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Li D, Elankumaran P, Kudinha T, Kidsley AK, Trott DJ, Jarocki VM, Djordjevic SP. Dominance of Escherichia coli sequence types ST73, ST95, ST127 and ST131 in Australian urine isolates: a genomic analysis of antimicrobial resistance and virulence linked to F plasmids. Microb Genom 2023; 9:mgen001068. [PMID: 37471138 PMCID: PMC10438821 DOI: 10.1099/mgen.0.001068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 06/20/2023] [Indexed: 07/21/2023] Open
Abstract
Extraintestinal pathogenic Escherichia coli (ExPEC) are the most frequent cause of urinary tract infections (UTIs) globally. Most studies of clinical E. coli isolates are selected based on their antimicrobial resistance (AMR) phenotypes; however, this selection bias may not provide an accurate portrayal of which sequence types (STs) cause the most disease. Here, whole genome sequencing (WGS) was performed on 320 E. coli isolates from urine samples sourced from a regional hospital in Australia in 2006. Most isolates (91%) were sourced from patients with UTIs and were not selected based on any AMR phenotypes. No significant differences were observed in AMR and virulence genes profiles across age sex, and uro-clinical syndromes. While 88 STs were identified, ST73, ST95, ST127 and ST131 dominated. F virulence plasmids carrying senB-cjrABC (126/231; 55%) virulence genes were a feature of this collection. These senB-cjrABC+ plasmids were split into two categories: pUTI89-like (F29:A-:B10 and/or >95 % identity to pUTI89) (n=73) and non-pUTI89-like (n=53). Compared to all other plasmid replicons, isolates with pUTI89-like plasmids carried fewer antibiotic resistance genes (ARGs), whilst isolates with senB-cjrABC+/non-pUTI89 plasmids had a significantly higher load of ARGs and class 1 integrons. F plasmids were not detected in 89 genomes, predominantly ST73. Our phylogenomic analyses identified closely related isolates from the same patient associated with different pathologies and evidence of strain-sharing events involving isolates sourced from companion and wild animals.
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Affiliation(s)
- Dmitriy Li
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Ultimo, NSW, Australia
- Australian Centre for Genomic Epidemiological Microbiology, University of Technology Sydney, NSW, Australia
| | - Paarthiphan Elankumaran
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Ultimo, NSW, Australia
- Australian Centre for Genomic Epidemiological Microbiology, University of Technology Sydney, NSW, Australia
| | - Timothy Kudinha
- Central West Pathology Laboratory, Charles Sturt University, Orange, NSW, Australia
| | - Amanda K. Kidsley
- School of Animal and Veterinary Science, The University of Adelaide, Adelaide, South Australia, Australia
| | - Darren J. Trott
- School of Animal and Veterinary Science, The University of Adelaide, Adelaide, South Australia, Australia
| | - Veronica Maria Jarocki
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Ultimo, NSW, Australia
- Australian Centre for Genomic Epidemiological Microbiology, University of Technology Sydney, NSW, Australia
| | - Steven Philip Djordjevic
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Ultimo, NSW, Australia
- Australian Centre for Genomic Epidemiological Microbiology, University of Technology Sydney, NSW, Australia
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Off-Target Integron Activity Leads to Rapid Plasmid Compensatory Evolution in Response to Antibiotic Selection Pressure. mBio 2023; 14:e0253722. [PMID: 36840554 PMCID: PMC10127599 DOI: 10.1128/mbio.02537-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023] Open
Abstract
Integrons are mobile genetic elements that have played an important role in the dissemination of antibiotic resistance. Under stress, the integron can generate combinatorial variation in resistance cassette expression by cassette reshuffling, accelerating the evolution of resistance. However, the flexibility of the integron integrase site recognition motif hints at potential off-target effects of the integrase on the rest of the genome that may have important evolutionary consequences. Here, we test this hypothesis by selecting for increased-piperacillin-resistance populations of Pseudomonas aeruginosa with a mobile integron containing a difficult-to-mobilize β-lactamase cassette to minimize the potential for adaptive cassette reshuffling. We found that integron activity can decrease the overall survival rate but also improve the fitness of the surviving populations. Off-target inversions mediated by the integron accelerated plasmid adaptation by disrupting costly conjugative genes otherwise mutated in control populations lacking a functional integrase. Plasmids containing integron-mediated inversions were associated with lower plasmid costs and higher stability than plasmids carrying mutations albeit at the cost of a reduced conjugative ability. These findings highlight the potential for integrons to create structural variation that can drive bacterial evolution, and they provide an interesting example showing how antibiotic pressure can drive the loss of conjugative genes. IMPORTANCE Tackling the public health challenge created by antibiotic resistance requires understanding the mechanisms driving its evolution. Mobile integrons are widespread genetic platforms heavily involved in the spread of antibiotic resistance. Through the action of the integrase enzyme, integrons allow bacteria to capture, excise, and shuffle antibiotic resistance gene cassettes. This integrase enzyme is characterized by its ability to recognize a wide range of recombination sites, which allows it to easily capture diverse resistance cassettes but which may also lead to off-target reactions with the rest of the genome. Using experimental evolution, we tested the off-target impact of integron activity. We found that integrons increased the fitness of the surviving bacteria through extensive genomic rearrangements of the plasmids carrying the integrons, reducing their ability to spread horizontally. These results show that integrons not only accelerate resistance evolution but also can generate extensive structural variation, driving bacterial evolution beyond antibiotic resistance.
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An XL, Abass OK, Zhao CX, Xu MR, Pan T, Pu Q, Liao H, Li H, Zhu YG, Su JQ. Nanopore sequencing analysis of integron gene cassettes in sewages and soils. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 817:152766. [PMID: 35007603 DOI: 10.1016/j.scitotenv.2021.152766] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 12/23/2021] [Accepted: 12/25/2021] [Indexed: 06/14/2023]
Abstract
Integrons are genetic elements that can facilitate rapid spread of antibiotic resistance by insertion and removal of genes. However, knowledge about the diversity and distribution of gene cassettes embedded in class 1 integron is still limited. In this study, we sequenced integron gene cassettes using nanopore sequencing and quantified antibiotic resistance genes (ARGs) and integrase genes in the manured soils and sewages of a bioreactor. The results showed that class 1 integron integrase genes were the most abundant in soils and sewages compared with class 2 and class 3 integrase genes. Long-term manure application exacerbated the enrichment of total ARGs, integrase genes and antibiotic resistance-associated gene cassettes, while antibiotics and heavy metals showed no impact on the overall resistome profile. Sewage treatment could efficiently remove the absolute abundance of integrase genes (~3 orders of magnitude, copies/L) and antibiotic resistance gene cassettes. The resistance gene cassettes mainly carried the ARGs conferring resistance to aminoglycoside and beta-lactams in soils and sewages, some of which were persistent during the sewage treatment. This study underlined that soil and sewage were potential reservoirs for integron-mediated ARGs transfer, indicating that anthropogenic activity played a vital role in the prevalence and diversity of resistance gene cassettes in integrons.
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Affiliation(s)
- Xin-Li An
- Fujian Key Laboratory of Watershed Ecology, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
| | - Olusegun K Abass
- School of Civil and Environmental Engineering, Nanyang Technological University, Nanyang Avenue, 639798, Singapore
| | - Cai-Xia Zhao
- Fujian Key Laboratory of Watershed Ecology, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; College of Resource and Environmental Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Mei-Rong Xu
- Fujian Key Laboratory of Watershed Ecology, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Ting Pan
- Fujian Key Laboratory of Watershed Ecology, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qiang Pu
- Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Hu Liao
- Fujian Key Laboratory of Watershed Ecology, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hu Li
- Fujian Key Laboratory of Watershed Ecology, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
| | - Yong-Guan Zhu
- Fujian Key Laboratory of Watershed Ecology, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; State Key Lab of Urban and Regional Ecology, Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jian-Qiang Su
- Fujian Key Laboratory of Watershed Ecology, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
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Néron B, Littner E, Haudiquet M, Perrin A, Cury J, Rocha EPC. IntegronFinder 2.0: Identification and Analysis of Integrons across Bacteria, with a Focus on Antibiotic Resistance in Klebsiella. Microorganisms 2022; 10:microorganisms10040700. [PMID: 35456751 PMCID: PMC9024848 DOI: 10.3390/microorganisms10040700] [Citation(s) in RCA: 59] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 03/19/2022] [Accepted: 03/22/2022] [Indexed: 02/07/2023] Open
Abstract
Integrons are flexible gene-exchanging platforms that contain multiple cassettes encoding accessory genes whose order is shuffled by a specific integrase. Integrons embedded within mobile genetic elements often contain multiple antibiotic resistance genes that they spread among nosocomial pathogens and contribute to the current antibiotic resistance crisis. However, most integrons are presumably sedentary and encode a much broader diversity of functions. IntegronFinder is a widely used software to identify novel integrons in bacterial genomes, but has aged and lacks some useful functionalities to handle very large datasets of draft genomes or metagenomes. Here, we present IntegronFinder version 2. We have updated the code, improved its efficiency and usability, adapted the output to incomplete genome data, and added a few novel functions. We describe these changes and illustrate the relevance of the program by analyzing the distribution of integrons across more than 20,000 fully sequenced genomes. We also take full advantage of its novel capabilities to analyze close to 4000 Klebsiella pneumoniae genomes for the presence of integrons and antibiotic resistance genes within them. Our data show that K. pneumoniae has a large diversity of integrons and the largest mobile integron in our database of plasmids. The pangenome of these integrons contains a total of 165 different gene families with most of the largest families being related with resistance to numerous types of antibiotics. IntegronFinder is a free and open-source software available on multiple public platforms.
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Affiliation(s)
- Bertrand Néron
- Bioinformatics and Biostatistics Hub, Institut Pasteur, Université de Paris Cité, 75015 Paris, France; (B.N.); (A.P.)
| | - Eloi Littner
- Microbial Evolutionary Genomics, Institut Pasteur, Université de Paris Cité, CNRS UMR3525, 75015 Paris, France; (E.L.); (M.H.)
- DGA CBRN Defence, 91710 Vert-le-Petit, France
- Collège Doctoral, Sorbonne Université, 75005 Paris, France
| | - Matthieu Haudiquet
- Microbial Evolutionary Genomics, Institut Pasteur, Université de Paris Cité, CNRS UMR3525, 75015 Paris, France; (E.L.); (M.H.)
- Ecole Doctorale FIRE–Programme Bettencourt, CRI, 75004 Paris, France
| | - Amandine Perrin
- Bioinformatics and Biostatistics Hub, Institut Pasteur, Université de Paris Cité, 75015 Paris, France; (B.N.); (A.P.)
- Microbial Evolutionary Genomics, Institut Pasteur, Université de Paris Cité, CNRS UMR3525, 75015 Paris, France; (E.L.); (M.H.)
- Collège Doctoral, Sorbonne Université, 75005 Paris, France
| | - Jean Cury
- Microbial Evolutionary Genomics, Institut Pasteur, Université de Paris Cité, CNRS UMR3525, 75015 Paris, France; (E.L.); (M.H.)
- Laboratoire Interdisciplinaire des Sciences du Numérique, Université Paris-Saclay, CNRS UMR 9015, INRIA, 91400 Orsay, France
- Correspondence: (J.C.); (E.P.C.R.)
| | - Eduardo P. C. Rocha
- Microbial Evolutionary Genomics, Institut Pasteur, Université de Paris Cité, CNRS UMR3525, 75015 Paris, France; (E.L.); (M.H.)
- Correspondence: (J.C.); (E.P.C.R.)
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Antelo V, Giménez M, Azziz G, Valdespino‐Castillo P, Falcón LI, Ruberto LAM, Mac Cormack WP, Mazel D, Batista S. Metagenomic strategies identify diverse integron-integrase and antibiotic resistance genes in the Antarctic environment. Microbiologyopen 2021; 10:e1219. [PMID: 34713606 PMCID: PMC8435808 DOI: 10.1002/mbo3.1219] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 06/24/2021] [Indexed: 11/08/2022] Open
Abstract
The objective of this study is to identify and analyze integrons and antibiotic resistance genes (ARGs) in samples collected from diverse sites in terrestrial Antarctica. Integrons were studied using two independent methods. One involved the construction and analysis of intI gene amplicon libraries. In addition, we sequenced 17 metagenomes of microbial mats and soil by high-throughput sequencing and analyzed these data using the IntegronFinder program. As expected, the metagenomic analysis allowed for the identification of novel predicted intI integrases and gene cassettes (GCs), which mostly encode unknown functions. However, some intI genes are similar to sequences previously identified by amplicon library analysis in soil samples collected from non-Antarctic sites. ARGs were analyzed in the metagenomes using ABRIcate with CARD database and verified if these genes could be classified as GCs by IntegronFinder. We identified 53 ARGs in 15 metagenomes, but only four were classified as GCs, one in MTG12 metagenome (Continental Antarctica), encoding an aminoglycoside-modifying enzyme (AAC(6´)acetyltransferase) and the other three in CS1 metagenome (Maritime Antarctica). One of these genes encodes a class D β-lactamase (blaOXA-205) and the other two are located in the same contig. One is part of a gene encoding the first 76 amino acids of aminoglycoside adenyltransferase (aadA6), and the other is a qacG2 gene.
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Affiliation(s)
- Verónica Antelo
- Laboratorio de Microbiología MolecularInstituto de Investigaciones Biológicas Clemente Estable (MECAv. Italia 3318MontevideoCP 11600Uruguay
| | - Matías Giménez
- Laboratorio de Microbiología MolecularInstituto de Investigaciones Biológicas Clemente Estable (MECAv. Italia 3318MontevideoCP 11600Uruguay
- Laboratorio de Genómica MicrobianaInstitut Pasteur Montevideo. Mataojo 2020MontevideoUruguay
| | - Gastón Azziz
- Laboratorio de MicrobiologíaFacultad de AgronomíaUdelaR. Av. Garzón 780. CP 12900MontevideoUruguay
| | - Patricia Valdespino‐Castillo
- Molecular Biophysics and Integrated Bioimaging DivisionBSISB ProgramLawrence Berkeley National LaboratoryOne Cyclotron RdBerkeleyCA94720USA
| | - Luisa I. Falcón
- Laboratorio de Ecología BacterianaInstituto de EcologíaUniversidad Nacional Autónoma de MéxicoCDMX04510Mexico
- UNAMParque Científico y Tecnológico de Yucatán97302Mexico
| | - Lucas A. M. Ruberto
- Instituto Antártico Argentino. Av25 de Mayo 1143San Martín, Buenos Aires1650Argentina
- Cátedra de BiotecnologíaFacultad de Farmacia y Bioquímica e Instituto Nanobiotec UBA‐CONICET. Ave. Junín 956Buenos Aires1113Argentina
| | - Walter P. Mac Cormack
- Instituto Antártico Argentino. Av25 de Mayo 1143San Martín, Buenos Aires1650Argentina
- Cátedra de BiotecnologíaFacultad de Farmacia y Bioquímica e Instituto Nanobiotec UBA‐CONICET. Ave. Junín 956Buenos Aires1113Argentina
| | - Didier Mazel
- Département Génomes et GénétiqueInstitut PasteurUnité Plasticité du Génome BactérienParisFrance
- CNRSUMR3525ParisFrance
| | - Silvia Batista
- Laboratorio de Microbiología MolecularInstituto de Investigaciones Biológicas Clemente Estable (MECAv. Italia 3318MontevideoCP 11600Uruguay
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Integrase-Controlled Excision of Metal-Resistance Genomic Islands in Acinetobacter baumannii. Genes (Basel) 2018; 9:genes9070366. [PMID: 30037042 PMCID: PMC6070778 DOI: 10.3390/genes9070366] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 07/10/2018] [Accepted: 07/16/2018] [Indexed: 12/13/2022] Open
Abstract
Genomic islands (GIs) are discrete gene clusters encoding for a variety of functions including antibiotic and heavy metal resistance, some of which are tightly associated to lineages of the core genome phylogenetic tree. We have investigated the functions of two distinct integrase genes in the mobilization of two metal resistant GIs, G08 and G62, of Acinetobacter baumannii. Real-time PCR demonstrated integrase-dependent GI excision, utilizing isopropyl β-d-1-thiogalactopyranoside IPTG-inducible integrase genes in plasmid-based mini-GIs in Escherichia coli. In A. baumannii, integrase-dependent excision of the original chromosomal GIs could be observed after mitomycin C induction. In both E. coli plasmids and A. baumannii chromosome, the rate of excision and circularization was found to be dependent on the expression level of the integrases. Susceptibility testing in A. baumannii strain ATCC 17978, A424, and their respective ΔG62 and ΔG08 mutants confirmed the contribution of the GI-encoded efflux transporters to heavy metal decreased susceptibility. In summary, the data evidenced the functionality of two integrases in the excision and circularization of the two Acinetobacter heavy-metal resistance GIs, G08 and G62, in E. coli, as well as when chromosomally located in their natural host. These recombination events occur at different frequencies resulting in genome plasticity and may participate in the spread of resistance determinants in A. baumannii.
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Class 1 integrons are low-cost structures in Escherichia coli. ISME JOURNAL 2017; 11:1535-1544. [PMID: 28387772 DOI: 10.1038/ismej.2017.38] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 01/30/2017] [Accepted: 02/06/2017] [Indexed: 01/18/2023]
Abstract
Resistance integrons are bacterial genetic platforms that can capture and express antibiotic resistance genes embedded within gene cassettes. The capture and shuffling of gene cassettes are mediated by the integrase IntI, the expression of which is regulated by the SOS response in Escherichia coli. Gene cassettes are expressed from a common Pc promoter. Despite the clinical and environmental relevance of integrons, the selective forces responsible for their evolution and maintenance are poorly understood. Here, we conducted pairwise competition experiments in order to assess the fitness cost of class 1 integrons in E. coli. We found that integrons are low-cost structures and that their cost is further reduced by their tight regulation. We show that the SOS response prevents the expression of costly integrases whose cost is activity dependent. Thus, when an integron is repressed, its cost depends mostly on the expression of its gene cassettes array and increases with Pc strength and the number of cassettes in the array. Furthermore, different cassettes have different costs. Lastly, we showed that subinhibitory antibiotic concentrations promoted the selection of integron-carrying bacteria, especially those with a strong Pc promoter. These results provide new insights into the evolutionary dynamics of integron-carrying bacterial populations.
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Cury J, Jové T, Touchon M, Néron B, Rocha EP. Identification and analysis of integrons and cassette arrays in bacterial genomes. Nucleic Acids Res 2016; 44:4539-50. [PMID: 27130947 PMCID: PMC4889954 DOI: 10.1093/nar/gkw319] [Citation(s) in RCA: 178] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 04/13/2016] [Indexed: 12/13/2022] Open
Abstract
Integrons recombine gene arrays and favor the spread of antibiotic resistance. Their broader roles in bacterial adaptation remain mysterious, partly due to lack of computational tools. We made a program – IntegronFinder – to identify integrons with high accuracy and sensitivity. IntegronFinder is available as a standalone program and as a web application. It searches for attC sites using covariance models, for integron-integrases using HMM profiles, and for other features (promoters, attI site) using pattern matching. We searched for integrons, integron-integrases lacking attC sites, and clusters of attC sites lacking a neighboring integron-integrase in bacterial genomes. All these elements are especially frequent in genomes of intermediate size. They are missing in some key phyla, such as α-Proteobacteria, which might reflect selection against cell lineages that acquire integrons. The similarity between attC sites is proportional to the number of cassettes in the integron, and is particularly low in clusters of attC sites lacking integron-integrases. The latter are unexpectedly abundant in genomes lacking integron-integrases or their remains, and have a large novel pool of cassettes lacking homologs in the databases. They might represent an evolutionary step between the acquisition of genes within integrons and their stabilization in the new genome.
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Affiliation(s)
- Jean Cury
- Microbial Evolutionary Genomics, Institut Pasteur, 28, rue Dr Roux, Paris, 75015, France CNRS, UMR3525, 28, rue Dr Roux, Paris, 75015, France
| | - Thomas Jové
- Univ. Limoges, INSERM, CHU Limoges, UMR_S 1092, F-87000 Limoges, France
| | - Marie Touchon
- Microbial Evolutionary Genomics, Institut Pasteur, 28, rue Dr Roux, Paris, 75015, France CNRS, UMR3525, 28, rue Dr Roux, Paris, 75015, France
| | - Bertrand Néron
- Centre d'Informatique pour la Biologie, C3BI, Institut Pasteur, Paris, France
| | - Eduardo Pc Rocha
- Microbial Evolutionary Genomics, Institut Pasteur, 28, rue Dr Roux, Paris, 75015, France CNRS, UMR3525, 28, rue Dr Roux, Paris, 75015, France
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Abstract
The integron is a powerful system which, by capturing, stockpiling, and rearranging new functions carried by gene encoding cassettes, confers upon bacteria a rapid adaptation capability in changing environments. Chromosomally located integrons (CI) have been identified in a large number of environmental Gram-negative bacteria. Integron evolutionary history suggests that these sedentary CIs acquired mobility among bacterial species through their association with transposable elements and conjugative plasmids. As a result of massive antibiotic use, these so-called mobile integrons are now widespread in clinically relevant bacteria and are considered to be the principal agent in the emergence and rise of antibiotic multiresistance in Gram-negative bacteria. Cassette rearrangements are catalyzed by the integron integrase, a site-specific tyrosine recombinase. Central to these reactions is the single-stranded DNA nature of one of the recombination partners, the attC site. This makes the integron a unique recombination system. This review describes the current knowledge on this atypical recombination mechanism, its implications in the reactions involving the different types of sites, attC and attI, and focuses on the tight regulation exerted by the host on integron activity through the control of attC site folding. Furthermore, cassette and integrase expression are also highly controlled by host regulatory networks and the bacterial stress (SOS) response. These intimate connections to the host make the integron a genetically stable and efficient system, granting the bacteria a low cost, highly adaptive evolution potential "on demand".
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10
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Engelstädter J, Harms K, Johnsen PJ. The evolutionary dynamics of integrons in changing environments. ISME JOURNAL 2016; 10:1296-307. [PMID: 26849314 DOI: 10.1038/ismej.2015.222] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 10/13/2015] [Accepted: 10/16/2015] [Indexed: 11/09/2022]
Abstract
Integrons are genetic elements that are common in bacteria and are hotspots for genome evolution. They facilitate the acquisition and reassembly of gene cassettes encoding a variety of functions, including drug resistance. Despite their importance in clinical settings, the selective forces responsible for the evolution and maintenance of integrons are poorly understood. We present a mathematical model of integron evolution within bacterial populations subject to fluctuating antibiotic exposures. Bacteria carrying a functional integrase that mediates reshuffling of cassette genes and thereby modulates gene expression patterns compete with bacteria without a functional integrase. Our results indicate that for a wide range of parameters, the functional integrase can be stably maintained in the population despite substantial fitness costs. This selective advantage arises because gene-cassette shuffling generates genetic diversity, thus enabling the population to respond rapidly to changing selective pressures. We also show that horizontal gene transfer promotes stable maintenance of the integrase and can also lead to de novo assembly of integrons. Our model generates testable predictions for integron evolution, including loss of functional integrases in stable environments and selection for intermediate gene-shuffling rates in changing environments. Our results highlight the need for experimental studies of integron population biology.
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Affiliation(s)
- Jan Engelstädter
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Klaus Harms
- Faculty of Health Sciences, Department of Pharmacy, UIT - The Arctic University of Norway, Tromsø, Norway.,Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark
| | - Pål J Johnsen
- Faculty of Health Sciences, Department of Pharmacy, UIT - The Arctic University of Norway, Tromsø, Norway
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11
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Abella J, Fahy A, Duran R, Cagnon C. Integron diversity in bacterial communities of freshwater sediments at different contamination levels. FEMS Microbiol Ecol 2015; 91:fiv140. [DOI: 10.1093/femsec/fiv140] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2015] [Indexed: 12/29/2022] Open
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12
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Deng Y, Bao X, Ji L, Chen L, Liu J, Miao J, Chen D, Bian H, Li Y, Yu G. Resistance integrons: class 1, 2 and 3 integrons. Ann Clin Microbiol Antimicrob 2015; 14:45. [PMID: 26487554 PMCID: PMC4618277 DOI: 10.1186/s12941-015-0100-6] [Citation(s) in RCA: 198] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 08/14/2015] [Indexed: 11/30/2022] Open
Abstract
As recently indiscriminate abuse of existing antibiotics in both clinical and veterinary treatment leads to proliferation of antibiotic resistance in microbes and poses a dilemma for the future treatment of such bacterial infection, antimicrobial resistance has been considered to be one of the currently leading concerns in global public health, and reported to widely spread and extended to a large variety of microorganisms. In China, as one of the currently worst areas for antibiotics abuse, the annual prescription of antibiotics, including both clinical and veterinary treatment, has approaching 140 gram per person and been roughly estimated to be 10 times higher than that in the United Kingdom, which is considered to be a potential area for the emergence of “Super Bugs”. Based on the integrons surveillance in Guangzhou, China in the past decade, this review thus aimed at summarizing the role of integrons in the perspective of both clinical setting and environment, with the focus on the occurrence and prevalence of class 1, 2 and 3 integrons.
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Affiliation(s)
- Yang Deng
- College of Light Industry and Food Sciences, South China University of Technology, Guangzhou, 510640, China.
| | - Xuerui Bao
- College of Light Industry and Food Sciences, South China University of Technology, Guangzhou, 510640, China.
| | - Lili Ji
- College of Light Industry and Food Sciences, South China University of Technology, Guangzhou, 510640, China.
| | - Lei Chen
- Institute of Agro-products Processing, Anhui Academy of Agricultural Sciences, Hefei, 230031, China.
| | - Junyan Liu
- College of Light Industry and Food Sciences, South China University of Technology, Guangzhou, 510640, China.
| | - Jian Miao
- College of Light Industry and Food Sciences, South China University of Technology, Guangzhou, 510640, China.
| | - Dingqiang Chen
- Department of Laboratory Medicine, First Affiliated Hospital of Guangzhou Medical College, Guangzhou, 510120, China.
| | - Huawei Bian
- The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510630, China.
| | - Yanmei Li
- Guangzhou Women and Children's Medical Center, 9 Jinsui Road, Guangzhou, 510620, China.
| | - Guangchao Yu
- First Affiliated Hospital of Jinan University, Guangzhou, 510620, China.
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Abella J, Bielen A, Huang L, Delmont TO, Vujaklija D, Duran R, Cagnon C. Integron diversity in marine environments. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015. [PMID: 26213132 DOI: 10.1007/s11356-015-5085-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Integrons are bacterial genetic elements known to be active vectors of antibiotic resistance among clinical bacteria. They are also found in bacterial communities from natural environments. Although integrons have become especially efficient for bacterial adaptation in the particular context of antibiotic usage, their role in natural environments in other contexts is still unknown. Indeed, most studies have focused on integrons and the spread of antibiotic resistance in freshwater or soil impacted by anthropogenic activities, with only few on marine environments. Notably, integrons show a wider diversity of both gene cassettes and integrase gene in natural environments than in clinical environments, suggesting a general role of integrons in bacterial adaptation. This article reviews the current knowledge on integrons in marine environments. We also present conclusions of our studies on polluted and nonpolluted backgrounds.
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Affiliation(s)
- Justine Abella
- Equipe Environnement et Microbiologie, MELODY Group, Université de Pau et des Pays de l'Adour, IPREM UMR CNRS 5254, BP 1155, 64013, Pau, Cedex, France
| | - Ana Bielen
- Laboratory for Molecular Genetics, Division of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, 10000, Zagreb, Croatia
- Laboratory for Biology and Microbial Genetics, Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, 10000, Zagreb, Croatia
| | - Lionel Huang
- Equipe Environnement et Microbiologie, MELODY Group, Université de Pau et des Pays de l'Adour, IPREM UMR CNRS 5254, BP 1155, 64013, Pau, Cedex, France
- Euro Engineering, Technopole Hélioparc Bât Newton, 4 rue Jules Ferry, CS N 99207, 64053, Pau, Cedex 09, France
| | - Tom O Delmont
- Equipe Environnement et Microbiologie, MELODY Group, Université de Pau et des Pays de l'Adour, IPREM UMR CNRS 5254, BP 1155, 64013, Pau, Cedex, France
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biology Laboratory, Woods Hole, MA, USA
| | - Dušica Vujaklija
- Laboratory for Molecular Genetics, Division of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, 10000, Zagreb, Croatia
| | - Robert Duran
- Equipe Environnement et Microbiologie, MELODY Group, Université de Pau et des Pays de l'Adour, IPREM UMR CNRS 5254, BP 1155, 64013, Pau, Cedex, France
| | - Christine Cagnon
- Equipe Environnement et Microbiologie, MELODY Group, Université de Pau et des Pays de l'Adour, IPREM UMR CNRS 5254, BP 1155, 64013, Pau, Cedex, France.
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Abstract
Integrons are versatile gene acquisition systems commonly found in bacterial genomes. They are ancient elements that are a hot spot for genomic complexity, generating phenotypic diversity and shaping adaptive responses. In recent times, they have had a major role in the acquisition, expression, and dissemination of antibiotic resistance genes. Assessing the ongoing threats posed by integrons requires an understanding of their origins and evolutionary history. This review examines the functions and activities of integrons before the antibiotic era. It shows how antibiotic use selected particular integrons from among the environmental pool of these elements, such that integrons carrying resistance genes are now present in the majority of Gram-negative pathogens. Finally, it examines the potential consequences of widespread pollution with the novel integrons that have been assembled via the agency of human antibiotic use and speculates on the potential uses of integrons as platforms for biotechnology.
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Harms K, Starikova I, Johnsen PJ. Costly Class-1 integrons and the domestication of the the functional integrase. Mob Genet Elements 2014; 3:e24774. [PMID: 23914313 PMCID: PMC3681742 DOI: 10.4161/mge.24774] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 04/15/2013] [Accepted: 04/22/2013] [Indexed: 11/19/2022] Open
Abstract
Class-1 integrons play an important role in the emergence and spread of antimicrobial resistance determinants. In a recent study we showed that host fitness was dramatically reduced following acquisition of these elements. These fitness costs were due to the presence of an active integrase and we suggested that the mechanistic explanation was due to reduced genetic stability through IntI1 mediated recombination events between attI/attC and non-canonical sites in the chromosome. Here we demonstrate that the attI degenerated target sequence is highly prevalent in our model organism Acinetobacter baylyi adding support to the hypothesis that IntI1 is costly due to genomic instability.
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Affiliation(s)
- Klaus Harms
- Department of Pharmacy, Faculty of Health Sciences, University of Tromsø, Norway
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Darrasse A, Carrère S, Barbe V, Boureau T, Arrieta-Ortiz ML, Bonneau S, Briand M, Brin C, Cociancich S, Durand K, Fouteau S, Gagnevin L, Guérin F, Guy E, Indiana A, Koebnik R, Lauber E, Munoz A, Noël LD, Pieretti I, Poussier S, Pruvost O, Robène-Soustrade I, Rott P, Royer M, Serres-Giardi L, Szurek B, van Sluys MA, Verdier V, Vernière C, Arlat M, Manceau C, Jacques MA. Genome sequence of Xanthomonas fuscans subsp. fuscans strain 4834-R reveals that flagellar motility is not a general feature of xanthomonads. BMC Genomics 2013; 14:761. [PMID: 24195767 PMCID: PMC3826837 DOI: 10.1186/1471-2164-14-761] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 10/26/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Xanthomonads are plant-associated bacteria responsible for diseases on economically important crops. Xanthomonas fuscans subsp. fuscans (Xff) is one of the causal agents of common bacterial blight of bean. In this study, the complete genome sequence of strain Xff 4834-R was determined and compared to other Xanthomonas genome sequences. RESULTS Comparative genomics analyses revealed core characteristics shared between Xff 4834-R and other xanthomonads including chemotaxis elements, two-component systems, TonB-dependent transporters, secretion systems (from T1SS to T6SS) and multiple effectors. For instance a repertoire of 29 Type 3 Effectors (T3Es) with two Transcription Activator-Like Effectors was predicted. Mobile elements were associated with major modifications in the genome structure and gene content in comparison to other Xanthomonas genomes. Notably, a deletion of 33 kbp affects flagellum biosynthesis in Xff 4834-R. The presence of a complete flagellar cluster was assessed in a collection of more than 300 strains representing different species and pathovars of Xanthomonas. Five percent of the tested strains presented a deletion in the flagellar cluster and were non-motile. Moreover, half of the Xff strains isolated from the same epidemic than 4834-R was non-motile and this ratio was conserved in the strains colonizing the next bean seed generations. CONCLUSIONS This work describes the first genome of a Xanthomonas strain pathogenic on bean and reports the existence of non-motile xanthomonads belonging to different species and pathovars. Isolation of such Xff variants from a natural epidemic may suggest that flagellar motility is not a key function for in planta fitness.
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Affiliation(s)
- Armelle Darrasse
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, F-49071, Beaucouzé, France
- AGROCAMPUS OUEST, UMR1345 Institut de Recherche en Horticulture et Semences, F-49045, Angers, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR 4207 QUASAV, PRES L’UNAM, F-49045, Angers, France
| | - Sébastien Carrère
- INRA, LIPM UMR 441, F-31326, Castanet-Tolosan, France
- CNRS, LIPM UMR 2594, F-31326, Castanet-Tolosan, France
| | - Valérie Barbe
- CEA, Genoscope, Centre National de Séquençage, F-91057, Evry Cedex, France
| | - Tristan Boureau
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, F-49071, Beaucouzé, France
- AGROCAMPUS OUEST, UMR1345 Institut de Recherche en Horticulture et Semences, F-49045, Angers, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR 4207 QUASAV, PRES L’UNAM, F-49045, Angers, France
| | - Mario L Arrieta-Ortiz
- Universidad de Los Andes, Laboratorio de Micología y Fitopatología Uniandes, Bogotá, Colombia
- current address: Department of Biology, Center for Genomics and Systems Biology, New York University, 10003, New York, NY, USA
| | - Sophie Bonneau
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, F-49071, Beaucouzé, France
- AGROCAMPUS OUEST, UMR1345 Institut de Recherche en Horticulture et Semences, F-49045, Angers, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR 4207 QUASAV, PRES L’UNAM, F-49045, Angers, France
| | - Martial Briand
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, F-49071, Beaucouzé, France
- AGROCAMPUS OUEST, UMR1345 Institut de Recherche en Horticulture et Semences, F-49045, Angers, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR 4207 QUASAV, PRES L’UNAM, F-49045, Angers, France
| | - Chrystelle Brin
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, F-49071, Beaucouzé, France
- AGROCAMPUS OUEST, UMR1345 Institut de Recherche en Horticulture et Semences, F-49045, Angers, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR 4207 QUASAV, PRES L’UNAM, F-49045, Angers, France
| | | | - Karine Durand
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, F-49071, Beaucouzé, France
- AGROCAMPUS OUEST, UMR1345 Institut de Recherche en Horticulture et Semences, F-49045, Angers, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR 4207 QUASAV, PRES L’UNAM, F-49045, Angers, France
| | - Stéphanie Fouteau
- CEA, Genoscope, Centre National de Séquençage, F-91057, Evry Cedex, France
| | - Lionel Gagnevin
- CIRAD, UMR PVBMT, F-97410, Saint-Pierre, La Réunion, France
- Université de la Réunion, UMR PVBMT, F-97715, Saint-Denis, La Réunion, France
| | - Fabien Guérin
- CIRAD, UMR PVBMT, F-97410, Saint-Pierre, La Réunion, France
- Université de la Réunion, UMR PVBMT, F-97715, Saint-Denis, La Réunion, France
| | - Endrick Guy
- INRA, LIPM UMR 441, F-31326, Castanet-Tolosan, France
- CNRS, LIPM UMR 2594, F-31326, Castanet-Tolosan, France
| | - Arnaud Indiana
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, F-49071, Beaucouzé, France
- AGROCAMPUS OUEST, UMR1345 Institut de Recherche en Horticulture et Semences, F-49045, Angers, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR 4207 QUASAV, PRES L’UNAM, F-49045, Angers, France
| | - Ralf Koebnik
- IRD, UMR RPB, F-34394, Montpellier Cedex 5, France
| | - Emmanuelle Lauber
- INRA, LIPM UMR 441, F-31326, Castanet-Tolosan, France
- CNRS, LIPM UMR 2594, F-31326, Castanet-Tolosan, France
| | - Alejandra Munoz
- Universidad de Los Andes, Laboratorio de Micología y Fitopatología Uniandes, Bogotá, Colombia
| | - Laurent D Noël
- INRA, LIPM UMR 441, F-31326, Castanet-Tolosan, France
- CNRS, LIPM UMR 2594, F-31326, Castanet-Tolosan, France
| | | | - Stéphane Poussier
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, F-49071, Beaucouzé, France
- AGROCAMPUS OUEST, UMR1345 Institut de Recherche en Horticulture et Semences, F-49045, Angers, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR 4207 QUASAV, PRES L’UNAM, F-49045, Angers, France
- Université de la Réunion, UMR PVBMT, F-97715, Saint-Denis, La Réunion, France
| | - Olivier Pruvost
- CIRAD, UMR PVBMT, F-97410, Saint-Pierre, La Réunion, France
- Université de la Réunion, UMR PVBMT, F-97715, Saint-Denis, La Réunion, France
| | - Isabelle Robène-Soustrade
- CIRAD, UMR PVBMT, F-97410, Saint-Pierre, La Réunion, France
- Université de la Réunion, UMR PVBMT, F-97715, Saint-Denis, La Réunion, France
| | - Philippe Rott
- CIRAD, UMR BGPI, F-34398, Montpellier Cedex 5, France
| | - Monique Royer
- CIRAD, UMR BGPI, F-34398, Montpellier Cedex 5, France
| | - Laurana Serres-Giardi
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, F-49071, Beaucouzé, France
- AGROCAMPUS OUEST, UMR1345 Institut de Recherche en Horticulture et Semences, F-49045, Angers, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR 4207 QUASAV, PRES L’UNAM, F-49045, Angers, France
| | - Boris Szurek
- IRD, UMR RPB, F-34394, Montpellier Cedex 5, France
| | | | | | - Christian Vernière
- CIRAD, UMR PVBMT, F-97410, Saint-Pierre, La Réunion, France
- Université de la Réunion, UMR PVBMT, F-97715, Saint-Denis, La Réunion, France
| | - Matthieu Arlat
- INRA, LIPM UMR 441, F-31326, Castanet-Tolosan, France
- CNRS, LIPM UMR 2594, F-31326, Castanet-Tolosan, France
- Université de Toulouse, Université Paul Sabatier, UMR LIPM, F-31326, Castanet-Tolosan Cedex, France
| | - Charles Manceau
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, F-49071, Beaucouzé, France
- AGROCAMPUS OUEST, UMR1345 Institut de Recherche en Horticulture et Semences, F-49045, Angers, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR 4207 QUASAV, PRES L’UNAM, F-49045, Angers, France
- current address: ANSES, Laboratoire de Santé des végétaux, F-49044, Angers, France
| | - Marie-Agnès Jacques
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, F-49071, Beaucouzé, France
- AGROCAMPUS OUEST, UMR1345 Institut de Recherche en Horticulture et Semences, F-49045, Angers, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR 4207 QUASAV, PRES L’UNAM, F-49045, Angers, France
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Analysis of hydrocarbon-contaminated groundwater metagenomes as revealed by high-throughput sequencing. Mol Biotechnol 2013; 54:900-12. [PMID: 23307295 DOI: 10.1007/s12033-012-9639-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The tendency for chlorinated aliphatics and aromatic hydrocarbons to accumulate in environments such as groundwater and sediments poses a serious environmental threat. In this study, the metabolic capacity of hydrocarbon (aromatics and chlorinated aliphatics)-contaminated groundwater in the KwaZulu-Natal province of South Africa has been elucidated for the first time by analysis of pyrosequencing data. The taxonomic data revealed that the metagenomes were dominated by the phylum Proteobacteria (mainly Betaproteobacteria). In addition, Flavobacteriales, Sphingobacteria, Burkholderiales, and Rhodocyclales were the predominant orders present in the individual metagenomes. These orders included microorganisms (Flavobacteria, Dechloromonas aromatica RCB, and Azoarcus) involved in the degradation of aromatic compounds and various other hydrocarbons that were present in the groundwater. Although the metabolic reconstruction of the metagenome represented composite cell networks, the information obtained was sufficient to address questions regarding the metabolic potential of the microbial communities and to correlate the data to the contamination profile of the groundwater. Genes involved in the degradation of benzene and benzoate, heavy metal-resistance mechanisms appeared to provide a survival strategy used by the microbial communities. Analysis of the pyrosequencing-derived data revealed that the metagenomes represent complex microbial communities that have adapted to the geochemical conditions of the groundwater as evidenced by the presence of key enzymes/genes conferring resistance to specific contaminants. Thus, pyrosequencing analysis of the metagenomes provided insights into the microbial activities in hydrocarbon-contaminated habitats.
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Koczura R, Mokracka J, Barczak A, Krysiak N, Kaznowski A. Association between the presence of class 1 integrons, virulence genes, and phylogenetic groups of Escherichia coli isolates from river water. MICROBIAL ECOLOGY 2013; 65:84-90. [PMID: 22903163 PMCID: PMC3541932 DOI: 10.1007/s00248-012-0101-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 07/23/2012] [Indexed: 05/08/2023]
Abstract
Ninety-six class 1 integron-positive and 96 integron-negative Escherichia coli isolates cultured from the water of the Warta River, Poland, were characterized for their phylogenetic group affiliation and for the presence of genes associated with virulence. Most strains belonged to phylogenetic group A, but phylogenetic group affiliation was not related with the presence of integrons. The occurrence of heat-stable toxin gene of enterotoxigenic E. coli, S fimbriae subunit gene sfaS, and siderophore receptor genes, fyuA and iutA, was associated with the presence of class 1 integrons. Moreover, virulence factor score (the total number of virulence-associated genes) was associated with the presence of integrons in groups. The results bring new insight into relations between the presence of integrons in E. coli, virulence traits, as well as phylogenetic group affiliation.
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Affiliation(s)
- Ryszard Koczura
- Department of Microbiology, Faculty of Biology, Adam Mickiewicz University in Poznań, ul. Umultowska 89, 61-614, Poznań, Poland.
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Starikova I, Harms K, Haugen P, Lunde TTM, Primicerio R, Samuelsen Ø, Nielsen KM, Johnsen PJ. A trade-off between the fitness cost of functional integrases and long-term stability of integrons. PLoS Pathog 2012; 8:e1003043. [PMID: 23209414 PMCID: PMC3510236 DOI: 10.1371/journal.ppat.1003043] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 10/05/2012] [Indexed: 11/23/2022] Open
Abstract
Horizontal gene transfer (HGT) plays a major role in bacterial microevolution as evident from the rapid emergence and spread of antimicrobial drug resistance. Few studies have however addressed the population dynamics of newly imported genetic elements after HGT. Here, we show that newly acquired class-1 integrons from Salmonella enterica serovar Typhimurium and Acinetobacter baumannii, free of associated transposable elements, strongly reduce host fitness in Acinetobacter baylyi. Insertional inactivation of the integron intI1 restored fitness, demonstrating that the observed fitness costs were due to the presence of an active integrase. The biological cost of harboring class-1 integrons was rapidly reduced during serial transfers due to intI1 frameshift mutations leading to inactivated integrases. We use a mathematical model to explore the conditions where integrons with functional integrases are maintained and conclude that environmental fluctuations and episodic selection is necessary for the maintenance of functional integrases. Taken together, the presented data suggest a trade-off between the ability to capture gene cassettes and long-term stability of integrons and provide an explanation for the frequent observation of inactive integron-integrases in bacterial populations. Horizontal acquisition of mobile and mobilizable genetic elements plays a major role in the development of antimicrobial drug resistance in bacteria. Despite their causal role in drug treatment failure, there is only limited understanding of how horizontal acquisitions of these elements affect bacterial fitness. A prominent group of such genetic elements are the integrons. These genetic elements harbor an integrase-gene that allows the integron to respond to environmental changes by capture and excision of gene cassettes. Here, we have experimentally determined if horizontal acquisition of an integron affect host fitness. The data demonstrate that the initial costs are substantial. However, inactivation of the integrase gene occurred rapidly by spontaneous mutation alleviating the detrimental effect of the integron on bacterial fitness. The same fitness restoring effects was also shown by targeted inactivation of the integrase gene. The inactivation results in a negative trade-off between host adaptation and loss of the ability to capture new gene cassettes. Importantly, our results explain the frequent observation of inactive integrase genes in integrons found in bacteria of different origins. Finally, we use mathematical modeling to determine the conditions necessary for maintaining functional integrases.
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Affiliation(s)
- Irina Starikova
- Department of Pharmacy, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
| | - Klaus Harms
- Department of Pharmacy, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
| | - Pål Haugen
- Department of Pharmacy, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
| | - Tracy T. M. Lunde
- Reference Centre for Detection of Antimicrobial Resistance, Department of Microbiology and Infection Control, University Hospital of North Norway, Tromsø, Norway
| | - Raul Primicerio
- Department of Pharmacy, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
| | - Ørjan Samuelsen
- Reference Centre for Detection of Antimicrobial Resistance, Department of Microbiology and Infection Control, University Hospital of North Norway, Tromsø, Norway
| | - Kaare M. Nielsen
- Department of Pharmacy, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
- GenØk, Center for Biosafety, Research Park, Tromsø, Norway
| | - Pål J. Johnsen
- Department of Pharmacy, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
- * E-mail:
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Nardelli M, Scalzo PM, Ramírez MS, Quiroga MP, Cassini MH, Centrón D. Class 1 integrons in environments with different degrees of urbanization. PLoS One 2012; 7:e39223. [PMID: 22761743 PMCID: PMC3382206 DOI: 10.1371/journal.pone.0039223] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Accepted: 05/17/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Class 1 integrons are one of the most successful elements in the acquisition, expression and spread of antimicrobial resistance genes (ARG) among clinical isolates. Little is known about the gene flow of the components of the genetic platforms of class 1 integrons within and between bacterial communities. Thus it is important to better understand the interactions among "environmental" intI1, its genetic platforms and its distribution with human activities. METHODOLOGY/PRINCIPAL FINDINGS An evaluation of two types of genetic determinants, ARG (sul1 and qacE1/qacEΔ1 genes) and lateral genetic elements (LGE) (intI1, ISCR1 and tniC genes) in a model of a culture-based method without antibiotic selection was conducted in a gradient of anthropogenic disturbances in a Patagonian island recognized as being one of the last regions containing wild areas. The intI1, ISCR1 genes and intI1 pseudogenes that were found widespread throughout natural communities were not associated with urbanization (p>0.05). Each ARG that is embedded in the most common genetic platform of clinical class 1 integrons, showed different ecological and molecular behaviours in environmental samples. While the sul1 gene frequency was associated with urbanization, the qacE1/qacEΔ1 gene showed an adaptive role to several habitats. CONCLUSIONS/SIGNIFICANCE The high frequency of intI1 pseudogenes suggests that, although intI1 has a deleterious impact within several genomes, it can easily be disseminated among natural bacterial communities. The widespread occurrence of ISCR1 and intI1 throughout Patagonian sites with different degree of urbanization, and within different taxa, could be one of the causes of the increasing frequency of multidrug-resistant isolates that have characterized Argentina for decades. The flow of ARG and LGE between natural and clinical communities cannot be explained with a single general process but is a direct consequence of the interaction of multiple factors operating at molecular, ecological, phylogenetic and historical levels.
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Affiliation(s)
- Maximiliano Nardelli
- Laboratorio de Investigaciones de los Mecanismos de Resistencia a Antibióticos, Facultad de Medicina, Instituto de Microbiología y Parasitología Médica (IMPaM, UBA-CONICET), Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
| | - Paula Marina Scalzo
- Laboratorio de Investigaciones de los Mecanismos de Resistencia a Antibióticos, Facultad de Medicina, Instituto de Microbiología y Parasitología Médica (IMPaM, UBA-CONICET), Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
| | - María Soledad Ramírez
- Laboratorio de Investigaciones de los Mecanismos de Resistencia a Antibióticos, Facultad de Medicina, Instituto de Microbiología y Parasitología Médica (IMPaM, UBA-CONICET), Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
| | - María Paula Quiroga
- Laboratorio de Investigaciones de los Mecanismos de Resistencia a Antibióticos, Facultad de Medicina, Instituto de Microbiología y Parasitología Médica (IMPaM, UBA-CONICET), Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
| | - Marcelo Hernán Cassini
- Grupo GEMA, Departamento de Ciencias Básicas, Universidad Nacional de Luján, Luján, Buenos Aires, Argentina
- Laboratorio de Biología del Comportamiento, IBYME, Ciudad Autónoma de Buenos Aires, Argentina
| | - Daniela Centrón
- Laboratorio de Investigaciones de los Mecanismos de Resistencia a Antibióticos, Facultad de Medicina, Instituto de Microbiología y Parasitología Médica (IMPaM, UBA-CONICET), Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
- * E-mail:
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Koczura R, Mokracka J, Jabłońska L, Gozdecka E, Kubek M, Kaznowski A. Antimicrobial resistance of integron-harboring Escherichia coli isolates from clinical samples, wastewater treatment plant and river water. THE SCIENCE OF THE TOTAL ENVIRONMENT 2012; 414:680-5. [PMID: 22119028 DOI: 10.1016/j.scitotenv.2011.10.036] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Revised: 10/19/2011] [Accepted: 10/19/2011] [Indexed: 05/08/2023]
Abstract
The presence and persistence of antibiotic resistant bacteria in the environment is thought to be a growing threat to public health. The route of the spread of multiresistant bacteria from human communities to aquatic environment may lead through wastewater treatment plants that release treated wastewater to a water reservoir. In this study we used multiplex PCR assay to determine the frequency of integron presence in Escherichia coli isolates cultured from wastewater treatment plant (WWTP) (integrons were detected in 11% of E. coli isolates), river water upstream (6%) and downstream (14%) the discharge of WWTP, and clinical specimens (56%). Antimicrobial resistance of the integron-positive isolates, determined by disk diffusion method, varied between E. coli of different origin. Isolates from the downstream river, compared to those cultured from upstream river, were more frequently resistant to kanamycin, cephalotin, co-trimoxazole, trimethoprim, and fluoroquinolones. Moreover, they displayed broader resistance ranges, expressed as the number of classes of antimicrobials to which they were resistant. The results may suggest that WWTP effluent contributes to increased frequency of integron-positive E. coli isolates in the river downstream the WWTP and to their elevated resistance level.
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Affiliation(s)
- Ryszard Koczura
- Department of Microbiology, Faculty of Biology, A Mickiewicz University, 61-614 Poznań, Poland.
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Elsaied H, Stokes HW, Kitamura K, Kurusu Y, Kamagata Y, Maruyama A. Marine integrons containing novel integrase genes, attachment sites, attI, and associated gene cassettes in polluted sediments from Suez and Tokyo Bays. THE ISME JOURNAL 2011; 5:1162-77. [PMID: 21248857 PMCID: PMC3146285 DOI: 10.1038/ismej.2010.208] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 10/14/2010] [Accepted: 12/14/2010] [Indexed: 11/21/2022]
Abstract
In order to understand the structure and biological significance of integrons and associated gene cassettes in marine polluted sediments, metagenomic DNAs were extracted from sites at Suez and Tokyo Bays. PCR amplicons containing new integrase genes, intI, linked with novel gene cassettes, were recovered and had sizes from 1.8 to 2.5 kb. This approach uncovered, for the first time, the structure and diversity of both marine integron attachment site, attI, and the first gene cassette, the most efficiently expressed integron-associated gene cassette. The recovered 13 and 20 intI phylotypes, from Suez and Tokyo Bay samples, respectively, showed a highly divergence, suggesting a difference in integron composition between the sampling sites. Some intI phylotypes showed similarity with that from Geobacter metallireducens, belonging to Deltaproteobacteria, the dominant class in both sampling sites, as determined by 16S rRNA gene analysis. Thirty distinct families of putative attI site, as determined by the presence of an attI-like simple site, were recovered. A total of 146 and 68 gene cassettes represented Suez and Tokyo Bay unsaturated cassette pools, respectively. Gene cassettes, including a first cassette, from both sampling sites encoded two novel families of glyoxalase/bleomycin antibiotic-resistance protein. Gene cassettes from Suez Bay encoded proteins similar to haloacid dehalogenases, protein disulfide isomerases and death-on-curing and plasmid maintenance system killer proteins. First gene cassettes from Tokyo Bay encoded a xenobiotic-degrading protein, cardiolipin synthetase, esterase and WD40-like β propeller protein. Many of the first gene cassettes encoded proteins with no ascribable function but some of them were duplicated and possessed signal functional sites, suggesting efficient adaptive functions to their bacterial sources. Thus, each sampling site had a specific profile of integrons and cassette types consistent with the hypothesis that the environment shapes the genome.
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Affiliation(s)
- Hosam Elsaied
- Microbial and Genetic Resources Research Group, Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, Higashi Tsukuba, Ibaraki, Japan
- Department of Genetics, National Institute of Oceanography, Cairo, Egypt
| | - Hatch W Stokes
- Institute for the Biotechnology of Infectious Diseases, University of Technology, Sydney, New South Wales, Australia
| | - Keiko Kitamura
- Microbial and Genetic Resources Research Group, Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, Higashi Tsukuba, Ibaraki, Japan
| | - Yasurou Kurusu
- Department of Molecular Microbiology, College of Agriculture, Ibaraki University, Ami, Ibaraki, Japan
| | - Yoichi Kamagata
- Microbial and Genetic Resources Research Group, Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, Higashi Tsukuba, Ibaraki, Japan
| | - Akihiko Maruyama
- Microbial and Genetic Resources Research Group, Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, Higashi Tsukuba, Ibaraki, Japan
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Cambray G, Sanchez-Alberola N, Campoy S, Guerin É, Da Re S, González-Zorn B, Ploy MC, Barbé J, Mazel D, Erill I. Prevalence of SOS-mediated control of integron integrase expression as an adaptive trait of chromosomal and mobile integrons. Mob DNA 2011; 2:6. [PMID: 21529368 PMCID: PMC3108266 DOI: 10.1186/1759-8753-2-6] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 04/30/2011] [Indexed: 11/26/2022] Open
Abstract
Background Integrons are found in hundreds of environmental bacterial species, but are mainly known as the agents responsible for the capture and spread of antibiotic-resistance determinants between Gram-negative pathogens. The SOS response is a regulatory network under control of the repressor protein LexA targeted at addressing DNA damage, thus promoting genetic variation in times of stress. We recently reported a direct link between the SOS response and the expression of integron integrases in Vibrio cholerae and a plasmid-borne class 1 mobile integron. SOS regulation enhances cassette swapping and capture in stressful conditions, while freezing the integron in steady environments. We conducted a systematic study of available integron integrase promoter sequences to analyze the extent of this relationship across the Bacteria domain. Results Our results showed that LexA controls the expression of a large fraction of integron integrases by binding to Escherichia coli-like LexA binding sites. In addition, the results provide experimental validation of LexA control of the integrase gene for another Vibrio chromosomal integron and for a multiresistance plasmid harboring two integrons. There was a significant correlation between lack of LexA control and predicted inactivation of integrase genes, even though experimental evidence also indicates that LexA regulation may be lost to enhance expression of integron cassettes. Conclusions Ancestral-state reconstruction on an integron integrase phylogeny led us to conclude that the ancestral integron was already regulated by LexA. The data also indicated that SOS regulation has been actively preserved in mobile integrons and large chromosomal integrons, suggesting that unregulated integrase activity is selected against. Nonetheless, additional adaptations have probably arisen to cope with unregulated integrase activity. Identifying them may be fundamental in deciphering the uneven distribution of integrons in the Bacteria domain.
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Affiliation(s)
- Guillaume Cambray
- Institut Pasteur, Unité Plasticité du Génome Bactérien, CNRS URA 2171, 75015 Paris, France
| | - Neus Sanchez-Alberola
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.,Department of Biological Sciences, University of Maryland Baltimore County, Baltimore 21228, USA
| | - Susana Campoy
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Émilie Guerin
- Université de Limoges, Faculté de Médecine, EA3175, INSERM, Equipe Avenir, Limoges 87000, France
| | - Sandra Da Re
- Université de Limoges, Faculté de Médecine, EA3175, INSERM, Equipe Avenir, Limoges 87000, France
| | - Bruno González-Zorn
- Departamento de Sanidad Animal, Facultad de Veterinaria, and VISAVET, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Marie-Cécile Ploy
- Université de Limoges, Faculté de Médecine, EA3175, INSERM, Equipe Avenir, Limoges 87000, France
| | - Jordi Barbé
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore 21228, USA
| | - Didier Mazel
- Institut Pasteur, Unité Plasticité du Génome Bactérien, CNRS URA 2171, 75015 Paris, France
| | - Ivan Erill
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore 21228, USA
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Frye JG, Lindsey RL, Meinersmann RJ, Berrang ME, Jackson CR, Englen MD, Turpin JB, Fedorka-Cray PJ. Related antimicrobial resistance genes detected in different bacterial species co-isolated from swine fecal samples. Foodborne Pathog Dis 2011; 8:663-79. [PMID: 21385089 DOI: 10.1089/fpd.2010.0695] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
A potential factor leading to the spread of antimicrobial resistance (AR) in bacteria is the horizontal transfer of resistance genes between bacteria in animals or their environment. To investigate this, swine fecal samples were collected on-farm and cultured for Escherichia coli, Salmonella enterica, Campylobacter spp., and Enterococcus spp. which are all commonly found in swine. Forty-nine of the samples from which all four bacteria were recovered were selected yielding a total of 196 isolates for analysis. Isolates were tested for antimicrobial susceptibility followed by hybridization to a DNA microarray designed to detect 775 AR-related genes. E. coli and Salmonella isolated from the same fecal sample had the most AR genes in common among the four bacteria. Genes detected encoded resistance to aminoglycosides (aac(3), aadA1, aadB, and strAB), β-lactams (ampC, ampR, and bla(TEM)), chloramphenicols (cat and floR), sulfanillic acid (sul1/sulI), tetracyclines (tet(A), tet(D), tet(C), tet(G), and tet(R)), and trimethoprim (dfrA1 and dfh). Campylobacter coli and Enterococcus isolated from the same sample frequently had tet(O) and aphA-3 genes detected in common. Almost half (47%) of E. coli and Salmonella isolated from the same fecal sample shared resistance genes at a significant level (χ², p < 0.0000001). These data suggest that there may have been horizontal exchange of AR genes between these bacteria or there may be a common source of AR genes in the swine environment for E. coli and Salmonella.
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Affiliation(s)
- Jonathan G Frye
- Bacterial Epidemiology and Antimicrobial Resistance Research Unit, Richard B. Russell Research Center, Agricultural Research Service, U.S. Department of Agriculture, Athens, Georgia 30605, USA.
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Koczura R, Mokracka J, Krzymińska S, Kaznowski A. Virulence properties and integron-associated antibiotic resistance of Klebsiella mobilis strains isolated from clinical specimens. J Med Microbiol 2011; 60:281-288. [DOI: 10.1099/jmm.0.024059-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
This study examined Klebsiella mobilis isolates cultured from clinical specimens for virulence-associated properties and antibiotic resistance. The strains produced a number of siderophores, including enterobactin, aerobactin and yersiniabactin. All isolates were able to adhere to and invade epithelial cells. They had cytotoxic activity, which caused destruction of human laryngeal epithelial HEp-2 cells and evoked lysis of murine macrophage J774 cells. Analyses of HEp-2 and J774 cellular morphology and DNA fragmentation in the cells showed features typical of cells undergoing apoptosis. Some K. mobilis strains harboured class 1 integrons carrying the aadA1 gene encoding an aminoglycoside adenyltransferase.
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Affiliation(s)
- Ryszard Koczura
- Department of Microbiology, Faculty of Biology, A. Mickiewicz University, Poznań, Poland
| | - Joanna Mokracka
- Department of Microbiology, Faculty of Biology, A. Mickiewicz University, Poznań, Poland
| | - Sylwia Krzymińska
- Department of Microbiology, Faculty of Biology, A. Mickiewicz University, Poznań, Poland
| | - Adam Kaznowski
- Department of Microbiology, Faculty of Biology, A. Mickiewicz University, Poznań, Poland
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Napolitano MG, Almagro-Moreno S, Boyd EF. Dichotomy in the evolution of pathogenicity island and bacteriophage encoded integrases from pathogenic Escherichia coli strains. INFECTION GENETICS AND EVOLUTION 2011; 11:423-36. [DOI: 10.1016/j.meegid.2010.12.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 12/01/2010] [Accepted: 12/01/2010] [Indexed: 11/29/2022]
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Xu Z, Li L, Shi L, Shirtliff ME. Class 1 integron in staphylococci. Mol Biol Rep 2011; 38:5261-79. [PMID: 21258866 DOI: 10.1007/s11033-011-0676-7] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2010] [Accepted: 01/10/2011] [Indexed: 10/18/2022]
Abstract
As a major concern in public health, methicillin-resistant staphylococci (MRS) still remains one of the most prevalent pathogens that cause nosocomial infections throughout the world and has been recently labeled as a "super bug" in antibiotic resistance. Thus, surveillance and investigation on antibiotic resistance mechanisms involved in clinical MRS strains may raise urgent necessity and utmost significance. As a novel antibiotic resistance mechanism, class 1 integron has been identified as a primary source of antimicrobial resistance genes in Gram-negative organisms. However, most available studies on integrons had been limited within Gram-negative microbes, little is known for clinical Gram-positive bacteria. Based on series studies of systematic integrons investigation in hundreds of staphylococci strains during 2001-2006, this review concentrated on the latest development of class 1 integron in MRS isolates, including summary of prevalence and occurrence of class 1 integron, analysis of correlation between integron and antibiotic resistance, further demonstration of the role integrons play as antibiotic determinants, as well as origin and evolution of integron-associated gene cassettes during this study period.
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Affiliation(s)
- Zhenbo Xu
- College of Light Industry and Food Sciences, South China University of Technology, Guangzhou, China
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Affiliation(s)
- Guillaume Cambray,
- Institut Pasteur, Unité Plasticité du Génome Bactérien, Département Génomes et Génétique, F-75015 Paris, France;
- CNRS, URA2171, F-75015 Paris, France
| | - Anne-Marie Guerout,
- Institut Pasteur, Unité Plasticité du Génome Bactérien, Département Génomes et Génétique, F-75015 Paris, France;
- CNRS, URA2171, F-75015 Paris, France
| | - Didier Mazel
- Institut Pasteur, Unité Plasticité du Génome Bactérien, Département Génomes et Génétique, F-75015 Paris, France;
- CNRS, URA2171, F-75015 Paris, France
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Michael CA, Labbate M. Gene cassette transcription in a large integron-associated array. BMC Genet 2010; 11:82. [PMID: 20843359 PMCID: PMC2945992 DOI: 10.1186/1471-2156-11-82] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2010] [Accepted: 09/15/2010] [Indexed: 11/16/2022] Open
Abstract
Background The integron/gene cassette system is a diverse and effective adaptive resource for prokaryotes. Short cassette arrays, with less than 10 cassettes adjacent to an integron, provide this resource through the expression of cassette-associated genes by an integron-borne promoter. However, the advantage provided by large arrays containing hundreds of cassettes is less obvious. In this work, using the 116-cassette array of Vibrio sp. DAT722 as a model, we investigated the theory that the majority of genes contained within large cassette arrays are widely expressed by intra-array promoters in addition to the integron-borne promoter. Results We demonstrated that the majority of the cassette-associated genes in the subject array were expressed. We further showed that cassette expression was conditional and that the conditionality varied across the array. We finally showed that this expression was mediated by a diversity of cassette-borne promoters within the array capable of responding to environmental stressors. Conclusions Widespread expression within large gene cassette arrays could provide an adaptive advantage to the host in proportion to the size of the array. Our findings explained the existence and maintenance of large cassette arrays within many prokaryotes. Further, we suggested that repeated rearrangement of cassettes containing genes and/or promoters within large arrays could result in the assembly of operon-like groups of co-expressed cassettes within an array. These findings add to our understanding of the adaptive repertoire of the integron/gene cassette system in prokaryotes and consequently, the evolutionary impact of this system.
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Affiliation(s)
- Carolyn A Michael
- Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia.
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Michael CA, Andrew NR. Co-assortment in integron-associated gene cassette assemblages in environmental DNA samples. BMC Genet 2010; 11:75. [PMID: 20698953 PMCID: PMC2927473 DOI: 10.1186/1471-2156-11-75] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Accepted: 08/10/2010] [Indexed: 12/02/2022] Open
Abstract
Background It has been shown that integron-associated gene cassettes exist largely in tandem arrays of variable size, ranging from antibiotic resistance arrays of three to five cassettes up to arrays of more than 100 cassettes associated with the vibrios. Further, the ecology of the integron/gene cassette system has been investigated by showing that very many different cassettes are present in even small environmental samples. In this study, we seek to extend the ecological perspective on the integron/gene cassette system by investigating the way in which this diverse cassette metagenome is apportioned amongst prokaryote lineages in a natural environment. Results We used a combination of PCR-based techniques applied to environmental DNA samples and ecological analytical techniques to establish co-assortment within cassette populations, then establishing the relationship between this co-assortment and genomic structures. We then assessed the distribution of gene cassettes within the environment and found that the majority of gene cassettes existed in large co-assorting groups. Conclusions Our results suggested that the gene cassette diversity of a relatively pristine sampling environment was structured into co-assorting groups, predominantly containing large numbers of cassettes per group. These co-assorting groups consisted of different gene cassettes in stoichiometric relationship. Conservatively, we then attributed co-assorting cassettes to the gene cassette complements of single prokaryote lineages and by implication, to large integron-associated arrays. The prevalence of large arrays in the environment raises new questions about the assembly, maintenance and utility of large cassette arrays in prokaryote populations.
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Affiliation(s)
- Carolyn A Michael
- Department of Biology, Macquarie University, Sydney, NSW, Australia.
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Expressed genome of Methylobacillus flagellatus as defined through comprehensive proteomics and new insights into methylotrophy. J Bacteriol 2010; 192:4859-67. [PMID: 20639322 DOI: 10.1128/jb.00512-10] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In recent years, techniques have been developed and perfected for high-throughput identification of proteins and their accurate partial sequencing by shotgun nano-liquid chromatography-tandem mass spectrometry (nano-LC-MS/MS), making it feasible to assess global protein expression profiles in organisms with sequenced genomes. We implemented comprehensive proteomics to assess the expressed portion of the genome of Methylobacillus flagellatus during methylotrophic growth. We detected a total of 1,671 proteins (64% of the inferred proteome), including all the predicted essential proteins. Nonrandom patterns observed with the nondetectable proteins appeared to correspond to silent genomic islands, as inferred through functional profiling and genome localization. The protein contents in methylamine- and methanol-grown cells showed a significant overlap, confirming the commonality of methylotrophic metabolism downstream of the primary oxidation reactions. The new insights into methylotrophy include detection of proteins for the N-methylglutamate methylamine oxidation pathway that appears to be auxiliary and detection of two alternative enzymes for both the 6-phosphogluconate dehydrogenase reaction (GndA and GndB) and the formate dehydrogenase reaction (FDH1 and FDH4). Mutant analysis revealed that GndA and FDH4 are crucial for the organism's fitness, while GndB and FDH1 are auxiliary.
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Pérez-Valdespino A, Fernández-Rendón E, Curiel-Quesada E. Detection and characterization of class 1 integrons in Aeromonas spp. isolated from human diarrheic stool in Mexico. J Basic Microbiol 2010; 49:572-8. [PMID: 19810047 DOI: 10.1002/jobm.200900095] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We determined the presence of class 1 integrons related to the acquisition of resistance to antimicrobials in Aeromonas spp. isolated from individuals with diarrhea. Species were identified as A. caviae, A. hydrophila, A. veronii and A. media using PCR-RFLP of the 16S rDNA. Selected isolates were further characterized by ERIC-PCR. Resistance to chloramphenicol, aztreonam, tetracycline, trimethoprim/sulfamethoxazole, nalidixic acid and streptomycin, among others, was determined using the Kirby-Bauer method. Integrons were detected by PCR amplification of the 5' conserved, variable, and 3' conserved regions. Sequencing of the variable regions revealed class 1 integrons with cassettes encoding resistance to trimethoprim (dfrA12, dfrA15, dfrB4), streptomycin/spectinomycin (aadA2, aadA1), oxacillin (oxa2) and chloramphenicol (catB3, cmlA4). Others had an open reading frame (orfD) or no insert at all. To our knowledge, this is the first description of the occurrence of genes cmlA4 and dfrA15 in Aeromonas class 1 integrons. Not all the integron-linked cassettes conferred their associated resistances, which suggests the inactivity of some cassettes. Most integrons were chromosomally located. The presence of class 1 integrons similar to those found in a wide variety of bacterial genera from different origins, including environmental and fish-borne Aeromonas, confirms the stability and horizontal transfer of these genetic elements.
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Affiliation(s)
- Abigail Pérez-Valdespino
- Department of Biochemistry, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Prolongación de Carpio y Plan de Ayala S/N, Col. Santo Tomás, CP 11340. Mexico City, Mexico
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Rosewarne CP, Pettigrove V, Stokes HW, Parsons YM. Class 1 integrons in benthic bacterial communities: abundance, association with Tn402-like transposition modules and evidence for coselection with heavy-metal resistance. FEMS Microbiol Ecol 2009; 72:35-46. [PMID: 20132306 DOI: 10.1111/j.1574-6941.2009.00823.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The integron/gene cassette system contributes to lateral gene transfer of genetic information in bacterial communities, with gene cassette-encoded proteins potentially playing an important role in adaptation to stress. Class 1 integrons are a particularly important class as they themselves seem to be broadly disseminated among the Proteobacteria and have an established role in the spread of antibiotic resistance genes. The abundance and structure of class 1 integrons in freshwater sediment bacterial communities was assessed through sampling of 30 spatially distinct sites encompassing different substrate and catchment types from the Greater Melbourne Area of Victoria, Australia. Real-time PCR was used to demonstrate that the abundance of intI1 was increased as a result of ecosystem perturbation, indicated by classification of sample locations based on the catchment type and a strong positive correlation with the first principal component factor score, comprised primarily of the heavy metals zinc, mercury, lead and copper. Additionally, the abundance of intI1 at sites located downstream from treated sewage outputs was associated with the percentage contribution of the discharge to the basal flow rate. Characterization of class 1 integrons in bacteria cultured from selected sediment samples identified an association with complete Tn402-like transposition modules, and the potential for coselection of heavy-metal and antibiotic resistance mechanisms in benthic environments.
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Affiliation(s)
- Carly P Rosewarne
- Department of Genetics, La Trobe University, Bundoora, Vic., Australia.
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Pinilla G, Muñoz L, Ruiz AI, Chavarro B, Cifuentes Y. Aislamiento de Staphylococcus epidermidis portador de integrón clase 1 en un paciente con sepsis neonatal. INFECTIO 2009. [DOI: 10.1016/s0123-9392(09)70150-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Worldwide prevalence of class 2 integrases outside the clinical setting is associated with human impact. Appl Environ Microbiol 2009; 75:5100-10. [PMID: 19502434 DOI: 10.1128/aem.00133-09] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An intI-targeted PCR assay was optimized to evaluate the frequency of partial class 2-like integrases relative to putative, environmental IntI elements in clone libraries generated from 17 samples that included various terrestrial, marine, and deep-sea habitats with different exposures to human influence. We identified 169 unique IntI phylotypes (< or =98% amino acid identity) relative to themselves and with respect to those previously described. Among these, six variants showed an undescribed, extended, IntI-specific additional domain. A connection between human influence and the dominance of IntI-2-like variants was also observed. IntI phylotypes 80 to 99% identical to class 2 integrases comprised approximately 70 to 100% (n = 65 to 87) of the IntI elements detected in samples with a high input of fecal waste, whereas IntI2-like sequences were undetected in undisturbed settings and poorly represented (1 to 10%; n = 40 to 79) in environments with moderate or no recent fecal or anthropogenic impact. Eleven partial IntI2-like sequences lacking the signature ochre 179 codon were found among samples of biosolids and agricultural soil supplemented with swine manure, indicating a wider distribution of potentially functional IntI2 variants than previously reported. To evaluate IntI2 distribution patterns beyond the usual hosts, namely, the Enterobacteriaceae, we coupled PCR assays targeted at intI and 16S rRNA loci to G+C fractionation of total DNA extracted from manured cropland. IntI2-like sequences and 16S rRNA phylotypes related to Firmicutes (Clostridium and Bacillus) and Bacteroidetes (Chitinophaga and Sphingobacterium) dominated a low-G+C fraction ( approximately 40 to 45%), suggesting that these groups could be important IntI2 hosts in manured soil. Moreover, G+G fractionation uncovered an additional set of 36 novel IntI phylotypes (< or =98% amino acid identity) undetected in bulk DNA and revealed the prevalence of potentially functional IntI2 variants in the low-G+C fraction.
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Quiroga C, Centrón D. Using Genomic Data to Determine the Diversity and Distribution of Target Site Motifs Recognized by Class C-attC Group II Introns. J Mol Evol 2009; 68:539-49. [DOI: 10.1007/s00239-009-9228-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Revised: 03/27/2009] [Accepted: 03/31/2009] [Indexed: 01/31/2023]
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Gillings MR, Holley MP, Stokes HW. Evidence for dynamic exchange of qac gene cassettes between class 1 integrons and other integrons in freshwater biofilms. FEMS Microbiol Lett 2009; 296:282-8. [PMID: 19459951 DOI: 10.1111/j.1574-6968.2009.01646.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Class 1 integrons carried by pathogens have acquired over 100 different gene cassettes encoding resistance to antimicrobial compounds, helping to generate a crisis in the management of infectious disease. It is presumed that these cassettes originated from environmental bacteria, but exchange of gene cassettes has surprisingly never been demonstrated outside laboratory or clinical contexts. We aimed to identify a natural environment where such exchanges might occur, and determine the phylogenetic range of participating integrons. Here we examine freshwater biofilms and show that families of cassettes conferring resistance to quaternary ammonium compounds (qac) are found on class 1 integrons identical to those from clinical contexts, on sequence variants of class 1 integrons only known from natural environments, and on other diverse classes of integrons only known from the chromosomes of soil and freshwater Proteobacteria. We conclude that gene cassettes might be readily shared between different integron classes found in environmental, commensal and pathogenic bacteria. This suggests that class 1 integrons in pathogens have access to a vast pool of gene cassettes, any of which could confer a phenotype of clinical relevance. Exploration of this resource might allow identification of resistance or virulence genes before they become part of multi-drug-resistant human pathogens.
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Affiliation(s)
- Michael R Gillings
- Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia.
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Abstract
New concepts have emerged in the past few years that help us to better understand the emergence and spread of antimicrobial resistance (AMR). These include, among others, the discovery of the mutator state and the concept of mutant selection window for resistances emerging primarily through mutations in existing genes. Our understanding of horizontal gene transfer has also evolved significantly in the past few years, and important new mechanisms of AMR transfer have been discovered, including, among others, integrative conjugative elements and ISCR (insertion sequences with common regions) elements. Simultaneously, large-scale studies have helped us to start comprehending the immense and yet untapped reservoir of both AMR genes and mobile genetic elements present in the environment. Finally, new PCR- and DNA sequencing-based techniques are being developed that will allow us to better understand the epidemiology of classical vectors of AMR genes, such as plasmids, and to monitor them in a more global and systematic way.
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Shearer JE, Summers AO. Intracellular Steady-State Concentration of Integron Recombination Products Varies with Integrase Level and Growth Phase. J Mol Biol 2009; 386:316-31. [DOI: 10.1016/j.jmb.2008.12.041] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Revised: 12/04/2008] [Accepted: 12/16/2008] [Indexed: 10/21/2022]
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