51
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Kim YT, Lee D, Heo HY, Kim DH, Seo TS. An integrated slidable and valveless microdevice with solid phase extraction, polymerase chain reaction, and immunochromatographic strip parts for multiplex colorimetric pathogen detection. LAB ON A CHIP 2015; 15:4148-4155. [PMID: 26394907 DOI: 10.1039/c5lc00801h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A total integrated genetic analysis microsystem was developed, which consisted of solid phase extraction (SPE), polymerase chain reaction (PCR), and immunochromatographic strip (ICS) parts for multiplex colorimetric detection of pathogenic Staphylococcus aureus (S. aureus) and Escherichia coli O157:H7 (E. coli O157:H7) on a portable genetic analyzer. Utilizing a slidable chamber, which is a movable glass wafer, complex microvalves could be eliminated for fluidic control in the microchannel, which could simplify the chip design and chip operation. The integrated slidable microdevice was composed of 4 layers: a 4-point Pt/Ti resistance temperature detector (RTD) wafer, a micro-patterned channel wafer, a 2 μL volume slidable chamber, and an ICS. The entire process from the DNA extraction in the SPE chamber to the detection of the target gene expression by the ICS was serially performed by simply sliding the slidable chamber from one part to another functional part. The total process for multiplex pathogenic S. aureus and E. coli O157:H7 detection on the integrated slidable microdevice was accomplished within 55 min with a detection limit of 5 cells. Furthermore, spiked bacteria samples in milk were also successfully analysed on the portable genetic analysis microsystem with sample-in-answer-out capability. The proposed total integrated microsystem is adequate for point-of-care DNA testing in that no microvalves and complex tubing systems are required due to the use of the slidable chamber and the bulky and expensive fluorescence or electrochemical detectors are not necessary due to the ICS based colorimetric detection.
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Affiliation(s)
- Yong Tae Kim
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Korea.
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Application of Isothermal Amplification Techniques for Identification of Madurella mycetomatis, the Prevalent Agent of Human Mycetoma. J Clin Microbiol 2015; 53:3280-5. [PMID: 26246484 DOI: 10.1128/jcm.01544-15] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 07/27/2015] [Indexed: 01/25/2023] Open
Abstract
Appropriate diagnosis and treatment of eumycetoma may vary significantly depending on the causative agent. To date, the most common fungus causing mycetoma worldwide is Madurella mycetomatis. This species fails to express any recognizable morphological characteristics, and reliable identification can therefore only be achieved with the application of molecular techniques. Recombinase polymerase amplification (RPA) and loop-mediated isothermal amplification (LAMP) are proposed as alternatives to phenotypic methods. Species-specific primers were developed to target the ribosomal DNA (rDNA) internal transcribed spacer (ITS) region of M. mycetomatis. Both isothermal amplification techniques showed high specificity and sufficient sensitivity to amplify fungal DNA and proved to be appropriate for detection of M. mycetomatis. Diagnostic performance of the techniques was assessed in comparison to conventional PCR using biopsy specimens from eumycetoma patients. RPA is reliable and easy to operate and has the potential to be implemented in areas where mycetoma is endemic. The techniques may be expanded to detect fungal DNA from environmental samples.
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53
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Song B, Jin W, Song Q, Jin Q, Mu Y. Rapid absolute determination platform of nucleic acid for point-of-care testing. Chem Res Chin Univ 2015. [DOI: 10.1007/s40242-015-4503-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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54
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Abstract
Clinical tests based on primer-initiated amplification of specific nucleic acid sequences achieve high levels of sensitivity and specificity. Despite these desirable characteristics, these tests have not reached their full potential because their complexity and expense limit their usefulness to centralized laboratories. This paper describes a device that integrates sample preparation and loop-mediated isothermal amplification (LAMP) with end point detection using a hand-held UV source and camera phone. The prototype device integrates paper microfluidics (to enable fluid handling) and a multilayer structure, or a "paper machine", that allows a central patterned paper strip to slide in and out of fluidic path and thus allows introduction of sample, wash buffers, amplification master mix, and detection reagents with minimal pipetting, in a hand-held, disposable device intended for point-of-care use in resource-limited environments. This device creates a dynamic seal that prevents evaporation during incubation at 65 °C for 1 h. This interval is sufficient to allow a LAMP reaction for the Escherichia coli malB gene to proceed with an analytical sensitivity of 1 double-stranded DNA target copy. Starting with human plasma spiked with whole, live E. coli cells, this paper demonstrates full integration of sample preparation with LAMP amplification and end point detection with a limit of detection of 5 cells. Further, it shows that the method used to prepare sample enables concentration of DNA from sample volumes commonly available from fingerstick blood draw.
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Affiliation(s)
- John T Connelly
- †Diagnostics For All, 840 Memorial Drive, Cambridge, Massachusetts 02139, United States
| | - Jason P Rolland
- †Diagnostics For All, 840 Memorial Drive, Cambridge, Massachusetts 02139, United States
| | - George M Whitesides
- ‡Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
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55
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Liu C, Sadik MM, Mauk MG, Edelstein PH, Bushman FD, Gross R, Bau HH. Nuclemeter: a reaction-diffusion based method for quantifying nucleic acids undergoing enzymatic amplification. Sci Rep 2014; 4:7335. [PMID: 25477046 PMCID: PMC4256561 DOI: 10.1038/srep07335] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 11/11/2014] [Indexed: 11/18/2022] Open
Abstract
Real-time amplification and quantification of specific nucleic acid sequences plays a major role in medical and biotechnological applications. In the case of infectious diseases, such as HIV, quantification of the pathogen-load in patient specimens is critical to assess disease progression and effectiveness of drug therapy. Typically, nucleic acid quantification requires expensive instruments, such as real-time PCR machines, which are not appropriate for on-site use and for low-resource settings. This paper describes a simple, low-cost, reaction-diffusion based method for end-point quantification of target nucleic acids undergoing enzymatic amplification. The number of target molecules is inferred from the position of the reaction-diffusion front, analogous to reading temperature in a mercury thermometer. The method was tested for HIV viral load monitoring and performed on par with conventional benchtop methods. The proposed method is suitable for nucleic acid quantification at point of care, compatible with multiplexing and high-throughput processing, and can function instrument-free.
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Affiliation(s)
- Changchun Liu
- Department of Mechanical Engineering and Applied Mechanics, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Mohamed M Sadik
- Department of Mechanical Engineering and Applied Mechanics, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Michael G Mauk
- Department of Mechanical Engineering and Applied Mechanics, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Paul H Edelstein
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Frederic D Bushman
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Robert Gross
- 1] Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA [2] Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Haim H Bau
- Department of Mechanical Engineering and Applied Mechanics, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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56
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Mani V, Wang S, Inci F, De Libero G, Singhal A, Demirci U. Emerging technologies for monitoring drug-resistant tuberculosis at the point-of-care. Adv Drug Deliv Rev 2014; 78:105-17. [PMID: 24882226 DOI: 10.1016/j.addr.2014.05.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 04/29/2014] [Accepted: 05/25/2014] [Indexed: 01/18/2023]
Abstract
Infectious diseases are the leading cause of death worldwide. Among them, tuberculosis (TB) remains a major threat to public health, exacerbated by the emergence of multiple drug-resistant (MDR) and extensively drug-resistant (XDR) Mycobacterium tuberculosis (Mtb). MDR-Mtb strains are resistant to first-line anti-TB drugs such as isoniazid and rifampicin; whereas XDR-Mtb strains are resistant to additional drugs including at least to any fluoroquinolone and one of the second-line anti-TB injectable drugs such as kanamycin, capreomycin, or amikacin. Clinically, these strains have significantly impacted the management of TB in high-incidence developing countries, where systemic surveillance of TB drug resistance is lacking. For effective management of TB on-site, early detection of drug resistance is critical to initiate treatment, to reduce mortality, and to thwart drug-resistant TB transmission. In this review, we discuss the diagnostic challenges to detect drug-resistant TB at the point-of-care (POC). Moreover, we present the latest advances in nano/microscale technologies that can potentially detect TB drug resistance to improve on-site patient care.
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57
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Electricity-free amplification and detection for molecular point-of-care diagnosis of HIV-1. PLoS One 2014; 9:e113693. [PMID: 25426953 PMCID: PMC4245218 DOI: 10.1371/journal.pone.0113693] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 10/28/2014] [Indexed: 11/28/2022] Open
Abstract
In resource-limited settings, the lack of decentralized molecular diagnostic testing and sparse access to centralized medical facilities can present a critical barrier to timely diagnosis, treatment, and subsequent control and elimination of infectious diseases. Isothermal nucleic acid amplification methods, including reverse transcription loop-mediated isothermal amplification (RT-LAMP), are well-suited for decentralized point-of-care molecular testing in minimal infrastructure laboratories since they significantly reduce the complexity of equipment and power requirements. Despite reduced complexity, however, there is still a need for a constant heat source to enable isothermal nucleic acid amplification. This requirement poses significant challenges for laboratories in developing countries where electricity is often unreliable or unavailable. To address this need, we previously developed a low-cost, electricity-free heater using an exothermic reaction thermally coupled with a phase change material. This heater achieved acceptable performance, but exhibited considerable variability. Furthermore, as an enabling technology, the heater was an incomplete diagnostic solution. Here we describe a more precise, affordable, and robust heater design with thermal standard deviation <0.5°C at operating temperature, a cost of approximately US$.06 per test for heater reaction materials, and an ambient temperature operating range from 16°C to 30°C. We also pair the heater with nucleic acid lateral flow (NALF)-detection for a visual readout. To further illustrate the utility of the electricity-free heater and NALF-detection platform, we demonstrate sensitive and repeatable detection of HIV-1 with a ß-actin positive internal amplification control from processed sample to result in less than 80 minutes. Together, these elements are building blocks for an electricity-free platform capable of isothermal amplification and detection of a variety of pathogens.
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58
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Zhang X, Lowe SB, Gooding JJ. Brief review of monitoring methods for loop-mediated isothermal amplification (LAMP). Biosens Bioelectron 2014; 61:491-9. [DOI: 10.1016/j.bios.2014.05.039] [Citation(s) in RCA: 194] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 05/14/2014] [Accepted: 05/15/2014] [Indexed: 01/20/2023]
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59
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Lillis L, Lehman D, Singhal MC, Cantera J, Singleton J, Labarre P, Toyama A, Piepenburg O, Parker M, Wood R, Overbaugh J, Boyle DS. Non-instrumented incubation of a recombinase polymerase amplification assay for the rapid and sensitive detection of proviral HIV-1 DNA. PLoS One 2014; 9:e108189. [PMID: 25264766 PMCID: PMC4180440 DOI: 10.1371/journal.pone.0108189] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 08/20/2014] [Indexed: 02/05/2023] Open
Abstract
Sensitive diagnostic tests for infectious diseases often employ nucleic acid amplification technologies (NAATs). However, most NAAT assays, including many isothermal amplification methods, require power-dependent instrumentation for incubation. For use in low resource settings (LRS), diagnostics that do not require consistent electricity supply would be ideal. Recombinase polymerase amplification (RPA) is an isothermal amplification technology that has been shown to typically work at temperatures ranging from 25–43°C, and does not require a stringent incubation temperature for optimal performance. Here we evaluate the ability to incubate an HIV-1 RPA assay, intended for use as an infant HIV diagnostic in LRS, at ambient temperatures or with a simple non-instrumented heat source. To determine the range of expected ambient temperatures in settings where an HIV-1 infant diagnostic would be of most use, a dataset of the seasonal range of daily temperatures in sub Saharan Africa was analyzed and revealed ambient temperatures as low as 10°C and rarely above 43°C. All 24 of 24 (100%) HIV-1 RPA reactions amplified when incubated for 20 minutes between 31°C and 43°C. The amplification from the HIV-1 RPA assay under investigation at temperatures was less consistent below 30°C. Thus, we developed a chemical heater to incubate HIV-1 RPA assays when ambient temperatures are between 10°C and 30°C. All 12/12 (100%) reactions amplified with chemical heat incubation from ambient temperatures of 15°C, 20°C, 25°C and 30°C. We also observed that incubation at 30 minutes improved assay performance at lower temperatures where detection was sporadic using 20 minutes incubation. We have demonstrated that incubation of the RPA HIV-1 assay via ambient temperatures or using chemical heaters yields similar results to using electrically powered devices. We propose that this RPA HIV-1 assay may not need dedicated equipment to be a highly sensitive tool to diagnose infant HIV-1 in LRS.
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Affiliation(s)
| | - Dara Lehman
- Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | | | | | | | - Paul Labarre
- PATH, Seattle, Washington, United States of America
| | | | - Olaf Piepenburg
- TwistDx Limited, Minerva Building, Babraham Research Campus, Babraham, Cambridge, United Kingdom
| | - Mathew Parker
- TwistDx Limited, Minerva Building, Babraham Research Campus, Babraham, Cambridge, United Kingdom
| | - Robert Wood
- Department of Atmospheric Sciences, University of Washington, Seattle, Washington, United States of America
| | - Julie Overbaugh
- Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - David S. Boyle
- PATH, Seattle, Washington, United States of America
- * E-mail:
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60
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Qiu W, Xu H, Takalkar S, Gurung AS, Liu B, Zheng Y, Guo Z, Baloda M, Baryeh K, Liu G. Carbon nanotube-based lateral flow biosensor for sensitive and rapid detection of DNA sequence. Biosens Bioelectron 2014; 64:367-72. [PMID: 25262062 DOI: 10.1016/j.bios.2014.09.028] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Revised: 09/04/2014] [Accepted: 09/14/2014] [Indexed: 01/31/2023]
Abstract
In this article, we describe a carbon nanotube (CNT)-based lateral flow biosensor (LFB) for rapid and sensitive detection of DNA sequence. Amine-modified DNA detection probe was covalently immobilized on the shortened multi-walled carbon nanotubes (MWCNTs) via diimide-activated amidation between the carboxyl groups on the CNT surface and amine groups on the detection DNA probes. Sandwich-type DNA hybridization reactions were performed on the LFB and the captured MWCNTs on test zone and control zone of LFB produced the characteristic black bands, enabling visual detection of DNA sequences. Combining the advantages of lateral flow chromatographic separation with unique physical properties of MWCNT (large surface area), the optimized LFB was capable of detecting of 0.1 nM target DNA without instrumentation. Quantitative detection could be realized by recording the intensity of the test line with the Image J software, and the detection limit of 40 pM was obtained. This detection limit is 12.5 times lower than that of gold nanoparticle (GNP)-based LFB (0.5 nM, Mao et al. Anal. Chem. 2009, 81, 1660-1668). Another important feature is that the preparation of MWCNT-DNA conjugates was robust and the use of MWCNT labels avoided the aggregation of conjugates and tedious preparation time, which were often met in the traditional GNP-based nucleic acid LFB. The applications of MWCNT-based LFB can be extended to visually detect protein biomarkers using MWCNT-antibody conjugates. The MWCNT-based LFB thus open a new door to prepare a new generation of LFB, and shows great promise for in-field and point-of-care diagnosis of genetic diseases and for the detection of infectious agents.
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Affiliation(s)
- Wanwei Qiu
- College of Food Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, PR China; Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58105, United States
| | - Hui Xu
- College of Food Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, PR China; Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58105, United States
| | - Sunitha Takalkar
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58105, United States
| | - Anant S Gurung
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58105, United States
| | - Bin Liu
- College of Food Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, PR China.
| | - Yafeng Zheng
- College of Food Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, PR China; Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58105, United States
| | - Zebin Guo
- College of Food Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, PR China; Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58105, United States
| | - Meenu Baloda
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58105, United States
| | - Kwaku Baryeh
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58105, United States
| | - Guodong Liu
- College of Food Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, PR China; Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58105, United States.
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61
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Chander Y, Koelbl J, Puckett J, Moser MJ, Klingele AJ, Liles MR, Carrias A, Mead DA, Schoenfeld TW. A novel thermostable polymerase for RNA and DNA loop-mediated isothermal amplification (LAMP). Front Microbiol 2014; 5:395. [PMID: 25136338 PMCID: PMC4117986 DOI: 10.3389/fmicb.2014.00395] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 07/14/2014] [Indexed: 11/13/2022] Open
Abstract
Meeting the goal of providing point of care (POC) tests for molecular detection of pathogens in low resource settings places stringent demands on all aspects of the technology. OmniAmp DNA polymerase (Pol) is a thermostable viral enzyme that enables true POC use in clinics or in the field by overcoming important barriers to isothermal amplification. In this paper, we describe the multiple advantages of OmniAmp Pol as an isothermal amplification enzyme and provide examples of its use in loop-mediated isothermal amplification (LAMP) for pathogen detection. The inherent reverse transcriptase activity of OmniAmp Pol allows single enzyme detection of RNA targets in RT-LAMP. Common methods of nucleic acid amplification are highly susceptible to sample contaminants, necessitating elaborate nucleic acid purification protocols that are incompatible with POC or field use. OmniAmp Pol was found to be less inhibited by whole blood components typical in certain crude sample preparations. Moreover, the thermostability of the enzyme compared to alternative DNA polymerases (Bst) and reverse transcriptases allows pretreatment of complete reaction mixes immediately prior to amplification, which facilitates amplification of highly structured genome regions. Compared to Bst, OmniAmp Pol has a faster time to result, particularly with more dilute templates. Molecular diagnostics in field settings can be challenging due to the lack of refrigeration. The stability of OmniAmp Pol is compatible with a dry format that enables long term storage at ambient temperatures. A final requirement for field operability is compatibility with either commonly available instruments or, in other cases, a simple, inexpensive, portable detection mode requiring minimal training or power. Detection of amplification products is shown using lateral flow strips and analysis on a real-time PCR instrument. Results of this study show that OmniAmp Pol is ideally suited for low resource molecular detection of pathogens.
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Affiliation(s)
| | | | | | | | | | - Mark R Liles
- Department of Biological Sciences, Auburn University Auburn, AL, USA
| | - Abel Carrias
- Department of Biological Sciences, Auburn University Auburn, AL, USA
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Loop-mediated isothermal amplification for Rickettsia typhi (the causal agent of murine typhus): problems with diagnosis at the limit of detection. J Clin Microbiol 2013; 52:832-8. [PMID: 24371248 PMCID: PMC3957756 DOI: 10.1128/jcm.02786-13] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Murine typhus is a flea-borne disease of worldwide distribution caused by Rickettsia typhi. Although treatment with tetracycline antibiotics is effective, treatment is often misguided or delayed due to diagnostic difficulties. As the gold standard immunofluorescence assay is imperfect, we aimed to develop and evaluate a loop-mediated isothermal amplification (LAMP) assay. LAMP assays have the potential to fulfill the WHO ASSURED criteria (affordable, sensitive, specific, user friendly, robust and rapid, equipment free, deliverable to those who need them) for diagnostic methodologies, as they can detect pathogen-derived nucleic acid with low technical expenditure. The LAMP assay was developed using samples of bacterial isolates (n = 41), buffy coat specimens from R. typhi PCR-positive Lao patients (n = 42), and diverse negative controls (n = 47). The method was then evaluated prospectively using consecutive patients with suspected scrub typhus or murine typhus (n = 266). The limit of detection was ∼40 DNA copies/LAMP reaction, with an analytical sensitivity of <10 DNA copies/reaction based on isolate dilutions. Despite these low cutoffs, the clinical sensitivity was disappointing, with 48% (95% confidence interval [95% CI], 32.5 to 62.7%) (specificity, 100% [95% CI, 100 to 100%]) in the developmental phase and 33% (95% CI, 9.2 to 56.8%) (specificity, 98.5% [95% CI, 97.0% to 100%]) in the prospective study. This low diagnostic accuracy was attributed to low patient R. typhi bacterial loads (median, 210 DNA copies/ml blood; interquartile range, 130 to 500). PCR-positive but LAMP-negative samples demonstrated significantly lower bacterial loads than LAMP-positive samples. Our findings highlight the diagnostic challenges for diseases with low pathogen burdens and emphasize the need to integrate pathogen biology with improved template production for assay development strategies.
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63
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Hickerson AI, Lu HW, Roskos K, Carey T, Niemz A. Disposable Miniature Check Valve Design Suitable for Scalable Manufacturing. SENSORS AND ACTUATORS. A, PHYSICAL 2013; 203:76-81. [PMID: 24825946 PMCID: PMC4016788 DOI: 10.1016/j.sna.2013.08.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We present a passive, miniature check valve which can be manufactured using standard techniques ideal for low-cost, disposable systems used in medical devices and other applications. The body of the valve consists of a hollow cylindrical core, closed at one end, with a side port and a cylindrical elastomeric sleeve placed over the core body, covering the side port. The pressure required for initial opening of the valve, referred to as cracking pressure, can be adjusted, and depends predominantly on the valve core outer diameter, the sleeve inner diameter, the sleeve wall thickness, and the sleeve material's modulus of elasticity. These parameters can be controlled to tight tolerances, while the tolerances on other features can be relaxed, which simplifies valve manufacturing and assembly. Valve embodiments produced from different materials, and with varying critical dimensions, exhibited distinct and reproducible cracking pressures in the range of 2 to 20 PSI. The cracking pressure did not vary significantly as a function of flow rate. No back flow leakage was encountered up to 30 PSI, the pressure limit of the sensor used in this experiment. Most of the valves tested had small internal volumes of 3-4 μL. The internal volume can be further reduced by selecting a core of smaller inner diameter. In contrast to lithography-based microvalves that generally must be manufactured in-situ within the fluidic device, the herein presented valve can be manufactured independently of, and can be readily integrated into fluidic systems manufactured via a wide selection of fabrication methods.
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Affiliation(s)
- Anna I. Hickerson
- Keck Graduate Institute of Applied Life Sciences, 535 Watson Drive, Claremont, CA 91711, USA
| | - Hsiang-Wei Lu
- Keck Graduate Institute of Applied Life Sciences, 535 Watson Drive, Claremont, CA 91711, USA
| | - Kristina Roskos
- Keck Graduate Institute of Applied Life Sciences, 535 Watson Drive, Claremont, CA 91711, USA
| | - Thomas Carey
- Harvey Mudd College, 301 Platt Boulevard, Claremont, CA 91711, USA
| | - Angelika Niemz
- Keck Graduate Institute of Applied Life Sciences, 535 Watson Drive, Claremont, CA 91711, USA
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