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Gigante AM, Hadis MA, Secker B, Shaw SC, Cooper PR, Palin WM, Milward MR, Atterbury RJ. Exposure to blue light reduces antimicrobial resistant Pseudomonas aeruginosa isolated from dog ear infections. Front Microbiol 2024; 15:1414412. [PMID: 39027093 PMCID: PMC11255781 DOI: 10.3389/fmicb.2024.1414412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Accepted: 06/14/2024] [Indexed: 07/20/2024] Open
Abstract
Introduction Pseudomonas aeruginosa is a leading cause of canine otitis externa. Enrofloxacin is often applied topically to treat this condition, although recalcitrant and recurring infections are common. There is evidence that exposure to blue light (400-470 nm) has a bactericidal effect on P. aeruginosa and other microorganisms. Methods In the present study, we tested the biocidal effect of blue light (375-450 nm), alone or in combination with enrofloxacin, against six isolates of P. aeruginosa from dogs with otitis externa (5 of which were resistant to enrofloxacin). Results Treatment of planktonic cell cultures with blue light resulted in significant (p < 0.5) reductions in Colony Forming Units (CFU) for all seven strains tested, in some cases below the limit of detection. The greatest bactericidal effect was observed following exposure to light at 405 nm wavelength (p < 0.05). Exposure to blue light for 20 min usually resulted in a greater reduction in Pseudomonas aeruginosa than enrofloxacin treatment, and combination treatment typically resulted in the largest reductions in CFU. Analysis of the genome sequences of these strains established that enrofloxacin resistance was likely the result of a S466F substitution in GyrB. However, there was no clear association between genotype and susceptibility to blue light treatment. Discussion These results suggest that blue light treatment, particularly at 405 nm wavelength, and especially in combination with enrofloxacin therapy, could be an effective treatment for otherwise recalcitrant canine otitis externa caused by Pseudomonas aeruginosa. It may also provide a way of extending the usefulness of enrofloxacin therapy which would otherwise be ineffective as a sole therapeutic agent.
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Affiliation(s)
- Adriano M. Gigante
- School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
| | - Mohammad A. Hadis
- School of Dentistry, University of Birmingham, Birmingham, United Kingdom
| | - Bailey Secker
- School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
| | - Stephen C. Shaw
- School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
| | - Paul R. Cooper
- School of Dentistry, University of Birmingham, Birmingham, United Kingdom
- Department of Oral Sciences, Faculty of Dentistry, University of Otago, Dunedin, New Zealand
| | - William M. Palin
- School of Dentistry, University of Birmingham, Birmingham, United Kingdom
| | - Michael R. Milward
- School of Dentistry, University of Birmingham, Birmingham, United Kingdom
| | - Robert J. Atterbury
- School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
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2
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Molecular Evolution of the Pseudomonas aeruginosa DNA Gyrase gyrA Gene. Microorganisms 2022; 10:microorganisms10081660. [PMID: 36014079 PMCID: PMC9415716 DOI: 10.3390/microorganisms10081660] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 08/10/2022] [Accepted: 08/13/2022] [Indexed: 11/29/2022] Open
Abstract
DNA gyrase plays important roles in genome replication in various bacteria, including Pseudomonasaeruginosa. The gyrA gene encodes the gyrase subunit A protein (GyrA). Mutations in GyrA are associated with resistance to quinolone-based antibiotics. We performed a detailed molecular evolutionary analyses of the gyrA gene and associated resistance to the quinolone drug, ciprofloxacin, using bioinformatics techniques. We produced an evolutionary phylogenetic tree using the Bayesian Markov Chain Monte Carlo (MCMC) method. This tree indicated that a common ancestor of the gene was present over 760 years ago, and the offspring formed multiple clusters. Quinolone drug-resistance-associated amino-acid substitutions in GyrA, including T83I and D87N, emerged after the drug was used clinically. These substitutions appeared to be positive selection sites. The molecular affinity between ciprofloxacin and the GyrA protein containing T83I and/or D87N decreased significantly compared to that between the drug and GyrA protein, with no substitutions. The rate of evolution of the gene before quinolone drugs were first used in the clinic, in 1962, was significantly lower than that after the drug was used. These results suggest that the gyrA gene evolved to permit the bacterium to overcome quinolone treatment.
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3
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Pedro SN, Gomes ATPC, Oskoei P, Oliveira H, Almeida A, Freire MG, Silvestre AJD, Freire CSR. Boosting antibiotics performance by new formulations with deep eutectic solvents. Int J Pharm 2022; 616:121566. [PMID: 35151818 DOI: 10.1016/j.ijpharm.2022.121566] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 02/01/2022] [Accepted: 02/07/2022] [Indexed: 11/26/2022]
Abstract
The critical scenario of antimicrobial resistance to antibiotics highlights the need for improved therapeutics and/or formulations. Herein, we demonstrate that deep eutectic solvents (DES) formulations are very promising to remarkably improve the solubility, stability and therapeutic efficacy of antibiotics, such as ciprofloxacin. DES aqueous solutions enhance the solubility of ciprofloxacin up to 430-fold while extending the antibiotic stability. The developed formulations can improve, by 2 to 4-fold, the susceptibility of Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacteria to the antibiotic. They also improve the therapeutic efficacy at concentrations where bacteria present resistance, without promoting tolerance development to ciprofloxacin. Furthermore, the incorporation of DES decreases the toxicity of ciprofloxacin towards immortalized human epidermal keratinocytes (HaCat cells). The results herein reveal the pioneering use of DES in fluoroquinolone-based formulations and their impact on the antibiotic's characteristics and on its therapeutic action.
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Affiliation(s)
- Sónia N Pedro
- CICECO-Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Ana T P C Gomes
- CESAM, Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Párástu Oskoei
- CESAM, Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Helena Oliveira
- CESAM, Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Adelaide Almeida
- CESAM, Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Mara G Freire
- CICECO-Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Armando J D Silvestre
- CICECO-Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Carmen S R Freire
- CICECO-Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
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4
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Jogula S, Krishna VS, Meda N, Balraju V, Sriram D. Design, synthesis and biological evaluation of novel Pseudomonas aeruginosa DNA gyrase B inhibitors. Bioorg Chem 2020; 100:103905. [PMID: 32388436 DOI: 10.1016/j.bioorg.2020.103905] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 04/29/2020] [Accepted: 04/30/2020] [Indexed: 12/22/2022]
Abstract
In the present study, we attempted to develop a novel class of compounds active against Pseudomonas aeruginosa (Pa) by exploring the pharmaceutically well exploited enzyme targets. Since, lack of Pa gyrase B crystal structures, Thermus thermophilus gyrase B in complex with novobiocin (1KIJ) was used as template to generate model structure by performing homology modeling. Further the best model was validated and used for high-throughput virtual screening, docking and dynamics simulations using the in-house database for identification of Pa DNA gyrase B inhibitors. This study led to an identification of three lead molecules with IC50 values in range of 6.25-15.6 µM against Pa gyrase supercoiling assay. Lead-1 optimization and expansion resulted in 15 compounds. Among the synthesized compounds six compounds were shown good enzyme inhibition than Lead-1 (IC50 6.25 µM). Compound 13 emerged as the most potential compound exhibiting inhibition of Pa gyrase supercoiling with an IC50 of 2.2 µM; and in-vitro Pa activity with MIC of 8 µg/mL in presence of efflux pump inhibitor; hence could be further developed as novel inhibitor for Pa gyrase B.
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Affiliation(s)
- Sridhar Jogula
- Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Jawahar Nagar, Hyderabad 500078, India
| | - Vagolu Siva Krishna
- Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Jawahar Nagar, Hyderabad 500078, India
| | - Nikhila Meda
- Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Jawahar Nagar, Hyderabad 500078, India
| | - Vadla Balraju
- Albany Molecular Research Hyderabad Research Centre Private Limited, MN Park, Genome valley, Hyderabad 500078, India
| | - Dharmarajan Sriram
- Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Jawahar Nagar, Hyderabad 500078, India.
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Hypermutator Pseudomonas aeruginosa Exploits Multiple Genetic Pathways To Develop Multidrug Resistance during Long-Term Infections in the Airways of Cystic Fibrosis Patients. Antimicrob Agents Chemother 2020; 64:AAC.02142-19. [PMID: 32071060 DOI: 10.1128/aac.02142-19] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 12/20/2019] [Indexed: 12/30/2022] Open
Abstract
Pseudomonas aeruginosa exploits intrinsic and acquired resistance mechanisms to resist almost every antibiotic used in chemotherapy. Antimicrobial resistance in P. aeruginosa isolates recovered from cystic fibrosis (CF) patients is further enhanced by the occurrence of hypermutator strains, a hallmark of chronic infections in CF patients. However, the within-patient genetic diversity of P. aeruginosa populations related to antibiotic resistance remains unexplored. Here, we show the evolution of the mutational resistome profile of a P. aeruginosa hypermutator lineage by performing longitudinal and transversal analyses of isolates collected from a CF patient throughout 20 years of chronic infection. Our results show the accumulation of thousands of mutations, with an overall evolutionary history characterized by purifying selection. However, mutations in antibiotic resistance genes appear to have been positively selected, driven by antibiotic treatment. Antibiotic resistance increased as infection progressed toward the establishment of a population constituted by genotypically diversified coexisting sublineages, all of which converged to multidrug resistance. These sublineages emerged by parallel evolution through distinct evolutionary pathways, which affected genes of the same functional categories. Interestingly, ampC and ftsI, encoding the β-lactamase and penicillin-binding protein 3, respectively, were found to be among the most frequently mutated genes. In fact, both genes were targeted by multiple independent mutational events, which led to a wide diversity of coexisting alleles underlying β-lactam resistance. Our findings indicate that hypermutators, apart from boosting antibiotic resistance evolution by simultaneously targeting several genes, favor the emergence of adaptive innovative alleles by clustering beneficial/compensatory mutations in the same gene, hence expanding P. aeruginosa strategies for persistence.
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6
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Aparicio T, de Lorenzo V, Martínez-García E. A Broad Host Range Plasmid-Based Roadmap for ssDNA-Based Recombineering in Gram-Negative Bacteria. Methods Mol Biol 2020; 2075:383-398. [PMID: 31584177 DOI: 10.1007/978-1-4939-9877-7_27] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Recombineering is the use of phage recombination proteins to improve and facilitate bacterial genome engineering. Depending on the nature of the DNA template, double-stranded or single-stranded, the system needs three proteins (Gam, Exo, and Beta) or just one (Beta) to work properly. The use of this technique has been fundamental not only toward solving fundamental biological questions with reverse genetics but also for the generation of deep-engineered E. coli chassis strains. Unfortunately, the use of ssDNA recombineering is still limited to a narrow number of bacterial species. One of the reasons for that is the lack of proper recombinases to be efficiently used in different microorganisms and the lack of proper genetic tools to deliver and express this activity in a controlled way. Here, we describe a protocol to follow a simple workflow to identify, clone, and quantify the function of the selected recombinases in the organism of choice by cloning and expressing them in standardized broad host range plasmids. As an example of the method, we tested the use of the Ssr recombinase in P. putida EM42 by introducing a complete deletion of the target gene pyrF. The example shows how two parameters of the mutagenic oligo, i.e., length and phosphorothioate protection, affect the final outcome of the procedure.
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Affiliation(s)
- Tomás Aparicio
- Systems and Synthetic Biology Program, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
| | - Víctor de Lorenzo
- Systems and Synthetic Biology Program, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain.
| | - Esteban Martínez-García
- Systems and Synthetic Biology Program, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
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7
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Aparicio T, Nyerges A, Nagy I, Pal C, Martínez‐García E, Lorenzo V. Mismatch repair hierarchy of
Pseudomonas putida
revealed by mutagenic ssDNA recombineering of the
pyrF
gene. Environ Microbiol 2019; 22:45-58. [DOI: 10.1111/1462-2920.14814] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 09/29/2019] [Accepted: 09/30/2019] [Indexed: 11/25/2022]
Affiliation(s)
- Tomas Aparicio
- Systems and Synthetic Biology ProgramCentro Nacional de Biotecnología (CNB‐CSIC), Campus de Cantoblanco Madrid 28049 Spain
| | - Akos Nyerges
- Synthetic and Systems Biology UnitInstitute of Biochemistry
| | - István Nagy
- Sequencing Platform, Biological Research CentreHungarian Academy of Sciences H‐6726 Szeged
- Sequencing LaboratorySeqOmics Biotechnology Ltd. 6782 Mórahalom Hungary
| | - Csaba Pal
- Synthetic and Systems Biology UnitInstitute of Biochemistry
| | - Esteban Martínez‐García
- Systems and Synthetic Biology ProgramCentro Nacional de Biotecnología (CNB‐CSIC), Campus de Cantoblanco Madrid 28049 Spain
| | - Víctor Lorenzo
- Systems and Synthetic Biology ProgramCentro Nacional de Biotecnología (CNB‐CSIC), Campus de Cantoblanco Madrid 28049 Spain
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8
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The Role of DNA Gyrase (gyrA) in Ciprofloxacin-Resistant Locally Isolates Pseudomonas aeruginosa in Al-Khadhmiya Teaching Hospital Baghdad, Iraq. JOURNAL OF PURE AND APPLIED MICROBIOLOGY 2019. [DOI: 10.22207/jpam.13.1.56] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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9
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Conjugation of LasR Quorum-Sensing Inhibitors with Ciprofloxacin Decreases the Antibiotic Tolerance of P. aeruginosaClinical Strains. J CHEM-NY 2019. [DOI: 10.1155/2019/8143739] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Pseudomonas aeruginosais a Gram-negative bacterium that commonly infects subjects with weakened immune system causing deadly infections above all at pulmonary level. During infection,P. aeruginosaproduces a well-organized bacterial structure, called biofilm, activating the quorum-sensing (QS) signaling, a mechanism of gene regulation. In this work, we synthesized already known QS inhibitors (QSi) designed on the scaffold of the N-(3-oxododecanoyl) homoserine lactone (3O-C12-HSL) QS molecule and conjugated them with ciprofloxacin to inhibitP. aeruginosabiofilm formation and increase the antibiotic susceptibility of clinical strains. We identified, for the first time, a QSi conjugated with ciprofloxacin (ET37), that is able to reduce the formation of biofilm and the onset of tolerant clones inP. aeruginosaclinical strains. This compound could have a wide application in clinical setting. The possibility to affect biofilm formation in chronically infected patients, such as patients affected by cystic fibrosis, and to reduce the onset of ciprofloxacin resistance would improve patient healing and allow to decrease antibiotic drug dosage.
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10
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Mao G, Song Y, Bartlam M, Wang Y. Long-Term Effects of Residual Chlorine on Pseudomonas aeruginosa in Simulated Drinking Water Fed With Low AOC Medium. Front Microbiol 2018; 9:879. [PMID: 29774019 PMCID: PMC5943633 DOI: 10.3389/fmicb.2018.00879] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 04/16/2018] [Indexed: 11/17/2022] Open
Abstract
Residual chlorine is often required to remain present in public drinking water supplies during distribution to ensure water quality. It is essential to understand how bacteria respond to long-term chlorine exposure, especially with the presence of assimilable organic carbon (AOC). This study aimed to investigate the effects of chlorination on Pseudomonas aeruginosa in low AOC medium by both conventional plating and culture-independent methods including flow cytometry (FCM) and quantitative PCR (qPCR). In a simulated chlorinated system using a bioreactor, membrane damage and DNA damage were measured by FCM fluorescence fingerprint. The results indicated membrane permeability occurred prior to DNA damage in response to chlorination. A regrowth of P. aeruginosa was observed when the free chlorine concentration was below 0.3 mg/L. The bacterial response to long-term exposure to a constant low level of free chlorine (0.3 mg/L) was subsequently studied in detail. Both FCM and qPCR data showed a substantial reduction during initial exposure (0–16 h), followed by a plateau where the cell concentration remained stable (16–76 h), until finally all bacteria were inactivated with subsequent continuous chlorine exposure (76–124 h). The results showed three-stage inactivation kinetics for P. aeruginosa at a low chlorine level with extended exposure time: an initial fast inactivation stage, a relatively stable middle stage, and a final stage with a slower rate than the initial stage. A series of antibiotic resistance tests suggested long-term exposure to low chlorine level led to the selection of antibiotic-resistant P. aeruginosa. The combined results suggest that depletion of residual chlorine in low AOC medium systems could reactivate P. aeruginosa, leading to a possible threat to drinking water safety.
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Affiliation(s)
- Guannan Mao
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin, China
| | - Yuhao Song
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin, China
| | - Mark Bartlam
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, China.,College of Life Sciences, Nankai University, Tianjin, China
| | - Yingying Wang
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin, China
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Ahmed S, Ning J, Cheng G, Ahmad I, Li J, Mingyue L, Qu W, Iqbal M, Shabbir MAB, Yuan Z. Receptor-based screening assays for the detection of antibiotics residues - A review. Talanta 2017; 166:176-186. [PMID: 28213220 DOI: 10.1016/j.talanta.2017.01.057] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 01/14/2017] [Accepted: 01/20/2017] [Indexed: 12/24/2022]
Abstract
Consumer and regulatory agencies have a high concern to antibiotic residues in food producing animals, so appropriate screening assays of fast, sensitive, low cost, and easy sample preparation for the identification of these residues are essential for the food-safety insurance. Great efforts in the development of a high-throughput antibiotic screening assay have been made in recent years. Concerning the screening of antibiotic residue, this review elaborate an overview on the availability, advancement and applicability of antibiotic receptor based screening assays for the safety assessment of antibiotics usage (i.e. radio receptor assay, enzyme labeling assays, colloidal gold receptor assay, enzyme colorimetry assay and biosensor assay). This manuscript also tries to shed a light on the selection, preparation and future perspective of receptor protein for antibiotic residue detection. These assays have been introduced for the screening of numerous food samples. Receptor based screening technology for antibiotic detection has high accuracy. It has been concluded that at the same time, it can detect a class of drugs for certain receptor, and realize the multi-residue detection. These assays offer fast, easy and precise detection of antibiotics.
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Affiliation(s)
- Saeed Ahmed
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MOA Key Laboratory for the Detection of Veterinary Drug Residues in Foods, Huazhong Agricultural University, Wuhan 430070, China
| | - Jianan Ning
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MOA Key Laboratory for the Detection of Veterinary Drug Residues in Foods, Huazhong Agricultural University, Wuhan 430070, China
| | - Guyue Cheng
- MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Huazhong Agricultural University, Wuhan 430070, China
| | - Ijaz Ahmad
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MOA Key Laboratory for the Detection of Veterinary Drug Residues in Foods, Huazhong Agricultural University, Wuhan 430070, China; The University of Agriculture Peshawar, Pakistan
| | - Jun Li
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MOA Key Laboratory for the Detection of Veterinary Drug Residues in Foods, Huazhong Agricultural University, Wuhan 430070, China
| | - Liu Mingyue
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MOA Key Laboratory for the Detection of Veterinary Drug Residues in Foods, Huazhong Agricultural University, Wuhan 430070, China
| | - Wei Qu
- MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Huazhong Agricultural University, Wuhan 430070, China
| | - Mujahid Iqbal
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MOA Key Laboratory for the Detection of Veterinary Drug Residues in Foods, Huazhong Agricultural University, Wuhan 430070, China
| | - M A B Shabbir
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MOA Key Laboratory for the Detection of Veterinary Drug Residues in Foods, Huazhong Agricultural University, Wuhan 430070, China
| | - Zonghui Yuan
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MOA Key Laboratory for the Detection of Veterinary Drug Residues in Foods, Huazhong Agricultural University, Wuhan 430070, China; MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Huazhong Agricultural University, Wuhan 430070, China.
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Abstract
The genus Burkholderia comprises metabolically diverse and adaptable Gram-negative bacteria, which thrive in often adversarial environments. A few members of the genus are prominent opportunistic pathogens. These include Burkholderia mallei and Burkholderia pseudomallei of the B. pseudomallei complex, which cause glanders and melioidosis, respectively. Burkholderia cenocepacia, Burkholderia multivorans, and Burkholderia vietnamiensis belong to the Burkholderia cepacia complex and affect mostly cystic fibrosis patients. Infections caused by these bacteria are difficult to treat because of significant antibiotic resistance. The first line of defense against antimicrobials in Burkholderia species is the outer membrane penetration barrier. Most Burkholderia contain a modified lipopolysaccharide that causes intrinsic polymyxin resistance. Contributing to reduced drug penetration are restrictive porin proteins. Efflux pumps of the resistance nodulation cell division family are major players in Burkholderia multidrug resistance. Third and fourth generation β-lactam antibiotics are seminal for treatment of Burkholderia infections, but therapeutic efficacy is compromised by expression of several β-lactamases and ceftazidime target mutations. Altered DNA gyrase and dihydrofolate reductase targets cause fluoroquinolone and trimethoprim resistance, respectively. Although antibiotic resistance hampers therapy of Burkholderia infections, the characterization of resistance mechanisms lags behind other non-enteric Gram-negative pathogens, especially ESKAPE bacteria such as Acinetobacter baumannii, Klebsiella pneumoniae and Pseudomonas aeruginosa.
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Affiliation(s)
- Katherine A Rhodes
- Department of Molecular Genetics and Microbiology, College of Medicine, Emerging Pathogens Institute and Institute for Therapeutic Innovation, University of Florida, Gainesville, FL, USA; Department of Microbiology Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, USA
| | - Herbert P Schweizer
- Department of Molecular Genetics and Microbiology, College of Medicine, Emerging Pathogens Institute and Institute for Therapeutic Innovation, University of Florida, Gainesville, FL, USA.
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Nouri R, Ahangarzadeh Rezaee M, Hasani A, Aghazadeh M, Asgharzadeh M. The role of gyrA and parC mutations in fluoroquinolones-resistant Pseudomonas aeruginosa isolates from Iran. Braz J Microbiol 2016; 47:925-930. [PMID: 27522930 PMCID: PMC5052375 DOI: 10.1016/j.bjm.2016.07.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 03/25/2016] [Indexed: 11/27/2022] Open
Abstract
The aim of this study was to examine mutations in the quinolone-resistance-determining region (QRDR) of gyrA and parC genes in Pseudomonas aeruginosa isolates. A total of 100 clinical P. aeruginosa isolates were collected from different university-affiliated hospitals in Tabriz, Iran. Minimum inhibitory concentrations (MICs) of ciprofloxacin and levofloxacin were evaluated by agar dilution assay. DNA sequences of the QRDR of gyrA and parC were determined by the dideoxy chain termination method. Of the total 100 isolates, 64 were resistant to ciprofloxacin. No amino acid alterations were detected in gyrA or parC genes of the ciprofloxacin susceptible or ciprofloxacin intermediate isolates. Thr-83 → Ile substitution in gyrA was found in all 64 ciprofloxacin resistant isolates. Forty-four (68.75%) of them had additional substitution in parC. A correlation was found between the number of the amino acid alterations in the QRDR of gyrA and parC and the level of ciprofloxacin and levofloxacin resistance of the P. aeruginosa isolates. Ala-88 → Pro alteration in parC was generally found in high level ciprofloxacin resistant isolates, which were suggested to be responsible for fluoroquinolone resistance. These findings showed that in P. aeruginosa, gyrA was the primary target for fluoroquinolone and additional mutation in parC led to highly resistant isolates.
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Affiliation(s)
- Roghayeh Nouri
- Tabriz University of Medical Sciences, Infectious and Tropical Diseases Research Center, Tabriz, Iran; Tabriz University of Medical Sciences, Faculty of Medicine, Department of Microbiology, Tabriz, Iran; Tabriz University of Medical Sciences, Student Research Committee, Tabriz, Iran
| | - Mohammad Ahangarzadeh Rezaee
- Tabriz University of Medical Sciences, Infectious and Tropical Diseases Research Center, Tabriz, Iran; Tabriz University of Medical Sciences, Faculty of Medicine, Department of Microbiology, Tabriz, Iran.
| | - Alka Hasani
- Tabriz University of Medical Sciences, Infectious and Tropical Diseases Research Center, Tabriz, Iran; Tabriz University of Medical Sciences, Faculty of Medicine, Department of Microbiology, Tabriz, Iran
| | - Mohammad Aghazadeh
- Tabriz University of Medical Sciences, Faculty of Medicine, Department of Microbiology, Tabriz, Iran
| | - Mohammad Asgharzadeh
- Tabriz University of Medical Sciences, Biotechnology Research Center, Tabriz, Iran
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Su HC, Khatun J, Kanavy DM, Giddings MC. Comparative genome analysis of ciprofloxacin-resistant Pseudomonas aeruginosa reveals genes within newly identified high variability regions associated with drug resistance development. Microb Drug Resist 2013; 19:428-36. [PMID: 23808957 DOI: 10.1089/mdr.2012.0258] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The alarming rise of ciprofloxacin-resistant Pseudomonas aeruginosa has been reported in several clinical studies. Though the mutation of resistance genes and their role in drug resistance has been researched, the process by which the bacterium acquires high-level resistance is still not well understood. How does the genomic evolution of P. aeruginosa affect resistance development? Could the exposure of antibiotics to the bacteria enrich genomic variants that lead to the development of resistance, and if so, how are these variants distributed through the genome? To answer these questions, we performed 454 pyrosequencing and a whole genome analysis both before and after exposure to ciprofloxacin. The comparative sequence data revealed 93 unique resistance strain variation sites, which included a mutation in the DNA gyrase subunit A gene. We generated variation-distribution maps comparing the wild and resistant types, and isolated 19 candidates from three discrete resistance-associated high variability regions that had available transposon mutants, to perform a ciprofloxacin exposure assay. Of these region candidates with transposon disruptions, 79% (15/19) showed a reduction in the ability to gain high-level resistance, suggesting that genes within these high variability regions might enrich for certain functions associated with resistance development.
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Affiliation(s)
- Hsun-Cheng Su
- 1 Department of Biochemistry & Biophysics, UNC School of Medicine , Chapel Hill, North Carolina
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15
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Abstract
Laboratory evolution experiments have led to important findings relating organism adaptation and genomic evolution. However, continuous monitoring of long-term evolution has been lacking for natural systems, limiting our understanding of these processes in situ. Here we characterize the evolutionary dynamics of a lineage of a clinically important opportunistic bacterial pathogen, Pseudomonas aeruginosa, as it adapts to the airways of several individual cystic fibrosis patients over 200,000 bacterial generations, and provide estimates of mutation rates of bacteria in a natural environment. In contrast to predictions based on in vitro evolution experiments, we document limited diversification of the evolving lineage despite a highly structured and complex host environment. Notably, the lineage went through an initial period of rapid adaptation caused by a small number of mutations with pleiotropic effects, followed by a period of genetic drift with limited phenotypic change and a genomic signature of negative selection, suggesting that the evolving lineage has reached a major adaptive peak in the fitness landscape. This contrasts with previous findings of continued positive selection from long-term in vitro evolution experiments. The evolved phenotype of the infecting bacteria further suggests that the opportunistic pathogen has transitioned to become a primary pathogen for cystic fibrosis patients.
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Abstract
Chronic infections in the respiratory tracts of cystic fibrosis (CF) patients are important to investigate, both from medical and from fundamental ecological points of view. Cystic fibrosis respiratory tracts can be described as natural environments harbouring persisting microbial communities with Pseudomonas aeruginosa as a dominant pathogen. Various factors contribute to the complexity of this ecosystem, including community composition, dynamics and interactions, as well as heterogeneous distribution and fluctuation of components of the immune system, antibiotics and nutrients. All these elements constitute the selective forces that drive the evolution of the microbes after they migrate from the outer environment to human airways. Pseudomonas aeruginosa adapts to the new environment through genetic changes and exhibits a special lifestyle in chronic CF airways. Understanding the persistent colonization of microbial pathogens in CF patients in the context of ecology and evolution will expand our knowledge of the pathogenesis of chronic infections and improve therapeutic strategies.
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Affiliation(s)
- Lei Yang
- Department of Systems Biology, DTU, 2800 Lyngby, Denmark
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17
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Wong A, Kassen R. Parallel evolution and local differentiation in quinolone resistance in Pseudomonas aeruginosa. MICROBIOLOGY-SGM 2011; 157:937-944. [PMID: 21292748 DOI: 10.1099/mic.0.046870-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The emergence and spread of antibiotic resistance in pathogens is a major impediment to the control of microbial disease. Here, we review mechanisms of quinolone resistance in Pseudomonas aeruginosa, an important nosocomial pathogen and a major cause of morbidity in cystic fibrosis (CF) patients. In this quantitative literature review, we find that mutations in DNA gyrase A, the primary target of quinolones in Gram-negative bacteria, are the most common resistance mutations identified in clinical samples of all origins, in keeping with previous observations. However, the identities of non-gyrase resistance mutations vary systematically between samples isolated from CF patients and those isolated from acute infections. CF-derived strains tend to harbour mutations in the efflux pump regulator nfxB, while non-CF strains tend to bear mutations in the efflux regulator mexR or in parC, which encodes one of two subunits of DNA topoisomerase IV. We suggest that differences in resistance mechanisms between CF and non-CF strains result either from local adaptation to different sites of infection or from differences in mutational processes between different environments. We further discuss the therapeutic implications of local differentiation in resistance mechanisms to a common antibiotic.
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Affiliation(s)
- Alex Wong
- Center for Advanced Research in Environmental Genomics, Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Rees Kassen
- Center for Advanced Research in Environmental Genomics, Department of Biology, University of Ottawa, Ottawa, ON, Canada
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18
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Su HC, Ramkissoon K, Doolittle J, Clark M, Khatun J, Secrest A, Wolfgang MC, Giddings MC. The development of ciprofloxacin resistance in Pseudomonas aeruginosa involves multiple response stages and multiple proteins. Antimicrob Agents Chemother 2010; 54:4626-35. [PMID: 20696867 PMCID: PMC2976116 DOI: 10.1128/aac.00762-10] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 07/14/2010] [Accepted: 07/30/2010] [Indexed: 01/17/2023] Open
Abstract
Microbes have developed resistance to nearly every antibiotic, yet the steps leading to drug resistance remain unclear. Here we report a multistage process by which Pseudomonas aeruginosa acquires drug resistance following exposure to ciprofloxacin at levels ranging from 0.5× to 8× the initial MIC. In stage I, susceptible cells are killed en masse by the exposure. In stage II, a small, slow to nongrowing population survives antibiotic exposure that does not exhibit significantly increased resistance according to the MIC measure. In stage III, exhibited at 0.5× to 4× the MIC, a growing population emerges to reconstitute the population, and these cells display heritable increases in drug resistance of up to 50 times the original level. We studied the stage III cells by proteomic methods to uncover differences in the regulatory pathways that are involved in this phenotype, revealing upregulation of phosphorylation on two proteins, succinate-semialdehyde dehydrogenase (SSADH) and methylmalonate-semialdehyde dehydrogenase (MMSADH), and also revealing upregulation of a highly conserved protein of unknown function. Transposon disruption in the encoding genes for each of these targets substantially dampened the ability of cells to develop the stage III phenotype. Considering these results in combination with computational models of resistance and genomic sequencing results, we postulate that stage III heritable resistance develops from a combination of both genomic mutations and modulation of one or more preexisting cellular pathways.
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Affiliation(s)
- Hsun-Cheng Su
- Department of Microbiology and Immunology, Curriculum in Bioinformatics and Computational Biology, Cystic Fibrosis/Pulmonary Research and Treatment Center, Department of Biomedical Engineering, Department of Computer Science, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Kevin Ramkissoon
- Department of Microbiology and Immunology, Curriculum in Bioinformatics and Computational Biology, Cystic Fibrosis/Pulmonary Research and Treatment Center, Department of Biomedical Engineering, Department of Computer Science, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Janet Doolittle
- Department of Microbiology and Immunology, Curriculum in Bioinformatics and Computational Biology, Cystic Fibrosis/Pulmonary Research and Treatment Center, Department of Biomedical Engineering, Department of Computer Science, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Martha Clark
- Department of Microbiology and Immunology, Curriculum in Bioinformatics and Computational Biology, Cystic Fibrosis/Pulmonary Research and Treatment Center, Department of Biomedical Engineering, Department of Computer Science, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Jainab Khatun
- Department of Microbiology and Immunology, Curriculum in Bioinformatics and Computational Biology, Cystic Fibrosis/Pulmonary Research and Treatment Center, Department of Biomedical Engineering, Department of Computer Science, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Ashley Secrest
- Department of Microbiology and Immunology, Curriculum in Bioinformatics and Computational Biology, Cystic Fibrosis/Pulmonary Research and Treatment Center, Department of Biomedical Engineering, Department of Computer Science, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Matthew C. Wolfgang
- Department of Microbiology and Immunology, Curriculum in Bioinformatics and Computational Biology, Cystic Fibrosis/Pulmonary Research and Treatment Center, Department of Biomedical Engineering, Department of Computer Science, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Morgan C. Giddings
- Department of Microbiology and Immunology, Curriculum in Bioinformatics and Computational Biology, Cystic Fibrosis/Pulmonary Research and Treatment Center, Department of Biomedical Engineering, Department of Computer Science, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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Lee YJ, Kim KS, Kim JH, Tak RB. Salmonella gallinarum gyrA mutations associated with fluoroquinolone resistance. Avian Pathol 2010; 33:251-7. [PMID: 15276996 DOI: 10.1080/0301945042000195759] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Salmonella enterica subsp. enterica serovar Gallinarum (S. gallinarum) is the causative organism of fowl typhoid, and an outbreak of fowl typhoid in Korea was confirmed in 1992. The aim of this study was to investigate possible changes in fluoroquinolone susceptibility among S. gallinarum isolates from 1995 to 2001, and to analyse mutations of the gyrA gene in fluoroquinolone-resistant isolates. Among 258 S. gallinarum isolates tested by the disk diffusion method, isolates from 1995 (n=18) were susceptible to all fluoroquinolones tested, whereas a number of isolates from 2001 (n=46) showed reduced susceptibility to enrofloxacin (6.5%), ciprofloxacin (10.9%), norfloxacin (52.5%) and ofloxacin (82.6%). The minimum inhibitory concentration range of enrofloxacin, ciprofloxacin, norfloxacin, ofloxacin and danofloxacin increased from < or =0.06 approximately 0.25 microg/ml in 1995 to 2 approximately 8 microg/ml in 2001. When amino acid changes in the gyrA were analysed by DNA sequencing, 22.5% and 14.7% among 258 isolates had a mutation at the Ser-83 and Asp-87 codons, respectively, and the prevalence of these mutants increased from 5.6% in 1995 to 89.1% in 2001. These mutants contained a change from Ser to Phe or Tyr at codon 83, or a change from Asp to Gly, Tyr or Asn at codon 87, and showed a range of minimum inhibitory concentrations of enrofloxacin from 0.5 to 8 microg/ml, ciprofloxacin from 0.25 to 4 microg/ml, norfloxacin from 2 to 32 microg/ml, ofloxacin from 0.5 to 4 microg/ml, and danofloxacin from 0.5 to 4 microg/ml. These results suggested an important association between the gyrA mutations and fluoroquinolone resistance of S. gallinarum.
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Affiliation(s)
- Young J Lee
- Department of Veterinary Medicine Kyungpook National University 702-701 Daegu.
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20
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Mutation ofgyrA andparC in clinical isolates ofAcinetobacter baumannii and its relationship with antimicrobial drugs resistance in Taiwan. ANN MICROBIOL 2009. [DOI: 10.1007/bf03178341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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21
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Lin XM, Li H, Wang C, Peng XX. Proteomic Analysis of Nalidixic Acid Resistance in Escherichia coli: Identification and Functional Characterization of OM Proteins. J Proteome Res 2008; 7:2399-405. [DOI: 10.1021/pr800073c] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xiang-min Lin
- Center for Proteomics, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Hui Li
- Center for Proteomics, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Chao Wang
- Center for Proteomics, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Xuan-xian Peng
- Center for Proteomics, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
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22
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Wong-Beringer A, Wiener-Kronish J, Lynch S, Flanagan J. Comparison of type III secretion system virulence among fluoroquinolone-susceptible and -resistant clinical isolates of Pseudomonas aeruginosa. Clin Microbiol Infect 2008; 14:330-6. [DOI: 10.1111/j.1469-0691.2007.01939.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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23
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Bu P, Riske PS, Zaya NE, Carey R, Bouchard CS. A comparison of topical chlorhexidine, ciprofloxacin, and fortified tobramycin/cefazolin in rabbit models of Staphylococcus and Pseudomonas keratitis. J Ocul Pharmacol Ther 2007; 23:213-20. [PMID: 17593004 DOI: 10.1089/jop.2006.81] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
AIMS Chlorhexidine was evaluated as a potential topical therapy for experimental bacterial keratitis. METHODS Chlorhexidine (0.01%) was compared to ciprofloxacin (0.3%) and tobramycin (1.36%)/cefazolin (5%) both in vitro and in vivo for the treatment of Staphylococcus aureus and Pseudomonas aeruginosa infections. The minimum inhibitory concentration (MIC) was established for each organism for each antibiotic, using a standardized method. One thousand (1000) colony-forming units (CFU) of S. aureus or P. aeruginosa was intrastromally injected into rabbit cornea. A total of 92 corneas were infected and then treated topically with antibiotics. The control eyes were treated with artificial tears. The rabbits were later sacrificed, and the corneal buttons were harvested. RESULTS The MIC for chlorhexidine was <or=40 microg/mL for both organisms. In the rabbit model of S. aureus keratitis, following the treatments, the median number of CFU of recoverable bacteria for chlorhexidine (n = 10), ciprofloxacin (n = 12), tobramycin/cefazolin (n = 12), and controls (n = 10) was 1.1 x 10(3), 4.7 x 10(4), 1.9 x 10(5), and 6.7 x 10(4), respectively. For S. aureus, the only treatment that showed a statistically significant reduction in CFU was chlorhexidine. In the P. aeruginosa keratitis group, CFU were significantly reduced with all treatments, compared to the control. CONCLUSIONS Chlorhexidine short-term treatment was an effective topical therapy for bacterial keratitis in the rabbit model, when compared with ciprofloxacin and tobramycin/cefazolin, in particular for S. aureus.
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Affiliation(s)
- Ping Bu
- Department of Ophthalmology, Loyola University Medical Center, Maywood, IL 60153, USA
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24
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Sekiguchi JI, Asagi T, Miyoshi-Akiyama T, Kasai A, Mizuguchi Y, Araake M, Fujino T, Kikuchi H, Sasaki S, Watari H, Kojima T, Miki H, Kanemitsu K, Kunishima H, Kikuchi Y, Kaku M, Yoshikura H, Kuratsuji T, Kirikae T. Outbreaks of multidrug-resistant Pseudomonas aeruginosa in community hospitals in Japan. J Clin Microbiol 2006; 45:979-89. [PMID: 17122009 PMCID: PMC1829129 DOI: 10.1128/jcm.01772-06] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
We previously reported an outbreak in a neurosurgery ward of catheter-associated urinary tract infection with multidrug-resistant (MDR) Pseudomonas aeruginosa strain IMCJ2.S1, carrying the 6'-N-aminoglycoside acetyltransferase gene [aac(6')-Iae]. For further epidemiologic studies, 214 clinical isolates of MDR P. aeruginosa showing resistance to imipenem (MIC >or= 16 microg/ml), amikacin (MIC >or= 64 microg/ml), and ciprofloxacin (MIC >or= 4 microg/ml) were collected from 13 hospitals in the same prefecture in Japan. We also collected 70 clinical isolates of P. aeruginosa that were sensitive to one or more of these antibiotics and compared their characteristics with those of the MDR P. aeruginosa isolates. Of the 214 MDR P. aeruginosa isolates, 212 (99%) were serotype O11. We developed a loop-mediated isothermal amplification (LAMP) assay and a slide agglutination test for detection of the aac(6')-Iae gene and the AAC(6')-Iae protein, respectively. Of the 212 MDR P. aeruginosa isolates, 212 (100%) and 207 (98%) were positive in the LAMP assay and in the agglutination test, respectively. Mutations of gyrA and parC genes resulting in amino acid substitutions were detected in 213 of the 214 MDR P. aeruginosa isolates (99%). Of the 214 MDR P. aeruginosa isolates, 212 showed pulsed-field gel electrophoresis patterns with >or=70% similarity to that of IMCJ2.S1 and 83 showed a pattern identical to that of IMCJ2.S1, indicating that clonal expansion of MDR P. aeruginosa occurred in community hospitals in this area. The methods developed in this study to detect aac(6')-Iae were rapid and effective in diagnosing infections caused by various MDR P. aeruginosa clones.
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Affiliation(s)
- Jun-Ichiro Sekiguchi
- Department of Infectious Diseases, Research Institute, International Medical Center of Japan, 1-21-1 Toyama, Shinjuku, Tokyo 162-8655, Japan
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Llanes C, Neuwirth C, El Garch F, Hocquet D, Plésiat P. Genetic analysis of a multiresistant strain of Pseudomonas aeruginosa producing PER-1 beta-lactamase. Clin Microbiol Infect 2006; 12:270-8. [PMID: 16451415 DOI: 10.1111/j.1469-0691.2005.01333.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A multiresistant strain of Pseudomonas aeruginosa, PA2345, belonging to serotype O:1, was isolated at the Teaching Hospital of Besançon, France. Resistance to beta-lactams, including third-generation cephalosporins, depended upon a chromosomally-located composite transposon carrying the bla(PER-1) gene encoding extended-spectrum beta-lactamase PER-1. PA2345 was unrelated genotypically to two previous PER-1-producing isolates of P. aeruginosa. Sequence analysis of the transposon in PA2345 revealed the presence of two insertion sequences (ISPa23 and ISPa24) with very different predicted transposases (TnpA1, TnpA2), which were both bordered by closely related 16-bp inverted repeats. High resistance of PA2345 to aminoglycosides was caused, in part, by a chromosomal class-I integron containing gene cassettes aadB, encoding an ANT(2'') enzyme, and aadA11, encoding a new ANT(3'') enzyme with 281 amino-acids that conferred elevated resistance to streptomycin and spectinomycin. Stable overproduction of efflux system MexXY contributed to resistance to amikacin, while mutations in the quinolone resistance-determining regions of gyrA and parC accounted for the high resistance of PA2345 to fluoroquinolones. The study indicates that multidrug resistance in P. aeruginosa might arise from sequential acquisition of a variety of mechanisms provided by both horizontal gene transfers and mutations in chromosomal genes.
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Affiliation(s)
- C Llanes
- Laboratoire de Bactériologie, Faculté de Médecine-Pharmacie, Besançon, France
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26
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Hansen GT, Zhao X, Drlica K, Blondeau JM. Mutant prevention concentration for ciprofloxacin and levofloxacin with Pseudomonas aeruginosa. Int J Antimicrob Agents 2006; 27:120-4. [PMID: 16426820 DOI: 10.1016/j.ijantimicag.2005.10.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2005] [Accepted: 10/06/2005] [Indexed: 11/20/2022]
Abstract
The mutant prevention concentration (MPC) was determined by population analysis using six fluoroquinolone-susceptible isolates of Pseudomonas aeruginosa applied to fluoroquinolone-containing agar plates. The MPCs were 3 mg/L and 9.5 mg/L for ciprofloxacin and levofloxacin, respectively. At high concentrations of either compound, single-step gyrA resistance mutants were recovered. Using a modified method for estimating the MPC, 151 clinical isolates were surveyed. Modal MPCs were 2 mg/L and 8 mg/L, respectively, for ciprofloxacin and levofloxacin. Thus, ciprofloxacin is three to four times more active than levofloxacin against resistant mutant subpopulations. For individual isolates, the MPC correlated poorly with the minimum inhibitory concentration (r(2) = 0.41 and 0.39 for ciprofloxacin and levofloxacin, respectively).
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Affiliation(s)
- Glen T Hansen
- Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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27
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Niga T, Ito H, Oyamada Y, Yamagishi JI, Kadono M, Nishino T, Gotoh N, Inoue M. Cooperation between alteration of DNA gyrase genes and over-expression of MexB and MexX confers high-level fluoroquinolone resistance in Pseudomonas aeruginosa strains isolated from a patient who received a liver transplant followed by treatment with fluoroquinolones. Microbiol Immunol 2005; 49:443-6. [PMID: 15905606 DOI: 10.1111/j.1348-0421.2005.tb03748.x] [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] [Indexed: 11/27/2022]
Abstract
Clinical isolates of highly fluoroquinolone-resistant Pseudomonas aeruginosa had a mutation in either A or B subunit of DNA gyrase and over-expressed MexB and MexX, the efflux system proteins. Introduction of wild-type gyrase genes of Escherichia coli into the isolates made them as fluoroquinolonesusceptible as the moderately fluoroquinolone-resistant strains that only over-expressed efflux system proteins. These findings demonstrate that high fluoroquinolone-resistance in P. aeruginosa is attributed to cooperation between alteration in DNA gyrase genes and over-expression of efflux systems proteins.
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Affiliation(s)
- Toshiyuki Niga
- Pharmacology & Microbiology Research Laboratories, Dainippon Pharmaceutical Co., Ltd, Suita, Osaka, Japan
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28
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Sekiguchi JI, Asagi T, Miyoshi-Akiyama T, Fujino T, Kobayashi I, Morita K, Kikuchi Y, Kuratsuji T, Kirikae T. Multidrug-resistant Pseudomonas aeruginosa strain that caused an outbreak in a neurosurgery ward and its aac(6')-Iae gene cassette encoding a novel aminoglycoside acetyltransferase. Antimicrob Agents Chemother 2005; 49:3734-42. [PMID: 16127047 PMCID: PMC1195402 DOI: 10.1128/aac.49.9.3734-3742.2005] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We characterized multidrug-resistant Pseudomonas aeruginosa strains isolated from patients involved in an outbreak of catheter-associated urinary tract infections that occurred in a neurosurgery ward of a hospital in Sendai, Japan. Pulsed-field gel electrophoresis of SpeI-, XbaI-, or HpaI-digested genomic DNAs from the isolates revealed that clonal expansion of a P. aeruginosa strain designated IMCJ2.S1 had occurred in the ward. This strain possessed broad-spectrum resistance to aminoglycosides, beta-lactams, fluoroquinolones, tetracyclines, sulfonamides, and chlorhexidine. Strain IMCJ2.S1 showed a level of resistance to some kinds of disinfectants similar to that of a control strain of P. aeruginosa, ATCC 27853. IMCJ2.S1 contained a novel class 1 integron, In113, in the chromosome but not on a plasmid. In113 contains an array of three gene cassettes of bla(IMP-1), a novel aminoglycoside resistance gene, and the aadA1 gene. The aminoglycoside resistance gene, designated aac(6')-Iae, encoded a 183-amino-acid protein that shared 57.1% identity with AAC(6')-Iq. Recombinant AAC(6')-Iae protein showed aminoglycoside 6'-N-acetyltransferase activity by thin-layer chromatography. Escherichia coli expressing exogenous aac(6')-Iae showed resistance to amikacin, dibekacin, isepamicin, kanamycin, netilmicin, sisomicin, and tobramycin but not to arbekacin, gentamicins, or streptomycin. Alterations of gyrA and parC at the amino acid sequence level were detected in IMCJ2.S1, suggesting that such mutations confer the resistance to fluoroquinolones observed for this strain. These results indicate that P. aeruginosa IMCJ2.S1 has developed multidrug resistance by acquiring resistance determinants, including a novel member of the aac(6')-I family and mutations in drug resistance genes.
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Affiliation(s)
- Jun-ichiro Sekiguchi
- Department of Infectious Diseases, Research Institute, International Medical Center of Japan, 1-21-1 Toyama, Shinjuku, Tokyo 162-8655, Japan
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Kim MJ, Hirono I, Aoki T. Detection of quinolone-resistance genes in Photobacterium damselae subsp. piscicida strains by targeting-induced local lesions in genomes. JOURNAL OF FISH DISEASES 2005; 28:463-71. [PMID: 16159364 DOI: 10.1111/j.1365-2761.2005.00652.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Quinolone-resistant strains of the fish-pathogenic bacterium, Photobacterium damselae subsp. piscicida are distributed widely in cultured yellowtail, Seriola quinqueradiata (Temminck & Schlegel), in Japan. The quinolone resistance-determining region (QRDR) was amplified with degenerate primers, followed by cassette ligation-mediated PCR. Open reading frames encoding proteins of 875 and 755 amino acid residues were detected in the gyrA and parC genes, respectively. Resistant strains of P. damselae subsp. piscicida carried a point mutation only in the gyrA QRDR leading to a Ser-to-Ile substitution at residue position 83. No amino acid alterations were discovered in the ParC sequence. A mutation in the gyrA gene was also detected in nalidixic acid-resistant mutants of strain SP96002 obtained from agar medium containing increased levels of quinolone. These results suggest that GyrA, as in other Gram-negative bacteria, is a target of quinolone in P. damselae subsp. piscicida. Furthermore, we attempted to detect a point mutation using targeting-induced local lesions in genomes (TILLING), which is a general strategy used for the detection of a variety of induced point mutations and naturally occurring polymorphisms. We developed a new detection method for the rapid and large-scale identification of quinolone-resistant strains of P. damselae subsp. piscicida using TILLING.
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Affiliation(s)
- M-J Kim
- Laboratory of Genome Science, Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, Tokyo, Japan
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30
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Horii T, Muramatsu H, Iinuma Y. Mechanisms of resistance to fluoroquinolones and carbapenems in Pseudomonas putida. J Antimicrob Chemother 2005; 56:643-7. [PMID: 16046469 DOI: 10.1093/jac/dki254] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Pseudomonas putida is an uncommon opportunistic pathogen, usually susceptible to antimicrobial agents. Data concerning resistance to antimicrobial agents in clinical P. putida isolates are limited. PATIENTS AND METHODS Susceptibilities to fluoroquinolones, carbapenems and other antibiotics were characterized in five clinical isolates of P. putida recovered from different patients with urinary tract infections as causative pathogens. Fluoroquinolone and carbapenem resistance were characterized genetically by the methods of PCR and DNA sequencing. Outer membrane protein (OMP) profiles were characterized by SDS-PAGE. RESULTS Four of five isolates were resistant or intermediate to both fluoroquinolones and carbapenems. Nucleotide sequences in the quinolone resistance-determining regions suggested that amino acid mutations such as Thr-83-->Ile in GyrA and Glu-469-->Asp in GyrB may contribute to high resistance to fluoroquinolones. Four metallo-beta-lactamase-producing isolates that showed resistance to carbapenems carried the IMP-type metallo-beta-lactamase genes. A combined effect of reduced production of 46 kDa OMP and metallo-beta-lactamase production was shown by a P. putida isolate exhibiting the highest MICs of carbapenems. CONCLUSIONS This study identified mechanisms of resistance to fluoroquinolones and carbapenems in clinical P. putida isolates.
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Affiliation(s)
- Toshinobu Horii
- Department of Laboratory Medicine, Hamamatsu University School of Medicine, 1-20-1 Handa-yama, Hamamatsu 431-3192, Japan.
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Lomholt JA, Kilian M. Ciprofloxacin susceptibility of Pseudomonas aeruginosa isolates from keratitis. Br J Ophthalmol 2003; 87:1238-40. [PMID: 14507757 PMCID: PMC1920786 DOI: 10.1136/bjo.87.10.1238] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIM To examine the ciprofloxacin susceptibility of 106 Pseudomonas aeruginosa eye isolates from the United Kingdom, Denmark, India, the United States, and Australia, and to determine the molecular mechanisms of resistance. METHODS Ciprofloxacin susceptibility was tested by an agar dilution method; genomic DNA corresponding to the quinolone target genes gyrA and parC, and the regulatory genes mexR and nfxB controlling drug efflux systems, was amplified by PCR and sequenced; multilocus enzyme electrophoresis was performed to examine the genetic relation among resistant strains. RESULTS Three out of 90 keratitis isolates (3.3%), one from the United Kingdom and two from India, exhibited MIC values of 16 mg/l or 32 mg/l. The UK isolate had a mutation in gyrA (Thr83Ile), whereas the two Indian isolates showed mutations in both gyrA (Thr83Ile) and parC (Ser87Leu). The remaining isolates from keratitis, endophthalmitis, contact lens associated red eye (CLARE), and contact lens storage cases showed MIC values below 1 mg/l. Several allelic forms of gyrA and a single variation in the mexR gene product were detected in 10 ciprofloxacin susceptible strains. CONCLUSIONS The vast majority of eye isolates of P aeruginosa from European countries are fully susceptible to ciprofloxacin and the concentration of ciprofloxacin eye drops used for local treatment (3000 mg/l) exceeds MIC values for strains recorded as resistant. Mutations in more than one target gene were associated with higher MIC values.
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Affiliation(s)
- J A Lomholt
- Department of Medical Microbiology and Immunology, University of Aarhus, Bartholin Building, Wilhelm Meyers allé, DK-8000 Aarhus C, Denmark.
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Jumbe N, Louie A, Leary R, Liu W, Deziel MR, Tam VH, Bachhawat R, Freeman C, Kahn JB, Bush K, Dudley MN, Miller MH, Drusano GL. Application of a mathematical model to prevent in vivo amplification of antibiotic-resistant bacterial populations during therapy. J Clin Invest 2003; 112:275-85. [PMID: 12865415 PMCID: PMC164285 DOI: 10.1172/jci16814] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The worldwide increase in the prevalence of multi-antibiotic-resistant bacteria has threatened the physician's ability to provide appropriate therapy for infections. The relationship between antimicrobial drug concentration and infecting pathogen population reduction is of primary interest. Using data derived from mice infected with the bacterium Pseudomonas aeruginosa and treated with a fluoroquinolone antibiotic, a mathematical model was developed that described relationships between antimicrobial drug exposures and changes in drug-susceptible and -resistant bacterial subpopulations at an infection site. Dosing regimens and consequent drug exposures that amplify or suppress the emergence of resistant bacterial subpopulations were identified and prospectively validated. Resistant clones selected in vivo by suboptimal regimens were characterized. No mutations were identified in the quinolone resistance-determining regions of gyrA/B or parC/E. However, all resistant clones demonstrated efflux pump overexpression. At base line, MexAB-OprM, MexCD-OprJ, and MexEF-OprN were represented in the drug-resistant population. After 28 hours of therapy, MexCD-OprJ became the predominant pump expressed in the resistant clones. The likelihood of achieving resistance-suppression exposure in humans with a clinically prescribed antibiotic dose was determined. The methods developed in this study provide insight regarding how mathematical models can be used to identify rational dosing regimens that suppress the amplification of the resistant mutant population.
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Affiliation(s)
- Nelson Jumbe
- Ordway Research Institute, Albany, New York 12208, USA
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Jumbe N, Louie A, Leary R, Liu W, Deziel MR, Tam VH, Bachhawat R, Freeman C, Kahn JB, Bush K, Dudley MN, Miller MH, Drusano GL. Application of a mathematical model to prevent in vivo amplification of antibiotic-resistant bacterial populations during therapy. J Clin Invest 2003. [DOI: 10.1172/jci200316814] [Citation(s) in RCA: 214] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Hocquet D, Bertrand X, Köhler T, Talon D, Plésiat P. Genetic and phenotypic variations of a resistant Pseudomonas aeruginosa epidemic clone. Antimicrob Agents Chemother 2003; 47:1887-94. [PMID: 12760863 PMCID: PMC155826 DOI: 10.1128/aac.47.6.1887-1894.2003] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
From May 1997 to December 2001, a serotype O:6 multidrug-resistant strain of Pseudomonas aeruginosa colonized or infected 201 patients in the University Hospital of Besançon (France). The susceptibility profile of this epidemic clone to fluoroquinolones and aminoglycosides was relatively stable during the outbreak but showed important isolate-to-isolate variations (up to 64-fold) in the MICs of beta-lactams. Analysis of 18 genotypically related isolates selected on a quarterly basis demonstrated alterations in the two DNA topoisomerases II and IV (Thr83-->Ile in GyrA and Ser87-->Leu in ParC) and production of an ANT(2")-I enzyme. Although constitutively overproduced in these bacteria, the MexXY efflux system did not appear to contribute significantly to aminoglycoside resistance. beta-Lactam resistance was associated with derepression of intrinsic AmpC beta-lactamase (with isolate-to-isolate variations of up to 58-fold) and sporadic deficiency in a 46-kDa protein identified as the carbapenem-selective porin OprD. Of the 18 isolates, 14 were also found to overproduce the efflux system MexAB-OprM as a result of alteration of the repressor protein MexR (His107-->Pro). However, complementation experiments with the cloned mexR gene demonstrated that MexAB-OprM contributed only marginally to beta-lactam and fluoroquinolone resistance. Of the four isolates exhibiting wild-type MexAB-OprM expression despite the MexR alteration, two appeared to harbor secondary mutations in the mexA-mexR intergenic region and one harbored secondary mutations in the putative ribosome binding site located upstream of the mexAB oprM operon. In conclusion, this study shows that many mechanisms were involved in the multiresistance phenotype of this highly epidemic strain of P. aeruginosa. Our results also demonstrate that the clone sporadically underwent substantial genetic and phenotypic variations during the course of the outbreak, perhaps in relation to local or individual selective drug pressures.
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Affiliation(s)
- Didier Hocquet
- Laboratoire de Bactériologie, Hôpital Jean Minjoz, Besançon, France
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35
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Weigel LM, Anderson GJ, Tenover FC. DNA gyrase and topoisomerase IV mutations associated with fluoroquinolone resistance in Proteus mirabilis. Antimicrob Agents Chemother 2002; 46:2582-7. [PMID: 12121936 PMCID: PMC127365 DOI: 10.1128/aac.46.8.2582-2587.2002] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mutations associated with fluoroquinolone resistance in clinical isolates of Proteus mirabilis were determined by genetic analysis of the quinolone resistance-determining region (QRDR) of gyrA, gyrB, parC, and parE. This study included the P. mirabilis type strain ATCC 29906 and 29 clinical isolates with reduced susceptibility (MIC, 0.5 to 2 microg/ml) or resistance (MIC, > or =4 microg/ml) to ciprofloxacin. Susceptibility profiles for ciprofloxacin, clinafloxacin, gatifloxacin, gemifloxacin, levofloxacin, moxifloxacin, and trovafloxacin were correlated with amino acid changes in the QRDRs. Decreased susceptibility and resistance were associated with double mutations involving both gyrA (S83R or -I) and parC (S80R or -I). Among these double mutants, MICs of ciprofloxacin varied from 1 to 16 microg/ml, indicating that additional factors, such as drug efflux or porin changes, also contribute to the level of resistance. For ParE, a single conservative change of V364I was detected in seven strains. An unexpected result was the association of gyrB mutations with high-level resistance to fluoroquinolones in 12 of 20 ciprofloxacin-resistant isolates. Changes in GyrB included S464Y (six isolates), S464F (three isolates), and E466D (two isolates). A three-nucleotide insertion, resulting in an additional lysine residue between K455 and A456, was detected in gyrB of one strain. Unlike any other bacterial species analyzed to date, mutation of gyrB appears to be a frequent event in the acquisition of fluoroquinolone resistance among clinical isolates of P. mirabilis.
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Affiliation(s)
- L M Weigel
- Division of Healthcare Quality Promotion, Anti-infectives Section (G-08), National Center for Infectious Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Atlanta, GA 30333, USA.
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Valdezate S, Vindel A, Echeita A, Baquero F, Cantó R. Topoisomerase II and IV quinolone resistance-determining regions in Stenotrophomonas maltophilia clinical isolates with different levels of quinolone susceptibility. Antimicrob Agents Chemother 2002; 46:665-71. [PMID: 11850246 PMCID: PMC127482 DOI: 10.1128/aac.46.3.665-671.2002] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The quinolone resistance-determining regions (QRDRs) of topoisomerase II and IV genes from Stenotrophomonas maltophilia ATCC 13637 were sequenced and compared with the corresponding regions of 32 unrelated S. maltophilia clinical strains for which ciprofloxacin MICs ranged from 0.1 to 64 microg/ml. GyrA (Leu-55 to Gln-155, Escherichia coli numbering), GyrB (Met-391 to Phe-513), ParC (Ile-34 to Arg-124), and ParE (Leu-396 to Leu-567) fragments from strain ATCC 13637 showed high degrees of identity to the corresponding regions from the phytopathogen Xylella fastidiosa, with the degrees of identity ranging from 85.0 to 93.5%. Lower degrees of identity to the corresponding regions from Pseudomonas aeruginosa (70.9 to 88.6%) and E. coli (73.0 to 88.6%) were observed. Amino acid changes were present in GyrA fragments from 9 of the 32 strains at positions 70, 85, 90, 103, 112, 113, 119, and 124; but there was no consistent relation to higher ciprofloxacin MICs. The absence of changes at positions 83 and 87, commonly involved in quinolone resistance in gram-negative bacteria, was unexpected. The GyrB sequences were identical in all strains, and only one strain (ciprofloxacin MIC, 16 microg/ml) showed a ParC amino acid change (Ser-80-->Arg). In contrast, a high frequency (16 of 32 strains) of amino acid replacements was present in ParE. The frequencies of alterations at positions 437, 465, 477, and 485 were higher (P < 0.05) in strains from cystic fibrosis patients, but these changes were not linked with high ciprofloxacin MICs. An efflux phenotype, screened by the detection of decreases of at least twofold doubling dilutions of the ciprofloxacin MIC in the presence of carbonyl cyanide m-chlorophenylhydrazone (0.5 microg/ml) or reserpine (10 microg/ml), was suspected in seven strains. These results suggest that topoisomerases II and IV may not be the primary targets involved in quinolone resistance in S. maltophilia.
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Affiliation(s)
- Sylvia Valdezate
- Servicio de Microbiología, Hospital Ramón y Cajal, Madrid-28034, Spain
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Akasaka T, Tanaka M, Yamaguchi A, Sato K. Type II topoisomerase mutations in fluoroquinolone-resistant clinical strains of Pseudomonas aeruginosa isolated in 1998 and 1999: role of target enzyme in mechanism of fluoroquinolone resistance. Antimicrob Agents Chemother 2001; 45:2263-8. [PMID: 11451683 PMCID: PMC90640 DOI: 10.1128/aac.45.8.2263-2268.2001] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The major mechanism of resistance to fluoroquinolones for Pseudomonas aeruginosa is the modification of type II topoisomerases (DNA gyrase and topoisomerase IV). We examined the mutations in quinolone-resistance-determining regions (QRDR) of gyrA, gyrB, parC, and parE genes of recent clinical isolates. There were 150 isolates with reduced susceptibilities to levofloxacin and 127 with reduced susceptibilities to ciprofloxacin among 513 isolates collected during 1998 and 1999 in Japan. Sequencing results predicted replacement of an amino acid in the QRDR of DNA gyrase (GyrA or GyrB) for 124 of the 150 strains (82.7%); among these, 89 isolates possessed mutations in parC or parE which lead to amino acid changes. Substitutions of both Ile for Thr-83 in GyrA and Leu for Ser-87 in ParC were the principal changes, being detected in 48 strains. These replacements were obviously associated with reduced susceptibilities to levofloxacin, ciprofloxacin, and sparfloxacin; however, sitafloxacin showed high activity against isolates with these replacements. We purified GyrA (The-83 to Ile) and ParC (Ser-87 to Leu) by site-directed mutagenesis and compared the inhibitory activities of the fluoroquinolones. Sitafloxacin showed the most potent inhibitory activities against both altered topoisomerases among the fluoroquinolones tested. These results indicated that, compared with other available quinolones, sitafloxacin maintained higher activity against recent clinical isolates with multiple mutations in gyrA and parC, which can be explained by the high inhibitory activities of sitafloxacin against both mutated enzymes.
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Affiliation(s)
- T Akasaka
- New Product Research Laboratories I, Daiichi Pharmaceutical Co., Ltd., Edogawa-ku, Tokyo 134-8630, Japan.
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38
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Miché L, Balandreau J. Effects of rice seed surface sterilization with hypochlorite on inoculated Burkholderia vietnamiensis. Appl Environ Microbiol 2001; 67:3046-52. [PMID: 11425720 PMCID: PMC92979 DOI: 10.1128/aem.67.7.3046-3052.2001] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2001] [Accepted: 04/23/2001] [Indexed: 11/20/2022] Open
Abstract
When a combination of hydrogen peroxide and hypochlorite was used to surface sterilize rice seeds, a 10(2)- to 10(4)-fold decrease in CFU was observed during the first 15 h after inoculation of the rice rhizosphere organism Burkholderia vietnamiensis TVV75. This artifact could not be eliminated simply by rinsing the seeds, even thoroughly, with sterile distilled water. When growth resumed, a significant increase in the frequency of rifampin- and nalidixic acid-resistant mutants in the population was observed compared to the control without seeds. This phenomenon was a specific effect of hypochlorite; it was not observed with hydrogen peroxide alone. It was also not observed when the effect of hypochlorite was counteracted by sodium thiosulfate. We hypothesized that the hypochlorite used for disinfection reacted with the rice seed surface, forming a chlorine cover which was not removed by rinsing and generated mutagenic chloramines. We studied a set of rifampin- and nalidixic acid-resistant mutants obtained after seed surface sterilization. The corresponding rpoB and gyrA genes were amplified and sequenced to characterize the induced mutations. The mutations in five of seven nalidixic acid-resistant mutants and all of the rifampin-resistant mutants studied were found to correspond to single amino acid substitutions. Hypochlorite surface sterilization can thus be a source of artifacts when the initial bacterial colonization of a plant is studied.
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Affiliation(s)
- L Miché
- Laboratoire d'Ecologie Microbienne, UMR 5557 CNRS-Université Claude Bernard Lyon 1, 69622 Villeurbanne cedex, France
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Nakano M, Yasuda M, Yokoi S, Takahashi Y, Ishihara S, Deguchi T. In vivo selection of Pseudomonas Aeruginosa with decreased susceptibilities to fluoroquinolones during fluoroquinolone treatment of urinary tract infection. Urology 2001; 58:125-8. [PMID: 11445503 DOI: 10.1016/s0090-4295(01)01110-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVES To present a case of fluoroquinolone treatment failure in urinary tract infection caused by Pseudomonas aeruginosa, accompanied by in vivo selection of the post-treatment isolate that showed decreased susceptibilities to fluoroquinolones, and to report fluoroquinolone resistance mechanisms in the post-treatment isolate. METHODS A patient with urinary tract infection was treated with a suboptimal dose of a fluorinated quinolone, gatifloxacin. P. aeruginosa strains were isolated before and after fluoroquinolone treatment. The pretreatment and post-treatment isolates were examined for relatedness by arbitrarily primed polymerase chain reaction. For these isolates, the minimum inhibitory concentration of antimicrobial agents was determined and mutations in the target genes (gyrA and parC) and regulatory genes (mexR and nfxB) for drug efflux pumps were analyzed. RESULTS Failure of fluoroquinolone treatment of urinary tract infection was observed. The post-treatment isolate, which was assumed to be isogenic to the pretreatment isolate, exhibited fourfold to 16-fold increases in the MIC of fluoroquinolones. In this isolate, a new mutation, not observed in the pretreatment isolate, was found only in the gyrA gene, resulting in an amino acid change of aspartic acid to asparagine in codon 87 of GyrA. CONCLUSIONS The P. aeruginosa isolate that was initially susceptible to fluoroquinolones showed decreased susceptibility to fluoroquinolones after treatment with a suboptimal dose of one fluoroquinolone. In the post-treatment isolate, the alteration of GyrA would be responsible for the decreased susceptibility to fluoroquinolones. We should be aware that inappropriate use of fluoroquinolones could select such a strain harboring a quinolone resistance-associated alteration of DNA gyrase.
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Affiliation(s)
- M Nakano
- Department of Urology, Gifu University School of Medicine, Gifu, Japan
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Wilson DL, Abner SR, Newman TC, Mansfield LS, Linz JE. Identification of ciprofloxacin-resistant Campylobacter jejuni by use of a fluorogenic PCR assay. J Clin Microbiol 2000; 38:3971-8. [PMID: 11060054 PMCID: PMC87527 DOI: 10.1128/jcm.38.11.3971-3978.2000] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fluoroquinolones are one class of antimicrobial agents commonly used to treat severe Campylobacter jejuni infection. C. jejuni strains resistant to high levels of the fluoroquinolone ciprofloxacin (MIC >/=16 microg/ml) have been predominantly characterized with a C-->T transition in codon 86 of gyrA. The gyrA gene encodes one subunit of DNA gyrase, which is a primary target for fluoroquinolone antibiotics. This study establishes a rapid PCR-based TaqMan method for identifying ciprofloxacin-resistant C. jejuni strains that carry the C-->T transition in codon 86 of gyrA. The assay uses real-time detection, eliminating the need for gel electrophoresis. Optimization of the assay parameters using purified Campylobacter DNA resulted in the ability to detect femtogram levels of DNA. The method should be useful for monitoring the development of ciprofloxacin resistance in C. jejuni. Compiled nucleotide sequence data on the quinolone resistance-determining region of gyrA in Campylobacter indicate that sequence comparison of this region is a useful method for tentative identification of Campylobacter isolates at the species level.
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Affiliation(s)
- D L Wilson
- National Food Safety and Toxicology Center, Michigan State University, East Lansing, Michigan 48824, USA
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Bébéar CM, Grau O, Charron A, Renaudin H, Gruson D, Bébéar C. Cloning and nucleotide sequence of the DNA gyrase (gyrA) gene from Mycoplasma hominis and characterization of quinolone-resistant mutants selected in vitro with trovafloxacin. Antimicrob Agents Chemother 2000; 44:2719-27. [PMID: 10991851 PMCID: PMC90142 DOI: 10.1128/aac.44.10.2719-2727.2000] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report the cloning and characterization of the gyrA gene of the Mycoplasma hominis DNA gyrase, which was previously shown to be associated with quinolone resistance in this organism. The 2,733-bp gyrA gene encodes a protein of 911 amino acids with a calculated molecular mass of 102.5 kDa. As expected, M. hominis GyrA exhibits higher homology with the GyrA subunits of the gram-positive bacteria Clostridium acetobutylicum, Bacillus subtilis, Streptococcus pneumoniae, and Staphylococcus aureus than with its Escherichia coli counterpart. Knowing the entire sequence of the gyrA gene of M. hominis could be very useful for confirming the role of the GyrA subunit in fluoroquinolone resistance. Twenty-nine mutants of M. hominis were selected stepwise for resistance to trovafloxacin, a new potent fluoroquinolone, and their gyrA, gyrB, parC, and parE quinolone resistance-determining regions were characterized. Three rounds of selection yielded 3 first-step, 12 second-step, and 14 third-step mutants. The first-step mutants harbored a single substitution, Glu460-->Lys (E. coli coordinates), in ParE. GyrA changes, Ser83-->Leu, Glu87-->Lys, and Ala119-->Glu or Val, were found only in the second round of selection. At the third step, additional substitutions, at ParC Ser80, Ser81, and Glu84 and ParE Leu440, associated with high-level resistance to fluoroquinolones, appeared. Thus, high-level resistance to trovafloxacin required three steps and was associated with alterations in both fluoroquinolone targets. According to these genetic data, in M. hominis, as in Staphylococcus aureus and Streptococcus pneumoniae, topoisomerase IV seems to be the primary target of trovafloxacin.
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Affiliation(s)
- C M Bébéar
- Laboratoire de Bactériologie, Université Victor Segalen Bordeaux 2, 33076 Bordeaux, France.
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Jalal S, Wretlind B. Mechanisms of quinolone resistance in clinical strains of Pseudomonas aeruginosa. Microb Drug Resist 2000; 4:257-61. [PMID: 9988043 DOI: 10.1089/mdr.1998.4.257] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Principal mechanisms of bacterial resistance to quinolones are modification of target enzymes, DNA gyrase (gyrA) and topoisomerase IV (parC), or reduction of intracellular concentration due to mutations in the regulatory genes for efflux systems, such as mexR and nfxB. We have examined gyrA, parC, mexR, and nfxB genes from 16 quinolone-resistant clinical isolates of Pseudomonas aeruginosa to determine the relation between mutations in DNA replicating enzymes or regulatory genes for efflux systems and to correlate the mutations with minimal inhibitory concentrations (MICs). The quinolone resistance-determining regions (QRDR) of these genes were amplified by PCR and sequenced by capillary electrophoresis. Fourteen of 16 isolates had mutations in gyrA, and 13/14 strains with MIC to norfloxacin > or = 8 mg/L had threonine at position 83 changed to isoleucine. Seven of 8 strains with MIC > or = 32 mg/L had mutations in parC. One of these strains showed a parC mutation at position 74 without any mutation in gyrA. Four strains had mexR and two strains nfxB mutations. The data indicate that gyrA mutation is the most important component of quinolone resistance, and simultaneous presence of parC mutations is associated with high-level resistance. parC mutation alone may contribute to resistance, and gyrA mutation may not be a prerequisite for parC mutation to express resistance. mexR and nfxB mutations were found mostly in strains with high-level resistance.
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Affiliation(s)
- S Jalal
- Division of Clinical and Oral Bacteriology, Huddinge University Hospital, Sweden
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Ridley A, Threlfall EJ. Molecular epidemiology of antibiotic resistance genes in multiresistant epidemic Salmonella typhimurium DT 104. Microb Drug Resist 2000; 4:113-8. [PMID: 9650997 DOI: 10.1089/mdr.1998.4.113] [Citation(s) in RCA: 140] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The epidemiology of antibiotic resistance genes in epidemic multiresistant S. typhimurium DT 104 of human and animal origin was investigated. DNA prepared from 45 human and 21 animal strains isolated between 1984 and 1997, including eight isolated in other European countries, the USA, Trinidad, and South Africa and resistant to ampicillin, chloramphenicol, streptomycin, sulphonamides, spectinomycin, tetracyclines (R-type ACSSuSpT) were examined for the presence of integrons by PCR. Integron hot spots were observed in all strains conferring resistance to ACSSuSpT in two copies, determined by two discrete bands of approximately 1.0 and 1.2 kb. Direct nucleotide sequencing of the individual amplicons of selected strains indicated that the 1.0 kb gene product was ant (3")-Ia, responsible for resistance to streptomycin and spectinomycin; the 1.2 kb amplicon contained the gene blaPSE-1, encoding the beta-lactamase PSE-1 (CARB-2). Both integrons were encoded on a single XbaI macrorestriction fragment of approximately 10 kb. All isolates of DT 104 of this resistance phenotype contained the same inserted gene cassettes, irrespective of source and country of origin, supporting the suggestion of the spread of an epidemic clone. Sequence analysis of the quinolone resistance determining region (QRDR) of gyrA of 15 multiresistant strains conferring additional resistance to nalidixic acid and ciprofloxacin (R-type ACSSuSpTNxCp) identified two discrete base substitutions at codon Asp-87. Conversion of Asp-87 --> Asn was most commonly observed, in 7/10 human and 4/5 animal isolates, suggesting that this codon plays a major role in the development of ciprofloxacin resistance in multiresistant S. typhimurium DT 104.
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MESH Headings
- Animals
- Anti-Infective Agents
- Bacteriophage Typing
- Ciprofloxacin/pharmacology
- DNA Gyrase
- DNA Topoisomerases, Type II/genetics
- DNA Transposable Elements
- DNA, Bacterial/analysis
- Disease Outbreaks
- Drug Resistance, Microbial/genetics
- Drug Resistance, Multiple/genetics
- Electrophoresis, Gel, Pulsed-Field
- Genes, Bacterial
- Humans
- Molecular Epidemiology
- Mutagenesis, Insertional
- Salmonella Infections/epidemiology
- Salmonella Infections/microbiology
- Salmonella Infections, Animal/microbiology
- Salmonella typhimurium/drug effects
- Salmonella typhimurium/genetics
- Sequence Analysis, DNA
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Affiliation(s)
- A Ridley
- Laboratory of Enteric Pathogens, PHLS Central Public Health Laboratory, London
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Ouabdesselam S, Tankovic J, Soussy CJ. Quinolone resistance mutations in the gyrA gene of clinical isolates of Salmonella. Microb Drug Resist 2000; 2:299-302. [PMID: 9158789 DOI: 10.1089/mdr.1996.2.299] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
S. typhimurium AlhR, S. enteritidis OulR, and S. hadar GueR resistant to fluoroquinolones (QR), ciprofloxacin MICs, 0.25 to 1 microgram/ml; norfloxacin MICs, 0.5 to 4 micrograms/ml; nalidixic acid MIC, 256 micrograms/ml were isolated from urinary tract infections (AlhR and OulR) during FQ therapy in immunocompromised patients infected by the parent FQ-susceptible strains (AlhS and OulS) (ciprofloxacin MICs, 0.032-0.063; norfloxacin MICs, 0.125-0.25; nalidixic acid MICs, 4-8) or from intestinal infection (GueR). Transformation of AlhR, OulR, and GueR by plasmid pJSW101 carrying the wild-type gyrA gene of Escherichia coli resulted in complementation (nalidixic acid MICs, 4 to 8), proving that these strains had a gyrA mutation. A 800-bp fragment of gyrA from the five strains was amplified by PCR. Direct DNA sequencing of 252-bp region of this fragment identified a single point mutation leading to a substitution Ser-83 to Tyr in AlhR and to a substitution Ser-83 to Phe in OulR and in GueR. These results emphasize the potential risk of selection of FQ-resistant Salmonella during FQ therapy in immunocompromised patients and suggest that these strains differ from the parent strains at least by one mutation in the gyrA gene. They also confirm the role of substitutions in position 83 of gyrA in FQ-resistant clinical isolates of Salmonella.
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Affiliation(s)
- S Ouabdesselam
- Centre Hospitalier Universitaire Henri Mondor, Créteil, France
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Jalal S, Ciofu O, Hoiby N, Gotoh N, Wretlind B. Molecular mechanisms of fluoroquinolone resistance in Pseudomonas aeruginosa isolates from cystic fibrosis patients. Antimicrob Agents Chemother 2000; 44:710-2. [PMID: 10681343 PMCID: PMC89751 DOI: 10.1128/aac.44.3.710-712.2000] [Citation(s) in RCA: 174] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Twenty P. aeruginosa isolates were collected from six cystic fibrosis (CF) patients, aged 27 to 33, in 1994 (9 isolates) and 1997 (11 isolates) at the CF Center, Copenhagen, Denmark, and were typed by pulse-field gel electrophoresis (PFGE) or ribotyping. Five of the patients had isolates with the same PFGE or ribotyping patterns in 1997 as in 1994, and ciprofloxacin had a two- to fourfold higher MIC for the isolates collected in 1997 than those from 1994. Genomic DNA was amplified for gyrA, parC, mexR, and nfxB by PCR and sequenced. Eleven isolates had mutations in gyrA, seven isolates had mutations at codon 83 (Thr to Ile), and four isolates had mutations at codon 87 (Asp to Asn or Tyr). Sixteen isolates had mutations in nfxB at codon 82 (Arg to Leu). Increased amounts of OprN were found in six isolates and OprJ in eight isolates as determined by immunoblotting. No isolates had mutations in parC or mexR. Six isolates had mutations in efflux pumps without gyrA mutations. The average number of mutations was higher in isolates from 1997 than in those from 1994. The results also suggested that efflux resistance mechanisms are more common in isolates from CF patients than in strains from urine and wounds from non-CF patients, in which mutations in gyrA and parC dominate (S. Jalal and B. Wretlind, Microb. Drug Resist. 4:257-261, 1998).
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Affiliation(s)
- S Jalal
- Division of Clinical Bacteriology, Huddinge University Hospital, S-14186 Huddinge, Sweden.
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Deguchi T, Yamaha M, Nakano M, Yasuda M, Nishino Y, Ishihara S, Kawada Y. Development of a rapid assay for screening point mutations associated with quinolone resistance in the Pseudomonas aeruginosa parC gene. J Infect Chemother 2000; 6:26-9. [PMID: 11810527 DOI: 10.1007/s101560050045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/1999] [Accepted: 10/08/1999] [Indexed: 10/28/2022]
Abstract
To detect quinolone resistance-associated mutations within the Ser-80 and Glu-84 codons of the Pseudomonas aeruginosa parC gene, we developed a rapid and simple assay based on polymerase chain reaction (PCR) amplification of the region of the parC gene containing the mutation sites and digestion of the PCR products with a restriction enzyme. The mutations generating alterations at Ser-80 and Glu-84 were detected as restriction fragment length polymorphisms of the PCR products digested with HinfI. Among 22 clinical isolates tested by this assay, mutations at the Ser-80 and Glu-84 codons were detected in all 10 isolates in which the presence of the mutations had been confirmed previously by DNA sequencing. This rapid and simple assay could be a useful screening device for genetic alterations associated with resistance to quinolones in the P. aeruginosa parC gene.
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Affiliation(s)
- T Deguchi
- Department of Urology, Gifu University School of Medicine, 40 Tsukasa-machi, Gifu 500-8705, Japan.
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Abstract
Fluoroquinolone resistance is mediated by target changes (DNA gyrase and/or topoisomerase IV) and/or decreased intracellular accumulation. The genes (gyrA/gyrB/parC/parE) and proteins of DNA topoisomerase IV show great similarity, both at the nucleotide and amino acid sequence level to those of DNA gyrase. It has been shown that there are hotspots, called the quinolone resistance determining region (QRDR), for mutations within gyrA and parC. Based on the Escherichia coli co-ordinates, the hotspots most favoured for giving rise to decreased susceptibility and/or full resistance to quinolones are at serine 83 and aspartate 87 of gyrA, and at serine 79 and aspartate 83 for parC. Few mutations in gyrB or parE/grlB of any bacteria have been described. Efflux of fluoroquinolones is the major cause of decreased accumulation of these agents; for Staphylococcus aureus, the efflux pump involved in norfloxacin resistance is NorA, and for Streptococcus pneumoniae, PmrA. By analysis of minimum inhibitory concentration (MIC) data derived in the presence and absence of the efflux inhibitor reserpine, it has been shown that up to 50% of ciprofloxacin-resistant clinical isolates of S. pneumoniae may possess enhanced efflux. This suggests that efflux may be an important mechanism of clinical resistance in this species. In Pseudomonas aeruginosa, several efflux operons have been demonstrated genetically and biochemically. These operons are encoded by mex (Multiple EffluX) genes: mexAmexB-oprM, mexCD-OprJ system and mexEF-oprN system. The E. coli efflux pump is the acrAB-tolC system. Both the mar operon and the sox operon can give rise to multiple antibiotic resistance. It has been shown that mutations giving rise to increased expression of the transcriptional activators marA and soxS affect the expression of a variety of different genes, including ompF and acrAB. The net result is that expression of OmpF is reduced and much less drug is able to enter the cell; expression of acrAB is increased, enhancing efflux from the cell.
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Affiliation(s)
- L J Piddock
- Division of Immunity and Infection, Medical School, University of Birmingham, Edgbaston, England.
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Jalal S, Wretlind G, Gotoh N, Wretlind B. Rapid identification of mutations in a multidrug efflux pump in Pseudomonas aeruginosa. APMIS 1999; 107:1109-16. [PMID: 10660141 DOI: 10.1111/j.1699-0463.1999.tb01516.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The gene mexR regulates negatively the expression of the MexA-MexB-OprM efflux pump in Pseudomonas aeruginosa, and mutations in mexR cause a multiple antibiotic resistance phenotype. Five hundred and forty resistant clones of P. aeruginosa PAO503 were isolated after selection for resistance to chloramphenicol or tetracycline. All isolates showed similar phenotypes and were resistant to tetracycline, chloramphenicol and norfloxacin. Nineteen randomly selected isolates were analyzed. Since mutational analysis by direct sequencing of all regions of interest in several strains is time-consuming and expensive, a screening method, Non-Isotopic RNase Cleavage Assay (NIRCA), was applied to identify mutant genes so that they could be targeted for DNA sequencing. NIRCA is a simple but rapid method for mutational analysis and can be performed in 3-4 h. Results of NIRCA analysis were compared with DNA sequencing. Both NIRCA and DNA sequencing analysis showed mexR gene mutations in 11 of 19 isolates but no alterations in 8 strains. An immunoblot assay showed overexpression of OprN, a component of another multidrug efflux pump, MexE-MexF-OprN, in those eight isolates. Nucleotide sequencing of quinolone resistance-determining regions of DNA gyrase (gyrA) or topoisomerase IV (parC) showed no alterations in any of the 19 mutants. The data indicate that two efflux pump systems, MexA-MexB-OprM and MexE-MexF-OprN, were involved in multidrug resistance including quinolones and that NIRCA is a sensitive method for screening mutations.
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Affiliation(s)
- S Jalal
- Division of Clinical Bacteriology, Huddinge University Hospital, Stockholm, Sweden
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Giraud E, Brisabois A, Martel JL, Chaslus-Dancla E. Comparative studies of mutations in animal isolates and experimental in vitro- and in vivo-selected mutants of Salmonella spp. suggest a counterselection of highly fluoroquinolone-resistant strains in the field. Antimicrob Agents Chemother 1999; 43:2131-7. [PMID: 10471553 PMCID: PMC89435 DOI: 10.1128/aac.43.9.2131] [Citation(s) in RCA: 168] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The occurrence of mutations in the genes coding for gyrase (gyrA and gyrB) and topoisomerase IV (parE and parC) of Salmonella typhimurium experimental mutants selected in vitro and in vivo and of 138 nalidixic acid-resistant Salmonella field isolates was investigated. The sequencing of the quinolone resistance-determining region of these genes in highly fluoroquinolone-resistant mutants (MICs of 4 to 16 microg/ml) revealed the presence of gyrA mutations at codons corresponding to Gly-81 or Ser-83, some of which were associated with a mutation at Asp-87. No mutations were found in the gyrB, parC, and parE genes. An assay combining allele-specific PCR and restriction fragment length polymorphism was developed to rapidly screen mutations at codons 81, 83, and 87 of gyrA. The MICs of ciprofloxacin for the field isolates reached only 2 microg/ml, versus 16 microg/ml for some in vitro-selected mutants. The field isolates, like the mutants selected in vivo, had only a single gyrA mutation at codon 83 or 87. Single gyrA mutations were also found in highly resistant in vitro-selected mutants (MIC of ciprofloxacin, 8 microg/ml), which indicates that mechanisms other than the unique modification of the intracellular targets could participate in fluoroquinolone resistance in Salmonella spp. A comparison of experimental mutants selected in vitro, field strains, and mutants selected in vivo suggests that highly fluoroquinolone-resistant strains are counterselected in field conditions in the absence of selective pressure.
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Affiliation(s)
- E Giraud
- Station de Pathologie Aviaire et de Parasitologie, Institut National de la Recherche Agronomique, Centre de Recherche de Tours-Nouzilly, 37380 Monnaie, France
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Lomovskaya O, Lee A, Hoshino K, Ishida H, Mistry A, Warren MS, Boyer E, Chamberland S, Lee VJ. Use of a genetic approach to evaluate the consequences of inhibition of efflux pumps in Pseudomonas aeruginosa. Antimicrob Agents Chemother 1999; 43:1340-6. [PMID: 10348749 PMCID: PMC89275 DOI: 10.1128/aac.43.6.1340] [Citation(s) in RCA: 154] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Drug efflux pumps in Pseudomonas aeruginosa were evaluated as potential targets for antibacterial therapy. The potential effects of pump inhibition on susceptibility to fluoroquinolone antibiotics were studied with isogenic strains that overexpress or lack individual efflux pumps and that have various combinations of efflux- and target-mediated mutations. Deletions in three efflux pump operons were constructed. As expected, deletion of the MexAB-OprM efflux pump decreased resistance to fluoroquinolones in the wild-type P. aeruginosa (16-fold reduction for levofloxacin [LVX]) or in the strain that overexpressed mexAB-oprM operon (64-fold reduction for LVX). In addition to that, resistance to LVX was significantly reduced even for the strains carrying target mutations (64-fold for strains for which LVX MICs were >4 microg/ml). We also studied the frequencies of emergence of LVX-resistant variants from different deletion mutants and the wild-type strain. Deletion of individual pumps or pairs of the pumps did not significantly affect the frequency of emergence of resistant variants (at 4x the MIC for the wild-type strain) compared to that for the wild type (10(-6) to 10(-7)). In the case of the strain with a triple deletion, the frequency of spontaneous mutants was undetectable (<10(-11)). In summary, inhibition of drug efflux pumps would (i) significantly decrease the level of intrinsic resistance, (ii) reverse acquired resistance, and (iii) result in a decreased frequency of emergence of P. aeruginosa strains highly resistant to fluoroquinolones in clinical settings.
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Affiliation(s)
- O Lomovskaya
- Microcide Pharmaceuticals Inc., Mountain View, California 94043, USA.
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