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References – Rapid tests / Point of Care testing

Modern Tools for Rapid Diagnostics of Antimicrobial Resistance

(Frontiers in cellular and infection microbiology, 2020)

Abstract: Fast, robust, and affordable antimicrobial susceptibility testing (AST) is required, as roughly 50% of antibiotic treatments are started with wrong antibiotics and without a proper diagnosis of the pathogen. Validated growth-based AST according to EUCAST or CLSI (European Committee on Antimicrobial Susceptibility Testing, Clinical Laboratory Standards Institute) recommendations is currently suggested to guide the antimicrobial therapy. Any new AST should be validated against these standard methods. Many rapid diagnostic techniques can already provide pathogen identification. Some of them can additionally detect the presence of resistance genes or resistance proteins, but usually isolated pure cultures are needed for AST. We discuss the value of the technologies applying nucleic acid amplification, whole genome sequencing, and hybridization as well as immunodiagnostic and mass spectrometry-based methods and biosensor-based AST. Additionally, we evaluate the potential of integrated systems applying microfluidics to integrate cultivation, lysis, purification, and signal reading steps. We discuss technologies and commercial products with potential for Point-of-Care Testing (POCT) and their capability to analyze polymicrobial samples without pre-purification steps. The purpose of this critical review is to present the needs and drivers for AST development, to show the benefits and limitations of AST methods, to introduce promising new POCT-compatible technologies, and to discuss AST technologies that are likely to thrive in the future.

Rapid microbiological tests for bloodstream infections due to multidrug-resistant Gram-negative bacteria: therapeutic implications

(Clinical Microbiology and Infection, 2019)

Background: Treating severe infections due to multidrug-resistant Gram-negative bacteria (MDR-GNB) is one of the most important challenges for clinicians worldwide, partly because resistance may remain unrecognized until identification of the causative agent and/or antimicrobial susceptibility testing (AST). Recently, some novel rapid test for identification and/or AST of MDR-GNB from positive blood cultures or the blood of patients with bloodstream infections (BSIs) have become available.
Objectives: The objective of this narrative review is to discuss the advantages and limitations of different rapid tests for identification and/or AST of MDR-GNB from positive blood cultures or the blood of patients with BSI, as well as the available evidence on their possible role to improve therapeutic decisions and antimicrobial stewardship.
Sources: Inductive PubMed search for publications relevant to the topic.
Content: The present review is structured in the following way: (a) rapid tests on positive blood cultures; (b) rapid tests directly on whole blood; (c) therapeutic implications.
Implications: Novel molecular and phenotypic rapid tests for identification and AST show the potential for favourably influencing patients’ outcomes and results of antimicrobial stewardship interventions by reducing both the time to effective treatment and the misuse of antibiotics, although the interpretation about their impact on actual therapeutic decisions and patients’ outcomes is still complex. Factors such as feasibility and personnel availability, as well as the detailed knowledge of the local microbiological epidemiology, need to be considered very carefully when implementing novel rapid tests in laboratory workflows and algorithms. Providing high-level, comparable evidence on the clinical impact of rapid identification and AST is becoming of paramount importance for MDR-GNB infections, since in the near future rapid identification of specific resistance mechanisms could be crucial for guiding rapid, effective, and targeted therapy against specific resistance mechanisms.

Rapid diagnostics for bloodstream infections: A primer for infection preventionists

(American Journal of Infection Control, 2018)

Abstract: Accurate and rapid antimicrobial susceptibility testing with pathogen identification in bloodstream infections is critical to life results for early sepsis intervention. Advancements in rapid diagnostics have shortened the time to results from days to hours and have had positive effects on clinical outcomes and on efforts to combat antimicrobial resistance when paired with robust antimicrobial stewardship programs. This article provides infection preventionists with a working knowledge of available rapid diagnostics for bloodstream infections.

The Cost-Effectiveness of Rapid Diagnostic Testing for the Diagnosis of Bloodstream Infections with or without Antimicrobial Stewardship

(Clinical Microbiology Reviews, 2018)

Summary: Bloodstream infections are associated with considerable morbidity and health care costs. Molecular rapid diagnostic tests (mRDTs) are a promising complement to conventional laboratory methods for the diagnosis of bloodstream infections and may reduce the time to effective therapy among patients with bloodstream infections. The concurrent implementation of antimicrobial stewardship programs (ASPs) may reinforce these benefits. The aim of this study was to evaluate the cost-effectivenesses of competing strategies for the diagnosis of bloodstream infection alone or combined with an ASP. To this effect, we constructed a decision-analytic model comparing 12 strategies for the diagnosis of bloodstream infection. The main arms compared the use of mRDT and conventional laboratory methods with or without an ASP. The baseline strategy used as the standard was the use of conventional laboratory methods without an ASP, and our decision-analytic model assessed the cost-effectivenesses of 5 principal strategies: mRDT (with and without an ASP), mRDT with an ASP, mRDT without an ASP, conventional laboratory methods with an ASP, and conventional laboratory methods without an ASP. Furthermore, based on the availability of data in the literature, we assessed the cost-effectivenesses of 7 mRDT subcategories, as follows: PCR with an ASP, matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) analysis with an ASP, peptide nucleic acid fluorescent in situ hybridization (PNA-FISH) with an ASP, a blood culture nanotechnology microarray system for Gram-negative bacteria (BC-GP) with an ASP, a blood culture nanotechnology microarray system for Gram-positive bacteria (BC-GN) with an ASP, PCR without an ASP, and PNA-FISH without an ASP. Our patient population consisted of adult inpatients in U.S. hospitals with suspected bloodstream infection. The time horizon of the model was the projected life expectancy of the patients. In a base-case analysis, cost-effectiveness was determined by calculating the numbers of bloodstream infection deaths averted, the numbers of quality-adjusted life years gained, and incremental cost-effectiveness ratios (ICERs). In a probabilistic analysis, uncertainty was addressed by plotting cost-effectiveness planes and acceptability curves for various willingness-to-pay thresholds. In the base-case analysis, MALDI-TOF analysis with an ASP was the most cost-effective strategy, resulting in savings of $29,205 per quality-adjusted life year and preventing 1 death per 14 patients with suspected bloodstream infection tested compared to conventional laboratory methods without an ASP (ICER, −$29,205/quality-adjusted life year). BC-GN with an ASP (ICER, −$23,587/quality-adjusted life year), PCR with an ASP (ICER, −$19,833/quality-adjusted life year), and PCR without an ASP (ICER, −$21,039/quality-adjusted life year) were other cost-effective options. In the probabilistic analysis, mRDT was dominant and cost-effective in 85.1% of simulations. Importantly, mRDT with an ASP had an 80.0% chance of being cost-effective, while mRDT without an ASP had only a 41.1% chance. In conclusion, our findings suggest that mRDTs are cost-effective for the diagnosis of patients with suspected bloodstream infection and can reduce health care expenditures. Notably, the combination of mRDT and an ASP can result in substantial health care savings

Rapid pathogen-specific phenotypic antibiotic susceptibility testing using digital LAMP quantification in clinical samples

(Science translational medicine, 2017)

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.

Existing and Emerging Technologies for Point-of-Care Testing

(The Clinical biochemist, 2014)

Abstract: The volume of point-of-care testing (PoCT) has steadily increased over the 40 or so years since its widespread introduction. That growth is likely to continue, driven by changes in healthcare delivery which are aimed at delivering less costly care closer to the patient’s home. In the developing world there is the challenge of more effective care for infectious diseases and PoCT may play a much greater role here in the future. PoCT technologies can be split into two categories, but in both, testing is generally performed by technologies first devised more than two decades ago. These technologies have undoubtedly been refined and improved to deliver easier-to-use devices with incremental improvements in analytical performance. Of the two major categories the first is small handheld devices, providing qualitative or quantitative determination of an increasing range of analytes. The dominant technologies here are glucose biosensor strips and lateral flow strips using immobilised antibodies to determine a range of parameters including cardiac markers and infectious pathogens. The second category of devices are larger, often bench-top devices which are essentially laboratory instruments which have been reduced in both size and complexity. These include critical care analysers and, more recently, small haematology and immunology analysers. New emerging devices include those that are utilising molecular techniques such as PCR to provide infectious disease testing in a sufficiently small device to be used at the point of care. This area is likely to grow with many devices being developed and likely to reach the commercial market in the next few years.

Economic Evidence and Point-of-Care Testing

(The Clinical biochemist. Reviews, 2013)

Abstract: Health economics has been an established feature of the research, policymaking, practice and management in the delivery of healthcare. However its role is increasing as the cost of healthcare begins to drive changes in most healthcare systems. Thus the output from cost effectiveness studies is now being taken into account when making reimbursement decisions, e.g. in Australia and the United Kingdom. Against this background it is also recognised that the health economic tools employed in healthcare, and particularly the output from the use of these tools however, are not always employed in the routine delivery of services. One of the notable consequences of this situation is the poor record of innovation in healthcare with respect to the adoption of new technologies, and the realisation of their benefits.

The evidence base for the effectiveness of diagnostic services is well known to be limited, and one consequence of this has been a very limited literature on cost effectiveness. One reason for this situation is undoubtedly the reimbursement strategies employed in laboratory medicine for many years, simplistically based on the complexity of the test procedure, and the delivery as a cost-per-test service. This has proved a disincentive to generate the required evidence, and little effort to generate an integrated investment and disinvestment business case, associated with care pathway changes.

Point-of-care testing creates a particularly challenging scenario because, on the one hand, the unit cost-per-test is larger through the loss of the economy of scale offered by automation, whilst it offers the potential of substantial savings through enabling rapid delivery of results, and reduction of facility costs. This is important when many health systems are planning for complete system redesign. We review the literature on economic assessment of point-of-care testing in the context of these developments.

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