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An Evaluation of the OLM CandID Real-Time PCR to Aid in the Diagnosis of Invasive Candidiasis When Testing Serum Samples. J Fungi (Basel) 2022; 8:jof8090935. [PMID: 36135660 PMCID: PMC9505555 DOI: 10.3390/jof8090935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 08/23/2022] [Accepted: 09/01/2022] [Indexed: 11/17/2022] Open
Abstract
Background: Treatment for invasive candidiasis (IC) is time-critical, and culture-based tests can limit clinical utility. Nonculture-based methods such as Candida PCR represent a promising approach to improving patient management but require further evaluation to understand their optimal role and incorporation into clinical algorithms. This study determined the performance of the commercially available OLM CandID real-time PCR when testing serum and developed a diagnostic algorithm for IC. Methods: The study comprised a retrospective performance evaluation of the CandID real-time PCR assay when testing surplus serum (n = 83 patients, 38 with IC), followed by a prospective consecutive cohort evaluation (n = 103 patients, 24 with IC) post incorporation into routine service. A combined diagnostic algorithm, also including (1-3)-β-D-Glucan testing, was generated. Results: Prospective CandID testing generated a sensitivity/specificity of 88%/82%, respectively. Specificity was improved (>95%) when both PCR replicates were positive and/or the patient had multiple positive samples. When combining CandID with (1-3)-β-D-Glucan testing, the probability of IC when both were positive or negative was >69% or <1%, respectively. Conclusions: The CandID provides excellent performance and a rapid time-to-result using methods widely available in generic molecular diagnostic laboratories. By combining nonculture diagnostics, it may be possible to accurately confirm or exclude IC.
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Comparison of Extraction Methods and Thermocyclers for SARS-CoV-2 Molecular Detection Using Clinical Specimens. J Clin Microbiol 2020; 58:JCM.01622-20. [PMID: 32665419 PMCID: PMC7512181 DOI: 10.1128/jcm.01622-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Scharf S, Bartels A, Kondakci M, Pfeffer K, Henrich B, Haas R. Introduction of a bead beating step improves fungal DNA extraction from selected patient specimens. Int J Med Microbiol 2020; 310:151443. [PMID: 32862838 DOI: 10.1016/j.ijmm.2020.151443] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 06/25/2020] [Accepted: 07/20/2020] [Indexed: 12/11/2022] Open
Abstract
In immunocompromised patients a colonisation with fungi carries the risk to develop serious invasive fungal infection. An early detection is therefore important, but not optimal hitherto. Fortunately, molecular genetic methods have increased the sensitivity of fungal detection and limited the time, until results are available. However, their success depends on an efficient extraction of genomic DNA from the fungal cell in the given diagnostic specimen. To improve the routine DNA preparation method for yeasts and moulds, the impact of bead beating on fungal DNA release was evaluated. PBS, blood and respiratory rinse were spiked with Candida glabrata or Aspergillus fumigatus. DNA was extracted by mechanical bead beating in addition to the different steps of the DNA preparation protocol, which comprised liquid nitrogen treatment, proteinase K digestion and DNA isolation using the EZ1 DNA Tissue Kit and Workstation. In every method variant tested, treatment with liquid nitrogen did not improve the DNA release. Bead beating once followed by proteinase K digestion and EZ1-work-up led to the highest DNA release from fungus, spiked in PBS, and increased the extracted DNA amount of C. glabrata about 100-fold and of A. fumigatus about 10-fold in relation to sole EZ1-work-up. In fungus-spiked respiratory rinse and blood, highest increase in DNA release was measured after triple bead beating with simultaneous proteinase K digestion. Fungal DNA release of C. glabrata increased for >100-fold in respiratory rinse and for >1000-fold in blood and of A. fumigatus for >10-fold in respiratory rinse and about 5- to 10-fold in blood. The data of this study clearly demonstrate that preparation of fungal DNA from human specimens is optimized by introduction of a bead beating step to the conventional DNA-preparation method without the necessity of a liquid nitrogen step.
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Affiliation(s)
- Sebastian Scharf
- Institute of Medical Microbiology and Hospital Hygiene, University of Duesseldorf, Germany; Department of Haematology, Oncology and Clinical Immunology, University of Duesseldorf, Medical Faculty, Duesseldorf, Germany
| | - Anna Bartels
- Department of Haematology, Oncology and Clinical Immunology, University of Duesseldorf, Medical Faculty, Duesseldorf, Germany
| | - Mustafa Kondakci
- Department of Haematology, Oncology and Clinical Immunology, University of Duesseldorf, Medical Faculty, Duesseldorf, Germany
| | - Klaus Pfeffer
- Institute of Medical Microbiology and Hospital Hygiene, University of Duesseldorf, Germany
| | - Birgit Henrich
- Institute of Medical Microbiology and Hospital Hygiene, University of Duesseldorf, Germany.
| | - Rainer Haas
- Department of Haematology, Oncology and Clinical Immunology, University of Duesseldorf, Medical Faculty, Duesseldorf, Germany
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4
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Abstract
Developing any diagnostic assay that receives United States Food and Drug Administration (FDA) approval can be a slow and difficult process. FDA-approved assays for fungal diagnosis are generally few in number and are focused mainly on diagnosing candidiasis, which is caused by several species of Candida, in addition to a limited number of systemic mycotic agents. While all microbial diagnostic assays face challenges before they are FDA approved and reach the market, there are a number of challenges to fungal diagnostic assay development that have been difficult hurdles to overcome. These hurdles include template preparation, fungal morphology, how many fungi should be identified in a single assay (scope), taxonomy and nomenclature, discriminating colonizers from invasive infection, combining identification with antifungal susceptibility, and navigating the administrative hurdles required to integrate an assay into a clinical laboratory. Some of these challenges are easier to overcome than others, but all seem to be particularly difficult for fungal diagnostic assays.
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Masiuk DМ, Nedzvetsky VS, Kokariev AV, Danchuk OV, Vasilenko TO, Yefimova OM. Evaluation of commercial methods to separate nucleic acids from intestinal tissues of pigs for diagnosis of porcine epidemic diarrhea. REGULATORY MECHANISMS IN BIOSYSTEMS 2019. [DOI: 10.15421/021970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The article presents the results of evaluating commercial methods for extracting nucleic acids from pig intestinal tissues for the diagnosis of PED. The study was based on samples of small intestine tissues and faeces from 3–5 day old pigs which died from PED. Nucleic acid extraction was performed using commercial kits with different nucleic acid separation strategies based on: silicon-sorbent; silicate membrane fixed in a microcentrifuge column and magnetic balls. The studies were conducted in two stages. The first was a comparison of the results of the amplification of the obtained nucleic acid extracts from the homogenate of the intestines of piglets by using the above-mentioned commercial kits for the extraction of nucleic acids. For this purpose, samples of homogenate were used which in weight corresponded to the guideline for the application of the test kits. The second step was directed to determining the efficiency of extraction of DNA and RNA from homogenate samples with a weight of 10, 50, 100 and 200 mg. Determination of the optimal methodological strategy of nucleic acid extraction for the diagnosis of porcine epidemic diarrhea by PCR has been investigated. The results of the PCR studies of RNA of the PED virus and a unique pig DNA fragment indicate that the extraction of nucleic acids by commercial kits has different levels of efficiency and depends on different factors. According to the research, it was found that the most important of them are the adsorption capacity of the solid-phase sorbent, its configuration and nature, which binds RNA and DNA molecules, the type of sample from which extraction takes place, its volume, or the tissue mass used for extraction. Based on the obtained results, it has been found that the most effective PED virus RNA extraction is by “ArtBioTech”, “Bio Extract Column”, and “Viral DNA/RNA Extraction Kit”, and pig genomic DNA extraction by the “ArtBioTech” and “Viral DNA / RNA extraction Kit”.
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7
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Barnes RA, White PL, Morton CO, Rogers TR, Cruciani M, Loeffler J, Donnelly JP. Diagnosis of aspergillosis by PCR: Clinical considerations and technical tips. Med Mycol 2018; 56:60-72. [PMID: 29087518 DOI: 10.1093/mmy/myx091] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 08/29/2017] [Indexed: 12/25/2022] Open
Abstract
Standardization of Aspergillus polymerase chain reaction (PCR) protocols has progressed, and analytical validity of blood-based assays has been formally established. It remains necessary to consider how the tests can be used in practice to maximize clinical utility. To determine the optimal diagnostic strategies and influence on patient management, several factors require consideration, including the patient population, incidence of invasive aspergillosis (and other fungal disease), and the local antifungal prescribing policy. Technical issues such as specimen type, ease of sampling, frequency of testing, access to testing centers, and time to reporting will also influence the use of PCR in clinical practice. Interpretation of all diagnostic tests is dependent on the clinical context and molecular assays are no exception, but with the proposal to incorporate Aspergillus PCR into the second revision of the consensus guidelines for defining invasive fungal disease the acceptance and understanding of molecular tests should improve.
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Affiliation(s)
| | - P Lewis White
- Public Health Wales Microbiology Cardiff, Cardiff, UK
| | | | | | - Mario Cruciani
- Center of Community Medicine and Infectious Diseases Service, ULSS 20 Verona
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Denis J, Forouzanfar F, Herbrecht R, Toussaint E, Kessler R, Sabou M, Candolfi E, Letsher-Bru V. Evaluation of Two Commercial Real-Time PCR Kits for Aspergillus DNA Detection in Bronchoalveolar Lavage Fluid in Patients with Invasive Pulmonary Aspergillosis. J Mol Diagn 2018; 20:298-306. [PMID: 29471112 PMCID: PMC7185652 DOI: 10.1016/j.jmoldx.2017.12.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 12/21/2017] [Accepted: 12/22/2018] [Indexed: 02/07/2023] Open
Abstract
Invasive pulmonary aspergillosis (IPA) is a common complication of immunosuppression. Rapid diagnosis using molecular techniques is essential to improve patient survival. PCR techniques are promising in enhancing Aspergillus detection in blood and respiratory samples. We evaluate for the first time the performances of two commercial real-time PCR kits, the A. fumigatus Bio-Evolution and the MycoGENIE A. fumigatus for the detection of A. fumigatus DNA in bronchoalveolar lavage (BAL) from patients with and without IPA. Seventy-three BAL samples were included. Thirty-one of them corresponded to patients with probable IPA, 11 to patients with possible IPA, and 31 to patients without aspergillosis, according to the 2008 European Organization for Research and Treatment of Cancer/Mycoses Study Group criteria. In the probable IPA group, A. fumigatus Bio-Evolution and the MycoGENIE A. fumigatus real-time PCR kits showed a specificity of 100% and a sensitivity of 81% and 71%, respectively. The A. fumigatus Bio-Evolution detected Aspergillus DNA in the 14 BAL samples with a positive Aspergillus culture result, whereas the MycoGENIE A. fumigatus PCR result was positive only for 12. In the possible IPA group, there were no positive real-time PCR or positive Aspergillus culture results. For the patients without aspergillosis, no positive result was observed for real-time PCR kit, despite the presence of various other non-Aspergillus pathogens in this group. Our study demonstrates an excellent specificity and a good sensitivity of A. fumigatus DNA detection in BAL samples with both kits.
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Affiliation(s)
- Julie Denis
- Laboratoire de Parasitologie et de Mycologie Médicale, Hôpitaux Universitaires de Strasbourg, Strasbourg, France.
| | - Faezeh Forouzanfar
- Laboratoire de Parasitologie et de Mycologie Médicale, Hôpitaux Universitaires de Strasbourg, Strasbourg, France; Institut de Parasitologie et de Pathologie Tropicale, Fédération de Médecine Translationnelle, Université de Strasbourg, Strasbourg, France
| | - Raoul Herbrecht
- Service d'Oncologie et d'Hématologie, Hôpital de Hautepierre, Hôpitaux Universitaires de Strasbourg & Université de Strasbourg, Strasbourg, France
| | - Elise Toussaint
- Service d'Oncologie et d'Hématologie, Hôpital de Hautepierre, Hôpitaux Universitaires de Strasbourg & Université de Strasbourg, Strasbourg, France
| | - Romain Kessler
- Pôle Pathologie thoracique, CHU de Strasbourg, Strasbourg, France
| | - Marcela Sabou
- Laboratoire de Parasitologie et de Mycologie Médicale, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Ermanno Candolfi
- Laboratoire de Parasitologie et de Mycologie Médicale, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Valérie Letsher-Bru
- Laboratoire de Parasitologie et de Mycologie Médicale, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
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9
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Abstract
Nucleic acid extraction is the first step of any amplification experiment no matter what kind of amplification is used to detect a specific pathogen. Efficient nucleic acid extraction is essential to obtain good results using any molecular test. The optimal extraction method should fulfill the following conditions: speed, short working time, cost-effectiveness, high sensitivity and specificity, good reproducibility, and safety. The methods can be divided into solution or column based according to differences of their principles. The automated extraction instruments have many advantages, and these have proven to be very useful. Moreover, in recent years, fully automated instruments combining NA extraction and amplification have been commercially available. However, the method itself does not provide assurance, and the DNA recovery can be different among various kits or instruments that use the similar principles. Therefore, it is important to carefully evaluate the performance of any extraction method used in the clinical microbiology laboratory even though manufacturers may have reported good validation results with specific organisms.
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Affiliation(s)
- Yi-Wei Tang
- Departments of Laboratory Medicine and Internal Medicine, Memorial Sloan Kettering Cancer Center, New York, NY USA
| | - Charles W. Stratton
- Department of Pathology, Microbiology and Immunology and Medicine, Vanderbilt University Medical Center, Nashville, TN USA
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Analytical and Clinical Evaluation of the PathoNostics AsperGenius Assay for Detection of Invasive Aspergillosis and Resistance to Azole Antifungal Drugs Directly from Plasma Samples. J Clin Microbiol 2017; 55:2356-2366. [PMID: 28515217 DOI: 10.1128/jcm.00411-17] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 05/09/2017] [Indexed: 11/20/2022] Open
Abstract
With the proposal to include Aspergillus PCR in the revised European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and National Institute of Allergy and Infectious Diseases Mycoses Study Group (EORTC/MSG) definitions for fungal disease, commercially manufactured assays may be required to provide standardization and accessibility. The PathoNostics AsperGenius assay represents one such test that has the ability to detect a range of Aspergillus species as well as azole resistance in Aspergillus fumigatus Its performance has been validated on bronchoalveolar lavage (BAL) fluid and serum specimens, but recent evidence suggests that testing of plasma may have enhanced sensitivity over that with serum. We decided to evaluate the analytical and clinical performances of the PathoNostics AsperGenius assay for testing of plasma. For the analytical evaluations, plasma was spiked with various concentrations of Aspergillus genomic DNA before extraction following international recommendations, using two automated platforms. For the clinical study, 211 samples from 10 proven/probable invasive aspergillosis (IA) and 2 possible IA cases and 27 controls were tested. The limits of detection for testing of DNA extracted using the bioMérieux EasyMag and Qiagen EZ1 extractors were 5 and 10 genomes/0.5-ml sample, respectively. In the clinical study, true positivity was significantly greater than false positivity (P < 0.0001). The sensitivity and specificity obtained using a single positive result as significant were 80% and 77.8%, respectively. If multiple samples were required to be positive, specificity was increased to 100%, albeit sensitivity was reduced to 50%. The AsperGenius assay provided good clinical performance, but the predicted improvement of testing with plasma was not seen, possibly as a result of target degradation attributed to sample storage. Prospective testing is required to determine the clinical utility of this assay, particularly for the diagnosis of azole-resistant disease.
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11
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Kalousová M, Levová K, Kuběna AA, Jáchymová M, Franková V, Zima T. Comparison of DNA isolation using salting-out procedure and automated isolation (MagNA system). Prep Biochem Biotechnol 2017; 47:703-708. [DOI: 10.1080/10826068.2017.1303613] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Marta Kalousová
- Institute of Medical Biochemistry and Laboratory Diagnostics, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Kateřina Levová
- Institute of Medical Biochemistry and Laboratory Diagnostics, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Aleš A. Kuběna
- Institute of Medical Biochemistry and Laboratory Diagnostics, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Marie Jáchymová
- Institute of Medical Biochemistry and Laboratory Diagnostics, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Věra Franková
- Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Tomáš Zima
- Institute of Medical Biochemistry and Laboratory Diagnostics, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
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12
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Abstract
PCR can aid in the diagnosis of invasive fungal disease (IFD). While the large number of "in-house" methodologies drives technological diversity, providing robustness, they make it difficult to identify optimal strategies, limiting standardization, and widespread acceptance. No matter how efficient, PCR utility will be limited by the quality of extracted nucleic acid. This chapter highlights benefits and limitations affecting the nucleic acid extraction process, before focusing on recent recommendations that through multicenter evaluation have provided optimal and standardized methodology.
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Affiliation(s)
- P Lewis White
- Public Health Wales Microbiology Cardiff, University Hospital of Wales, Heath Park, Cardiff, CF14 4XW, UK.
| | - Rosemary A Barnes
- Public Health Wales Microbiology Cardiff, University Hospital of Wales, Heath Park, Cardiff, CF14 4XW, UK.,Department of Infection and Immunity, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK
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13
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Barnes RA, White PL. PCR Technology for Detection of Invasive Aspergillosis. J Fungi (Basel) 2016; 2:jof2030023. [PMID: 29376940 PMCID: PMC5753136 DOI: 10.3390/jof2030023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 07/20/2016] [Accepted: 07/26/2016] [Indexed: 11/16/2022] Open
Abstract
The application of molecular technologies to aid diagnosis and management of infectious diseases has had a major impact and many assays are in routine use. Diagnosis of aspergillosis has lagged behind. Lack of standardization and limited commercial interest have meant that PCR was not included in consensus diagnostic criteria for invasive fungal disease. In the last ten years careful evaluation and validation by the Aspergillus European PCR initiative with the development of standardized extraction, amplification and detection protocols for various specimen types, has provided the opportunity for clinical utility to be investigated. PCR has the potential to not only exclude a diagnosis of invasive aspergillosis but in combination with antigen testing may offer an approach for the early diagnosis and treatment of invasive aspergillosis in high-risk populations, with the added benefit of detection of genetic markers associated with antifungal resistance.
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Affiliation(s)
- Rosemary A Barnes
- Department of Medical Microbiology and Infectious Diseases, Cardiff University School of Medicine, Cardiff CF14 4XN, UK.
| | - P Lewis White
- Public Health Wales Microbiology, Cardiff CF14 4 XW, UK.
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14
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Abstract
The direct detection of Aspergillus nucleic acid in clinical specimens has the potential to improve the diagnosis of aspergillosis by offering more rapid and sensitive identification of invasive infections than is possible with traditional techniques, such as culture or histopathology. Molecular tests for Aspergillus have been limited historically by lack of standardization and variable sensitivities and specificities. Recent efforts have been directed at addressing these limitations and optimizing assay performance using a variety of specimen types. This review provides a summary of standardization efforts and outlines the complexities of molecular testing for Aspergillus in clinical mycology.
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White PL, Wingard JR, Bretagne S, Löffler J, Patterson TF, Slavin MA, Barnes RA, Pappas PG, Donnelly JP. Aspergillus Polymerase Chain Reaction: Systematic Review of Evidence for Clinical Use in Comparison With Antigen Testing. Clin Infect Dis 2015; 61:1293-303. [PMID: 26113653 PMCID: PMC4583581 DOI: 10.1093/cid/civ507] [Citation(s) in RCA: 133] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 06/13/2015] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Aspergillus polymerase chain reaction (PCR) was excluded from the European Organisation for the Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG) definitions of invasive fungal disease because of limited standardization and validation. The definitions are being revised. METHODS A systematic literature review was performed to identify analytical and clinical information available on inclusion of galactomannan enzyme immunoassay (GM-EIA) (2002) and β-d-glucan (2008), providing a minimal threshold when considering PCR. Categorical parameters and statistical performance were compared. RESULTS When incorporated, GM-EIA and β-d-glucan sensitivities and specificities for diagnosing invasive aspergillosis were 81.6% and 91.6%, and 76.9% and 89.4%, respectively. Aspergillus PCR has similar sensitivity and specificity (76.8%-88.0% and 75.0%-94.5%, respectively) and comparable utility. Methodological recommendations and commercial PCR assays assist standardization. Although all tests have limitations, currently, PCR is the only test with independent quality control. CONCLUSIONS We propose that there is sufficient evidence that is at least equivalent to that used to include GM-EIA and β-d-glucan testing, and that PCR is now mature enough for inclusion in the EORTC/MSG definitions.
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Affiliation(s)
- P. Lewis White
- Public Health Wales, Microbiology Cardiff, United Kingdom
| | | | | | | | - Thomas F. Patterson
- University of Texas Health Science Center and South Texas Veterans Health Care System, San Antonio
| | - Monica A. Slavin
- Peter MacCallum Cancer Centre, University of Melbourne, Australia
| | - Rosemary A. Barnes
- Infection, Immunity and Biochemistry, Cardiff University, United Kingdom
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Cain-Hom C, Pabalate R, Pham A, Patel HN, Wiler R, Cox JC. Mammalian Genotyping Using Acoustic Droplet Ejection for Enhanced Data Reproducibility, Superior Throughput, and Minimized Cross-Contamination. ACTA ACUST UNITED AC 2015; 21:37-48. [PMID: 26311060 DOI: 10.1177/2211068215601637] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Indexed: 12/20/2022]
Abstract
Genetically engineered animal models are major tools of a drug discovery pipeline because they facilitate understanding of the molecular and biochemical basis of disease. These highly complex models of human disease often require increasingly convoluted genetic analysis. With growing needs for throughput and consistency, we find that traditional aspiration-and-dispense liquid-handling robots no longer have the required speed, quality, or reproducibility.We present an adaptation and installation of an acoustic droplet ejection (ADE) liquid-handling system for ultra-high-throughput screening of genetically engineered models. An ADE system is fully integrated with existing laboratory processes and platforms to facilitate execution of PCR and quantitative PCR (qPCR) reactions. Such a configuration permits interrogation of highly complex genetic models in a variety of backgrounds. Our findings demonstrate that a single ADE system replaces 8-10 traditional liquid-handling robots while increasing quality and reproducibility.We demonstrate significant improvements achieved by transitioning to an ADE device: extremely low detectable cross-contamination in PCR and qPCR despite extensive use, greatly increased data reproducibility (large increases in data quality and Cq consistency), lowered reaction volumes for large cost savings, and nearly a magnitude increase in speed per instrument. We show several comparisons between traditional- and ADE-based pipetting for a qPCR-based workflow.
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Affiliation(s)
- Carol Cain-Hom
- Department of Transgenic Technology, Genentech Inc., San Francisco, CA, USA
| | - Ryan Pabalate
- Department of Transgenic Technology, Genentech Inc., San Francisco, CA, USA
| | - Anna Pham
- Department of Transgenic Technology, Genentech Inc., San Francisco, CA, USA
| | - Hetal N Patel
- Department of Transgenic Technology, Genentech Inc., San Francisco, CA, USA
| | - Rhonda Wiler
- Department of Transgenic Technology, Genentech Inc., San Francisco, CA, USA
| | - J Colin Cox
- Department of Transgenic Technology, Genentech Inc., San Francisco, CA, USA
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Analytical and Clinical Evaluation of the PathoNostics AsperGenius Assay for Detection of Invasive Aspergillosis and Resistance to Azole Antifungal Drugs during Testing of Serum Samples. J Clin Microbiol 2015; 53:2115-21. [PMID: 25903571 DOI: 10.1128/jcm.00667-15] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 04/17/2015] [Indexed: 11/20/2022] Open
Abstract
The commercially developed PathoNostics AsperGenius species assay is a multiplex real-time PCR capable of detecting aspergillosis and genetic markers associated with azole resistance. The assay is validated for testing bronchoalveolar lavage fluids, replacing the requirement for culture and benefiting patient management. Application of this assay to less invasive, easily obtainable samples (e.g., serum) might be advantageous. The aim of this study was to determine the analytical and clinical performance of the AsperGenius species and resistance assays for testing serum samples. For the analytical evaluations, serum samples were spiked with various concentrations of Aspergillus genomic DNA for extraction, following international recommendations. For the clinical study, 124 DNA extracts from 14 proven/probable invasive aspergillosis (IA) cases, 2 possible IA cases, and 33 controls were tested. The resistance assay was performed on Aspergillus fumigatus PCR-positive samples when a sufficient fungal burden was evident. The limits of detection of the species and resistance assays for A. fumigatus DNA were 10 and ≥75 genomes/sample, respectively. Nonreproducible detection at lower burdens was achievable for all markers. With a positivity threshold of 39 cycles, the sensitivity and specificity of the species assay were 78.6% and 100%, respectively. For 7 IA cases, at least one genetic region potentially associated with azole resistance was successfully amplified, although no resistance markers were detected in this small cohort. The AsperGenius assay provides good clinical performance with the added ability to detect azole resistance directly from noninvasive samples. While the available burden will limit application, it remains a significant advancement in the diagnosis and management of aspergillosis.
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Frickmann H, Hinz R, Hagen RM. Comparison of an automated nucleic acid extraction system with the column-based procedure. Eur J Microbiol Immunol (Bp) 2015; 5:94-102. [PMID: 25883797 DOI: 10.1556/eujmi-d-14-00040] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 12/23/2014] [Indexed: 12/21/2022] Open
Abstract
Here, we assessed the extraction efficiency of a deployable bench-top nucleic acid extractor EZ1 in comparison to the column-based approach with complex sample matrices. A total of 48 EDTA blood samples and 81 stool samples were extracted by EZ1 automated extraction and the column-based QIAamp DNA Mini Kit. Blood sample extractions were assessed by two real-time malaria PCRs, while stool samples were analyzed by six multiplex real-time PCR assays targeting bacterial, viral, and parasitic stool pathogens. Inhibition control PCR testing was performed as well. In total, 147 concordant and 13 discordant pathogen-specific PCR results were obtained. The latter comprised 11 positive results after column-based extraction only and two positive results after EZ1 extraction only. EZ1 extraction showed a higher frequency of inhibition. This phenomenon was, however, inconsistent for the different PCR schemes. In case of concordant PCR results, relevant differences of cycle threshold numbers for the compared extraction schemes were not observed. Switches from well-established column-based extraction to extraction with the automated EZ1 system do not lead to a relevantly reduced yield of target DNA when complex sample matrices are used. If sample inhibition is observed, column-based extraction from another sample aliquot may be considered.
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