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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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Zhang X, Li X, Wang W, Qi J, Wang D, Xu L, Liu Y, Zhang Y, Guo K. Diverse Gene Cassette Arrays Prevail in Commensal Escherichia coli From Intensive Farming Swine in Four Provinces of China. Front Microbiol 2020; 11:565349. [PMID: 33154738 PMCID: PMC7591504 DOI: 10.3389/fmicb.2020.565349] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 09/01/2020] [Indexed: 12/14/2022] Open
Abstract
Multiple-drug resistance bacteria containing antimicrobial resistance genes (ARGs) are a concern for public health. Integrons are bacterial genetic elements that can capture, rearrange, and express mobile gene cassettes responsible for the spread of ARGs. Few studies link genotype and phenotype of swine-related ARGs in the context of mobile gene cassette arrays among commensal Escherichia coli (E. coli) in nonclinical livestock isolates from intensive farms. In the present study, a total of 264 isolates were obtained from 330 rectal swabs to determine the prevalence and characteristics of antibiotic-resistant gene being carried by commensal E. coli in the healthy swine from four intensive farms at Anhui, Hebei, Shanxi, and Shaanxi, in China. Antimicrobial resistance phenotypes of the recovered isolates were determined for 19 antimicrobials. The E. coli isolates were commonly nonsusceptible to doxycycline (75.8%), tetracycline (73.5%), sulfamethoxazole-trimethoprim (71.6%), amoxicillin (68.2%), sulfasalazine (67.1%), ampicillin (58.0%), florfenicol (56.1%), and streptomycin (53.0%), but all isolates were susceptible to imipenem (100%). Isolates [184 (69.7%)] exhibited multiple drug resistance with 11 patterns. Moreover, 197 isolates (74.6%) were detected carrying the integron-integrase gene (intI1) of class 1 integrons. A higher incidence of antimicrobial resistance was observed in the intI1-positive E. coli isolates than in the intI1-negative E. coli isolates. Furthermore, there were 17 kinds of gene cassette arrays in the 70 integrons as detected by sequencing amplicons of variable regions, with 66 isolates (94.3%) expressing their gene cassettes encoding for multiple drug resistance phenotypes for streptomycin, neomycin, gentamicin, kanamycin, amikacin, sulfamethoxazole-trimethoprim, sulfasalazine, and florfenicol. Notably, due to harboring multiple, hybrid, and recombination cassettes, complex cassette arrays were attributed to multiple drug resistance patterns than simple arrays. In conclusion, we demonstrated that the prevalence of multiple drug resistance and the incidence of class 1 integrons were 69.7 and 74.6% in commensal E. coli isolated from healthy swine, which were lower in frequency than that previously reported in China.
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Affiliation(s)
- Xiuping Zhang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China.,College of Animal Science, Tarim University, Alar, China
| | - Xinxin Li
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Weihua Wang
- Weinan Vocational and Technical College, Weinan, China
| | - Jiali Qi
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Dong Wang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Lei Xu
- College of Life Science, Northwest A&F University, Yangling, China
| | - Yong Liu
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Yanming Zhang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Kangkang Guo
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
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The Peril and Promise of Integrons: Beyond Antibiotic Resistance. Trends Microbiol 2020; 28:455-464. [PMID: 31948729 DOI: 10.1016/j.tim.2019.12.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 11/13/2019] [Accepted: 12/09/2019] [Indexed: 12/11/2022]
Abstract
Integrons are bacterial genetic elements that can capture, rearrange, and express mobile gene cassettes. They are best known for their role in disseminating antibiotic-resistance genes among pathogens. Their ability to rapidly spread resistance phenotypes makes it important to consider what other integron-mediated traits might impact human health in the future, such as increased virulence, pathogenicity, or resistance to novel antimicrobial strategies. Exploring the functional diversity of cassettes and understanding their de novo creation will allow better pre-emptive management of bacterial growth, while also facilitating development of technologies that could harness integron activity. If we can control integrons and cassette formation, we could use integrons as a platform for enzyme discovery and to construct novel biochemical pathways, with applications in bioremediation or biosynthesis of industrial and therapeutic molecules. Integron activity thus holds both peril and promise for humans.
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Goswami C, Fox S, Holden M, Connor M, Leanord A, Evans TJ. Genetic analysis of invasive Escherichia coli in Scotland reveals determinants of healthcare-associated versus community-acquired infections. Microb Genom 2018; 4. [PMID: 29932391 PMCID: PMC6096937 DOI: 10.1099/mgen.0.000190] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bacteraemia caused by Escherichia coli is a growing problem with a significant mortality. The factors that influence the acquisition and outcome of these infections are not clear. Here, we have linked detailed genetic data from the whole-genome sequencing of 162 bacteraemic isolates collected in Scotland, UK, in 2013–2015, with clinical data in order to delineate bacterial and host factors that influence the acquisition in hospital or the community, outcome and antibiotic resistance. We identified four major sequence types (STs) in these isolates: ST131, ST69, ST73 and ST95. Nearly 50 % of the bacteraemic isolates had a urinary origin. ST69 was genetically distinct from the other STs, with significantly less sharing of accessory genes and with a distinct plasmid population. Virulence genes were widespread and diversely distributed between the dominant STs. ST131 was significantly associated with hospital-associated infections (HAIs), and ST69 with those from the community. However, there was no association of ST with outcome, although patients with HAI had a higher immediate mortality compared to those with community-associated infections (CAIs). Genome-wide association studies revealed genes involved in antibiotic persistence as significantly associated with HAIs and those encoding elements of a type VI secretion system with CAIs. Antibiotic resistance was common, and there were networks of correlated resistance genes and phenotypic antibiotic resistance. This study has revealed the complex interactions between the genotype of E. coli and its ability to cause bacteraemia, and some of the determinants influencing hospital or community acquisition. In part, these are shaped by antibiotic usage, but strain-specific factors are also important.
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Affiliation(s)
- Cosmika Goswami
- 1Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
| | - Stephen Fox
- 1Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
| | | | | | - Alistair Leanord
- 1Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
| | - Thomas J Evans
- 1Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
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Do Nascimento V, Day MR, Doumith M, Hopkins KL, Woodford N, Godbole G, Jenkins C. Comparison of phenotypic and WGS-derived antimicrobial resistance profiles of enteroaggregative Escherichia coli isolated from cases of diarrhoeal disease in England, 2015–16. J Antimicrob Chemother 2017; 72:3288-3297. [DOI: 10.1093/jac/dkx301] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 07/25/2017] [Indexed: 12/24/2022] Open
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Chen CM, Lai CH, Wu HJ, Wu LT. Genetic characteristic of class 1 integrons in proteus mirabilis isolates from urine samples. Biomedicine (Taipei) 2017; 7:9. [PMID: 28612707 PMCID: PMC5479437 DOI: 10.1051/bmdcn/2017070202] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Accepted: 01/20/2017] [Indexed: 11/14/2022] Open
Abstract
Background: Proteus mirabilis is an opportunistic pathogen, commonly associated with complicated urinary tract infections (UTIs). UTIs caused by multidrug-resistant Proteus mirabilis have increased worldwide. Multidrug-resistance of Gram-negative enteric bacteria is usually associated with class 1 integrons. Purposes: To investigate the prevalence and characterize gene cassettes of class 1 integrons in multidrug-resistant P. mirabilis Methods: From 2006 to 2008, 314 P. mirabilis isolates from urine were collected from a regional teaching hospital. Antimicrobial resistance of the isolates was determined by disk diffusion methods. The phenotypic confirmatory test of extended-spectrum β-lactamase (ESBL) production was performed as described in the Clinical and Laboratory Standards Institute (CLSI) guideline. The genetic organization of the class 1 integron cassettes was investigated by PCR, cloning, and sequencing of the regions surrounding these genes. Results: Seventy-nine (25%, 79/314) P. mirabilis isolates were ESBL-producing and most ESBL-producing P. mirabilis were positive for blaCTX-M. Class 1 integrons were presented in 76 isolates (24.2%, 76/314), and were more frequently found in ESBL-positive (55/79, 70%) than ESBL-negative (21/235, 8.9%) P. mirabilis isolates. The most prevalence of the cassettes encoded resistance genes were aminoglycoside (aac(6’)-Ib, aacA7, aadAl, aadA2, and aadAla), trimethoprim (dfrAl and dfrA12) and chloramphenicol (catB3 and cmlA6). The most prevalent cassette of dfr12-orfF-aadA2 was found in 49 isolates. The cassette array aadB-catB3-oxa10-aadA1 was first found in P. mirabilis. The enterobacterial repetitive intergenic consensus (ERIC)-PCR fingerprinting patterns were detected in these 76 integron positive P. mirabilis isolates and belonged to 8 profiles. Conclusion: This study investigated the prevalence and characterized gene cassettes of class 1 integrons in MDR P. mirabilis isolates from urine samples. The frequency of gene cassettes in P. mirabilis were partially by clonal spread of the carriers and the results could provide information for effective antimicrobial therapy and infection control.
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Affiliation(s)
- Chih-Ming Chen
- Division of Infectious Disease, Department of Internal Medicine, Tungs' Taichung MetroHarbor Hospital, Taichung 433, Taiwan - Department of Health Food, Chung Chou University of Science and Technology, Changhua 510, Taiwan
| | - Chih-Ho Lai
- Graduate Institute of Biomedical Sciences, Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan - Molecular Infectious Disease Research Center, Department of Pediatrics, Chang Gung Children's Hospital and Chang Gung Memorial Hospital, Taoyuan 333, Taiwan - Graduate Institute of Basic Medical Science, School of Medicine, China Medical University, Taichung 404, Taiwan - Department of Medical Research and Department of Laboratory Medicine, China Medical University Hospital, Taichung 404, Taiwan - Department of Nursing, Asia University, Taichung 413, Taiwan
| | - Hwa-Jene Wu
- Department of Clinical Laboratory, Jen-Ai Hospital, Taichung 412, Taiwan
| | - Lii-Tzu Wu
- Graduate Institute of Basic Medical Science, School of Medicine, China Medical University, Taichung 404, Taiwan
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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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Le V, Nhu NTK, Cerdeno-Tarraga A, Campbell JI, Tuyen HT, Nhu TDH, Tam PTT, Schultsz C, Thwaites G, Thomson NR, Baker S. Genetic characterization of three qnrS1-harbouring multidrug-resistance plasmids and qnrS1-containing transposons circulating in Ho Chi Minh City, Vietnam. J Med Microbiol 2015; 64:869-878. [PMID: 26272054 PMCID: PMC4635468 DOI: 10.1099/jmm.0.000100] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Plasmid-mediated quinolone resistance (PMQR) refers to a family of closely related genes that confer decreased susceptibility to fluoroquinolones. PMQR genes are generally associated with integrons and/or plasmids that carry additional antimicrobial resistance genes active against a range of antimicrobials. In Ho Chi Minh City (HCMC), Vietnam, we have previously shown a high frequency of PMQR genes within commensal Enterobacteriaceae. However, there are limited available sequence data detailing the genetic context in which the PMQR genes reside, and a lack of understanding of how these genes spread across the Enterobacteriaceae. Here, we aimed to determine the genetic background facilitating the spread and maintenance of qnrS1, the dominant PMQR gene circulating in HCMC. We sequenced three qnrS1-carrying plasmids in their entirety to understand the genetic context of these qnrS1-embedded plasmids and also the association of qnrS1-mediated quinolone resistance with other antimicrobial resistance phenotypes. Annotation of the three qnrS1-containing plasmids revealed a qnrS1-containing transposon with a closely related structure. We screened 112 qnrS1-positive commensal Enterobacteriaceae isolated in the community and in a hospital in HCMC to detect the common transposon structure. We found the same transposon structure to be present in 71.4 % (45/63) of qnrS1-positive hospital isolates and in 36.7 % (18/49) of qnrS1-positive isolates from the community. The resulting sequence analysis of the qnrS1 environment suggested that qnrS1 genes are widely distributed and are mobilized on elements with a common genetic background. Our data add additional insight into mechanisms that facilitate resistance to multiple antimicrobials in Gram-negative bacteria in Vietnam.
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Affiliation(s)
- Vien Le
- Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam.,Division of Infectious Diseases, Department of Medicine, University of California, San Francisco, CA, USA
| | - Nguyen Thi Khanh Nhu
- Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam.,School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Australia
| | | | - James I Campbell
- Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam.,Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, Oxford University, UK
| | - Ha Thanh Tuyen
- Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
| | - Tran Do Hoang Nhu
- Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
| | - Pham Thi Thanh Tam
- Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
| | - Constance Schultsz
- Department of Medical Microbiology, Academic Medical Centre, University of Amsterdam, The Netherlands
| | - Guy Thwaites
- Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam.,Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, Oxford University, UK
| | - Nicholas R Thomson
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK.,London School of Hygiene and Tropical Medicine, London, UK
| | - Stephen Baker
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, Oxford University, UK.,Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam.,London School of Hygiene and Tropical Medicine, London, UK
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Nawaz M, Sung K, Kweon O, Khan S, Nawaz S, Steele R. Characterisation of novel mutations involved in quinolone resistance in Escherichia coli isolated from imported shrimp. Int J Antimicrob Agents 2015; 45:471-6. [DOI: 10.1016/j.ijantimicag.2014.11.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 11/13/2014] [Indexed: 10/24/2022]
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10
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Shahcheraghi F, Rahmati Ghezelgeh F, Nobari S, Torabi E, Mousavi SF, Aslani MM, Shahcheraghi F. Identification and characterization of class 1 integrons among atypical enteropathogenic Escherichia coli isolated from children under 5 years of age. IRANIAN JOURNAL OF MICROBIOLOGY 2014; 6:156-62. [PMID: 25870748 PMCID: PMC4393491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND AND OBJECTIVES The therapeutic options for diseases caused by Escherichia coli are limited. In this study we investigated the presence of virulence factors among Enteropathogenic Escherichia coli (EPEC) strains and their antibiotic resistance patterns. The isolates were also checked for the presence of class1 integrons and gene cassettes. MATERIALS AND METHODS This study included 70 EPEC strains isolated from children. Antimicrobial resistance patterns were determined using diffusion methods. The broth microdilution methods was used to determine the minimum inhibitory concentration. PCR was used to detect eaeA, bfpA genes. The 5' and 3' conserved sequences (CSs) of class 1 integrons and intI gene were amplified to investigate the presence of integrons and gene cassettes. RESULTS Antimicrobial susceptibility testing showed that 4 (5.7%), 3 (4.2%), and 2 (2.8 %) isolates were resistant to ampicillin, trimethoprim-sulfamethoxazole, and ceftazidime, respectively. Resistance rates to ciprofloxacin and aztreonam were 1.4%. Thirteen (18.5%) isolates showed resistance to tetracycline, and 4 (5.7%) were kanamycin resistant. Class I integron detected in 22 (31.4%) isolates. All the gene cassettes found in class I integrons corresponded to different variants of dfr and aadA genes. CONCLUSION Prevalence of class I integrons in EPEC strains was high. Presence of aadA and dfr gene cassettes in integrons represents high distribution of resistance determinants in EPEC strains.
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Affiliation(s)
| | | | - Saman Nobari
- Department of Bacteriology & Microbiology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Elham Torabi
- Department of Bacteriology & Microbiology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Seyed Fazlollah Mousavi
- Department of Bacteriology & Microbiology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Mohammad Mehdi Aslani
- Department of Bacteriology & Microbiology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Fereshteh Shahcheraghi
- Department of Bacteriology & Microbiology Research Center, Pasteur Institute of Iran, Tehran, Iran,Corresponding author: Fereshteh Shahcheraghi, Address: Department of Bacteriology, Pasteur Institute of Iran, Tehran, Iran. Telfax: +98-21-66405535,
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Abstract
Two carbapenem-resistant Raoultella planticola clinical isolates were isolated from patients with pneumonia and Port-A catheter-related bacteremia, respectively, in Taiwan. These isolates remained susceptible to fluoroquinolone, aminoglycoside, and colistin. Though the two isolates had the same antibiogram, plasmidic carbapenemase blaIMP-8, class 1 integron cassette (dfrA12-orfF-aadA2), and qnrB2, they had different pulsed-field gel electrophoresis patterns, plasmid sizes, and outer membrane protein loss profiles. To our knowledge, this is the first report of blaIMP-8 found in R. planticola. Interestingly, blaIMP-8 is the most common carbapenemase found in Klebsiella pneumoniae in Taiwan. In the literature, carbapenemase genes in R. planticola in each country were also found in carbapenem-resistant Enterobacteriaceae in the same country.
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Loot C, Ducos-Galand M, Escudero JA, Bouvier M, Mazel D. Replicative resolution of integron cassette insertion. Nucleic Acids Res 2012; 40:8361-70. [PMID: 22740653 PMCID: PMC3458562 DOI: 10.1093/nar/gks620] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Site-specific recombination catalyzed by tyrosine recombinases follows a common pathway consisting of two consecutive strand exchanges. The first strand exchange generates a Holliday junction (HJ), which is resolved by a second strand exchange. In integrons, attC sites recombine as folded single-stranded substrates. Only one of the two attC site strands, the bottom one, is efficiently bound and cleaved by the integrase during the insertion of gene cassettes at the double-stranded attI site. Due to the asymmetry of this complex, a second strand exchange on the attC bottom strand (bs) would form linearized abortive recombination products. We had proposed that HJ resolution would rely on an uncharacterized mechanism, probably replication. Using an attC site carried on a plasmid with each strand specifically tagged, we followed the destiny of each strand after recombination. We demonstrated that only one strand, the one carrying the attC bs, is exchanged. Furthermore, we show that the recombination products contain the attC site bs and its entire de novo synthesized complementary strand. Therefore, we demonstrate the replicative resolution of single-strand recombination in integrons and rule out the involvement of a second strand exchange of any kind in the attC × attI reaction.
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Affiliation(s)
- Céline Loot
- Institut Pasteur, Unité Plasticité du Génome Bactérien, CNRS UMR3525, Paris 75724, France
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Guo X, Xia R, Han N, Xu H. Genetic diversity analyses of class 1 integrons and their associated antimicrobial resistance genes in Enterobacteriaceae strains recovered from aquatic habitats in China. Lett Appl Microbiol 2011; 52:667-75. [PMID: 21496063 DOI: 10.1111/j.1472-765x.2011.03059.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS To characterize the molecular diversity of class 1 integrons and antibiotic resistance (AR) genes of Enterobacteriaceae strains recovered from aquatic habitats in Jinan, Shandong Province, China. METHODS AND RESULTS Six hundred and thirty-eight antimicrobial-resistant Enterobacteriaceae isolated from wastewater were examined for class 1 integron. Of these, 293 were positive for the class 1 integrase gene intI1; among these, 34 gene cassettes and 29 AR genes were detected. Twenty-nine distinct gene cassette arrays were identified by restriction fragment length polymorphism (RFLP). Seven strains harboring novel gene cassette arrays were subjected to further study, in which antimicrobial susceptibility profiles were determined, and the presence of other AR genes outside of the integrons was assayed. Several of the resistance determinants were found to be transferable by conjugation or transformation. CONCLUSIONS This study established the assessment of class 1 integron and antimicrobial resistance gene patterns among environmental Enterobacteriaceae. Also, a restriction enzyme EcoRII was employed to develop a rapid and simple method for characterizing gene cassette arrays by RFLP analysis, which facilitated further study of novel gene cassette arrays. SIGNIFICANCE AND IMPACT OF STUDY These data not only illustrated the diversity of class 1 integron gene cassettes but also provided direct evidence that integrons mobilized gene cassettes, generating new linkages of resistance genes, and they could be integrated in gene transfer units such as conjugative plasmids to contribute to the dissemination of AR genes by horizontal gene transfer (HGT) in aquatic environments.
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Affiliation(s)
- X Guo
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, Shandong, China
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14
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Abstract
Antibiotic resistance in Gram-negative bacteria is often due to the acquisition of resistance genes from a shared pool. In multiresistant isolates these genes, together with associated mobile elements, may be found in complex conglomerations on plasmids or on the chromosome. Analysis of available sequences reveals that these multiresistance regions (MRR) are modular, mosaic structures composed of different combinations of components from a limited set arranged in a limited number of ways. Components common to different MRR provide targets for homologous recombination, allowing these regions to evolve by combinatorial evolution, but our understanding of this process is far from complete. Advances in technology are leading to increasing amounts of sequence data, but currently available automated annotation methods usually focus on identifying ORFs and predicting protein function by homology. In MRR, where the genes are often well characterized, the challenge is to identify precisely which genes are present and to define the boundaries of complete and fragmented mobile elements. This review aims to summarize the types of mobile elements involved in multiresistance in Gram-negative bacteria and their associations with particular resistance genes, to describe common components of MRR and to illustrate methods for detailed analysis of these regions.
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Affiliation(s)
- Sally R Partridge
- Centre for Infectious Diseases and Microbiology, The University of Sydney, Westmead Hospital, Sydney, NSW 2145, Australia.
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Xu H, Broersma K, Miao V, Davies J. Class 1 and class 2 integrons in multidrug-resistant gram-negative bacteria isolated from the Salmon River, British Columbia. Can J Microbiol 2011; 57:460-7. [DOI: 10.1139/w11-029] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Using an enrichment protocol, we isolated 16 gram-negative, multidrug-resistant strains of known or opportunistic bacterial pathogens from the Salmon River in south-central British Columbia from 2005 to 2009, and investigated the genetic basis of their resistance to a variety of antibiotics. Of the 16 strains, 13 carried class 1 integrons and three carried class 2 integrons. Genes found in cassettes associated with the integrons included those for dihydrofolate reductases (dfrA1, dfrA12, dfrA17, and dfrB7), aminoglycoside adenyltransferases (aadA1, aadA2, aadA5, and aadB), streptothricin acetyltransferase (sat), and hypothetical proteins (orfF and orfC). A new gene cassette of unknown function, orf1, was discovered between dfrA1 and aadA5 in Escherichia sp. Other genes for resistance to tetracycline, chloramphenicol, streptomycin, and kanamycin (tetA, tetB, tetD; catA; strA-strB; and aphA1-Iab, respectively) were outside the integrons. Several of these resistance determinants were transferable by conjugation. The detection of organisms and resistance determinants normally associated with clinical settings attest to their widespread dispersal and suggest that regular monitoring of their presence in aquatic habitats should become a part of the overall effort to understand the epidemiology of antibiotic resistance genes in bacteria.
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Affiliation(s)
- Hai Xu
- State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, Shandong, People’s Republic of China
| | - Klaas Broersma
- Agriculture and Agri-Food Canada, 3015 Ord Road, Kamloops, BC V2B 8A9, Canada
| | - Vivian Miao
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Julian Davies
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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16
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Bailey JK, Pinyon JL, Anantham S, Hall RM. Distribution of the blaTEM gene and blaTEM-containing transposons in commensal Escherichia coli. J Antimicrob Chemother 2011; 66:745-51. [DOI: 10.1093/jac/dkq529] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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17
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Dahmen S, Mansour W, Boujaafar N, Arlet G, Bouallègue O. Distribution of Cotrimoxazole Resistance Genes Associated with Class 1 Integrons in Clinical Isolates of Enterobacteriaceae in a University Hospital in Tunisia. Microb Drug Resist 2010; 16:43-7. [DOI: 10.1089/mdr.2009.0091] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Safia Dahmen
- “Infections with multiresistant bacteria to antibiotics” (UR/29/04), Department of Microbiology, University Hospital of Sahloul, Sousse, Tunisia
- Department of Bacteriology, University of Medecine Pierre and Marie-Curie, Paris VI, Paris, France
| | - Wejdene Mansour
- “Infections with multiresistant bacteria to antibiotics” (UR/29/04), Department of Microbiology, University Hospital of Sahloul, Sousse, Tunisia
| | - Noureddine Boujaafar
- “Infections with multiresistant bacteria to antibiotics” (UR/29/04), Department of Microbiology, University Hospital of Sahloul, Sousse, Tunisia
| | - Guillaume Arlet
- Department of Bacteriology, University of Medecine Pierre and Marie-Curie, Paris VI, Paris, France
| | - Olfa Bouallègue
- “Infections with multiresistant bacteria to antibiotics” (UR/29/04), Department of Microbiology, University Hospital of Sahloul, Sousse, Tunisia
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18
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Chang CY, Fang YT, Tsai SM, Chang LL, Yu WL. Characterization of class 1 integrons and gene cassettes in clinical isolates of Klebsiella pneumoniae from Taiwan. Diagn Microbiol Infect Dis 2009; 65:214-6. [PMID: 19748438 DOI: 10.1016/j.diagmicrobio.2009.06.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Revised: 06/04/2009] [Accepted: 06/04/2009] [Indexed: 10/20/2022]
Abstract
We surveyed the prevalence and contents of class 1 integrons in clinical Klebsiella pneumoniae isolates collected from Kaohsiung, Taiwan, during 2 periods (1993 and 2004). Class 1 integrons were present in 78 isolates (34.2%) from 1993 (n = 228) and 129 (32.9%) from 2004 (n = 392) and contained varied gene cassette number, type, and array. We found 2 atypical sul3-associated class 1 integrons and identified 26 different gene cassettes, including an aac(6')-Ib-cr cassette here firstly described in K. pneumoniae from Taiwan. The continuing evolution of class 1 integrons is threatening to undermine the effectiveness of antimicrobial therapy for K. pneumoniae.
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Affiliation(s)
- Chung-Yu Chang
- Department of Microbiology, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan
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19
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Diverse aadA gene cassettes on class 1 integrons introduced into soil via spread manure. Res Microbiol 2009; 160:427-33. [DOI: 10.1016/j.resmic.2009.06.005] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 06/11/2009] [Accepted: 06/12/2009] [Indexed: 11/21/2022]
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20
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Nawaz M, Khan AA, Khan S, Sung K, Kerdahi K, Steele R. Molecular Characterization of Tetracycline-Resistant Genes and Integrons from Avirulent Strains ofEscherichia coliIsolated from Catfish. Foodborne Pathog Dis 2009; 6:553-9. [DOI: 10.1089/fpd.2008.0204] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Mohamed Nawaz
- Division of Microbiology, National Center for Toxicological Research, Jefferson, Arkansas
| | - Ashraf A. Khan
- Division of Microbiology, National Center for Toxicological Research, Jefferson, Arkansas
| | - Saeed Khan
- Division of Microbiology, National Center for Toxicological Research, Jefferson, Arkansas
| | - Kidon Sung
- Division of Microbiology, National Center for Toxicological Research, Jefferson, Arkansas
| | | | - Roger Steele
- Division of Microbiology, National Center for Toxicological Research, Jefferson, Arkansas
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21
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Partridge SR, Tsafnat G, Coiera E, Iredell JR. Gene cassettes and cassette arrays in mobile resistance integrons. FEMS Microbiol Rev 2009; 33:757-84. [PMID: 19416365 DOI: 10.1111/j.1574-6976.2009.00175.x] [Citation(s) in RCA: 447] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Gene cassettes are small mobile elements, consisting of little more than a single gene and recombination site, which are captured by larger elements called integrons. Several cassettes may be inserted into the same integron forming a tandem array. The discovery of integrons in the chromosome of many species has led to the identification of thousands of gene cassettes, mostly of unknown function, while integrons associated with transposons and plasmids carry mainly antibiotic resistance genes and constitute an important means of spreading resistance. An updated compilation of gene cassettes found in sequences of such 'mobile resistance integrons' in GenBank was facilitated by a specially developed automated annotation system. At least 130 different (<98% identical) cassettes that carry known or predicted antibiotic resistance genes were identified, along with many cassettes of unknown function. We list exemplar GenBank accession numbers for each and address some nomenclature issues. Various modifications to cassettes, some of which may be useful in tracking cassette epidemiology, are also described. Despite potential biases in the GenBank dataset, preliminary analysis of cassette distribution suggests interesting differences between cassettes and may provide useful information to direct more systematic studies.
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Affiliation(s)
- Sally R Partridge
- Centre for Infectious Diseases and Microbiology, University of Sydney, Westmead Hospital, Sydney, NSW, Australia.
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Unusual class 1 integron-associated gene cassette configuration found in IncA/C plasmids from Salmonella enterica. Antimicrob Agents Chemother 2009; 53:2640-2. [PMID: 19307357 DOI: 10.1128/aac.00233-09] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
IncA/C plasmids carrying an unusual cassette configuration in a class 1 integron and five further shared resistance genes, aacC4, aphA1, hph, sul2, and tetA(D) were found in Salmonella enterica serovars Senftenberg and Ohio. A deletion formed using a short region of homology in the 5' conserved segment and the orfF cassette created an array with only part of orfF followed by the aadA2 cassette. The IncA/C plasmids were not recoverable by conjugation, but additional conjugative resistance plasmids were present in some strains.
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Sunde M, Solheim H, Slettemeås JS. Genetic linkage between class 1 integrons with the dfrA12-orfF-aadA2 cassette array and sul3 in Escherichia coli. Vet Microbiol 2008; 130:422-5. [DOI: 10.1016/j.vetmic.2008.02.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2008] [Revised: 01/07/2008] [Accepted: 02/07/2008] [Indexed: 10/22/2022]
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SGI2, a relative of Salmonella genomic island SGI1 with an independent origin. Antimicrob Agents Chemother 2008; 52:2529-37. [PMID: 18443113 DOI: 10.1128/aac.00189-08] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Multiply antibiotic-resistant Salmonella enterica serovar Emek strains isolated in Australia and the United Kingdom had similar features, suggesting that they all belong to a single clone. These strains all contain SGI2 (formerly SGI1-J), an independently formed relative of Salmonella genomic island SGI1. In SGI2, the complex class 1 integron which includes all of the resistance genes is not located between tnpR (S027) and S044 as in SGI1 and SGI1 variants. Instead, tnpR was found to be adjacent to S044, and the integron is located 6.9 kb away, within S023. In both SGI1 and SGI2, the 25-bp inverted repeats that mark the outer ends of class 1 integrons are flanked by a 5-bp duplication of the target, indicating that incorporation of the integron was by transposition. A small number of differences between the sequences of the backbones of SGI1 and SGI2 were also found. Hence, a class 1 integron has entered two different variants of the SGI backbone to generate two distinct lineages. Despite this, the integron in SGI2 has a complex structure that is very similar to that of In104 in SGI1. Differences are in the cassette arrays and in the gene which encodes the chloramphenicol and florfenicol efflux protein. The CmlA9 protein, encoded by InEmek, is only 92.8% identical to FloRc (also a CmlA family protein) from SGI1. A variant form of SGI2, SGI2-A, which has lost the tet(G) and cmlA9 resistance determinants, was found in one strain.
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Associations between antimicrobial resistance genes in fecal generic Escherichia coli isolates from cow-calf herds in western Canada. Appl Environ Microbiol 2008; 74:3658-66. [PMID: 18424533 DOI: 10.1128/aem.02505-07] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The objective of this study was to examine associations among the genetic determinants of antimicrobial resistance (AMR) in 207 fecal generic Escherichia coli isolates obtained from 77 cow-calf herds in western Canada. Twenty-three resistance genes corresponding to six different antimicrobial families were assessed using DNA hybridization and PCR. The most common resistance genes in the study sample (207 isolates) were sul2 (48.3%), tet(B) (45.4%), and ant(3'')-Ia (aadA1) (19.3%). Several statistically significant associations between the examined resistance genes were detected. The strongest associations observed were those between genes for resistance to chloramphenicol (catI) and trimethoprim (dhfrI) (odds ratio [OR] = 214; P = 0.0001), sulfonamide (sul1) and chloramphenicol (catI) (OR = 96.9; P = 0.0001), streptomycin [ant(3'')-Ia (aadA1)] and trimethoprim (dhfrI) (OR = 96.2; P = 0.0001), sulfonamide (sul1) and streptomycin [ant(3'')-Ia (aadA1)] (OR = 79.3; P = 0.0001), and tetracycline [tet(B)] and sulfonamides (sul2) (OR = 25.7; P = 0.0001). At least one of the resistance genes corresponding to each nonaminoglycoside family of antimicrobials examined in this study was associated with the two aminoglycoside resistance genes ant(3'')-Ia (aadA1) and aph(3')-Ia. The multiple, strong associations between genes and the diverse nature of the associations described in this study demonstrate the complexity of resistance gene selection in cow-calf herds and should be considered in the planning of AMR control practices for cow-calf operations.
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Bae IK, Lee YN, Lee WG, Lee SH, Jeong SH. Novel complex class 1 integron bearing an ISCR1 element in an Escherichia coli isolate carrying the blaCTX-M-14 gene. Antimicrob Agents Chemother 2007; 51:3017-9. [PMID: 17517851 PMCID: PMC1932499 DOI: 10.1128/aac.00279-07] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This work identifies an ISCR1-related bla(CTX-M-14) gene, which has never been reported before, from a clinical isolate of Escherichia coli. The bla(CTX-M-14) gene was preceded by an ISCR1 element that was followed by a class 1 integron containing three different insert gene cassettes, i.e., dfrA12, orfF, and aadA2.
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Affiliation(s)
- Il Kwon Bae
- Research Institute for Antimicrobial Resistance and Department of Laboratory Medicine, Kosin University College of Medicine, 34 Amnam-Dong, Suh-Gu, Busan, Republic of Korea
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Frank T, Gautier V, Talarmin A, Bercion R, Arlet G. Characterization of sulphonamide resistance genes and class 1 integron gene cassettes in Enterobacteriaceae, Central African Republic (CAR). J Antimicrob Chemother 2007; 59:742-5. [PMID: 17350987 DOI: 10.1093/jac/dkl538] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES The aim of this study was to characterize genes encoding sulphonamide resistance and gene cassettes associated with class 1 integrons in trimethoprim-sulphamethoxazole resistant Enterobacteriaceae recovered from Bangui, Central African Republic (CAR). METHODS We studied 78 clinical Enterobacteriaceae isolates, including 16 extended-spectrum beta-lactamases producers, 10 Salmonella and 9 Shigella, resistant to trimethoprim-sulphamethoxazole as assessed by the disc diffusion method. PCR was used to test for sul1 and sul2 genes. Class 1 integron resistance gene cassettes were characterized by directly sequencing PCR products obtained with primers recognising 5' and 3' conserved regions. RESULTS The sul1 gene was found in 67 isolates, the sul2 gene in 72 isolates and both genes in 62 isolates, while the int1 gene was found in 74 isolates. The most prevalent dfr genes were dfrA7 (49%), dfrA1 (17%) and dfrA2d (13%). CONCLUSION These results illustrate the wide distribution of sulphonamide and trimethoprim resistance genes among Enterobacteriaceae in Bangui (CAR).
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Affiliation(s)
- Thierry Frank
- Institut Pasteur de Bangui, Bangui, Central African Republic
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28
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Novais A, Cantón R, Valverde A, Machado E, Galán JC, Peixe L, Carattoli A, Baquero F, Coque TM. Dissemination and persistence of blaCTX-M-9 are linked to class 1 integrons containing CR1 associated with defective transposon derivatives from Tn402 located in early antibiotic resistance plasmids of IncHI2, IncP1-alpha, and IncFI groups. Antimicrob Agents Chemother 2006; 50:2741-50. [PMID: 16870767 PMCID: PMC1538643 DOI: 10.1128/aac.00274-06] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This study analyzes the diversity of In60, a class 1 integron bearing CR1 and containing bla(CTX-M-9), and its association with Tn402, Tn21, and classical conjugative plasmids among 45 CTX-M-9-producing clinical strains (41 Escherichia coli strains, 2 Klebsiella pneumoniae strains, 1 Salmonella enterica strain, and 1 Enterobacter cloacae strain). Forty-five patients in a Spanish tertiary care hospital were studied (1996 to 2003). The diversity of In60 and association of In60 with Tn402 or mercury resistance transposons were investigated by overlapping PCR assays and/or hybridization. Plasmid characterization included comparison of restriction fragment length polymorphism patterns and determination of incompatibility group by PCR-based replicon typing, sequencing, and hybridization. CTX-M-9 plasmids belonged to IncHI2 (n = 26), IncP-1alpha (n = 10), IncFI (n = 4), and IncI (n = 1) groups. Genetic platforms containing bla(CTX-M-9) were classified in six types in relation to the In60 backbone and in eight subtypes in relation to Tn402 derivatives. They were associated with Tn21 sequences when located in IncP-1alpha or IncHI2 plasmids. Our study identified bla(CTX-M-9) in a high diversity of CR1-bearing class 1 integrons linked to different Tn402 derivatives, often to Tn21, highlighting the role of recombination events in the evolution of antibiotic resistance plasmids. The presence of bla(CTX-M-9) on broad-host-range IncP-1alpha plasmids might contribute to its dissemination to hosts that were not members of the family Enterobacteriaceae.
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Affiliation(s)
- Angela Novais
- Hospital Universitario Ramón y Cajal, IMSALUD, Madrid 28034, Spain
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