Point Of Care Use Research Articles

DUETS for Light's in separating exudate from transudate.

Fifty years since its inception, Light's criteria have aided in classifying pleural effusions (PEs) as exudates if 1 or more criteria are met. Thoracic ultrasound (US) emerges as a non-invasive technique for point of care use especially if pleural procedures are contemplated. We aimed to develop a score based on radiological and US features that could separate exudates from transudates without serum and pleural fluid biochemical tests necessary for Light's criteria. A prospective review of consecutive patients with PE who underwent thoracocentesis was performed. CXRs were evaluated for laterality followed by US for echogenicity, pleural nodularity, thickening and septations. PE was classified as exudate or transudate according to Light's criteria and corroborated with albumin gradient. A score combining radiological and US features was developed. We recruited 201 patients with PE requiring thoracocentesis. Mean age was 64 years, 51% were females, 164 (81.6%) were exudates, and 37 (18.4%) were transudates. Assigning 1-point for Diaphragmatic nodularity, Unilateral, Echogenicity, Pleural Thickening and Septations, DUETS ranged from 1 to 5. DUETS ≥2 indicated high likelihood for exudate (PPV 98.8%, NPV 100%) with 1% misclassification versus 6.9% using Light's criteria (p < 0.001). DUETS separated exudates from transudates with good accuracy, and could obviate paired serum and pleural fluid tests necessary for Light's criteria computation. Our study reflected real world practice where DUETS performed better than Light's criteria for PE that arose from more than one disease processes, and in the evaluation of patients with PE who have received diuretics.

A-171 Novel Fluorometric Assay for Pediatric Anti-Factor Xa Testing: Minimizing Bilirubin and Hemolysis Interference in Whole Blood

Abstract Background High bilirubin levels are common in pediatric patients and are noted in patients undergoing extracorporeal membrane oxygenation (ECMO). Acute anticoagulation therapy necessitates frequent monitoring of anti-Factor Xa activity (aFXa), and high bilirubin levels cause interference in chromogenic assays. Moreover, large volumes of blood lead to iatrogenic anemia in pediatric and neonatal patients. We developed a fluorescence assay to measure aFXa activity on a near-patient digital microfluidic (DMF) platform using low volume whole blood samples (&amp;lt; 50 μL) and present the results of interference of bilirubin and hemolysis on aFXa activity. Methods aFXa assay was performed on a DMF cartridge wherein 50 μL whole blood was loaded into the cartridge which separates plasma droplets through agglutination within the cartridge followed by incubation with a droplet containing exogenous FXa and a fluorogenic substrate. The fluorescence is inversely proportional to the concentration of heparin in the sample. All required reagents for the aFXa assay are dried within the cartridge, allowing for integrated sample preparation and assay automation for point of care use. To test the interference of bilirubin, we spiked into whole blood different concentrations of unconjugated bilirubin, ranging from 0-40 mg/dL. We also tested hemoglobin interference by testing 4 different concentrations of hemolysate (0-1,000 mg/dL) on the aFXa assay. All experiments were performed with 6 replicates of each concentration. Results Across each bilirubin concentration, we saw uniform measurements of aFXa activity (see Table). We observed &amp;lt; 5% CV in aFXa activity with 0, 13.33 and 26.67 mg/dL bilirubin levels. All measured unfractionated heparin values for hemolysate interference were &amp;lt;5% CV. Conclusions Our interference results suggest that high bilirubin and hemolysate levels do not interfere with our novel aFXa fluorescence assay. Further clinical studies are underway to establish clinical performance.

INTRODUCING EFRAILTY: SIMPLIFYING SELECTION OF FRAILTY ASSESSMENT TOOLS

Abstract Health care providers recognize the importance of frailty assessment for older adults, but they may be unfamiliar with which frailty assessment tool to use. We sought to create an accessible website to assist clinicians in choosing an effective, evidence-based frailty screening tool. We selected commonly used frailty tools based on the literature and worked with a web designer to develop the eFrailty website prototype. A short description of each tool’s key features and estimated time for assessment is included for each frailty tool. An algorithm based on differences in patient characteristics, clinical scenarios, available information, and time for assessment was created to guide users. Modeled after the highly popular ePrognosis website, eFrailty is designed to guide clinicians to select the ideal frailty tool for their clinical context. The site prompts clinicians to choose between patients considering stressful treatment (e.g., major surgery), or patients with or without serious illness. Depending on available information, clinicians choose between ‘Self reports/records only,’ or ‘Performance tests available’ including cognitive screens or physical performance testing. Alternatively, Clinicians may use the eFrailty comparison table which builds on the work of several systematic reviews of frailty identification tools to easily select the best instrument for their patient. A recent addition to the site is a crosswalk to compare scores between different frailty assessment tools. Future directions for eFrailty include beta testing to gather clinician input from point of care use.

Bioimpedance based determination of cardiac index does not show enough trueness for point of care use in patients with systolic heart failure.

Cardiac output (CO) is a key parameter in diagnostics and therapy of heart failure (HF). The thermodilution method (TD) as gold standard for CO determination is an invasive procedure with corresponding risks. As an alternative, thoracic bioimpedance (TBI) has gained popularity for CO estimation as it is non-invasive. However, systolic heart failure (HF) itself might worsen its validity. The present study validated TBI against TD.In patients with and without systolic HF (LVEF ≤ 50% or > 50% and NT-pro-BNP < 125 pg/ml, respectively) right heart catheterization including TD was performed. TBI (Task Force Monitor©, CNSystems, Graz, Austria) was conducted semi-simultaneously. 14 patients with and 17 patients without systolic HF were prospectively enrolled in this study.In all participants, TBI was obtainable. Bland-Altman analysis indicated a mean bias of 0.3L/min (limits of agreement ± 2.0L/min, percentage error or PE 43.3%) for CO and a bias of -7.3 ml (limits of agreement ± 34 ml) for cardiac stroke volume (SV). PE was markedly higher in patients with compared to patients without systolic HF (54% vs. 35% for CO).Underlying systolic HF substantially decreases the validity of TBI for estimation of CO and SV. In patients with systolic HF, TBI clearly lacks diagnostic accuracy and cannot be recommended for point-of-care decision making. Depending on the definition of an acceptable PE, TBI may be considered sufficient when systolic HF is absent.Trial registration number: DRKS00018964 (German Clinical Trial Register, retrospectively registered).

Dynamic Sickling Assay: Using Enzymatically Induced Hypoxia to Assess Real-Time Sickling Scalable from Large Erythrocyte Populations to Individual Cells

Background: There is a pressing need for assays to assess both patient condition and to monitor the progress of Sickle Cell Disease (SCD) therapies. It would be beneficial for an assay to allow assessment of oxygen dissociation, hemoglobin polymerization and Red Blood Cell (RBc) sickling under both equilibrium (mimicking longer-term effects) and non-equilibrium (simulating in-vivo process) conditions. Also desirable is the CLIA-waived system suitable for use in clinical trials and ultimately for clinical management of patients on SCD therapies including those those targeting Hb oxygen affinity. Our proposed work introduces an RBC hypoxia-induced sickling assay as a clinical tool to assess SCD patient condition and to assist in development, monitoring, and optimization of SCD therapies. Methods: The system uses an enzymatic oxygen scrubbing system allowing for a wide range of deoxygenation rates and final hypoxia severity. Diluted blood samples were supplemented with Protocatechuic acid (PCA) and then with Protocatechuate 3,4-Dioxygenase (PCD) enzyme inducing hypoxia at a predetermined rate. The sample was injected into an anaerobic microfluidic chamber with the resulting Red Blood Cell (RBC) morphological changes observed through time-lapsed photography. Image analysis allows for identification and quantification of sickled RBC linked to different polymerization scenarios/mechanisms. An oxygen probe was used to track the rate of medium deoxygenation. Sickling profiles were constructed to represent a percent of sickled RBC in a total cell population measured every two seconds after the enzymatic reaction is initiated. Profiles were assessed though i) percent sickling at normoxia, ii) morphological Point of Sickling (mPoS) and iii) time delay of sickling both measured at 5% increase in sickling over the normoxia sickling baseline, iv rate of sickling, v) size of the sickling fraction and vi) Area under the Curve (AUC). The last four parameters are measured for each sickling fraction if more than one such is present. Results: In control experiments PCA/PCD system was shown to allow reliable and reproducible sample deoxygenation currently enabled in a range from seconds to hours. Comprehensive multidimensional profiles were constructed presenting fraction of sickled RBC as a function of a) time from enzymatic reaction initiation, and b) one or more of rate of oxygen consumption, end of reaction hypoxia level, or oxygen tension in the medium. Such profiling allows for fast optimization of assay parameters to target assay conditions most suitable for detection of desired effects.Significant changes in sickling profiles, with marked delay in sickling, were observed upon treatment of RBC with hemoglobin-modifying drugs like voxelotor.Sickling profiles of Sickle Trait (SCT) patients showed significant delay in sickling compared to SS-type SCD patients. The method shows the potential to differentiate SCT patients based on the risk of adverse conditions to occur due to the patient's trait status.By stopping the flow, the system allows tracking of morphological status of individual cells over the full course of medium deoxygenation. Individual cells show pronounced differences in their propensity to sickle, potentially correlated to individual cell Hb F content. Change in morphology of sickling cells from biconcave disk to crescent and then to holly leaf and granular forms had been observed upon progressively decreasing medium oxygen tension.RBC microparticle formation can be observed and tracked over time as an additional metric of erythrocyte response to developing hypoxia Conclusions: By using enzymatically induced hypoxia in a microfluidic environment, presented system allows comprehensive analysis of RBC sickling dynamics in a wide range of deoxygenation rates and conditions. It would find utility in SCD therapy development by offering a robust and high throughput method for assessing critical RBC response to therapies. With no need for cumbersome gas cylinders and low training requirements, a stand-alone system with single use disposable cartridges would also have utility in clinical trials both in the US and abroad, due to simplicity of use suitable for developing countries with limited infrastructure. When validated, the system can be adapted for Point of Care use either as complementary to other blood tests or in an independent monitoring mode.

Electrochemical antibiotic susceptibility testing: An emerging approach for fast and accurate determination of antibiotic effect in complex samples

With the emergence of drug resistant infections it is becoming increasingly important to develop technologies which accelerate and enhance prescription of antibiotics. For routine hospital testing in advanced economies, gold standard analysis techniques usually identify the correct antibiotic for treatment of an infection in 12–72 h. Current techniques are highly automated, can handle many samples but are inflexible, can be time consuming, and are not amenable to point of care use. Electrochemical approaches lend themselves very well to antibiotic susceptibility testing (AST) because of the possibility of developing low cost miniaturised systems which can be deployed at the point of need or as high throughput systems which can be used in centralised hospital laboratories. This article will detail recent advances in the field of electrochemical AST and offer commentary on the current state of the field and the prospects for translation of electrochemical AST systems into real world use. • Antimicrobial resistance (AMR) is a growing global health problem with potential to cause 10 million deaths per year by 2050. • New technologies which better guide rational prescription of antibiotics are needed. • Electrochemical systems are beginning to show great promise for enhancing antibiotic stewardship. • Low cost, portability, high sensitivity and multiplex capability are attractive features of electrochemical AST systems.

The Impact of a Mobile Phone Application for Retention of Bleeding Control Skills

The American College of Surgeons Bleeding Control Course (B-Con) empowers bystanders with hemorrhage control skills to manage prehospital emergencies, but demonstrates poor skill retention. The point of care use of a free Stop the Bleed mobile phone application on the retention of hemorrhage control skills from the B-Con Course was explored. Convenience sample of college students previously trained in B-Con were randomized into mobile application (MA) or control groups. The use of a mobile application during a simulated emergency scenario with tourniquet and situational awareness skills was assessed. Wound packing skill retention without intervention was also assessed. Survey data allowed for comparison of participant perceptions of skills with actual performances. MA (n = 30) was superior to control (n = 32) in correct tourniquet application (62.5% versus 30.0%; P = 0.01) with longer placement times (163 sec versus 95 sec; P < 0.001) and in calling 911 (31.3% versus 3.3%, P = 0.004). Participants maintain inflated perceptions of their skills, but generally feel underprepared for a future bleeding emergency. Mobile apps improve tourniquet and situational awareness skills and may serve as potential aids to improve bystander hemorrhage control skills in real-time, but require further prospective investigation into its use.

A Bacteriophage-Based Electrochemical Biosensor for Detection of Methicillin-Resistant Staphylococcus aureus

Bacterial pathogens are important targets for detection and early diagnostics of infection in healthcare. Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium that can cause severe complications such as pneumonia and septicemia from surgical site infections. In this work, a carbon nanotube (CNT)-based impedimetric biosensor using SATA-8505, a bacteriophage, as a recognition element was developed for the detection of MRSA USA300, a common strain of MRSA found in surgical infections. The biosensor allows for fast and selective detection of viable MRSA cells by measuring impedance changes on the electrode surface as a result of bacterial capture by the phage-functionalized CNT electrode. The immobilization of the bacteriophage was achieved by inducing an electric-field and using a charge-directed orientation strategy, and activity of the immobilized phage was confirmed by an infectivity study using disk diffusion methods. The biosensing platform showed high selectivity and sensitivity toward MRSA USA300 with a limit of detection of 1.23 × 102 CFU/ml in aqueous solution and 1.29 × 102 CFU/ml in blood plasma. The biosensing platform could potentially be integrated into a lab-on-a-chip platform for point of care use and for other pathogens such as Pseudomonas aeruginosa, Klebsiella and Listeria monocytogenes.

P6536Implementation of a mass atrial fibrillation screening program in Canadian community practice

Abstract Background Atrial fibrillation is the most common arrhythmia seen in clinical practice, and is an important cause of stroke. In up to 10% of patients, stroke is the first clinical manifestation of undiagnosed atrial fibrillation (AF). Early detection of AF is therefore desirable, as it would provide an opportunity to initiate appropriate stroke prevention with anticoagulation. While European guidelines recommend screening for AF as part of routine care in patients with risk factors, the optimal modality has not yet been determined. Smartphone enabled single lead ECG devices have been shown to be highly accurate and could prove to be an effective point of care tool for uncovering AF in the community and may facilitate implementation of screening recommendations. Purpose We sought to describe the integration of a smartphone enabled single lead ECG device into the practice of selected Canadian community-based physicians and its impact on patient care. Methods Canadian community-based physicians were provided with a smartphone enabled single lead ECG device for a period of six months. Physicians were instructed to perform a single 30 second ECG recording in patients over the age of 65 who present for a regular follow-up visit. Patients with previous AF diagnosis were excluded. Outcomes related to screening, and stroke prevention-treatment initiation were prospectively ascertained and documented using a patient flow tracker. Results Among 612 physicians who were invited to participate in the program, 315 (51%) agreed to track and report the use of the device that was provided to them. During this program, 315 physicians screened a total of 15,538 patients. AF was detected 1103 patients (7.1%). The majority of patients with a positive screen underwent a subsequent 12-lead ECG confirmatory exam (79%). AF could not be confirmed in 277 patients (31.7% of patients undergoing 12-lead ECG). A total of 677 patients were initiated on oral anticoagulation (OAC), with 262 patients (24%) being initiated on OAC prior to ECG confirmation. Conclusion Undiagnosed AF is common in patients &gt;65 years of age in community practice. The results of this program indicate that single lead mobile ECG devices can be integrated into routine point of care use for Canadian physicians and, can be a valuable tool to detect previously undiagnosed AF. While this approach identified a large number of undiagnosed AF patients eligible for OAC therapy, undertreatment with OAC remains a concern. Acknowledgement/Funding Bristol-Myers Squibb/Pfizer Alliance

Biosensor for Detection of Methicillin-Resistant Staphylococcus Aureus

Bacterial pathogens are ubiquitous in nature and are important targets for detection in various applications. In the healthcare industry, Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterial pathogen that is resistant to many antibiotics. MRSA, if not treated promptly, can cause severe complications such as bloodstream infections, pneumonia, and surgical site infections leading to sepsis and eventual death [1]. Current conventional detection methods for pathogens usually take a few hours to days for identification and need skilled experts and tools such as cefoxitin disk screen tests, latex agglutination tests, and real-time PCR for analyses [2]. Biosensors, on the other hand, are simple, easy to use, and provide rapid results as well as aid in real-time monitoring. Specifically, electrochemical biosensors are advantageous over conventional methods with their ease of use, high specificity and sensitivity [3]. In the current work, a carbon nanotube-based impedimetric biosensor was developed for rapid and selective detection of live MRSA cells [4]. MRSA USA300 specific phage SATA-8505 was used as the recognition element for selective detection of its host bacteria cells. The detection mechanism uses an impedimetric measurement of the resistance changes on an electrode, where bacteriophages were immobilized onto functionalized carbon nanotube using an electric field-induced, charge-directed orientation strategy. Infectivity study using disk diffusion methods showed activity retention of immobilized bacteriophages on the electrodes. The established biosensor showed high selectivity toward MRSA USA300. The biosensor could potentially be integrated into lab-on-a-chip platforms for point of care use and for other health-care associated pathogens, such as Pseudomonas aeruginosa and Klebsiella pneumoniae.

A New Contraception Curriculum in the Internal Medicine Residency Primary Care Clinic.

Nearly half of all pregnancies in the USA are unintended with a relatively higher proportion occurring in military populations, which can have a large impact on military readiness. Military and civilian internal medicine residency programs do not place an emphasis on contraception in the primary care setting. This intervention sought to elucidate the perceptions of contraception in an internal medicine primary care setting in a military residency and improve confidence in contraceptive counseling and prescribing. Residents at a military internal residency program were given an hour-long didactic presentation on contraception that was followed 5 weeks later by the implementation of a pocket card for point of care use with key information from the presentation. Residents became certified in the placement and removal of the etonogestrel implant. Pre- and post-intervention surveys were administered to assess for changes in attitudes and confidence in prescribing and counseling. This project was determined to be a quality improvement project by the IRB board of the home institution. Forty-two of 75 (56%) residents responded initially and 40 of 75 (53%) responded after the intervention. There was a significant improvement in resident attitudes towards the applicability of contraception training in internal medicine (p = 0.03) as well as acquiring the skill of etonogestrel implant placement (p = 0.001). There was a trend towards significance in confidence in prescribing oral contraception (p = 0.053). There was no change in residents' confidence in counseling on oral contraception (p = 0.45). A change in the contraception curriculum led to improved residents' skills in etonogestrel placement, and attitudes regarding the applicability of training in contraception to internal medicine, but did not significantly improve confidence in contraceptive counseling. These results suggest that internal medicine residencies should focus on teaching contraception to improve the attitudes in future internists who will need to address contraception in the military population. Future studies could include assessing physician preparedness for addressing contraception during general medical officer tours.

Status of diagnostics for three arbovirus infections in resource-limited settings

Climate change, travel, and urbanization contribute to increasing exposure to Zika, Dengue and Chikungunya. Lab-based diagnostics are required because of overlapping clinical presentations. Here we review the current diagnostic methods, and find them poorly adapted to point of care use in resource-limited settings: generally, serologic assays are hindered by cross-reactivity while molecular assays require laboratory conditions. We conclude that a differential diagnostic device is critically needed, requiring a simpler molecular assay kit that maintains high sensitivity and specificity.

Ultrasound as a Screening Tool for Central Venous Catheter Positioning and Exclusion of Pneumothorax.

Although real-time ultrasound guidance during central venous catheter insertion has become a standard of care, postinsertion chest radiograph remains the gold standard to confirm central venous catheter tip position and rule out associated lung complications like pneumothorax. We hypothesize that a combination of transthoracic echocardiography and lung ultrasound is noninferior to chest radiograph when used to accurately assess central venous catheter positioning and screen for pneumothorax. All operating rooms and surgical and trauma ICUs at the institution. Single-center, prospective noninferiority study. Patients receiving ultrasound-guided subclavian or internal jugular central venous catheters. During ultrasound-guided central venous catheter placement, correct positioning of central venous catheter was accomplished by real-time visualization of the guide wire and positive right atrial swirl sign using the subcostal four-chamber view. After insertion, pneumothorax was ruled out by the presence of lung sliding and seashore sign on M-mode. Data analysis was done for 137 patients. Chest radiograph ruled out pneumothorax in 137 of 137 patients (100%). Lung ultrasound was performed in 123 of 137 patients and successfully screened for pneumothorax in 123 of 123 (100%). Chest radiograph approximated accurate catheter tip position in 136 of 137 patients (99.3%). Adequate subcostal four-chamber views could not be obtained in 13 patients. Accurate positioning of central venous catheter with ultrasound was then confirmed in 121 of 124 patients (97.6%) as described previously. Transthoracic echocardiography and lung ultrasound are noninferior to chest x-ray for screening of pneumothorax and accurate central venous catheter positioning. Thus, the point of care use of ultrasound can reduce central venous catheter insertion to use time, exposure to radiation, and improve patient safety.

Point of care diagnosis of multiple schistosome parasites: Species-specific DNA detection in urine by loop-mediated isothermal amplification (LAMP)

Schistosomes are easily transmitted and high chance of repeat infection, so if control strategies based on targeted mass drug administration (MDA) are to succeed it is essential to have a test that is sensitive, accurate and simple to use. It is known and regularly demonstrated that praziquantel does not always eliminate an infection so in spite of the successes of control programs a residual of the reservoir survives to re-infect snails. The issue of diagnostic sensitivity becomes more critical in the assessment of program effectiveness. While serology, such as antigen capture tests might improve sensitivity, it has been shown that the presence of species-specific DNA fragments will indicate, most effectively, the presence of active parasites. Polymerase chain reaction (PCR) can amplify and detect DNA from urine residue captured on Whatman No. 3 filter paper that is dried after filtration. Previously we have detected S. mansoni and S. haematobium parasite-specific small repeat DNA fragment from filtered urine on filter paper by PCR. In the current study, we assessed the efficacy of detection of 86 urine samples for either or both schistosome parasites by PCR and loop-mediated isothermal amplification (LAMP) that were collected from a low to moderate transmission area in Ghana. Two different DNA extraction methods, standard extraction kit and field usable LAMP-PURE kit were also evaluated by PCR and LAMP amplification. With S. haematobium LAMP amplification for both extractions showed similar sensitivity and specificity when compared with PCR amplification (100%) verified by gel electrophoresis. For S. mansoni sensitivity was highest for LAMP amplification (100%) for standard extraction than PCR and LAMP with LAMP-PURE (99% and 94%). The LAMP-PURE extraction produced false negatives, which require further investigation for this field usable extraction kit. Overall high positive and negative predictive values (90% − 100%) for both species demonstrated a highly robust approach. The LAMP approach is close to point of care use and equally sensitive and specific to detection of species-specific DNA by PCR. LAMP can be an effective means to detect low intensity infection due to its simplicity and minimal DNA extraction requirement. This will enhance the effectiveness of surveillance and MDA control programs of schistosomiasis.

Performance of the SAMBA I and II HIV-1 Semi-Q Tests for viral load monitoring at the point-of-care

Although access to antiretroviral therapy for HIV infection is increasing in resource-poor countries, viral load testing for monitoring of treatment efficacy remains limited, expensive, and confined to centralized laboratories. The SAMBA HIV-1 Semi-Q Test is a nucleic acid–based amplification assay developed for viral load monitoring performed on either the semi-automated SAMBA I system for laboratory use or the fully automated SAMBA II system for point-of care use. We have assessed the performance characteristics of the SAMBA HIV-1 Semi-Q Test on SAMBA I and SAMBA II systems according to the Common Technical Specifications of the European Community's 98/79 In Vitro Diagnostic Medical Devices Directive. The sensitivity, specificity, reproducibility, and viral subtype coverage of the test were similar on the SAMBA I and SAMBA II platforms. The clinical performance on the SAMBA I system was compared with the Roche CAP/CTM assay and evaluated in-house with 130 patient specimens from London as well as in the field with 390 specimens in Kenya and Zimbabwe. The overall concordance between the SAMBA and CAP/CTM assays was 98.1%. The clinical performance of the test on the SAMBA II platform in comparison with the Abbott HIV-1 RealTime Assay was evaluated in-house with 150 specimens from Ukraine, yielding a concordance of 98.0%. The results thus show that the SAMBA HIV-1 Semi-Q Test performs equivalently on SAMBA I and SAMBA II, and they suggest that the test is suitable for implementation at the point-of-care in resource-poor regions where viral load testing is desperately needed but often unavailable.

The Sensitivity and Specificity of Loop-Mediated Isothermal Amplification (LAMP) Assay for Tuberculosis Diagnosis in Adults with Chronic Cough in Malawi.

BackgroundCurrent tuberculosis diagnostics lack sensitivity, and are expensive. Highly accurate, rapid and cheaper diagnostic tests are required for point of care use in low resource settings with high HIV prevalence.ObjectiveTo investigate the sensitivity and specificity, and cost of loop-mediated isothermal amplification (LAMP) assay for tuberculosis diagnosis in adults with chronic cough compared to Xpert® MTB/RIF, fluorescence smear microscopy.MethodsBetween October 2013 and March 2014, consecutive adults at a primary care clinic were screened for cough, offered HIV testing and assessed for tuberculosis using LAMP, Xpert® MTB/RIF and fluorescence smear microscopy. Sensitivity and specificity (with culture as reference standard), and costs were estimated.ResultsOf 273 adults recruited, 44.3% (121/273) were HIV-positive and 19.4% (53/273) had bacteriogically confirmed tuberculosis. The sensitivity of LAMP compared to culture was 65.0% (95% CI: 48.3% to 79.4%) with 100% (95% CI: 98.0% to 100%) specificity. The sensitivity of Xpert® MTB/RIF (77.5%, 95% CI: 61.5% to 89.2%) was similar to that of LAMP, p = 0.132. The sensitivity of concentrated fluorescence smear microscopy with routine double reading (87.5%, 95% CI: 73.2% to 95.8%) was higher than that of LAMP, p = 0.020. All three tests had high specificity. The lowest cost per test of LAMP was at batch size of 14 samples (US$ 9.98); this was lower than Xpert® MTB/RIF (US$ 13.38) but higher than fluorescence smear microscopy (US$ 0.65).ConclusionThe sensitivity of LAMP was similar to Xpert® MTB/RIF but lower than fluorescence smear microscopy; all three tests had high specificity. These findings support the Malawi policy that recommends a combination of fluorescence smear microscopy and Xpert® MTB/RIF prioritised for people living with HIV, already found to be smear-negative, or being considered for retreatment of tuberculosis.

Label- and amplification-free electrochemical detection of bacterial ribosomal RNA

Current approaches to molecular diagnostics rely heavily on PCR amplification and optical detection methods which have restrictions when applied to point of care (POC) applications. Herein we describe the development of a label-free and amplification-free method of pathogen detection applied to Escherichia coli which overcomes the bottleneck of complex sample preparation and has the potential to be implemented as a rapid, cost effective test suitable for point of care use. Ribosomal RNA is naturally amplified in bacterial cells, which makes it a promising target for sensitive detection without the necessity for prior in vitro amplification.Using fluorescent microarray methods with rRNA targets from a range of pathogens, an optimal probe was selected from a pool of probe candidates identified in silico. The specificity of probes was investigated on DNA microarray using fluorescently labeled 16S rRNA target. The probe yielding highest specificity performance was evaluated in terms of sensitivity and a LOD of 20 pM was achieved on fluorescent glass microarray. This probe was transferred to an EIS end point format and specificity which correlated to microarray data was demonstrated. Excellent sensitivity was facilitated by the use of uncharged PNA probes and large 16S rRNA target and investigations resulted in an LOD of 50 pM. An alternative kinetic EIS assay format was demonstrated with which rRNA could be detected in a species specific manner within 10–40min at room temperature without wash steps.

Commentary On: Performance of the Cobas(®) Influenza A/B Assay for Rapid Pcr-Based Detection of Influenza Compared to Prodesse ProFlu+ and Viral Culture: Molecular Technology Poised to Change Testing for Influenza at the Point-of-Care.

Commentary On: Performance of the Cobas(®) Influenza A/B Assay for Rapid Pcr-Based Detection of Influenza Compared to Prodesse ProFlu+ and Viral Culture: Molecular Technology Poised to Change Testing for Influenza at the Point-of-Care.

Current and future strategies for prevention of neonatal early-onset group B streptococcus disease

Group B streptococci (GBS) have been recognized as a leading cause of serious early-onset neonatal sepsis for 30 years. Introduction of intrapartum antibiotic prophylaxis (IAP) has led to a decrease in neonatal early-onset GBS (EOGBS) disease and in early neonatal sepsis-related mortality in many countries. At present decisions concerning the administration of IAP are usually based on either the presence of risk factors at the time of labor, or on screening of women at 35-37 weeks gestation. A new generation of rapid test for GBS suitable for point of care use offer the prospect of accurately detecting GBS during labor, which might improve targeting of IAP. Looking further ahead, active immunization of women before or during pregnancy may become the mainstay of prevention of neonatal EOGBS disease. In this article the role of GBS as a neonatal pathogen, and current and possible future strategies for prevention of neonatal EOGBS disease, are reviewed.

Precision chemical heating for diagnostic devices.

Decoupling nucleic acid amplification assays from infrastructure requirements such as grid electricity is critical for providing effective diagnosis and treatment at the point of care in low-resource settings. Here, we outline a complete strategy for the design of electricity-free precision heaters compatible with medical diagnostic applications requiring isothermal conditions, including nucleic acid amplification and lysis. Low-cost, highly energy dense components with better end-of-life disposal options than conventional batteries are proposed as an alternative to conventional heating methods to satisfy the unique needs of point of care use.