-
Talanta Dec 2023Dipstick-type lateral flow immunosensors are used widely for on-site detection of food allergens. The weakness of the immunosensors of this type, however, is their low...
Dipstick-type lateral flow immunosensors are used widely for on-site detection of food allergens. The weakness of the immunosensors of this type, however, is their low sensitivity. Contrary to current methods, that focus on improving detection capability through the introduction of novel labels or multistep protocols, this work exploits macromolecular crowding to modify and regulate the microenvironment of the immunoassay, thus promoting the interactions that are responsible for allergen recognition and signal generation. The effect of 14 macromolecular crowding agents was explored using, as a model, commercially available and widely applied dipstick immunosensors, which are already optimized in terms of reagents and conditions for peanut allergen detection. An about 10-fold improvement in detection capability was achieved by using polyvinylpyrrolidone, Mr 29,000, as a macromolecular crowder without compromising simplicity and practicality. The proposed approach is complementary to other methods of improving the sensitivity by using novel labels. Because biomacromolecular interactions have a fundamental role in all types of biosensors, we foresee that the proposed strategy will also find applications in other biosensors and analytical devices.
Topics: Allergens; Biosensing Techniques; Immunoassay; Macromolecular Substances
PubMed: 37421795
DOI: 10.1016/j.talanta.2023.124899 -
The Journal of Antimicrobial... Aug 2023Given the lack of accurate rapid diagnostics for urinary tract infection (UTI) in women, many countries have developed guidelines aiming to support appropriate... (Randomized Controlled Trial)
Randomized Controlled Trial
OBJECTIVES
Given the lack of accurate rapid diagnostics for urinary tract infection (UTI) in women, many countries have developed guidelines aiming to support appropriate antibiotic prescribing, but some guidelines have not been validated. We performed a diagnostic accuracy validation study of two guidelines: Public Health England (GW-1263) and Scottish Intercollegiate Guidelines Network (SIGN160).
METHODS
We used data from women with symptoms suggestive of uncomplicated UTI from a randomized controlled trial comparing urine collection devices. Symptom information was recorded via baseline questionnaire and primary care assessment. Women provided urine samples for dipstick testing and culture. We calculated the number within each risk category of diagnostic flowcharts who had positive/mixed growth/no significant growth urine culture. Results were presented as positive/negative predictive values, with 95% CIs.
RESULTS
Of women aged under 65 years, 311/509 (61.1%, 95% CI 56.7%-65.3%) classified to the highest risk category (recommended to consider immediate antibiotic prescribing) and 80/199 (40.2%, 95% CI 33.4%-47.4%) classified to the lowest risk category (recommended to reassure that UTI is less likely) by the GW-1263 guideline (n = 810) had positive culture. For the SIGN160 guideline (n = 814), the proportion with positive culture ranged from 60/82 (73.2%, 95% CI 62.1%-82.1%) in those for whom immediate treatment was indicated to 33/76 (43.4%, 95% CI 32.3%-55.3%) in those recommended a self-care/waiting strategy.
CONCLUSIONS
Clinicians should be aware of the potential for diagnostic error when using diagnostic guidelines for managing uncomplicated UTI and making antimicrobial prescribing decisions. Infection cannot be excluded on the basis of symptoms and dipstick testing alone.
Topics: Humans; Female; Urinalysis; Urinary Tract Infections; Anti-Bacterial Agents; Predictive Value of Tests; Primary Health Care
PubMed: 37401673
DOI: 10.1093/jac/dkad212 -
Applied and Environmental Microbiology Jul 2023Campylobacter jejuni is recognized as the most common species in the genus Campylobacter that causes foodborne diseases. The main reservoirs harboring C. jejuni are...
Campylobacter jejuni is recognized as the most common species in the genus Campylobacter that causes foodborne diseases. The main reservoirs harboring C. jejuni are poultry products, which are associated with most illnesses, creating a demand for effective detection methods to achieve point-of-need diagnostics. We developed an easy-to-use, hybrid paper/polymer-based microfluidic device that integrates paper-based DNA extraction, isothermal nucleic acid amplification, and lateral flow detection. Overall, the recombinase polymerase amplification (RPA) reaction was completed in 20 min and demonstrated 100% specificity to C. jejuni, including 2 reference strains and 6 wild strains isolated from the agroecosystem, 9 other Campylobacter subspecies strains, and 11 non-Campylobacter strains. The limit of detection (LOD) was 46 CFU/mL with DNA extracted on the cellulose paper. The sensitivity was reduced to 460 CFU/mL on the integrated hybrid paper/polymer-based microfluidic device. This device could detect C. jejuni spiked at concentrations ranging from 10 to 10 CFU/g in chicken meat after an enrichment of 5 to 10 h. For C. jejuni levels of >10 CFU/g, it managed to confirm positive results immediately, without bacterial enrichment. RPA reagents and primers remained stable on the paper platform at 22°C for 12 h. After lyophilization and storage on paper, the RPA reaction showed consistent sensitivity for 3 days, and the LOD was reduced to 10 CFU/mL when storage was extended to 25 days. The use of this hybrid paper/polymer-based microfluidic device enabled detection of Campylobacter in foods with high specificity and sensitivity, demonstrating its potential as a reliable point-of-need diagnostic platform for on-site conditions due to its low cost, portability, and simplicity. The global health and economic burden of Campylobacter prompts the development of novel detection techniques that can be implemented in resource-limited and on-site settings. This study described point-of-need identification of C. jejuni using a hybrid paper/polymer-based microfluidic device that is easy to operate. This device had high specificity and sensitivity toward C. jejuni and significantly reduced the total analysis time compared to conventional culture-based methods. Nucleic acid extraction was simplified from intensive pipetting to a paper dipstick, making it more convenient for use in the field as a promising tool for future routine surveillance and outbreak investigation.
Topics: Animals; Campylobacter jejuni; Chickens; Campylobacter; Nucleic Acid Amplification Techniques; Lab-On-A-Chip Devices; Nucleic Acids; Sensitivity and Specificity
PubMed: 37382522
DOI: 10.1128/aem.00695-23 -
Journal of Veterinary Diagnostic... Sep 2023Standard visual urine dipstick analysis (UDA) is performed routinely in veterinary medicine; results can be influenced by both the operator and the method. We evaluated...
Standard visual urine dipstick analysis (UDA) is performed routinely in veterinary medicine; results can be influenced by both the operator and the method. We evaluated the agreement of results for canine and feline urine samples analyzed using a 10-patch dipstick (Multistix10SG; Siemens), both visually under double-anonymized conditions by students and a laboratory technician, and with an automated device (AD; Clinitek Status, Siemens). The mean concordance for semiquantitative urinalysis results between students and the technician and between students and the AD was fair (κ0.21-0.40) in dogs and cats; concordance was moderate between the technician and the AD (κ0.41-0.60) in dogs and good (κ0.61-0.80) in cats. For pH, the mean concordance between students and the technician and between the technician and the AD was good (ρ0.80-0.92) in dogs and cats; concordance was good between students and the AD (ρ0.80-0.92) in dogs and moderate (ρ0.59-0.79) in cats. Repeatability was higher ( < 0.001) for the technician and the AD than for a student. We found good agreement between UDA performed by an experienced operator and an AD in dogs and cats but found low reproducibility and low repeatability for urinalysis performed by an inexperienced operator.
Topics: Cats; Dogs; Animals; Cat Diseases; Reproducibility of Results; Observer Variation; Dog Diseases; Reagent Strips; Urinalysis
PubMed: 37326167
DOI: 10.1177/10406387231181579 -
ACS Sensors Jun 2023Rising consumption, large-scale production, and widespread distribution have been accompanied by an increase in the number of infections reported to implicate...
Rising consumption, large-scale production, and widespread distribution have been accompanied by an increase in the number of infections reported to implicate contaminated food products. We developed a portable origami microfluidic device that enabled rapid detection of from sample preparation to end-point detection, including nucleic acid extraction on paper dipstick without pipetting, nucleic acid amplification using isothermal recombinase polymerase amplification (RPA), and lateral flow assay for results readout. We also explored the feasibility of the polyethersulfone (PES) membrane as a new reaction matrix against the widely used chromatography paper to optimize nucleic acid amplification. Nucleic acid amplification was achieved within 20 min and demonstrated 100% specificity to . The limit of detection of this PES-based microfluidic device was 260 CFU/mL and equivalent to RPA reaction in tube. A chromatography paper-based microfluidic device was found 1-log less in sensitivity for detection compared to the use of PES. This PES-based microfluidic device could detect in lettuce, chicken breast, and milk at concentrations of 6 CFU/g, 9 CFU/g, and 58 CFU/mL, respectively, after 6 h enrichment. PES has shown high compatibility to isothermal nucleic acid amplification and great potential to be implemented as an integrated sample-to-answer microfluidic device for the detection of pathogens in various food commodities.
Topics: Salmonella enterica; Recombinases; Nucleic Acids; DNA; Lab-On-A-Chip Devices
PubMed: 37228176
DOI: 10.1021/acssensors.3c00387 -
The Journal of the Association of... Jan 2023Spontaneous bacterial peritonitis (SBP) is a common and serious complication in cirrhosis patients with an incidence and mortality of about 30% and 25% respectively in... (Observational Study)
Observational Study
INTRODUCTION
Spontaneous bacterial peritonitis (SBP) is a common and serious complication in cirrhosis patients with an incidence and mortality of about 30% and 25% respectively in hospitalised patients. Currently the diagnostic criteria is presence of >250 neutrophils per microlitre in ascitic fluid, but these facilities are not available at all timings and often the results are delayed. A rapid and bedside test is needed for diagnosis of SBP which aids in timely treatment.Dipsticks based on detection of leukocyte esterase in fluid are available everywhere and widely used for detecting urinary tract infection. In this study we aimed to find out the diagnostic utility of these dipsticks in SBP for immediate diagnosis.
MATERIALS
An observational cross sectional study was conducted among 75 patients with cirrhosis suspected of having SBP clinically. Relevant investigations, diagnostic paracentesis and dipstick test of ascitic fluid was done. The patients were divided into two groups with and without SBP.The ascitic fluid neutrophil count and dipstick results were compared in both groups.
RESULT
26 patients (34.6%) had SBP out of total 75 patients. AKI and hepatic encephalopathy were significantly higher in SBP patients (53% and 50% respectively in SBP patients; 28% and 18% in patients without SBP). Sensitivity and specificity of dipstick test with cutoff of more than 1+ was 96% and 75% respectively; with cutoff of more than 2 was 80% and 91% respectively.
CONCLUSION
The dipstick can be used as a bedside maneuver for immediate diagnosis of SBP. Having a good negative predictive value, it can also be used to exclude SBP, thus avoiding unnecessary antibiotics administration. References Koulaouzidis A. Diagnosis of spontaneous bacterial peritonitis: an update on leucocyte esterase reagent strips. World J Gastroenterol 2011;17(9):1091-1094. Oey RC, Kuiper JJ, Van Buuren HR, et al. Reagent strips are efficient to rule out spontaneous bacterial peritonitis in cirrhotics. Neth J Med 2016;74(6):257-261.
Topics: Humans; Reagent Strips; Cross-Sectional Studies; Bacterial Infections; Ascitic Fluid; Peritonitis; Liver Cirrhosis
PubMed: 37116047
DOI: No ID Found -
Talanta Jun 2023Fast and precise identification of toxic G-series nerve agents in the solution and vapor phase is urgently needed to save human beings from unwanted wars and terrorist...
Fast and precise identification of toxic G-series nerve agents in the solution and vapor phase is urgently needed to save human beings from unwanted wars and terrorist attacks, which is challenging to execute practically. In this article, we have designed and synthesized a sensitive and selective phthalimide-based chromo-fluorogenic sensor, DHAI, by a simple condensation process that shows ratiometric and turns on chromo-fluorogenic behavior towards Sarin gas mimic diethylchlorophosphate (DCP) in liquid and vapor phases, respectively. A colorimetric change, from yellow to colorless, is observed in the DHAI solution due to the introduction of DCP in daylight. A remarkable cyan color photoluminescence enhancement is noticed in the presence of DCP in the DHAI solution, which is observable to the naked under a portable 365 nm UV lamp. The mechanistic aspects of the detection of DCP by employing DHAI have been revealed by time-resolved photoluminescence decay analysis and H NMR titration investigation. Our probe DHAI exhibits linear photoluminescence enhancement from 0 to 500 μM with a detection limit of nanomolar range from non-aqueous to semi-aqueous media. For practical utility, a DHAI-stained test kit employing Whatman-41 filter paper has been fabricated and used as a portable and displayable photonic device for on-site detection of Sarin gas surrogate, DCP. Also, a dip-stick experiment has been demonstrated to identify the vapor of Sarin gas mimics DCP colorimetrically and fluorometrically. The concentrations of DCP in various water samples have been evaluated with the help of a standard fluorescence curve for real sample analysis.
PubMed: 36940571
DOI: 10.1016/j.talanta.2023.124448 -
Frontiers in Veterinary Science 2023Mastitis is one of the most serious diseases affecting dairy farming, causing huge economic losses worldwide. is the main pathogenic bacterium of contagious mastitis...
INTRODUCTION
Mastitis is one of the most serious diseases affecting dairy farming, causing huge economic losses worldwide. is the main pathogenic bacterium of contagious mastitis and can deliver a devastating blow to a farm's economy. Rapid detection is the key to disease control.
METHODS
In this study, a rapid detection method for was established. This method combines filter paper extraction, multienzyme isothermal rapid amplification (MIRA), and lateral flow dipsticks (LFD). To simplify the extraction procedure, we designed a disposable extraction device (DED). First, DED performance was evaluated by polymerase chain reaction (PCR) and then the lysis formula and extraction time were optimized. Second, this study compared the extraction performance of a filter paper and an automatic nucleic acid extraction instrument. After screening primers, MIRA for was established and combined with LFD. Specificity and sensitivity were evaluated after optimizing the reaction conditions.
RESULTS
The results showed that the lowest extraction line for DED was 0.01-0.001 ng/μl. In the specificity study, 12 different bacteria were tested, and only was found to be positive. In the sensitivity study, seven dilution gradients were established, and the lowest detection line was 3.52 × 10 CFU/ml.
DISCUSSION
In summary, the method established in this study does not require laboratory equipment and is suitable for on-site detection. The entire method takes only 15 min, is low in cost, has high precision and low technical requirements for operators, which is in contrast with the high cost and cumbersome operation of traditional methods, and is suitable for on-site testing in areas with limited facilities.
PubMed: 36876018
DOI: 10.3389/fvets.2023.1100246 -
Topics in Spinal Cord Injury... 2023To explore the association between dipstick results and urinary symptoms. (Observational Study)
Observational Study
OBJECTIVES
To explore the association between dipstick results and urinary symptoms.
METHOD
This was a prospective 12-month observational study of real-time self-administered urine dipstick results and symptoms in a community setting that included 52 spinal cord injury/disease (SCI/D) participants with neurogenic lower urinary tract dysfunction (NLUTD) who use an indwelling catheter. Symptoms were collected using the Urinary Symptom Questionnaire for Neurogenic Bladder-Indwelling Catheter (USQNB-IDC). The USQNB-IDC includes actionable (A), bladder (B1), urine quality (B2), and other (C) symptoms; analyses focused on A, B1, and B2 symptoms. Dipstick results include nitrite (NIT +/-), and leukocyte esterase (LE; negative, trace, small, moderate, or large). Dipstick outcomes were defined as strong positive (LE = moderate/large and NIT+), inflammation positive (LE = moderate/large and NIT-), negative (LE = negative/trace and NIT-), and indeterminate (all others).
RESULTS
Nitrite positive dipsticks and moderate or large LE positive dipsticks were each observed in over 50% of the sample in every week. Strong positive dipstick results were observed in 35% to 60% of participants in every week. A, B1, or B2 symptoms co-occurred less than 50% of the time with strong positive dipsticks, but they also co-occurred with negative dipsticks. Participants were asymptomatic with a strong positive dipstick an average of 30.2% of the weeks. On average, 73% of the time a person had a negative dipstick, they also had no key symptoms (95% CI, .597-.865).
CONCLUSION
No association was observed between A, B1, and B2 symptoms and positive dipstick. A negative dipstick with the absence of key symptoms may better support clinical decision-making.
Topics: Humans; Urinary Tract Infections; Nitrites; Urinary Bladder; Prospective Studies; Predictive Value of Tests; Catheters, Indwelling; Spinal Cord Injuries; Spinal Cord Diseases
PubMed: 36819928
DOI: 10.46292/sci22-00095 -
Sensors and Actuators. B, Chemical May 2023A fully-enclosed prototype 'pen' for rapid detection of SARS-CoV-2 based on reverse transcriptase isothermal recombinase polymerase amplification (RT-RPA) with dipstick...
A fully-enclosed prototype 'pen' for rapid detection of SARS-CoV-2 based on reverse transcriptase isothermal recombinase polymerase amplification (RT-RPA) with dipstick assay was developed. The integrated handheld device, consisting of amplification, detection and sealing modules, was developed to perform rapid nucleic acid amplification and detection under a fully enclosed condition. After RT-RPA amplification with a metal bath or a normal PCR instrument, the amplicons were mixed with dilution buffer prior to being detected on a lateral flow strip. To avoid aerosol contamination causing false-positive, from amplification to final detection, the detection 'pen' had been enclosed to isolate from the environment. With colloidal gold strip-based detection, the detection results could be directly observed by eyes. By cooperating with other inexpensive and rapid methods for POC nucleic acid extraction, the developed 'pen' could detect COVID-19 or other infectious diseases in a convenient, simple and reliable way.
PubMed: 36811084
DOI: 10.1016/j.snb.2023.133531