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Edgar RH, Samson AP, Kocsis T, Viator JA. Photoacoustic Flow Cytometry Using Functionalized Microspheres for Selective Detection of Bacteria. MICROMACHINES 2023; 14:573. [PMID: 36984980 PMCID: PMC10057399 DOI: 10.3390/mi14030573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 02/16/2023] [Accepted: 02/17/2023] [Indexed: 06/18/2023]
Abstract
Photoacoustic flow cytometry is a method to detect rare analytes in fluids. We developed photoacoustic flow cytometry to detect pathological cells in body fluids, such as circulating tumor cells or bacteria in blood. In order to induce specific optical absorption in bacteria, we use modified bacteriophage that precisely target bacterial species or subspecies for rapid identification. In order to reduce detection variability and to halt the lytic lifescycle that results in lysis of the bacteria, we attached dyed latex microspheres to the tail fibers of bacteriophage that retained the bacterial recognition binding sites. We tested these microsphere complexes using Salmonella enterica (Salmonella) and Escherichia coli (E. coli) bacteria and found robust and specific detection of targeted bacteria. In our work we used LT2, a strain of Salmonella, against K12, a strain of E. coli. Using Det7, a bacteriophage that binds to LT2 and not to K12, we detected an average of 109.3±9.0 of LT2 versus 2.0±1.7 of K12 using red microspheres and 86.7±13.2 of LT2 versus 0.3±0.6 of K12 using blue microspheres. These results confirmed our ability to selectively detect bacterial species using photoacoustic flow cytometry.
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Affiliation(s)
- Robert H. Edgar
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Anie-Pier Samson
- Department of Engineering, Duquesne University, Pittsburgh, PA 15282, USA
| | - Tori Kocsis
- Department of Engineering, Duquesne University, Pittsburgh, PA 15282, USA
| | - John A. Viator
- Department of Engineering, Duquesne University, Pittsburgh, PA 15282, USA
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2
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Edgar RH, Samson AP, Kowalski RP, Kellum JA, Hempel J, Viator JA, Jhanji V. Differentiating methicillin resistant and susceptible Staphylococcus aureus from ocular infections using photoacoustic labeling. Front Med (Lausanne) 2023; 10:1017192. [PMID: 36910486 PMCID: PMC9995766 DOI: 10.3389/fmed.2023.1017192] [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: 08/11/2022] [Accepted: 01/30/2023] [Indexed: 02/25/2023] Open
Abstract
Introduction Antibiotic resistance in bacterial species constitutes a growing problem in the clinical management of infections. Not only does it limit therapeutic options, but application of ineffective antibiotics allows resistant species to progress prior to prescribing more effective treatment to patients. Methicillin resistance in Staphylococcus aureus is a major problem in clinical infections as it is the most common hospital acquired infection. Methods We developed a photoacoustic flow cytometer using engineered bacteriophage as probes for rapid determination of methicillin resistance in Staphylococcus aureus with thirteen clinical samples obtained from keratitis patients. This method irradiates cells under flow with 532 nm laser light and selectively generates acoustic waves in labeled bacterial cells, thus enabling detection and enumeration of them. Staphylococcus aureus isolates were classified from culture isolation as either methicillin resistant or susceptible using cefoxitin disk diffusion testing. The photoacoustic method enumerates bacterial cells before and after treatment with antibiotics. Decreasing counts of bacteria after treatment indicate susceptible strains. We quantified the bacterial cells in the treated and untreated samples. Results Using k-means clustering on the data, we achieved 100% concordance with the classification of Staphylococcus aureus resistance using culture. Discussion Photoacoustics can be used to differentiate methicillin resistant and susceptible strains of bacteria from ocular infections. This method may be generalized to other bacterial species using appropriate bacteriophages and testing for resistance using other antibiotics.
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Affiliation(s)
- Robert H Edgar
- Swanson School of Engineering, Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States
| | - Anie-Pier Samson
- Department of Engineering, Duquesne University, Pittsburgh, PA, United States
| | - Regis P Kowalski
- School of Medicine and Ophthalmology, University of Pittsburgh, Pittsburgh, PA, United States
| | - John A Kellum
- Center for Central Care Nephrology, Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA, United States.,Spectral Medical, Toronto, ON, Canada
| | - John Hempel
- Department of Engineering, Duquesne University, Pittsburgh, PA, United States
| | - John A Viator
- Swanson School of Engineering, Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States.,Department of Engineering, Duquesne University, Pittsburgh, PA, United States
| | - Vishal Jhanji
- School of Medicine and Ophthalmology, University of Pittsburgh, Pittsburgh, PA, United States
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Van Ngoc H, Quyen TL, Vinayaka AC, Bang DD, Wolff A. Point-of-care system for rapid real-time detection of SARS-CoV-2 virus based on commercially available Arduino platforms. Front Bioeng Biotechnol 2022; 10:917573. [PMID: 35992344 PMCID: PMC9385952 DOI: 10.3389/fbioe.2022.917573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 06/27/2022] [Indexed: 11/13/2022] Open
Abstract
The COVID-19 pandemic emphasized the importance of rapid, portable, and on-site testing technologies necessary for resource-limited settings for effective testing and screening to reduce spreading of the infection. Realizing this, we developed a fluorescence-based point-of-care (fPOC) detection system with real-time reverse transcriptase loop-mediated isothermal amplification for rapid and quantitative detection of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. The system is built based on the Arduino platform compatible with commercially available open-source hardware-software and off-the-shelf electronic components. The fPOC system comprises of three main components: 1) an instrument with integrated heaters, 2) optical detection components, and 3) an injection-molded polymeric cartridge. The system was tested and experimentally proved to be able to use for fast detection of the SARS-CoV-2 virus in real-time in less than 30 min. Preliminary results of testing the performance of the fPOC revealed that the fPOC could detect the SARS-CoV-2 virus at a limit of detection (LOD50%) at two to three copies/microliter (15.36 copies/reaction), which was comparable to reactions run on a standard commercial thermocycler. The performance of the fPOC was evaluated with 12 SARS-CoV-2 clinical throat swab samples that included seven positive and five negative samples, as confirmed by reverse transcription-polymerase chain reaction. The fPOC showed 100% agreement with the commercial thermocycler. This simple design of the fPOC system demonstrates the potential to greatly enhance the practical applicability to develop a totally integrated point-of-care system for rapid on-site screening of the SARS-CoV-2 virus in the management of the pandemic.
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Affiliation(s)
- Huynh Van Ngoc
- BioLabChip Group, Department of Biotechnology and Biomedicine, Technical University of Denmark (DTU-Bioengineering), Lyngby, Denmark
| | - Than Linh Quyen
- BioLabChip Group, Department of Biotechnology and Biomedicine, Technical University of Denmark (DTU-Bioengineering), Lyngby, Denmark
| | - Aaydha Chidambara Vinayaka
- Laboratory of Applied Micro and Nanotechnology (LAMINATE), Department of Biotechnology and Biomedicine, Technical University of Denmark (DTU-Bioengineering), Lyngby, Denmark
| | - Dang Duong Bang
- Laboratory of Applied Micro and Nanotechnology (LAMINATE), Department of Biotechnology and Biomedicine, Technical University of Denmark (DTU-Bioengineering), Lyngby, Denmark
| | - Anders Wolff
- BioLabChip Group, Department of Biotechnology and Biomedicine, Technical University of Denmark (DTU-Bioengineering), Lyngby, Denmark
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Quyen TL, Vinayaka AC, Golabi M, Ngoc HV, Bang DD, Wolff A. Elimination of Carryover Contamination in Real-Time Reverse Transcriptase Loop-Mediated Isothermal Amplification for Rapid Detection of the SARS-CoV-2 Virus in Point-of-Care Testing. Front Cell Infect Microbiol 2022; 12:856553. [PMID: 35521217 PMCID: PMC9065284 DOI: 10.3389/fcimb.2022.856553] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 03/23/2022] [Indexed: 11/13/2022] Open
Abstract
Loop-mediated isothermal amplification (LAMP) is being used as a robust rapid diagnostic tool to prevent the transmission of infectious diseases. However, carryover contamination of LAMP-amplified products originating from previous tests has been a problem in LAMP-based bio-analytical assays. In this study, we developed a Cod-uracil-DNA-glycosylase real-time reverse transcriptase LAMP assay (Cod-UNG-rRT-LAMP) for the elimination of carryover contamination and the rapid detection of SARS-CoV-2 in point-of-care (POC) testing. Using the Cod-UNG-rRT-LAMP assay, the SARS-CoV-2 virus could be detected as low as 2 copies/µl (8 copies/reaction) within 45 min of amplification and 2.63 ± 0.17 pg (equivalent to 2.296 × 109 copies) of contaminants per reaction could be eliminated. Analysis of clinical SARS-CoV-2 samples using the Cod-UNG-rRT-LAMP assay showed an excellent agreement with a relative accuracy of 98.2%, sensitivity of 97.1%, and specificity of 95.2% in comparison to rRT-PCR. The results obtained in this study clearly demonstrate the feasibility of the use of the Cod-UNG-rRT-LAMP assay for applications toward the POC diagnosis of SARS-CoV-2 and on-site testing of other pathogens.
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Affiliation(s)
- Than Linh Quyen
- Biolabchip Group, Department of Bioengineering, Technical University of Denmark, Lyngby, Denmark
| | - Aaydha Chidambara Vinayaka
- Laboratory of Applied Micro and Nanotechnology (LAMINATE), Department of Bioengineering, Technical University of Denmark, Lyngby, Denmark
| | - Mohsen Golabi
- Laboratory of Applied Micro and Nanotechnology (LAMINATE), Department of Bioengineering, Technical University of Denmark, Lyngby, Denmark
| | - Huynh Van Ngoc
- Biolabchip Group, Department of Bioengineering, Technical University of Denmark, Lyngby, Denmark
| | - Dang Duong Bang
- Laboratory of Applied Micro and Nanotechnology (LAMINATE), Department of Bioengineering, Technical University of Denmark, Lyngby, Denmark
| | - Anders Wolff
- Biolabchip Group, Department of Bioengineering, Technical University of Denmark, Lyngby, Denmark
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5
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Miłobedzka A, Ferreira C, Vaz-Moreira I, Calderón-Franco D, Gorecki A, Purkrtova S, Dziewit L, Singleton CM, Nielsen PH, Weissbrodt DG, Manaia CM. Monitoring antibiotic resistance genes in wastewater environments: The challenges of filling a gap in the One-Health cycle. JOURNAL OF HAZARDOUS MATERIALS 2022; 424:127407. [PMID: 34629195 DOI: 10.1016/j.jhazmat.2021.127407] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 09/22/2021] [Accepted: 09/29/2021] [Indexed: 05/10/2023]
Abstract
Antibiotic resistance (AR) is a global problem requiring international cooperation and coordinated action. Global monitoring must rely on methods available and comparable across nations to quantify AR occurrence and identify sources and reservoirs, as well as paths of AR dissemination. Numerous analytical tools that are gaining relevance in microbiology, have the potential to be applied to AR research. This review summarizes the state of the art of AR monitoring methods, considering distinct needs, objectives and available resources. Based on the overview of distinct approaches that are used or can be adapted to monitor AR, it is discussed the potential to establish reliable and useful monitoring schemes that can be implemented in distinct contexts. This discussion places the environmental monitoring within the One-Health approach, where two types of risk, dissemination across distinct environmental compartments, and transmission to humans, must be considered. The plethora of methodological approaches to monitor AR and the variable features of the monitored sites challenge the capacity of the scientific community and policy makers to reach a common understanding. However, the dialogue between different methods and the production of action-oriented data is a priority. The review aims to warm up this discussion.
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Affiliation(s)
- Aleksandra Miłobedzka
- Department of Water Technology and Environmental Engineering, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic; Institute of Evolutionary Biology, University of Warsaw, Warsaw, Poland.
| | - Catarina Ferreira
- Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Rua Diogo Botelho 1327, 4169-005 Porto, Portugal
| | - Ivone Vaz-Moreira
- Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Rua Diogo Botelho 1327, 4169-005 Porto, Portugal
| | | | - Adrian Gorecki
- Department of Environmental Microbiology and Biotechnology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland
| | - Sabina Purkrtova
- Department of Biochemistry and Microbiology, Faculty of Food and Biochemical Technology, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic
| | - Lukasz Dziewit
- Department of Environmental Microbiology and Biotechnology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland
| | - Caitlin M Singleton
- Department of Chemistry and Bioscience, Center for Microbial Communities, Aalborg University, Aalborg, Denmark
| | - Per Halkjær Nielsen
- Department of Chemistry and Bioscience, Center for Microbial Communities, Aalborg University, Aalborg, Denmark
| | | | - Célia M Manaia
- Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Rua Diogo Botelho 1327, 4169-005 Porto, Portugal.
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Cui L, Li HZ, Yang K, Zhu LJ, Xu F, Zhu YG. Raman biosensor and molecular tools for integrated monitoring of pathogens and antimicrobial resistance in wastewater. Trends Analyt Chem 2021. [DOI: 10.1016/j.trac.2021.116415] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Recent Development of Rapid Antimicrobial Susceptibility Testing Methods through Metabolic Profiling of Bacteria. Antibiotics (Basel) 2021; 10:antibiotics10030311. [PMID: 33803002 PMCID: PMC8002737 DOI: 10.3390/antibiotics10030311] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 03/07/2021] [Accepted: 03/08/2021] [Indexed: 11/17/2022] Open
Abstract
Due to the inappropriate use and overuse of antibiotics, the emergence and spread of antibiotic-resistant bacteria are increasing and have become a major threat to human health. A key factor in the treatment of bacterial infections and slowing down the emergence of antibiotic resistance is to perform antimicrobial susceptibility testing (AST) of infecting bacteria rapidly to prescribe appropriate drugs and reduce the use of broad-spectrum antibiotics. Current phenotypic AST methods based on the detection of bacterial growth are generally reliable but are too slow. There is an urgent need for new methods that can perform AST rapidly. Bacterial metabolism is a fast process, as bacterial cells double about every 20 to 30 min for fast-growing species. Moreover, bacterial metabolism has shown to be related to drug resistance, so a comparison of differences in microbial metabolic processes in the presence or absence of antimicrobials provides an alternative approach to traditional culture for faster AST. In this review, we summarize recent developments in rapid AST methods through metabolic profiling of bacteria under antibiotic treatment.
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Nguyen T, Chidambara VA, Andreasen SZ, Golabi M, Huynh VN, Linh QT, Bang DD, Wolff A. Point-of-care devices for pathogen detections: The three most important factors to realise towards commercialization. Trends Analyt Chem 2020. [DOI: 10.1016/j.trac.2020.116004] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Schoepp NG, Liaw EJ, Winnett A, Savela ES, Garner OB, Ismagilov RF. Differential DNA accessibility to polymerase enables 30-minute phenotypic β-lactam antibiotic susceptibility testing of carbapenem-resistant Enterobacteriaceae. PLoS Biol 2020; 18:e3000652. [PMID: 32191697 PMCID: PMC7081982 DOI: 10.1371/journal.pbio.3000652] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 02/14/2020] [Indexed: 12/22/2022] Open
Abstract
The rise in carbapenem-resistant Enterobacteriaceae (CRE) infections has created a global health emergency, underlining the critical need to develop faster diagnostics to treat swiftly and correctly. Although rapid pathogen-identification (ID) tests are being developed, gold-standard antibiotic susceptibility testing (AST) remains unacceptably slow (1-2 d), and innovative approaches for rapid phenotypic ASTs for CREs are urgently needed. Motivated by this need, in this manuscript we tested the hypothesis that upon treatment with β-lactam antibiotics, susceptible Enterobacteriaceae isolates would become sufficiently permeabilized, making some of their DNA accessible to added polymerase and primers. Further, we hypothesized that this accessible DNA would be detectable directly by isothermal amplification methods that do not fully lyse bacterial cells. We build on these results to develop the polymerase-accessibility AST (pol-aAST), a new phenotypic approach for β-lactams, the major antibiotic class for gram-negative infections. We test isolates of the 3 causative pathogens of CRE infections using ceftriaxone (CRO), ertapenem (ETP), and meropenem (MEM) and demonstrate agreement with gold-standard AST. Importantly, pol-aAST correctly categorized resistant isolates that are undetectable by current genotypic methods (negative for β-lactamase genes or lacking predictive genotypes). We also test contrived and clinical urine samples. We show that the pol-aAST can be performed in 30 min sample-to-answer using contrived urine samples and has the potential to be performed directly on clinical urine specimens.
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Affiliation(s)
- Nathan G. Schoepp
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Eric J. Liaw
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Alexander Winnett
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Emily S. Savela
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Omai B. Garner
- Department of Pathology and Laboratory Medicine, UCLA, Los Angeles, California, United States of America
| | - Rustem F. Ismagilov
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, United States of America
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, United States of America
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10
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Quyen TL, Nordentoft S, Vinayaka AC, Ngo TA, Engelsmenn P, Sun Y, Madsen M, Bang DD, Wolff A. A Sensitive, Specific and Simple Loop Mediated Isothermal Amplification Method for Rapid Detection of Campylobacter spp. in Broiler Production. Front Microbiol 2019; 10:2443. [PMID: 31708907 PMCID: PMC6821646 DOI: 10.3389/fmicb.2019.02443] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 10/10/2019] [Indexed: 01/01/2023] Open
Abstract
Campylobacteriosis is one of the most common foodborne diseases worldwide. Two Campylobacter species - C. jejuni and C. coli in poultry and poultry products are considered to be the main source of human campylobacteriosis. Therefore, studying Campylobacter status in poultry flocks is needed to prevent transmission of disease and reduce human risk, health cost, and economic losses. In this study, we adapted and used a Loop-Mediated Isothermal Amplification (LAMP) assay for specific, sensitive, simple and cost-effective rapid detection of C. jejuni and C. coli in the poultry production chain. Amplified LAMP products were detected using a small, low-cost portable commercial blue LED transilluminator and a direct visual detection strategy was demonstrated. By using optimized conditions for amplification a limit of detection (LOD) of 50 CFU/ml was achieved for testing of C. jejuni and C. coli in spiked chicken feces without enrichment. The method took 60-70 min from receiving the samples to the final results (including 30 min for amplification). The optimized LAMP showed a relative accuracy of 98.4%, a specificity of 97.9%, and a sensitivity of 100% in comparison to real-time PCR method. Cohen's kappa index also showed an excellent agreement (0.94) between the two methods. The results showed that the method is specific, sensitive and is suitable to develop for rapid detection of Campylobacter spp. at poultry production.
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Affiliation(s)
- Than Linh Quyen
- Department of Biotechnology and Biomedicine, Technical University of Denmark (DTU-Bioengineering), Lyngby, Denmark
| | - Steen Nordentoft
- National Food Institute, Technical University of Denmark (DTU-Food), Lyngby, Denmark
| | | | - Tien Anh Ngo
- National Food Institute, Technical University of Denmark (DTU-Food), Lyngby, Denmark
| | - Pia Engelsmenn
- National Food Institute, Technical University of Denmark (DTU-Food), Lyngby, Denmark
| | - Yi Sun
- Department of Health Technology, Technical University of Denmark (DTU-Health Tech), Lyngby, Denmark
| | - Mogens Madsen
- Department of Biotechnology and Biomedicine, Technical University of Denmark (DTU-Bioengineering), Lyngby, Denmark
| | - Dang Duong Bang
- National Food Institute, Technical University of Denmark (DTU-Food), Lyngby, Denmark
| | - Anders Wolff
- Department of Biotechnology and Biomedicine, Technical University of Denmark (DTU-Bioengineering), Lyngby, Denmark
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Quyen TL, Ngo TA, Bang DD, Madsen M, Wolff A. Classification of Multiple DNA Dyes Based on Inhibition Effects on Real-Time Loop-Mediated Isothermal Amplification (LAMP): Prospect for Point of Care Setting. Front Microbiol 2019; 10:2234. [PMID: 31681184 PMCID: PMC6803449 DOI: 10.3389/fmicb.2019.02234] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 09/11/2019] [Indexed: 12/16/2022] Open
Abstract
LAMP has received great interest and is widely utilized in life sciences for nucleic acid analysis. To monitor a real-time LAMP assay, a fluorescence DNA dye is an indispensable component and therefore the selection of a suitable dye for real-time LAMP is a need. To aid this selection, we investigated the inhibition effects of twenty-three DNA dyes on real-time LAMP. Threshold time (Tt) values of each real-time LAMP were determined and used as an indicator of the inhibition effect. Based on the inhibition effects, the dyes were classified into four groups: (1) non-inhibition effect, (2) medium inhibition effect, (3) high inhibition effect, and (4) very high inhibition effect. The signal to noise ratio (SNR) and the limit of detection (LOD) of the dyes in groups 1, 2, and 3 were further investigated, and possible inhibition mechanisms of the DNA dyes on the real-time LAMP are suggested and discussed. Furthermore, a comparison of SYTO 9 in different LAMP reactions and different systems is presented. Of the 23 dyes tested, SYTO 9, SYTO 82, SYTO 16, SYTO 13, and Miami Yellow were the best dyes with no inhibitory effect, low LOD and high SNR in the real-time LAMP reactions. The present classification of the dyes will simplify the selection of fluorescence dye for real-time LAMP assays in point of care setting.
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Affiliation(s)
- Than Linh Quyen
- Department of Biotechnology and Biomedicine, Technical University of Denmark (DTU-Bioengineering), Lyngby, Denmark
| | - Tien Anh Ngo
- Laboratory of Applied Micro and Nanotechnology (LAMINATE), National Food Institute, Technical University of Denmark (DTU-Food), Lyngby, Denmark
| | - Dang Duong Bang
- Laboratory of Applied Micro and Nanotechnology (LAMINATE), National Food Institute, Technical University of Denmark (DTU-Food), Lyngby, Denmark
| | - Mogens Madsen
- Department of Biotechnology and Biomedicine, Technical University of Denmark (DTU-Bioengineering), Lyngby, Denmark
| | - Anders Wolff
- Department of Biotechnology and Biomedicine, Technical University of Denmark (DTU-Bioengineering), Lyngby, Denmark
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Ota Y, Furuhashi K, Nanba T, Yamanaka K, Ishikawa J, Nagura O, Hamada E, Maekawa M. A rapid and simple detection method for phenotypic antimicrobial resistance in Escherichia coli by loop-mediated isothermal amplification. J Med Microbiol 2019; 68:169-177. [PMID: 30624176 DOI: 10.1099/jmm.0.000903] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
PURPOSE In infectious disease therapy, administration of adequate antimicrobial agents is essential for preventing the emergence and spread of resistant bacteria. However, conventional antimicrobial susceptibility testing (AST), based on bacterial growth, is time consuming; therefore, a rapid, simple assay is needed for the timely selection of appropriate antibiotics in clinical laboratories. Here, we established a simple, cost-effective, time-saving and highly sensitive AST assay based on loop-mediated isothermal amplification (LAMP). METHODOLOGY The targeted bacteria were cultivated for a short period with or without antibiotic before the LAMP reaction. The time to detect a positive reaction with LAMP was used to generate a threshold time (Tt) value, and subtraction of the Tt value for an antibiotic-free sample from the Tt value in an antibiotic-exposed sample generated the ΔTt value, which was used as a marker of antimicrobial susceptibility. The ΔTt value generated using the LAMP-based assay simply and quickly detected antimicrobial resistance in clinical Escherichia coli isolates. RESULTS Detection of susceptibility to levofloxacin using the ΔTt value perfectly matched with the results of the conventional assay. In addition, the sensitivity and specificity for the detection of ampicillin, trimethoprim-sulfamethoxazole and fosfomycin resistance were 100 %, 93.8 %, 100 % and 80.0 %, 93.3 %, 97.6 %, respectively. CONCLUSION These results showed that this LAMP-based AST has high sensitivity and specificity for detecting resistant strains and a significant time advantage compared with the conventional method.
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Affiliation(s)
- Yusuke Ota
- Department of Laboratory Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Kazuki Furuhashi
- Department of Laboratory Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Takamasa Nanba
- Department of Laboratory Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Katsumasa Yamanaka
- Department of Laboratory Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Jinko Ishikawa
- Department of Laboratory Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Osanori Nagura
- Department of Laboratory Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Etsuko Hamada
- Department of Laboratory Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Masato Maekawa
- Department of Laboratory Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
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Contributions and Challenges of High Throughput qPCR for Determining Antimicrobial Resistance in the Environment: A Critical Review. Molecules 2019; 24:molecules24010163. [PMID: 30609875 PMCID: PMC6337382 DOI: 10.3390/molecules24010163] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 12/28/2018] [Accepted: 12/29/2018] [Indexed: 12/12/2022] Open
Abstract
Expansion in whole genome sequencing and subsequent increase in antibiotic resistance targets have paved the way of high throughput qPCR (HT-qPCR) for analyzing hundreds of antimicrobial resistance genes (ARGs) in a single run. A meta-analysis of 51 selected studies is performed to evaluate ARGs abundance trends over the last 7 years. WaferGenTM SmartChip is found to be the most widely used HT-qPCR platform among others for evaluating ARGs. Up till now around 1000 environmental samples (excluding biological replicates) from different parts of the world have been analyzed on HT-qPCR. Calculated detection frequency and normalized ARGs abundance (ARGs/16S rRNA gene) reported in gut microbiome studies have shown a trend of low ARGs as compared to other environmental matrices. Disparities in the HT-qPCR data analysis which are causing difficulties to researchers in precise interpretation of results have been highlighted and a possible way forward for resolving them is also suggested. The potential of other amplification technologies and point of care or field deployable devices for analyzing ARGs have also been discussed in the review. Our review has focused on updated information regarding the role, current status and future perspectives of HT-qPCR in the field of antimicrobial resistance.
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Maxson T, Blancett CD, Graham AS, Stefan CP, Minogue TD. Rapid antibiotic susceptibility testing from blood culture bottles with species agnostic real-time polymerase chain reaction. PLoS One 2018; 13:e0209042. [PMID: 30543695 PMCID: PMC6292663 DOI: 10.1371/journal.pone.0209042] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 11/27/2018] [Indexed: 01/21/2023] Open
Abstract
Development and implementation of rapid antimicrobial susceptibility testing is critical for guiding patient care and improving clinical outcomes, especially in cases of sepsis. One approach to reduce the time-to-answer for antimicrobial susceptibility is monitoring the inhibition of DNA production, as differences in DNA concentrations are more quickly impacted compared to optical density changes in traditional antimicrobial susceptibility testing. Here, we use real-time PCR to rapidly determine antimicrobial susceptibility after short incubations with antibiotic. Application of this assay to a collection of 144 isolates in mock blood culture, covering medically relevant pathogens displaying high rates of resistance, provided susceptibility data in under 4 hours. This assay provided categorical agreement with a reference method in 96.3% of cases across all species. Sequencing of a subset of PCR amplicons showed accurate genus level identification. Overall, implementation of this method could provide accurate susceptibility results with a reduced time-to-answer for a number of medically relevant bacteria commonly isolated from blood culture.
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Affiliation(s)
- Tucker Maxson
- Diagnostic Systems Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland, United States of America
| | - Candace D. Blancett
- Diagnostic Systems Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland, United States of America
| | - Amanda S. Graham
- Diagnostic Systems Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland, United States of America
| | - Christopher P. Stefan
- Diagnostic Systems Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland, United States of America
| | - Timothy D. Minogue
- Diagnostic Systems Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland, United States of America
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15
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Veses-Garcia M, Antypas H, Löffler S, Brauner A, Andersson-Svahn H, Richter-Dahlfors A. Rapid Phenotypic Antibiotic Susceptibility Testing of Uropathogens Using Optical Signal Analysis on the Nanowell Slide. Front Microbiol 2018; 9:1530. [PMID: 30042754 PMCID: PMC6048231 DOI: 10.3389/fmicb.2018.01530] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 06/20/2018] [Indexed: 01/30/2023] Open
Abstract
Achieving fast antimicrobial susceptibility results is a primary goal in the fight against antimicrobial resistance. Standard antibiotic susceptibility testing (AST) takes, however, at least a day from patient sample to susceptibility profile. Here, we developed and clinically validated a rapid phenotypic AST based on a miniaturized nanotiter plate, the nanowell slide, that holds 672 wells in a 500 nl format for bacterial cultivation. The multitude of nanowells allows multiplexing with a panel of six antibiotics relevant for urinary tract infections. Inclusion of seven concentrations per antibiotic plus technical replicates enabled us to determine a precise minimum inhibitory concentration for 70 clinical uropathogenic Escherichia coli isolates. By combining optical recordings of bacterial growth with an algorithm for optical signal analysis, we calculated Tlag, the point of transition from lag to exponential phase, in each nanoculture. Algorithm-assisted analysis determined antibiotic susceptibility as early as 3 h 40 min. In comparison to standard disk diffusion assays, the nanowell AST showed a total categorical agreement of 97.9% with 2.6% major errors and 0% very major errors for all isolate-antibiotic combination tested. Taking advantage of the optical compatibility of the nanowell slide, we performed microscopy to illustrate its potential in defining susceptibility profiles based on bacterial morphotyping. The excellent clinical performance of the nanowell AST, combined with a short detection time, morphotyping, and the very low consumption of reagents clearly show the advantage of this phenotypic AST as a diagnostic tool in a clinical setting.
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Affiliation(s)
- Marta Veses-Garcia
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Haris Antypas
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Susanne Löffler
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Annelie Brauner
- Department of Microbiology, Tumor and Cell Biology, Division of Clinical Microbiology, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
| | - Helene Andersson-Svahn
- Division of Proteomics and Nanobiotechnology, Science for Life Laboratory, KTH-Royal Institute of Technology, Stockholm, Sweden
| | - Agneta Richter-Dahlfors
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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16
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Schoepp NG, Schlappi TS, Curtis MS, Butkovich SS, Miller S, Humphries RM, Ismagilov RF. Rapid pathogen-specific phenotypic antibiotic susceptibility testing using digital LAMP quantification in clinical samples. Sci Transl Med 2018; 9:9/410/eaal3693. [PMID: 28978750 DOI: 10.1126/scitranslmed.aal3693] [Citation(s) in RCA: 152] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 06/30/2017] [Accepted: 09/05/2017] [Indexed: 12/30/2022]
Abstract
Rapid antimicrobial susceptibility testing (AST) is urgently needed for informing treatment decisions and preventing the spread of antimicrobial resistance resulting from the misuse and overuse of antibiotics. To date, no phenotypic AST exists that can be performed within a single patient visit (30 min) directly from clinical samples. We show that AST results can be obtained by using digital nucleic acid quantification to measure the phenotypic response of Escherichia coli present within clinical urine samples exposed to an antibiotic for 15 min. We performed this rapid AST using our ultrafast (~7 min) digital real-time loop-mediated isothermal amplification (dLAMP) assay [area under the curve (AUC), 0.96] and compared the results to a commercial (~2 hours) digital polymerase chain reaction assay (AUC, 0.98). The rapid dLAMP assay can be used with SlipChip microfluidic devices to determine the phenotypic antibiotic susceptibility of E. coli directly from clinical urine samples in less than 30 min. With further development for additional pathogens, antibiotics, and sample types, rapid digital AST (dAST) could enable rapid clinical decision-making, improve management of infectious diseases, and facilitate antimicrobial stewardship.
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Affiliation(s)
- Nathan G Schoepp
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Travis S Schlappi
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Matthew S Curtis
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Slava S Butkovich
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Shelley Miller
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, 10888 Le Conte Avenue, Brentwood Annex, Los Angeles, CA 90095, USA
| | - Romney M Humphries
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, 10888 Le Conte Avenue, Brentwood Annex, Los Angeles, CA 90095, USA
| | - Rustem F Ismagilov
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA.
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17
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Váradi L, Luo JL, Hibbs DE, Perry JD, Anderson RJ, Orenga S, Groundwater PW. Methods for the detection and identification of pathogenic bacteria: past, present, and future. Chem Soc Rev 2018. [PMID: 28644499 DOI: 10.1039/c6cs00693k] [Citation(s) in RCA: 265] [Impact Index Per Article: 44.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In order to retard the rate of development of antibacterial resistance, the causative agent must be identified as rapidly as possible, so that directed patient treatment and/or contact precautions can be initiated. This review highlights the challenges associated with the detection and identification of pathogenic bacteria, by providing an introduction to the techniques currently used, as well as newer techniques that are in development. Focusing on the chemical basis for these techniques, the review also provides a comparison of their advantages and disadvantages.
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Affiliation(s)
- Linda Váradi
- Faculty of Pharmacy, The University of Sydney, Sydney, NSW 2006, Australia.
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18
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Williams MR, Stedtfeld RD, Engle C, Salach P, Fakher U, Stedtfeld T, Dreelin E, Stevenson RJ, Latimore J, Hashsham SA. Isothermal amplification of environmental DNA (eDNA) for direct field-based monitoring and laboratory confirmation of Dreissena sp. PLoS One 2017; 12:e0186462. [PMID: 29036210 PMCID: PMC5643059 DOI: 10.1371/journal.pone.0186462] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 10/02/2017] [Indexed: 02/01/2023] Open
Abstract
Loop-mediated isothermal amplification (LAMP) of aquatic invasive species environmental DNA (AIS eDNA) was used for rapid, sensitive, and specific detection of Dreissena sp. relevant to the Great Lakes (USA) basin. The method was validated for two uses including i) direct amplification of eDNA using a hand filtration system and ii) confirmation of the results after DNA extraction using a conventional thermal cycler run at isothermal temperatures. Direct amplification eliminated the need for DNA extraction and purification and allowed detection of target invasive species in grab or concentrated surface water samples, containing both free DNA as well as larger cells and particulates, such as veligers, eggs, or seeds. The direct amplification method validation was conducted using Dreissena polymorpha and Dreissena bugensis and uses up to 1 L grab water samples for high target abundance (e.g., greater than 10 veligers (larval mussels) per L for Dreissena sp.) or 20 L samples concentrated through 35 μm nylon screens for low target abundance, at less than 10 veligers per liter water. Surface water concentrate samples were collected over a period of three years, mostly from inland lakes in Michigan with the help of a network of volunteers. Field samples collected from 318 surface water locations included i) filtered concentrate for direct amplification validation and ii) 1 L grab water sample for eDNA extraction and confirmation. Though the extraction-based protocol was more sensitive (resulting in more positive detections than direct amplification), direct amplification could be used for rapid screening, allowing for quicker action times. For samples collected between May and August, results of eDNA direct amplification were consistent with known presence/absence of selected invasive species. A cross-platform smartphone application was also developed to disseminate the analyzed results to volunteers. Field tests of the direct amplification protocol using a portable device (Gene-Z) showed the method could be used in the field to obtain results within one hr (from sample to result). Overall, the direct amplification has the potential to simplify the eDNA-based monitoring of multiple aquatic invasive species. Additional studies are warranted to establish quantitative correlation between eDNA copy number, veliger, biomass or organismal abundance in the field.
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Affiliation(s)
- Maggie R. Williams
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, Michigan, United States of America
| | - Robert D. Stedtfeld
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, Michigan, United States of America
| | - Cathrine Engle
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, Michigan, United States of America
| | - Paul Salach
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, Michigan, United States of America
| | - Umama Fakher
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, Michigan, United States of America
| | - Tiffany Stedtfeld
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, Michigan, United States of America
| | - Erin Dreelin
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, Michigan, United States of America
- Center for Water Sciences, Michigan State University, East Lansing, Michigan, United States of America
| | - R. Jan Stevenson
- Center for Water Sciences, Michigan State University, East Lansing, Michigan, United States of America
- Department of Integrative Biology, Michigan State University, East Lansing, Michigan, United States of America
| | - Jo Latimore
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, Michigan, United States of America
| | - Syed A. Hashsham
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, Michigan, United States of America
- Center for Microbial Ecology, Michigan State University, East Lansing, Michigan, United States of America
- * E-mail:
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19
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Williams MR, Stedtfeld RD, Stedtfeld TM, Tiedje JM, Hashsham SA. Quantification of microRNAs directly from body fluids using a base-stacking isothermal amplification method in a point-of-care device. Biomed Microdevices 2017; 19:45. [PMID: 28536858 PMCID: PMC5896010 DOI: 10.1007/s10544-017-0191-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
MicroRNAs have been proposed to be a class of biomarkers of disease as expression levels are significantly altered in various tissues and body fluids when compared to healthy controls. As such, the detection and quantification of microRNAs is imperative. While many methods have been established for quantification of microRNAs, they typically rely on time consuming handling such as RNA extraction, purification, or ligation. Here we describe a novel method for quantification of microRNAs using direct amplification in body fluids without upstream sample preparation. Tested with a point-of-care device (termed Gene-Z), the presence of microRNA promotes base-stacking hybridization, and subsequent amplification between two universal strands. The base-stacking approach, which was achieved in <60 min, provided a sensitivity of 1.4 fmol per reaction. Tested in various percentages of whole blood, plasma, and faeces, precision (coefficient of variation = 2.6%) was maintained and comparable to amplification in pristine samples. Overall, the developed method represents a significant step towards rapid, one-step detection of microRNAs.
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Affiliation(s)
- Maggie R Williams
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, 48824, USA
| | - Robert D Stedtfeld
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, 48824, USA
| | - Tiffany M Stedtfeld
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, 48824, USA
| | - James M Tiedje
- Center for Microbial Ecology, Michigan State University, East Lansing, MI, 48824, USA
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, 48824, USA
| | - Syed A Hashsham
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, 48824, USA.
- Center for Microbial Ecology, Michigan State University, East Lansing, MI, 48824, USA.
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20
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Stedtfeld RD, Stedtfeld TM, Waseem H, Fitschen-Brown M, Guo X, Chai B, Williams MR, Shook T, Logan A, Graham A, Chae JC, Sul WJ, VanHouten J, Cole JR, Zylstra GJ, Tiedje JM, Upham BL, Hashsham SA. Isothermal assay targeting class 1 integrase gene for environmental surveillance of antibiotic resistance markers. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2017; 198:213-220. [PMID: 28460328 PMCID: PMC5513725 DOI: 10.1016/j.jenvman.2017.04.079] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 04/20/2017] [Accepted: 04/24/2017] [Indexed: 05/05/2023]
Abstract
Antimicrobial resistance genes (ARGs) present in the environment pose a risk to human health due to potential for transfer to human pathogens. Surveillance is an integral part of mitigating environmental dissemination. Quantification of the mobile genetic element class 1 integron-integrase gene (intI1) has been proposed as a surrogate to measuring multiple ARGs. Measurement of such indicator genes can be further simplified by adopting emerging nucleic acids methods such as loop mediated isothermal amplification (LAMP). In this study, LAMP assays were designed and tested for estimating relative abundance of the intI1 gene, which included design of a universal bacteria 16S rRNA gene assay. Following validation of sensitivity and specificity with known bacterial strains, the assays were tested using DNA extracted from river and lake samples. Results showed a significant Pearson correlation (R2 = 0.8) between the intI1 gene LAMP assay and ARG relative abundance (measured via qPCR). To demonstrate the ruggedness of the LAMP assays, experiments were also run in the hands of relatively "untrained" personnel by volunteer undergraduate students at a local community college using a hand-held real-time DNA analysis device - Gene-Z. Overall, results support use of the intI1 gene as an indicator of ARGs and the LAMP assays exhibit the opportunity for volunteers to monitor environmental samples for anthropogenic pollution outside of a specialized laboratory.
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Affiliation(s)
- Robert D Stedtfeld
- Department of Civil and Environmental Engineering, East Lansing, MI, 48824, USA
| | - Tiffany M Stedtfeld
- Department of Civil and Environmental Engineering, East Lansing, MI, 48824, USA
| | - Hassen Waseem
- Department of Civil and Environmental Engineering, East Lansing, MI, 48824, USA
| | | | - Xueping Guo
- Center for Microbial Ecology, Michigan State University, East Lansing, MI, 48824, USA
| | - Benli Chai
- Center for Microbial Ecology, Michigan State University, East Lansing, MI, 48824, USA
| | - Maggie R Williams
- Department of Civil and Environmental Engineering, East Lansing, MI, 48824, USA
| | - Trevor Shook
- Science Division, Delta College, University Center, MI, 48710, USA
| | - Amanda Logan
- Science Division, Delta College, University Center, MI, 48710, USA
| | - Ally Graham
- Science Division, Delta College, University Center, MI, 48710, USA
| | - Jong-Chan Chae
- Division of Biotechnology, Chonbuk National University, Iksan, 54596, Republic of Korea
| | - Woo-Jun Sul
- Department of Systems Biotechnology, Chung Ang University, Anseong, 17546, Republic of Korea
| | - Jacob VanHouten
- Science Division, Delta College, University Center, MI, 48710, USA
| | - James R Cole
- Center for Microbial Ecology, Michigan State University, East Lansing, MI, 48824, USA
| | - Gerben J Zylstra
- Department of Biochemistry & Microbiology, Rutgers University, New Brunswick, NJ, 08901, USA
| | - James M Tiedje
- Center for Microbial Ecology, Michigan State University, East Lansing, MI, 48824, USA
| | - Brad L Upham
- Pediatrics and Human Development, Michigan State University, East Lansing, MI, 48824, USA
| | - Syed A Hashsham
- Department of Civil and Environmental Engineering, East Lansing, MI, 48824, USA; Center for Microbial Ecology, Michigan State University, East Lansing, MI, 48824, USA.
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21
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Waseem H, Williams MR, Stedtfeld T, Chai B, Stedtfeld RD, Cole JR, Tiedje JM, Hashsham SA. Virulence factor activity relationships (VFARs): a bioinformatics perspective. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2017; 19:247-260. [PMID: 28261716 PMCID: PMC5897045 DOI: 10.1039/c6em00689b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Virulence factor activity relationships (VFARs) - a concept loosely based on quantitative structure-activity relationships (QSARs) for chemicals was proposed as a predictive tool for ranking risks due to microorganisms relevant to water safety. A rapid increase in sequencing capabilities and bioinformatics tools has significantly increased the potential for VFAR-based analyses. This review summarizes more than 20 bioinformatics databases and tools, developed over the last decade, along with their virulence and antimicrobial resistance prediction capabilities. With the number of bacterial whole genome sequences exceeding 241 000 and metagenomic analysis projects exceeding 13 000 and the ability to add additional genome sequences for few hundred dollars, it is evident that further development of VFARs is not limited by the availability of information at least at the genomic level. However, additional information related to co-occurrence, treatment response, modulation of virulence due to environmental and other factors, and economic impact must be gathered and incorporated in a manner that also addresses the associated uncertainties. Of the bioinformatics tools, a majority are either designed exclusively for virulence/resistance determination or equipped with a dedicated module. The remaining have the potential to be employed for evaluating virulence. This review focusing broadly on omics technologies and tools supports the notion that these tools are now sufficiently developed to allow the application of VFAR approaches combined with additional engineering and economic analyses to rank and prioritize organisms important to a given niche. Knowledge gaps do exist but can be filled with focused experimental and theoretical analyses that were unimaginable a decade ago. Further developments should consider the integration of the measurement of activity, risk, and uncertainty to improve the current capabilities.
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Affiliation(s)
- Hassan Waseem
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA.
| | - Maggie R Williams
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA.
| | - Tiffany Stedtfeld
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA.
| | - Benli Chai
- Center for Microbial Ecology, Michigan State University, East Lansing, MI 48824, USA
| | - Robert D Stedtfeld
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA.
| | - James R Cole
- Center for Microbial Ecology, Michigan State University, East Lansing, MI 48824, USA
| | - James M Tiedje
- Center for Microbial Ecology, Michigan State University, East Lansing, MI 48824, USA and Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824, USA
| | - Syed A Hashsham
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA. and Center for Microbial Ecology, Michigan State University, East Lansing, MI 48824, USA and Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824, USA
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22
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Williams MR, Stedtfeld RD, Waseem H, Stedtfeld T, Upham B, Khalife W, Etchebarne B, Hughes M, Tiedje JM, Hashsham SA. Implications of direct amplification for measuring antimicrobial resistance using point-of-care devices. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2017; 9:1229-1241. [PMID: 29657581 PMCID: PMC5898395 DOI: 10.1039/c6ay03405e] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Antimicrobial resistance (AMR) is recognized as a global threat to human health. Rapid detection and characterization of AMR is a critical component of most antibiotic stewardship programs. Methods based on amplification of nucleic acids for detection of AMR are generally faster than culture-based approaches but they still require several hours to more than a day due to the need for transporting the sample to a centralized laboratory, processing of sample, and sometimes DNA purification and concentration. Nucleic acids-based point-of-care (POC) devices are capable of rapidly diagnosing antibiotic-resistant infections which may help in making timely and correct treatment decisions. However, for most POC platforms, sample processing for nucleic acids extraction and purification is also generally required prior to amplification. Direct amplification, an emerging possibility for a number of polymerases, has the potential to eliminate these steps without significantly impacting diagnostic performance. This review summarizes direct amplification methods and their implication for rapid measurement of AMR. Future research directions that may further strengthen the possibility of integrating direct amplification methods with POC devices are also summarized.
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Affiliation(s)
- M R Williams
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA
| | - R D Stedtfeld
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA
| | - H Waseem
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA
| | - T Stedtfeld
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA
| | - B Upham
- Pediatrics and Human Development, Michigan State University, East Lansing, MI 48824, USA
| | - W Khalife
- Department of Microbiology, Sparrow Laboratories, Sparrow Health System, Lansing, MI 48912, USA
| | - B Etchebarne
- Osteopathic Medical Specialties, Section of Emergency Medicine, Michigan State University, East Lansing, MI 4882, USA
| | - M Hughes
- Osteopathic Medical Specialties, Section of Emergency Medicine, Michigan State University, East Lansing, MI 4882, USA
| | - J M Tiedje
- Center for Microbial Ecology, Michigan State University, East Lansing, MI 48824, USA
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, USA
| | - S A Hashsham
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA
- Center for Microbial Ecology, Michigan State University, East Lansing, MI 48824, USA
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, USA
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23
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Wang H, Wang J, Yu P, Ge P, Jiang Y, Xu R, Chen R, Liu X. Identification of antibiotic resistance genes in the multidrug-resistant Acinetobacter baumannii strain, MDR-SHH02, using whole-genome sequencing. Int J Mol Med 2016; 39:364-372. [PMID: 28035408 PMCID: PMC5358717 DOI: 10.3892/ijmm.2016.2844] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 12/07/2016] [Indexed: 01/28/2023] Open
Abstract
This study aimed to investigate antibiotic resistance genes in the multidrug-resistant (MDR) Acinetobacter baumannii (A. baumanii) strain, MDR-SHH02, using whole-genome sequencing (WGS). The antibiotic resistance of MDR-SHH02 isolated from a patient with breast cancer to 19 types of antibiotics was determined using the Kirby-Bauer method. WGS of MDR-SHH02 was then performed. Following quality control and transcriptome assembly, functional annotation of genes was conducted, and the phylogenetic tree of MDR-SHH02, along with another 5 A. baumanii species and 2 Acinetobacter species, was constructed using PHYLIP 3.695 and FigTree v1.4.2. Furthermore, pathogenicity islands (PAIs) were predicted by the pathogenicity island database. Potential antibiotic resistance genes in MDR-SHH02 were predicted based on the information in the Antibiotic Resistance Genes Database (ARDB). MDR-SHH02 was found to be resistant to all of the tested antibiotics. The total draft genome length of MDR-SHH02 was 4,003,808 bp. There were 74.25% of coding sequences to be annotated into 21 of the Clusters of Orthologous Groups (COGs) of protein terms, such as 'transcription' and 'amino acid transport and metabolism'. Furthermore, there were 45 PAIs homologous to the sequence MDRSHH02000806. Additionally, a total of 12 gene sequences in MDR-SHH02 were highly similar to the sequences of antibiotic resistance genes in ARDB, including genes encoding aminoglycoside-modifying enzymes [e.g., aac(3)-Ia, ant(2″)-Ia, aph33ib and aph(3′)-Ia], β-lactamase genes (bl2b_tem and bl2b_tem1), sulfonamide-resistant dihydropteroate synthase genes (sul1 and sul2), catb3 and tetb. These results suggest that numerous genes mediate resistance to various antibiotics in MDR-SHH02, and provide a clinical guidance for the personalized therapy of A. baumannii-infected patients.
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Affiliation(s)
- Hualiang Wang
- Department of Molecular Biology Laboratory, Shanghai Centre for Clinical Laboratory, Shanghai 200126, P.R. China
| | - Jinghua Wang
- Department of Microbiology Laboratory, Shanghai Centre for Clinical Laboratory, Shanghai 200126, P.R. China
| | - Peijuan Yu
- Department of Clinical Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215004, P.R. China
| | - Ping Ge
- Department of Microbiology Laboratory, Shanghai Centre for Clinical Laboratory, Shanghai 200126, P.R. China
| | - Yanqun Jiang
- Department of Clinical Laboratory, The Sixth People's Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 200233, P.R. China
| | - Rong Xu
- Department of Microbiology Laboratory, Shanghai Centre for Clinical Laboratory, Shanghai 200126, P.R. China
| | - Rong Chen
- Department of Microbiology Laboratory, Shanghai Centre for Clinical Laboratory, Shanghai 200126, P.R. China
| | - Xuejie Liu
- Department of Microbiology Laboratory, Shanghai Centre for Clinical Laboratory, Shanghai 200126, P.R. China
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24
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Stedtfeld RD, Stedtfeld TM, Samhan F, Kanitkar YH, Hatzinger PB, Cupples AM, Hashsham SA. Direct loop mediated isothermal amplification on filters for quantification of Dehalobacter in groundwater. J Microbiol Methods 2016; 131:61-67. [PMID: 27720723 DOI: 10.1016/j.mimet.2016.09.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Revised: 09/30/2016] [Accepted: 09/30/2016] [Indexed: 12/12/2022]
Abstract
Nucleic acid amplification of biomarkers is increasingly used to monitor microbial activity and assess remedial performance in contaminated aquifers. Previous studies described the use of filtration, elution, and direct isothermal amplification (i.e. no DNA extraction and purification) as a field-able means to quantify Dehalococcoides spp. in groundwater. This study expands previous work with direct loop mediated isothermal amplification (LAMP) for the detection and quantification of Dehalobacter spp. in groundwater. Experiments tested amplification of DNA with and without crude lysis and varying concentrations of humic acid. Three separate field-able methods of biomass concentration with eight aquifer samples were also tested, comparing direct LAMP with traditional DNA extraction and quantitative PCR (qPCR). A new technique was developed where filters were amplified directly within disposable Gene-Z chips. The direct filter amplification (DFA) method eliminated an elution step and provided a detection limit of 102Dehalobacter cells per 100mL. LAMP with crudely lysed Dehalobacter had a negligible effect on threshold time and sensitivity compared to lysed samples. The LAMP assay was more resilient than traditional qPCR to humic acid in sample, amplifying with up to 100mg per L of humic acid per reaction compared to 1mg per L for qPCR. Of the tested field-able concentrations methods, DFA had the lowest coefficient of variation among Dehalobacter spiked groundwater samples and lowest threshold time indicating high capture efficiency and low inhibition. While demonstrated with Dehalobacter, the DFA method can potentially be used for a number of applications requiring field-able, rapid (<60min) and highly sensitive quantification of microorganisms in environmental water samples.
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Affiliation(s)
- Robert D Stedtfeld
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA
| | - Tiffany M Stedtfeld
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA
| | - Farag Samhan
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA; Department of Water Pollution Control, National Research Centre, 33 El-Bohouth, P.O. 12622, Ad-Doqi, Giza, Egypt
| | - Yogendra H Kanitkar
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA
| | | | - Alison M Cupples
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA
| | - Syed A Hashsham
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA
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Schoepp NG, Khorosheva EM, Schlappi TS, Curtis MS, Humphries RM, Hindler JA, Ismagilov RF. Digital Quantification of DNA Replication and Chromosome Segregation Enables Determination of Antimicrobial Susceptibility after only 15 Minutes of Antibiotic Exposure. Angew Chem Int Ed Engl 2016; 55:9557-61. [PMID: 27357747 PMCID: PMC5215780 DOI: 10.1002/anie.201602763] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 05/05/2016] [Indexed: 01/11/2023]
Abstract
Rapid antimicrobial susceptibility testing (AST) would decrease misuse and overuse of antibiotics. The "holy grail" of AST is a phenotype-based test that can be performed within a doctor visit. Such a test requires the ability to determine a pathogen's susceptibility after only a short antibiotic exposure. Herein, digital PCR (dPCR) was employed to test whether measuring DNA replication of the target pathogen through digital single-molecule counting would shorten the required time of antibiotic exposure. Partitioning bacterial chromosomal DNA into many small volumes during dPCR enabled AST results after short exposure times by 1) precise quantification and 2) a measurement of how antibiotics affect the states of macromolecular assembly of bacterial chromosomes. This digital AST (dAST) determined susceptibility of clinical isolates from urinary tract infections (UTIs) after 15 min of exposure for all four antibiotic classes relevant to UTIs. This work lays the foundation to develop a rapid, point-of-care AST and strengthen global antibiotic stewardship.
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Affiliation(s)
- Nathan G Schoepp
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA, 91125, USA
| | - Eugenia M Khorosheva
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA, 91125, USA
| | - Travis S Schlappi
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA, 91125, USA
| | - Matthew S Curtis
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA, 91125, USA
| | - Romney M Humphries
- Pathology and Laboratory Medicine, University of California, Los Angeles, 10888 Le Conte Avenue, Brentwood Annex, Los Angeles, CA, 90095, USA
| | - Janet A Hindler
- Pathology and Laboratory Medicine, University of California, Los Angeles, 10888 Le Conte Avenue, Brentwood Annex, Los Angeles, CA, 90095, USA
| | - Rustem F Ismagilov
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA, 91125, USA.
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Schoepp NG, Khorosheva EM, Schlappi TS, Curtis MS, Humphries RM, Hindler JA, Ismagilov RF. Digital Quantification of DNA Replication and Chromosome Segregation Enables Determination of Antimicrobial Susceptibility after only 15 Minutes of Antibiotic Exposure. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201602763] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Nathan G. Schoepp
- Division of Chemistry and Chemical Engineering; California Institute of Technology; 1200 E. California Blvd. Pasadena CA 91125 USA
| | - Eugenia M. Khorosheva
- Division of Chemistry and Chemical Engineering; California Institute of Technology; 1200 E. California Blvd. Pasadena CA 91125 USA
| | - Travis S. Schlappi
- Division of Chemistry and Chemical Engineering; California Institute of Technology; 1200 E. California Blvd. Pasadena CA 91125 USA
| | - Matthew S. Curtis
- Division of Chemistry and Chemical Engineering; California Institute of Technology; 1200 E. California Blvd. Pasadena CA 91125 USA
| | - Romney M. Humphries
- Pathology and Laboratory Medicine; University of California, Los Angeles; 10888 Le Conte Avenue, Brentwood Annex Los Angeles CA 90095 USA
| | - Janet A. Hindler
- Pathology and Laboratory Medicine; University of California, Los Angeles; 10888 Le Conte Avenue, Brentwood Annex Los Angeles CA 90095 USA
| | - Rustem F. Ismagilov
- Division of Chemistry and Chemical Engineering; California Institute of Technology; 1200 E. California Blvd. Pasadena CA 91125 USA
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27
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Stedtfeld RD, Williams MR, Fakher U, Johnson TA, Stedtfeld TM, Wang F, Khalife WT, Hughes M, Etchebarne BE, Tiedje JM, Hashsham SA. Antimicrobial resistance dashboard application for mapping environmental occurrence and resistant pathogens. FEMS Microbiol Ecol 2016; 92:fiw020. [PMID: 26850162 PMCID: PMC5968356 DOI: 10.1093/femsec/fiw020] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 01/30/2016] [Indexed: 02/04/2023] Open
Abstract
An antibiotic resistance (AR) Dashboard application is being developed regarding the occurrence of antibiotic resistance genes (ARG) and bacteria (ARB) in environmental and clinical settings. The application gathers and geospatially maps AR studies, reported occurrence and antibiograms, which can be downloaded for offline analysis. With the integration of multiple data sets, the database can be used on a regional or global scale to identify hot spots for ARGs and ARB; track and link spread and transmission, quantify environmental or human factors influencing presence and persistence of ARG harboring organisms; differentiate natural ARGs from those distributed via human or animal activity; cluster and compare ARGs connections in different environments and hosts; and identify genes that can be used as proxies to routinely monitor anthropogenic pollution. To initially populate and develop the AR Dashboard, a qPCR ARG array was tested with 30 surface waters, primary influent from three waste water treatment facilities, ten clinical isolates from a regional hospital and data from previously published studies including river, park soil and swine farm samples. Interested users are invited to download a beta version (available on iOS or Android), submit AR information using the application, and provide feedback on current and prospective functionalities.
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Affiliation(s)
- Robert D Stedtfeld
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA
| | - Maggie R Williams
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA
| | - Umama Fakher
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA
| | - Timothy A Johnson
- The Center for Microbial Ecology, Michigan State University, East Lansing, MI 48824, USA
| | - Tiffany M Stedtfeld
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA
| | - Fang Wang
- The Center for Microbial Ecology, Michigan State University, East Lansing, MI 48824, USA State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China
| | - Walid T Khalife
- Department of Microbiology, Sparrow Laboratories, Sparrow Health System, Lansing, MI 48912, USA
| | - Mary Hughes
- Department of Osteopathic Medical Specialties, Section of Emergency Medicine, College of Osteopathic Medicine, Michigan State University, East Lansing, MI 48824, USA
| | - Brett E Etchebarne
- Department of Osteopathic Medical Specialties, Section of Emergency Medicine, College of Osteopathic Medicine, Michigan State University, East Lansing, MI 48824, USA
| | - James M Tiedje
- The Center for Microbial Ecology, Michigan State University, East Lansing, MI 48824, USA Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
| | - Syed A Hashsham
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA The Center for Microbial Ecology, Michigan State University, East Lansing, MI 48824, USA
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Selection of fluorescent DNA dyes for real-time LAMP with portable and simple optics. J Microbiol Methods 2015; 119:223-7. [PMID: 26554941 DOI: 10.1016/j.mimet.2015.11.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 11/04/2015] [Accepted: 11/07/2015] [Indexed: 12/16/2022]
Abstract
Loop-mediated isothermal amplification (LAMP) is increasingly used for point-of-care nucleic acid based diagnostics. LAMP can be monitored in real-time by measuring the increase in fluorescence of DNA binding dyes. However, there is little information comparing the effect of various fluorescent dyes on signal to noise ratio (SNR) or threshold time (Tt). This information is critical for implementation with field deployable diagnostic tools that require small, low power consumption, robust, and inexpensive optical components with reagent saving low volume reactions. In this study, SNR and Tt during real-time LAMP was evaluated with eleven fluorescent dyes. Of all dyes tested, SYTO-82, SYTO-84, and SYTOX Orange resulted in the shortest Tt, and SYTO-81 had the widest range of working concentrations. The optimized protocol detected 10 genome copies of Mycobacterium tuberculosis in less than 10 min, 10 copies of Giardia intestinalis in ~20 min, and 10 copies of Staphylococcus aureus or Salmonella enterica in less than 15 min. Results demonstrate that reaction efficiency depends on both dye type and concentration and the selected polymerase. The optimized protocol was evaluated in the Gene-Z™ device, a hand-held battery operated platform characterized via simple and low cost optics, and a multiple assay microfluidic chip with micron volume reaction wells. Compared to the more conventional intercalating dye (SYBR Green), reliable amplification was only observed in the Gene-Z™ when using higher concentrations of SYTO-81.
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