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Velasco Garcia WJ, Araripe Dos Santos Neto N, Borba Rios T, Rocha Maximiano M, Souza CMD, Franco OL. Genetic basis of antibiotic resistance in bovine mastitis and its possible implications for human and ecological health. Crit Rev Microbiol 2024:1-14. [PMID: 38916977 DOI: 10.1080/1040841x.2024.2369140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 06/11/2024] [Indexed: 06/27/2024]
Abstract
Bovine mastitis is a mammary gland inflammation that can occur due to infectious pathogens, Staphylococcus aureus and Escherichia coli, which are, respectively, the most prevalent Gram-positive and Gram-negative bacteria associated with this disease. Currently, antibiotic treatment has become more complicated due to the presence of resistant pathogens. This review, therefore, aims to identify the most common resistance genes reported for these strains in the last four years. During the review, it was noted that blaZ, blaSHV, blaTEM, and blaampC are the most reported genes for S. aureus and E. coli, associated with drug inactivation, mainly β-lactamases. They are characterized by generating bacterial resistance to β-lactam antibiotics, the most common treatment in animal and human bacterial treatments (penicillins and cephalosporins, among others). Genes associated with efflux systems were also present in the two strains and included norA, tetA, tetC, and tetK, which generate resistance to macrolide and tetracycline antibiotics. Additionally, the effects of spreading resistance between animals and humans through direct contact (such as consumption of contaminated milk) or indirect contact (through environmental contamination) has been deeply discussed, emphasizing the importance of having adequate sanitation and antibiotic control and administration protocols.
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Affiliation(s)
- Wendy Johana Velasco Garcia
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília, Brazil
| | - Nilton Araripe Dos Santos Neto
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília, Brazil
- Universidade de Brasília, Pós-Graduação em Patologia Molecular, Brasília, DF, Brazil
| | - Thuanny Borba Rios
- S-Inova Biotech, Programa de Pós-Graduação em Biotecnologia, Universidade Católica Dom Bosco, Campo Grande, Brazil
| | - Mariana Rocha Maximiano
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília, Brazil
- S-Inova Biotech, Programa de Pós-Graduação em Biotecnologia, Universidade Católica Dom Bosco, Campo Grande, Brazil
| | - Camila Maurmann de Souza
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília, Brazil
- S-Inova Biotech, Programa de Pós-Graduação em Biotecnologia, Universidade Católica Dom Bosco, Campo Grande, Brazil
| | - Octávio Luiz Franco
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília, Brazil
- Universidade de Brasília, Pós-Graduação em Patologia Molecular, Brasília, DF, Brazil
- S-Inova Biotech, Programa de Pós-Graduação em Biotecnologia, Universidade Católica Dom Bosco, Campo Grande, Brazil
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García V, Lestón L, Parga A, García-Meniño I, Fernández J, Otero A, Olsen JE, Herrero-Fresno A, Mora A. Genomics, biofilm formation and infection of bladder epithelial cells in potentially uropathogenic Escherichia coli (UPEC) from animal sources and human urinary tract infections (UTIs) further support food-borne transmission. One Health 2023; 16:100558. [PMID: 37363240 PMCID: PMC10288081 DOI: 10.1016/j.onehlt.2023.100558] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 04/29/2023] [Accepted: 05/01/2023] [Indexed: 06/28/2023] Open
Abstract
Escherichia coli is the main cause of urinary tract infections (UTI). While genomic comparison of specific clones recovered from animals, and human extraintestinal infections show high identity, studies demonstrating the uropathogenicity are lacking. In this study, comparative genomics combined with bladder-cell and biofilm formation assays, were performed for 31 E. coli of different origins: 7 from meat (poultry, beef, and pork); 2 from avian-farm environment; 12 from human uncomplicated UTI, uUTI; and 10 from human complicated UTI, cUTI. These isolates were selected based on their genetic uropathogenic (UPEC) status and phylogenetic background. In silico analysis revealed similar virulence-gene profiles, with flagella, type 1 and curli fimbriae, outer-membrane proteins (agn43, ompT, iha), and iron-uptake (iutA, entA, and fyuA) associated-traits as the most prevalent (>65%). In bladder-cell assays, moderate to strong values of association (83%, 60%, 77.8%) and invasion (0%, 70%, 55.5%) were exhibited by uUTI, cUTI, and animal-derived isolates, respectively. Of interest, uUTI isolates exhibited a significantly lower invasive capacity than cUTI isolates (p < 0.05). All isolates but one produced measurable biofilm. Notably, 1 turkey meat isolate O11:H6-F-ST457, and 2 cUTI isolates of the pandemic lineages O83:H42-F-ST1485-CC648 and O25b:H4-B2-ST131, showed strong association, invasion and biofilm formation. These isolates showed common carriage of type 1 fimbriae and csg operons, toxins (hlyF, tsh), iron uptake systems (iutA, entA, iroN), colicins, protectins (cvaC, iss, kpsM, traT), ompT, and malX. In summary, the similar in vitro behaviour found here for certain E. coli clones of animal origin would further reinforce the role of food-producing animals as a potential source of UPEC. Bladder-cell infection assays, combined with genomics, might be an alternative to in vivo virulence models to assess uropathogenicity.
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Affiliation(s)
- Vanesa García
- Laboratorio de Referencia de Escherichia coli (LREC), Dpto. de Microbioloxía e Parasitoloxía, Universidade de Santiago de Compostela (USC), Lugo 27002, Spain
- Instituto de Investigación Sanitaria de Santiago de Compostela (IDIS), Santiago 15706, Spain
| | - Luz Lestón
- Laboratorio de Referencia de Escherichia coli (LREC), Dpto. de Microbioloxía e Parasitoloxía, Universidade de Santiago de Compostela (USC), Lugo 27002, Spain
| | - Ana Parga
- Departamento de Microbioloxía e Parasitoloxía, Facultade de Bioloxía, Edificio CIBUS, Universidade de Santiago de Compostela, Santiago de Compostela 15782, Spain
| | - Isidro García-Meniño
- Laboratorio de Referencia de Escherichia coli (LREC), Dpto. de Microbioloxía e Parasitoloxía, Universidade de Santiago de Compostela (USC), Lugo 27002, Spain
- Instituto de Investigación Sanitaria de Santiago de Compostela (IDIS), Santiago 15706, Spain
- Department for Biological Safety, German Federal Institute for Risk Assessment, Berlin 10589, Germany
| | - Javier Fernández
- Servicio de Microbiología, Hospital Universitario Central de Asturias (HUCA), Oviedo 33011, Spain
- Grupo de Microbiología Traslacional, Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Oviedo 33011, Spain
- Research & Innovation, Artificial Intelligence and Statistical Department, Pragmatech AI Solutions, Oviedo 33011, Spain
- CIBER de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III, Madrid, Spain
| | - Ana Otero
- Departamento de Microbioloxía e Parasitoloxía, Facultade de Bioloxía, Edificio CIBUS, Universidade de Santiago de Compostela, Santiago de Compostela 15782, Spain
| | - John E. Olsen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg 1870, Denmark
| | - Ana Herrero-Fresno
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg 1870, Denmark
| | - Azucena Mora
- Laboratorio de Referencia de Escherichia coli (LREC), Dpto. de Microbioloxía e Parasitoloxía, Universidade de Santiago de Compostela (USC), Lugo 27002, Spain
- Instituto de Investigación Sanitaria de Santiago de Compostela (IDIS), Santiago 15706, Spain
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Tavares RDS, Tacão M, Figueiredo AS, Duarte AS, Esposito F, Lincopan N, Manaia CM, Henriques I. Genotypic and phenotypic traits of bla CTX-M-carrying Escherichia coli strains from an UV-C-treated wastewater effluent. WATER RESEARCH 2020; 184:116079. [PMID: 32717492 DOI: 10.1016/j.watres.2020.116079] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 06/12/2020] [Accepted: 06/15/2020] [Indexed: 06/11/2023]
Abstract
Wastewater treatment plants (WWTPs) are relevant sources of antibiotic resistance into aquatic environments. Disinfection of WWTPs' effluents (e.g. by UV-C irradiation) may attenuate this problem, though some clinically relevant bacteria have been shown to survive disinfection. In this study we characterized 25 CTX-M-producing Escherichia coli strains isolated from a WWTP's UV-C-irradiated effluent, aiming to identify putative human health hazards associated with such effluents. Molecular typing indicated that the strains belong to the phylogroups A, B2 and C and clustered into 9 multilocus sequence types (STs), namely B2:ST131 (n = 7), A:ST58 (n = 1), A:ST155 (n = 4), C:ST410 (n = 2), A:ST453 (n = 2), A:ST617 (n = 2), A:ST744 (n = 1), A:ST1284 (n = 3) and a putative novel ST (n = 3). PCR-screening identified 9 of the 20 antibiotic resistance genes investigated [i.e. sul1, sul2, sul3, tet(A), tet(B), blaOXA-1-like, aacA4, aacA4-cr and qnrS1]. The more prevalent were sul1, sul2 (n = 15 isolates) and tet(A) (n = 14 isolates). Plasmid restriction analysis indicated diverse plasmid content among strains (14 distinct profiles) and mating assays yielded cefotaxime-resistant transconjugants for 8 strains. Two of the transconjugants displayed a multi-drug resistance (MDR) phenotype. All strains were classified as cytotoxic to Vero cells (9 significantly more cytotoxic than the positive control) and 10 of 21 strains were invasive towards this cell line (including all B2:ST131 strains). The 10 strains tested against G. mellonella larvae exhibited a virulent behaviour. Twenty-four and 7 of the 25 strains produced siderophores and haemolysins, respectively. Approximately 66% of the strains formed biofilms. Genome analysis of 6 selected strains identified several virulence genes encoding toxins, siderophores, and colonizing, adhesion and invasion factors. Freshwater microcosms assays showed that after 28 days of incubation 3 out of 6 strains were still detected by cultivation and 4 strains by qPCR. Resistance phenotypes of these strains remained unaltered. Overall, we confirmed WWTP's UV-C-treated outflow as a source of MDR and/or virulent E. coli strains, some probably capable of persisting in freshwater, and that carry conjugative antibiotic resistance plasmids. Hence, disinfected wastewater may still represent a risk for human health. More detailed evaluation of strains isolated from wastewater effluents is urgent, to design treatments that can mitigate the release of such bacteria.
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Affiliation(s)
- Rafael D S Tavares
- Centre for Environmental and Marine Studies (CESAM), University of Aveiro, Campus Universitário Santiago, 3810-193, Aveiro, Portugal; Department of Biology, University of Aveiro, Campus Universitário Santiago, 3810-193, Aveiro, Portugal
| | - Marta Tacão
- Centre for Environmental and Marine Studies (CESAM), University of Aveiro, Campus Universitário Santiago, 3810-193, Aveiro, Portugal; Department of Biology, University of Aveiro, Campus Universitário Santiago, 3810-193, Aveiro, Portugal.
| | - Ana S Figueiredo
- Department of Biology, University of Aveiro, Campus Universitário Santiago, 3810-193, Aveiro, Portugal
| | - Ana S Duarte
- Universidade Católica Portuguesa, Faculdade de Medicina Dentária, Centro de Investigação Interdisciplinar Em Saúde (CIIS), Estrada da Circunvalação, 3504-505, Viseu, Portugal
| | - Fernanda Esposito
- Department of Clinical Analysis, Faculty of Pharmacy, University of São Paulo, São Paulo, Brazil
| | - Nilton Lincopan
- Department of Clinical Analysis, Faculty of Pharmacy, University of São Paulo, São Paulo, Brazil; Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Célia M Manaia
- Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina, Laboratório Associado, Escola Superior de Biotecnologia, Rua de Diogo Botelho 1327, 4169-005, Porto, Portugal
| | - Isabel Henriques
- Centre for Environmental and Marine Studies (CESAM), University of Aveiro, Campus Universitário Santiago, 3810-193, Aveiro, Portugal; University of Coimbra, Department of Life Sciences, Faculty of Sciences and Technology, Calçada Martins de Freitas, 3000-456, Coimbra, Portugal
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Guzman-Hernandez R, Contreras-Rodriguez A, Hernandez-Velez R, Perez-Martinez I, Lopez-Merino A, Zaidi MB, Estrada-Garcia T. Mexican unpasteurised fresh cheeses are contaminated with Salmonella spp., non-O157 Shiga toxin producing Escherichia coli and potential uropathogenic E. coli strains: A public health risk. Int J Food Microbiol 2016; 237:10-16. [DOI: 10.1016/j.ijfoodmicro.2016.08.018] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 08/09/2016] [Accepted: 08/11/2016] [Indexed: 12/01/2022]
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Genetic Features of MCR-1-Producing Colistin-Resistant Escherichia coli Isolates in South Africa. Antimicrob Agents Chemother 2016; 60:4394-7. [PMID: 27161623 DOI: 10.1128/aac.00444-16] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 04/22/2016] [Indexed: 02/03/2023] Open
Abstract
A series of colistin-resistant Escherichia coli clinical isolates was recovered from hospitalized and community patients in South Africa. Seven clonally unrelated isolates harbored the mcr-1 gene located on different plasmid backbones. Two distinct plasmids were fully sequenced, and identical 2,600-bp-long DNA sequences defining a mcr-1 cassette were identified. Promoter sequences responsible for the expression of mcr-1, deduced from the precise identification of the +1 transcription start site for mcr-1, were characterized.
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Manges A. Escherichia coli and urinary tract infections: the role of poultry-meat. Clin Microbiol Infect 2016; 22:122-129. [DOI: 10.1016/j.cmi.2015.11.010] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 11/23/2015] [Accepted: 11/24/2015] [Indexed: 12/31/2022]
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Yahiaoui M, Robin F, Bakour R, Hamidi M, Bonnet R, Messai Y. Antibiotic Resistance, Virulence, and Genetic Background of Community-Acquired Uropathogenic Escherichia coli from Algeria. Microb Drug Resist 2015; 21:516-26. [PMID: 26430940 DOI: 10.1089/mdr.2015.0045] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The aim of the study was to investigate antibiotic resistance mechanisms, virulence traits, and genetic background of 150 nonrepetitive community-acquired uropathogenic Escherichia coli (CA-UPEC) from Algeria. A rate of 46.7% of isolates was multidrug resistant. bla genes detected were blaTEM (96.8% of amoxicillin-resistant isolates), blaCTX-M-15 (4%), overexpressed blaAmpC (4%), blaSHV-2a, blaTEM-4, blaTEM-31, and blaTEM-35 (0.7%). All tetracycline-resistant isolates (51.3%) had tetA and/or tetB genes. Sulfonamides and trimethoprim resistance genes were sul2 (60.8%), sul1 (45.9%), sul3 (6.7%), dfrA14 (25.4%), dfrA1 (18.2%), dfrA12 (16.3%), and dfrA25 (5.4%). High-level fluoroquinolone resistance (22.7%) was mediated by mutations in gyrA (S83L-D87N) and parC (S80I-E84G/V or S80I) genes. qnrB5, qnrS1, and aac(6')-Ib-cr were rare (5.3%). Class 1 and/or class 2 integrons were detected (40.7%). Isolates belonged to phylogroups B2+D (50%), A+B1 (36%), and F+C+Clade I (13%). Most of D (72.2%) and 38.6% of B2 isolates were multidrug resistant; they belong to 14 different sequence types, including international successful ST131, ST73, and ST69, reported for the first time in the community in Algeria and new ST4494 and ST4529 described in this study. Besides multidrug resistance, B2 and D isolates possessed virulence factors of colonization, invasion, and long-term persistence. The study highlighted multidrug-resistant CA-UPEC with high virulence traits and an epidemic genetic background.
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Affiliation(s)
- Merzouk Yahiaoui
- 1 Laboratory of Cellular and Molecular Biology, Faculty of Biological Sciences, University of Sciences and Technology Houari Boumediene , Algiers, Algeria
| | - Frédéric Robin
- 2 CHU Clermont-Ferrand, Laboratoire de Bactériologie , Clermont-Ferrand, France .,3 Clermont Université, Université d'Auvergne , Evolution des Bactéries Pathogènes et Susceptibilité de l'Hôte, Clermont-Ferrand, France
| | - Rabah Bakour
- 1 Laboratory of Cellular and Molecular Biology, Faculty of Biological Sciences, University of Sciences and Technology Houari Boumediene , Algiers, Algeria
| | | | - Richard Bonnet
- 2 CHU Clermont-Ferrand, Laboratoire de Bactériologie , Clermont-Ferrand, France .,3 Clermont Université, Université d'Auvergne , Evolution des Bactéries Pathogènes et Susceptibilité de l'Hôte, Clermont-Ferrand, France
| | - Yamina Messai
- 1 Laboratory of Cellular and Molecular Biology, Faculty of Biological Sciences, University of Sciences and Technology Houari Boumediene , Algiers, Algeria
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Zou L, Meng J, McDermott PF, Wang F, Yang Q, Cao G, Hoffmann M, Zhao S. Presence of disinfectant resistance genes in Escherichia coli isolated from retail meats in the USA. J Antimicrob Chemother 2014; 69:2644-9. [PMID: 24908046 DOI: 10.1093/jac/dku197] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES To examine the distribution of all genes known to be responsible for resistance to quaternary ammonium compounds (QACs), and their association with resistance to QACs and other antimicrobials, in Escherichia coli recovered from retail meats. METHODS A total of 570 strains of E. coli isolated from US retail meats in 2006 were screened for the presence of 10 QAC resistance genes [qacE, qacEΔ1, qacF, qacG, emrE, sugE(c), sugE(p), mdfA and ydgE/ydgF]. The MICs of six common disinfectants were determined using an agar dilution method. Possible associations between the presence of the gene and bacterial resistance to QACs and antimicrobials were investigated. RESULTS emrE, sugE(c), mdfA and ydgE/ydgF were commonly present (77.2%-100%) in the E. coli isolates, but qac and sugE(p) were less prevalent (0.4%-22.3%). emrE-mdfA-sugE(c)-ydgE/F was the most common QAC resistance gene profile. A significant association was found between antimicrobial resistance and the presence of sugE(p) and qacEΔ1 (P < 0.05). Antimicrobial-resistant E. coli isolates tended to contain more diverse combinations of disinfectant resistance genes than susceptible ones. All isolates showed reduced susceptibility to five of six disinfectants compared with the control strains. Higher MICs were generally associated with the presence of qac and sugE(p) genes. CONCLUSIONS The QAC resistance genes were commonly present among E. coli isolated from retail meats, and the qac and sugE(p) genes were highly associated with multidrug resistance phenotypes. Using QACs in the food industry may not be as effective as expected and could provide selection pressure for strains with acquired resistance to other antimicrobials.
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Affiliation(s)
- Likou Zou
- Department of Nutrition and Food Science, University of Maryland, College Park, MD, USA The Laboratory of Microbiology, Sichuan Agricultural University, Dujiangyan, Sichuan, P. R. China
| | - Jianghong Meng
- Department of Nutrition and Food Science, University of Maryland, College Park, MD, USA
| | - Patrick F McDermott
- Division of Animal and Food Microbiology, Office of Research, Center for Veterinary Medicine, U.S. Food and Drug Administration, Laurel, MD, USA
| | - Fei Wang
- Department of Nutrition and Food Science, University of Maryland, College Park, MD, USA
| | - Qianru Yang
- Department of Food Science, Louisiana State University Agricultural Center, 111 Food Science Building, Baton Rouge, Louisiana, USA
| | - Guojie Cao
- Department of Nutrition and Food Science, University of Maryland, College Park, MD, USA
| | - Maria Hoffmann
- Department of Nutrition and Food Science, University of Maryland, College Park, MD, USA Division of Animal and Food Microbiology, Office of Research, Center for Veterinary Medicine, U.S. Food and Drug Administration, Laurel, MD, USA
| | - Shaohua Zhao
- Division of Animal and Food Microbiology, Office of Research, Center for Veterinary Medicine, U.S. Food and Drug Administration, Laurel, MD, USA
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Dang TND, Zhang L, Zöllner S, Srinivasan U, Abbas K, Marrs CF, Foxman B. Uropathogenic Escherichia coli are less likely than paired fecal E. coli to have CRISPR loci. INFECTION GENETICS AND EVOLUTION 2013; 19:212-8. [DOI: 10.1016/j.meegid.2013.07.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 07/01/2013] [Accepted: 07/16/2013] [Indexed: 11/26/2022]
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Clonal composition and community clustering of drug-susceptible and -resistant Escherichia coli isolates from bloodstream infections. Antimicrob Agents Chemother 2012; 57:490-7. [PMID: 23147723 DOI: 10.1128/aac.01025-12] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Multidrug-resistant Escherichia coli strains belonging to a single lineage frequently account for a large proportion of extraintestinal E. coli infections in many parts of the world. However, limited information exists on the community prevalence and clonal composition of drug-susceptible E. coli strains. Between July 2007 and September 2010, we analyzed all consecutively collected Gram-negative bacterial isolates from patients with bloodstream infection (BSI) admitted to a public hospital in San Francisco for drug susceptibility and associated drug resistance genes. The E. coli isolates were genotyped for fimH single nucleotide polymorphisms (SNPs) and multilocus sequence types (MLSTs). Among 539 isolates, E. coli accounted for 249 (46%); 74 (30%) of them were susceptible to all tested drugs, and 129 (52%) were multidrug resistant (MDR). Only five MLST genotypes accounted for two-thirds of the E. coli isolates; the most common were ST131 (23%) and ST95 (18%). Forty-seven (92%) of 51 ST131 isolates, as opposed to only 8 (20%) of 40 ST95 isolates, were MDR (P < 0.0001). The Simpson's diversity index for drug-susceptible ST genotypes was 87%, while the index for MDR ST genotypes was 81%. ST95 strains were comprised of four fimH types, and one of these (f-6) accounted for 67% of the 21 susceptible isolates (P < 0.003). A large proportion (>70%) of both MDR and susceptible E. coli BSI isolates represented community-onset infections. These observations show that factors other than the selective pressures of antimicrobial agents used in hospitals contribute to community-onset extraintestinal infections caused by clonal groups of E. coli regardless of their drug resistance.
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