gyrB, reflecting a high degree of genetic parallelism across the independent lineages. During evolution, the T83I change in GyrA occurred first, followed by G78D or S80R in ParC and D87N in GyrA, or S464Y or D426N in GyrB. By constructing isogenic strains, we showed that the progressive increase in resistance was linked to a precise order of mutation substitution, but also to the co-existence of several subpopulations of bacteria bearing different mutations. CONCLUSIONS Specific mutational trajectories were identified, strongly suggesting that intermolecular epistatic interactions between DNA topoisomerases underlie the mechanism of fluoroquinolone resistance in L. pneumophila. Our results suggest that L. pneumophila has strong potential to become resistant to fluoroquinolone compounds and warrant further investigation of resistance in clinical and environmental strains of this pathogen.
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Affiliation(s)
- Iyad Almahmoud
- Laboratoire Adaptation et Pathogénie des Micro-organismes, Université Joseph Fourier Grenoble 1, Institut Jean Roget, Campus Santé, Domaine de la Merci, BP 170, F-38042 Grenoble cedex 9, France
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22
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Melting curve analysis for rapid detection of topoisomerase gene mutations in Haemophilus influenzae. J Clin Microbiol 2009; 47:781-4. [PMID: 19129413 DOI: 10.1128/jcm.01645-08] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We established a real-time PCR assay with melting curve analysis to rapidly genotype quinolone resistance-determining regions (QRDRs) of gyrase A and topoisomerase IV genes in Haemophilus influenzae. This assay is a useful tool for the detection of fluoroquinolone resistance and for the early detection of preexisting QRDR mutations.
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Drlica K, Hiasa H, Kerns R, Malik M, Mustaev A, Zhao X. Quinolones: action and resistance updated. Curr Top Med Chem 2009; 9:981-98. [PMID: 19747119 PMCID: PMC3182077 DOI: 10.2174/156802609789630947] [Citation(s) in RCA: 235] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Accepted: 07/30/2009] [Indexed: 11/22/2022]
Abstract
The quinolones trap DNA gyrase and DNA topoisomerase IV on DNA as complexes in which the DNA is broken but constrained by protein. Early studies suggested that drug binding occurs largely along helix-4 of the GyrA (gyrase) and ParC (topoisomerase IV) proteins. However, recent X-ray crystallography shows drug intercalating between the -1 and +1 nucleotides of cut DNA, with only one end of the drug extending to helix-4. These two models may reflect distinct structural steps in complex formation. A consequence of drug-enzyme-DNA complex formation is reversible inhibition of DNA replication; cell death arises from subsequent events in which bacterial chromosomes are fragmented through two poorly understood pathways. In one pathway, chromosome fragmentation stimulates excessive accumulation of highly toxic reactive oxygen species that are responsible for cell death. Quinolone resistance arises stepwise through selective amplification of mutants when drug concentrations are above the MIC and below the MPC, as observed with static agar plate assays, dynamic in vitro systems, and experimental infection of rabbits. The gap between MIC and MPC can be narrowed by compound design that should restrict the emergence of resistance. Resistance is likely to become increasingly important, since three types of plasmid-borne resistance have been reported.
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Affiliation(s)
- Karl Drlica
- Public Health Research Institute, New Jersey Medical School, UMDNJ, 225 Warren Street, Newark, NJ 07103, USA.
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Ohnsman C, Ritterband D, O'Brien T, Girgis D, Kabat A. Comparison of azithromycin and moxifloxacin against bacterial isolates causing conjunctivitis. Curr Med Res Opin 2007; 23:2241-9. [PMID: 17688706 DOI: 10.1185/030079907x226276] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVE To examine in vitro resistance to azithromycin and moxifloxacin in bacterial conjunctivitis isolates. METHODS MIC90s (Minimum Inhibitory Concentration) and resistance rates to azithromycin and moxifloxacin were determined based upon microtiter broth dilution and/or antimicrobial gradient test strips in a multicenter phase III study and confirmed externally. RESULTS The most common isolates collected from bacterial conjunctivitis patients in the phase III study were Haemophilus influenzae (40.6%), followed by Staphylococcus epidermidis (19.3%), Propionibacterium acnes (17.3%), Streptococcus pneumoniae (16.8%), and Staphylococcus aureus (0.06%). MIC90s for all of these organisms were well below established resistance breakpoints for moxifloxacin, indicating no bacterial resistance. On the other hand, the MIC90 for H. influenzae was 3-fold higher than the resistance breakpoint for azithromycin, > or = 128-fold higher for S. epidermidis, 16-fold higher for S. pneumoniae and > or = 128-fold higher for S. aureus, indicating moderate to very high bacterial resistance to azithromycin. CONCLUSIONS Resistance to azithromycin is more common than resistance to moxifloxacin in clinical isolates causing bacterial conjunctivitis.
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Morgan-Linnell SK, Zechiedrich L. Contributions of the combined effects of topoisomerase mutations toward fluoroquinolone resistance in Escherichia coli. Antimicrob Agents Chemother 2007; 51:4205-8. [PMID: 17682104 PMCID: PMC2151436 DOI: 10.1128/aac.00647-07] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In defined, isogenic strains, at least three mutations, two of which must be in gyrA, were required to exceed the CLSI breakpoint for fluoroquinolone resistance. Strains with double mutations in both gyrA and parC had even higher MICs of fluoroquinolones than strains with totals of three mutations.
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Affiliation(s)
- Sonia K Morgan-Linnell
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, One Baylor Plaza, Mail-stop BCM-280, Houston, TX 77030-3411, USA
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Jones RN, Fritsche TR, Sader HS, Stilwell MG. Activity of garenoxacin, an investigational des-F(6)-quinolone, tested against pathogens from community-acquired respiratory tract infections, including those with elevated or resistant-level fluoroquinolone MIC values. Diagn Microbiol Infect Dis 2007; 58:9-17. [PMID: 17408903 DOI: 10.1016/j.diagmicrobio.2007.01.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2007] [Accepted: 01/27/2007] [Indexed: 10/23/2022]
Abstract
Garenoxacin, a novel des-F(6)-quinolone, was tested against 40423 pathogenic isolates associated with community-acquired respiratory tract infections (CA-RTIs). The strains included Streptococcus pneumoniae (18887), Haemophilus influenzae (15555), and Moraxella catarrhalis (5981), each isolated from a significant infection monitored by the SENTRY Antimicrobial Surveillance Program (1999-2005; North America, Latin America, and Europe). All tests were performed by reference broth microdilution methods for garenoxacin and 19 comparison agents. The garenoxacin MIC(90) and percentage (%) of strains inhibited at < or =1 microg/mL (proposed susceptible breakpoint) were S. pneumoniae (0.06 microg/mL, >99.9% susceptible), H. influenzae (< or =0.03 microg/mL, >99.9%), and M. catarrhalis (< or =0.03 microg/mL, 100.0%). The garenoxacin potency versus the pneumococci was 16- to 32-fold greater than levofloxacin or ciprofloxacin and 2-fold superior to moxifloxacin (MIC(90), 0.12 microg/mL). Resistances to other classes of antimicrobials did not adversely influence garenoxacin MIC results. Ciprofloxacin- or levofloxacin-resistant (MIC, > or =4 microg/mL) S. pneumoniae had higher garenoxacin MIC(90) values (1 microg/mL), but 90.6% to 97.5% of strains remained susceptible. Strains of all 3 monitored pathogens with mutations in the quinolone resistance determining region (QRDR) had higher garenoxacin MIC results, with > or =3 to 4 QRDR mutations required to elevate garenoxacin MIC values to > or =2 microg/mL. In conclusion, garenoxacin possesses a potent activity against pneumococci, H. influenzae, and M. catarrhalis strains worldwide, at a level significantly greater than the available tested agents in the fluoroquinolone class (ciprofloxacin, levofloxacin, and moxifloxacin). Only 13 and 4 isolates (0.07% and 0.03%) of S. pneumoniae and H. influenzae, respectively, had a garenoxacin MIC at > or =2 microg/mL, thus, making this new "respiratory antipneumococcal" quinolone an attractive candidate for the therapy of contemporary CA-RTI (bronchitis, pneumonia, and sinusitis).
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Jones RN, Sader HS, Stilwell MG, Fritsche TR. Garenoxacin activity against isolates form patients hospitalized with community-acquired pneumonia and multidrug-resistant Streptococcus pneumoniae. Diagn Microbiol Infect Dis 2007; 58:1-7. [PMID: 17408904 DOI: 10.1016/j.diagmicrobio.2007.01.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Accepted: 01/27/2007] [Indexed: 11/18/2022]
Abstract
Community-acquired pneumonia (CAP) continues to cause significant morbidity worldwide, and the principal bacterial pathogens (Streptococcus pneumoniae and Haemophilus influenzae) have acquired numerous resistance mechanisms over the last few decades. CAP treatment guidelines have suggested the use of broader spectrum agents, such as antipneumococcal fluoroquinolones as the therapy for at-risk patient population. In this report, we studied 3087 CAP isolates from the SENTRY Antimicrobial Surveillance Program (1999-2005) worldwide and all respiratory tract infection (RTI) isolate population of pneumococci (14665 strains) grouped by antibiogram patterns against a new des-F(6)-quinolone, garenoxacin. Results indicated that garenoxacin was highly active against CAP isolates of S. pneumoniae (MIC(90), 0.06 microg/mL) and H. influenzae (MIC(90), < or =0.03 microg/mL). This garenoxacin potency was 8- to 32-fold greater than gatifloxacin, levofloxacin, and ciprofloxacin against the pneumococci and >99.9% of strains were inhibited at < or =1 microg/mL (proposed susceptible breakpoint). Garenoxacin MIC values were not affected by resistances among S. pneumoniae strains to penicillin or erythromycin; however, coresistances were high among the beta-lactams (penicillins and cephalosporins), macrolides, tetracyclines, and trimethoprim/sulfamethoxazole. Analysis of S. pneumoniae isolates with various antimicrobial resistance patterns to 6 drug classes demonstrated that garenoxacin was active against >99.9% (MIC, < or =1 microg/mL) of strains, and the most resistant pneumococci (6-drug resistance, 1051 strains or 7.2% of all isolates) were completely susceptible (100.0% at < or =1 microg/mL) to garenoxacin (MIC(90), 0.06 microg/mL). These results illustrate the high activity of garenoxacin against contemporary CAP isolates and especially against multidrug-resistant (MDR) S. pneumoniae that have created therapeutic dilemmas for all RTI presentations. Garenoxacin appears to be a welcome addition to the CAP treatment options, particularly for the emerging MDR pneumococci strains.
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Drlica K, Zhao X. Mutant selection window hypothesis updated. Clin Infect Dis 2007; 44:681-8. [PMID: 17278059 DOI: 10.1086/511642] [Citation(s) in RCA: 257] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2006] [Accepted: 11/13/2006] [Indexed: 11/03/2022] Open
Abstract
The mutant selection window hypothesis postulates that, for each antimicrobial-pathogen combination, an antimicrobial concentration range exists in which selective amplification of single-step, drug-resistant mutants occurs. This hypothesis suggests an antimutant dosing strategy that is keyed to the upper boundary of the selection window: the mutant prevention concentration. Correlations are described between the mutant prevention concentration--a static parameter that is measured with agar plates--and fluctuating drug concentrations that restrict mutant amplification in vitro and in animals. When drug resistance is acquired stepwise, the mutant selection window increases, making the suppression of each successive mutant increasingly more difficult. For agents that kill drug-resistant mutants in a drug concentration-dependent manner, the use of the area under the 24-h time-drug concentration curve value divided by the value of the mutant prevention concentration is suggested as an index for designing antimutant dosing regimens. The need for such regimens is emphasized by a clinical example in which acquisition of drug resistance occurs concurrently with eradication of susceptible bacterial cells. These data support using the mutant selection window to optimize antimicrobial dosing regimens.
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Affiliation(s)
- Karl Drlica
- Public Health Research Institute, Newark, NJ 07103, USA.
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29
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Wetzstein HG. Comparative mutant prevention concentrations of pradofloxacin and other veterinary fluoroquinolones indicate differing potentials in preventing selection of resistance. Antimicrob Agents Chemother 2005; 49:4166-73. [PMID: 16189094 PMCID: PMC1251556 DOI: 10.1128/aac.49.10.4166-4173.2005] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2005] [Revised: 07/01/2005] [Accepted: 07/15/2005] [Indexed: 11/20/2022] Open
Abstract
Pradofloxacin (PRA) is an 8-cyano-fluoroquinolone (FQ) being developed to treat bacterial infections in dogs and cats. Its mutant prevention concentrations (MPC) were determined for Escherichia coli ATCC 8739 at 0.225 microg/ml, and for Staphylococcus aureus ATCC 6538 at 0.55 microg/ml. At drug concentrations equal to or above the MPC, growth (implying selective clonal expansion) of first-step FQ-resistant variants, naturally present in large bacterial populations, was inhibited. MPC(90) derived from 10 clinical isolates each of E. coli and Staphylococcus intermedius, the latter species being of greater clinical relevance than S. aureus in companion-animal medicine, amounted to 0.2 to 0.225 and 0.30 to 0.35 microg/ml, respectively. MPCs of other veterinary FQs were assessed to determine relative in vitro potencies. The MPCs of marbofloxacin, enrofloxacin, danofloxacin, sarafloxacin, orbifloxacin, and difloxacin were 1.2-, 1.4-, 2.3-, 2.4-, 5-, and 7-fold higher than the MPC of PRA for E. coli ATCC 8739, and 6-, 6-, 19-, 15-, 15-, and 31-fold higher than the MPC of PRA for S. aureus ATCC 6538, respectively. MPC curves revealed a pronounced heterogeneity in susceptibility within populations of > or =4 x 10(9) CFU employed, extending to 10-fold above the MICs. The duration of incubation and, for S. aureus, inoculum density profoundly affected the MPCs. With appropriate dosing, PRA may combine high therapeutic efficacy with a high potential for restricting the selection for FQ resistance under field conditions in the species analyzed.
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Affiliation(s)
- H-G Wetzstein
- Bayer HealthCare AG, Animal Health Division, Leverkusen, Germany.
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30
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Abstract
Quinolones are one of the largest classes of antimicrobial agents used worldwide. This review considers the quinolones that are available currently and used widely in Europe (norfoxacin, ciprofloxacin, ofloxacin, levofloxacin and moxifloxacin) within their historical perspective, while trying to position them in the context of recent and possible future advances based on an understanding of: (1) their chemical structures and how these impact on activity and toxicity; (2) resistance mechanisms (mutations in target genes, efflux pumps); (3) their pharmacodynamic properties (AUC/MIC and Cmax/MIC ratios; mutant prevention concentration and mutant selection window); and (4) epidemiological considerations (risk of emergence of resistance, clonal spread). Their main indications are examined in relation to their advantages and drawbacks. Overall, it is concluded that these important agents should be used in an educated fashion, based on a careful balance between their ease of use and efficacy vs. the risk of emerging resistance and toxicity. However, there is now substantial evidence to support use of the most potent drug at the appropriate dose whenever this is required.
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Affiliation(s)
- F Van Bambeke
- Unit of Cellular and Molecular Pharmacology, Catholic University of Louvain, Brussels.
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