Rapid Lateral Flow Research Articles

A Novel Immunochromatographic Test Strip Using Lanthanide-Labeled Fluorescent Nanoparticles for the Serological Detection of Toxoplasma gondii in Dogs and Cats

Toxoplasma gondii (T. gondii) is an important zoonotic pathogen which induces both acute and chronic toxoplasmosis. Timely diagnosis of T. gondii is crucial for effective disease management. Here, we present a pioneering approach using europium (III)-chelated nanoparticles (EuNPs) in a rapid lateral flow immunochromatographic test strip (ICTS) for detecting T. gondii antibodies in serum samples. By conjugating EuNPs with Staphylococcus aureus protein A, we efficiently captured T. gondii-specific antibodies, which bound to T. gondii antigens on the test line (T-line), generating a distinct fluorescent signal. Employing this novel method, we conducted an extensive epidemiological investigation of T. gondii infections among dogs and cats in Shanghai, China. This innovative ICTS allows for rapid results within 25 min, which include a qualitative result through naked-eye observation under an ultraviolet lamp and a quantitative one derived using a strip reader. With a detection limit of 1:6400 for dog positive serum and no cross-reactivity with other canine and feline pathogens, the EuNPs-ICTS demonstrated excellent consistency with standard enzyme-linked immunosorbent assay results for dogs (κ = 0.91) and cats (κ = 0.92). In addition, 20.38% of 996 dog serum samples and 14.18% of 416 cat serum samples revealed T. gondii antibodies, highlighting the efficacy of this approach. Our study presents a rapid, sensitive, specific, and reproducible EuNPs-ICTS, serving as a promising tool for on-the-spot diagnosis of T. gondii infections in dogs and cats.

Long afterglow nanoprobes labeled image enhancement using deep learning in rapid and sensitive lateral flow immunoassay

Point-of-care testing (POCT) is currently the predominant method of in vitro diagnostics, with lateral flow immunoassay(LFIA) being commonly utilized in POCT. The performance of the probe in LFIA will directly affect the results of the detection. Therefore, the selection of probes is particularly important. However, the current commercially produced probes generally suffer from short luminescence lifetime, high detection cost, and poor anti-interference capability. Meanwhile, the traditional detection system has difficulties in detecting weakly positive samples. These ultimately lead to the problem of poor detection sensitivity. In order to address the above issues, we have synthesized an ultralong organic phosphorescence nanoprobe (UOPN). The UOPNs exhibit a long afterglow phosphorescence signal of around 300 ms after being excited, which can be used to eliminate endogenous interference. Meanwhile, focusing on the problem of poor detection of weakly positive samples in conventional detection systems, and the weak inherent signal of UOPNs, resulting in a low signal-to-noise ratio, we have developed a detection system that combines image processing and neural network-driven analysis for long afterglow image analysis. Through the analysis of the long afterglow images of serum amyloid A (SAA) in human blood, a detection limit of 0.01 μg/mL and a linear range of 0.1–251 μg/mL were achieved. The whole analysis was completed within 5 minutes. After pre-processing with the denoising algorithm, the system demonstrated an impressive classification accuracy of 99.24 %, validating the reliability of the detection system. This approach has further enhanced the sensitivity of immunoassay, contributing to the advancement of point-of-care testing.

Rapid lateral flow test for Mycobacterium tuberculosis complex and non-tuberculous mycobacteria differentiation

The diagnosis of mycobacterial infections, including both the Mycobacterium tuberculosis complex (MTBC) and non-tuberculous mycobacteria (NTM), poses a significant global medical challenge. This study proposes a novel approach using immunochromatographic (IC) strip tests for the simultaneous detection of MTBC and NTM. Traditional methods for identifying mycobacteria, such as culture techniques, are hindered by delays in distinguishing between MTBC and NTM, which can affect patient care and disease control. Molecular methods, while sensitive, are resource-intensive and unable to differentiate between live and dead bacteria. In this research, we developed unique monoclonal antibodies (mAbs) against Ag85B, a mycobacterial secretory protein, and successfully implemented IC strip tests named 8B and 9B. These strips demonstrated high concordance rates with conventional methods for detecting MTBC, with positivity rates of 93.9% and 85.9%, respectively. For NTM detection, the IC strip tests achieved a 63.2% detection rate compared to culture methods, considering variations in growth rates among different NTM species. Furthermore, this study highlights a significant finding regarding the potential of MPT64 and Ag85B proteins as markers for MTBC detection. In conclusion, our breakthrough method enables rapid and accurate detection of both MTBC and NTM bacteria within the BACTEC MGIT system. This approach represents a valuable tool in clinical settings for distinguishing between MTBC and NTM infections, thereby enhancing the management and control of mycobacterial diseases.Key points• Panel of mAbs for differentiating MTB versus NTM• IC strips for diagnosing MTBC and NTM after the BACTEC MGIT• Combined detection of MTP64 and Ag85B enhances diagnostic accuracy

Lessons learned: drive-through COVID-19 clinic testing during an adaptive epidemic response and a point-of-care test assessment of a computer-read rapid lateral flow immunoassay with fluorescence-based detection.

Background. The COVID-19 pandemic demonstrated a need for robust SARS-CoV-2 test evaluation infrastructure to underpin biosecurity and protect the population during a pandemic health emergency.Gap statement. The first generation of rapid antigen tests was less accurate than molecular methods due to their inherent sensitivity and specificity shortfalls, compounded by the consequences of self-testing. This created a need for more accurate point-of-care SARS-CoV-2 detection methods.Aim. Here we present the lessons-learned during the COVID-19 emergency response in Western Australia including the detailed set-up, evaluation and operation of rapid antigen test in a state-run drive-through sample collection service during the COVID-19 pandemic after the strict border shutdown ended.Methods. We report a conformity assessment of a novel, second-generation rapid antigen test (Virulizer) comprising a technician-operated rapid lateral flow immunoassay with fluorescence-based detection.Results. The Virulizer rapid antigen test demonstrated up to 100% sensitivity (95% CI: 61.0-100%), 91.94% specificity (95% CI: 82.5-96.5%) and 92.65% accuracy when compared to a commercial PCR assay method. Wide confidence intervals in our series reflect the limits of small sample size. Nevertheless, the Virulizer assay performance was well-suited to point-of-care screening for SARS-CoV-2 in a drive-through clinic setting.Conclusion. The adaptive evaluation process necessary under changing pandemic conditions enabled assessment of a simple sample collection and point-of-care testing process, and showed how this system could be rapidly deployed for SARS-CoV-2 testing, including to regional and remote settings.

Intestinal parasitic co-infections associated with Helicobacter pylori among paediatric patients with gastrointestinal illness attending a general hospital in southern Ethiopia

BackgroundConcurrent infections or co-infections caused by intestinal parasites and Helicobacter pylori are quite rampant in paediatrics living in endemic areas of sub-Saharan Africa, including Ethiopia, and if left untreated, can result in severe complications and hence must be addressed to ensure their health and well-being.ObjectivesTo determine the prevalence of intestinal parasitic and H. pylori co-infections and associated factors among paediatric patients with gastrointestinal symptoms who attended the Arba Minch General Hospital (AMGH), Arba Minch, southern Ethiopia, from September to November 2020.MethodsA cross-sectional study was conducted among a study population of 299 paediatric patients with gastrointestinal symptoms who visited AMGH. Stool samples were collected and analysed to detect H. pylori and intestinal parasites. A rapid lateral flow chromatographic immunoassay was employed to identify the H. pylori copra antigen, whereas the latter was detected using wet mount saline preparation and formol-ether concentration method. Socio-demographic, clinical, behavioural and other factors were obtained by means of a pre-tested structured questionnaire. Descriptive statistics and logistic regression analysis were done by Statistical Package for Social Service (SPSS) version 25; P values < 0.05 were considered statistically significant.ResultsThe prevalence of Helicobacter pylori and intestinal parasites was 14% (n = 42) and 37.1% (n = 111), respectively, whereas that of the co-infections with these pathogens was 6.4% (n = 19). Giardia lamblia was the most prevailing parasite, 21.4% (n = 64). Informal maternal education [AOR = 5.14; 95% CI: 1.98–15.70] and lack of hand washing practice were significantly associated with the extent of co-infections [AOR = 4.18; 95% CI: 1.36–12.80].ConclusionNearly one in twenty pediatric patients with gastrointestinal symptoms had intestinal parasitic infections and H. pylori co-infections, representing a silent health problem that is to be addressed through effective control strategies. Health administrators should consider the importance of co-infections in clinical diagnosis and planning aimed at its prevention.

Systematic Review of Strongyloides stercoralis Infection Diagnosis in Southeast Asia: Insights from Parasitological, Molecular, and Serological Approaches.

Accurate diagnosis of strongyloidiasis is crucial for effective treatment and prevention of complications. We reviewed the current landscape of diagnostic assays used in detecting Strongyloides infection in Southeast Asia. A literature search was performed using Scopus, PubMed, and Web of Science databases spanning the last three decades. Based on the exclusion and inclusion criteria, 52 papers were included in this review. We outlined the diagnostic methods used and their advantages and drawbacks. Insensitive parasitological methods were commonly used, thus underscoring the underestimation of Strongyloides infection rates in Southeast Asia. A combination of diagnostic methods (i.e., microscopy, molecular techniques, and serology) is preferred because it leads to more effective detection and higher prevalence rates. New approaches have been developed, including urine ELISAs and rapid lateral flow tests. Improving and standardizing diagnostics and making them more accessible can improve Strongyloides prevalence estimates and facilitate control efforts.

Development of a multienzyme isothermal and lateral flow dipstick combination assay for the rapid detection of goose astrovirus II.

Goose astrovirus (GAstV) is a newly emerging pathogen that is currently widespread among geese, causing visceral gout and leading to substantial gosling mortalities, posing a severe threat to the waterfowl industry. GAstV II is the predominant epidemic strain, characterized by its high morbidity and mortality rate. Consequently, there is an urgent necessity to develop an effective diagnostic approach to control the dissemination of GAstV II, particularly in clinical farms with limited laboratory resources. In this study, a novel multi-enzyme isothermal rapid amplification (MIRA) and lateral flow dipstick (LFD) combined assay was developed. Different primers designed specific targeting a highly conserved region within the viral RdRp gene for the detection of GAstV II. Primers optimized and MIRA-LFD assay analyzed its performance regarding limits of detection, specificity, and efficiency of detection. The developed MIRA amplification is conducted at a constant temperature and accomplished within 10 minutes. Subsequent naked-eye observation of the LFD strips merely takes 5 minutes. The established MIRA-LFD method exhibits high specificity, with no cross-reaction with other pathogens and attains a detection sensitivity of 1 copy/μl, which is consistent with the reverse transcription quantitative PCR (RT-qPCR) assay. Further evaluation with clinical samples indicates that the accuracy of this MIRA-LFD method correlates well with RT-qPCR for the detection of GAstV II. In summary, the convenience, sensitivity, and rapidity of this newly developed detection method offer a significant advantage for on-site diagnosis of GAstV II.

Status on the incidence of coronaviral infection (CCoV) in canine cases of haemorrhagic gastroenteritis by rapid lateral flow assay (LFA) in Namakkal

Status on the incidence of coronaviral infection (CCoV) in canine cases of haemorrhagic gastroenteritis by rapid lateral flow assay (LFA) in Namakkal

Anti-SARS-CoV-2 Neutralizing Responses in Various Populations: Use of a Rapid Surrogate Lateral Flow Assay and Correlations with Anti-RBD Antibody Levels.

After the global COVID-19 crisis, understanding post-infectious immunity and vaccine efficacy remains crucial. This study aims to assess anti-SARS-CoV-2 immunity through a quantitative analysis of anti-receptor-binding domain (RBD) antibodies and rapid functional testing of the neutralizing humoral response. A retrospective analysis was conducted on samples from various cohorts, including partially vaccinated, fully vaccinated, post-COVID/no-vaccination, and post-COVID/vaccination individuals with various immune-competency statuses. The anti-RBD antibodies were measured using an automated chemiluminescence assay, while the neutralizing antibodies' (NAbs') activity was assessed through the lateral flow ichroma COVID-19 nAb test (LFT), a surrogate neutralization assay. The analysis revealed various levels of anti-RBD antibodies and seroneutralization responses across cohorts, with the post-COVID/vaccination group demonstrating the most robust protection. A correlation between anti-RBD antibodies and seroneutralization was observed, albeit with varying strength depending on the subgroup analyzed. Longitudinal assessment following natural infection showed an initial surge followed by a decline in both measures. A cutoff of 3.0 log10 BAU/mL was established to predict significant seroneutralization. The ichroma™ COVID-19 nAb test displayed high specificity and emerged as a valuable tool for monitoring anti-SARS-CoV-2 immunity. These findings contribute to understand the antibody response dynamics and underscore the potential of rapid tests in predicting protection against SARS-CoV-2 infection.

Rapid lateral flow immunoassay for fluorescence detection of canine distemper virus (CDV).

Canine distemper virus (CDV) is a highly contagious and potentially lethal virus that affects dogs and other members of the Canidae family, including wolves, foxes, and coyotes. Here, we present a fluorescent lateral flow immunoassay (FLFA) platform for the detection of CDV, which utilizes fluorescent microspheres - fusion protein monoclonal antibody (mAb)-labeled monoclonal antibody. The assay detected CDV within 5 min, with a detection limit threshold of 3 × 102 TCID50/mL. Notably, the assay demonstrated no cross-reactivity with canine parvovirus, canine coronavirus, canine adenovirus, feline calicivirus, feline herpesvirus, or feline parvovirus. Field and clinical applicability of the assay was evaluated using 63 field samples, including 30 canine fecal samples, 18 swab samples, and 15 blood samples. The coincidence rate between the detection results of clinical samples obtained through FLFA and reverse transcription polymerase chain reaction (RT-PCR) was 96.83%. Thus, this assay offers a significant advancement for the rapid diagnosis of CDV at the point of care.

A SARS-CoV-2 outbreak in a public order and safety training facility in England, June 2021.

The public order and safety (POS) sector remains susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreaks, as workplace attendance is typically compulsory and close physical contact is often needed. Here, we report on a SARS-CoV-2 outbreak with an attack rate of 39% (9/23), which occurred between 19 and 29 June 2021 among a cohort of new POS recruits participating in a mandatory 18-week training programme in England. The COVID-OUT (COVID-19 Outbreak investigation to Understand Transmission) study team undertook a multidisciplinary outbreak investigation, including viral surface sampling, workplace environmental assessment, participant viral and antibody testing, and questionnaires, at the two associated training facilities between 5 July and 24 August 2021. Environmental factors, such as ventilation, were deemed inadequate in some areas of the workplace, with carbon dioxide (CO2) levels exceeding 1,500 ppm on multiple occasions within naturally ventilated classrooms. Activities during safety training required close contact, with some necessitating physical contact, physical exertion, and shouting. Furthermore, most participants reported having physical contact with colleagues (67%) and more than one close work contact daily (97%). Our investigation suggests that site- and activity-specific factors likely contributed to the transmission risks within the POS trainee cohort. Potential interventions for mitigating SARS-CoV-2 transmission in this POS training context could include implementing regular rapid lateral flow testing, optimizing natural ventilation, using portable air cleaning devices in classrooms, and expanding use of well-fitted FFP2/FFP3 respirators during activities where prolonged close physical contact is required.

Accuracy of rapid lateral flow immunoassays for human leptospirosis diagnosis: A systematic review and meta-analysis.

In the last two decades, several rapid lateral flow immunoassays (LFIs) for the diagnosis of human leptospirosis were developed and commercialized. However, the accuracy and reliability of these LFIs are not well understood. In this study, we aimed to evaluate the accuracy of leptospirosis LFIs as well as the factors affecting the test efficiency using systematic review and meta-analysis. Original articles reporting the accuracy of human leptospirosis LFIs against microagglutination tests (MAT) or immunofluorescent assays (IFA) were searched from PubMed, Embase, and Scopus, and selected as per pre-set inclusion and exclusion criteria. A total of 49 data entries extracted from 24 eligible records published between 2003 and 2023 were included for meta-analysis. A meta-analysis was performed using STATA. The quality of the included studies was assessed according to the revised QUADAS-2. Only nine studies (32.1%) were considered to have a low risk of bias and no concern for applicability. Pooled sensitivity and specificity were calculated to be 68% (95% confidence interval, CI: 57-78) and 93% (95% CI: 90-95), respectively. However, the ranges of sensitivity (3.6 - 100%) and specificity (53.5 - 100%) of individual entries are dramatically broad, possibly due to the heterogeneity found in both study designs and LFIs themselves. Subgroup analysis demonstrated that IgM detection has better sensitivity than detection of IgG alone. Moreover, the test performance seems to be unaffected by samples from different phases of infection. The pooled specificity of LFIs observed is somewhat acceptable, but the pooled sensitivity is low. These results, however, must be interpreted with caution because of substantial heterogeneity. Further evaluations of the LFIs with well-standardized design and reference test will be needed for a greater understanding of the test performance. Additionally, IgM detection type should be employed when leptospirosis LFIs are developed in the future.

The Development of a Multienzyme Isothermal Rapid Amplification Assay to Visually Detect Duck Hepatitis B Virus.

Duck hepatitis B virus (DHBV) is widely prevalent in global ducks and has been identified in Chinese geese with a high prevalence; the available detection techniques are time-consuming and require sophisticated equipment. In this study, an assay combining multienzyme isothermal rapid amplification (MIRA) and lateral flow dipstick (LFD) was developed for the efficient and rapid detection of DHBV. The primary reaction condition of the MIRA assay for DHBV detection was 10 min at 38 °C without a temperature cycler. Combined with the LFD assay, the complete procedure of the newly developed MIRA assay for DHBV detection required only 15 min, which is about one-fourth of the reaction time for routine polymerase chain reaction assay. And electrophoresis and gel imaging equipment were not required for detection and to read the results. Furthermore, the detection limit of MIRA was 45.6 copies per reaction, which is approximately 10 times lower than that of a routine polymerase chain reaction assay. The primer set and probe had much simpler designs than loop-mediated isothermal amplification, and they were only specific to DHBV, with no cross-reactivity with duck hepatitis A virus subtype 1 and duck hepatitis A virus subtype 3, goose parvovirus, duck enteritis virus, duck circovirus, or Riemerella anatipestifer. In this study, we offer a simple, fast, and accurate assay method to identify DHBV in clinical serum samples of ducks and geese, which would be suitable for widespread application in field clinics.

Development of an immunochromatographic test strip to detect pneumolysin by monoclonal antibody capture method

BackgroundThe currently available methods for the detection of Streptococcus pneumoniae are labour-intensive, and involve time-consuming steps needing skilled technicians to perform the assays. Therefore, we developed a rapid lateral flow based immunochromatographic test strip for detection of S. pneumoniae using pneumolysin using monoclonal antibody capture approach. Methodology − The strip was designed by assembling a sample pad, conjugation pad, nitrocellulose membrane and adsorbent pad supported by a plastic backing card. Optimization of control spot was done by using three different concentrations of monoclonal antibody (0.1 µg, 0.25 g and 0.5 µg). Monoclonal antibody coupled with gold nanoparticles was immobilized on conjugate pad. Recombinant pneumolysin at three different concentrations (10 ng/ml, 50 ng/ml and 100 ng/ml) was used. Diluted pneumolysin was poured onto the sample pad which migrated through the conjugate pad containing gold antibody conjugate and the antigen–antibody complex migrated to the test spot to bind to the polyclonal antibody. The remaining free antibody bound to the control spot to visualize a control spot. Results: Control spot was optimized at 0.5 µg of mouse IgG. Of three different concentrations of Pneumolysin, the spot was best visualized at 50 ng/ml Pneumolysin concentration. Conclusion: Our ICT based device could detect a commercially available recombinant Pneumolysin of S. pneumoniae. Future study is directed to validate the strip for detection of Pneumolysin using biological fluids of patients (particularly children) infected with S. pneumoniae.

Rapid and sensitive lateral flow biosensor for the detection of GII human norovirus based on immunofluorescent nanomagnetic microspheres.

Human norovirus (HuNoV) is the most predominant viral agents of acute gastroenteritis. Point-of-care testing (POCT) based on lateral flow immunochromatography (LIFC) has become an important tool for rapid diagnosis of HuNoVs. However, low sensitivity and lack of quantitation are the bottlenecks of traditional LIFC. Thus, we established a rapid and accurate technique that combined immunomagnetic enrichment (IM) with LFIC to identify GII HuNoVs in fecal specimens. Before preparing immunofluorescent nanomagnetic microspheres and achieving the effect of HuNoV enrichment in IM and fluorescent signal in LFIC, amino-functionalized magnetic beads (MBs) and carboxylated quantum dots (QDs) were coupled at a mass ratio of 4:10. Anti-HuNoV monoclonal antibody was then conjugated with QDs-MB. The limit of detection was 1.56 × 104 copies/mL, and the quantitative detection range was 1.56 × 104 copies/mL-1 × 106 copies/mL under optimal circumstances. The common HuNoV genotypes GII.2, GII.3, GII.4, and GII.17 can be detected, there was no cross-reaction with various enteric viruses, including rotavirus, astrovirus, enterovirus, and sapovirus. A comparison between IM-LFIC and RT-qPCR for the detection of 87 fecal specimens showed a high level of agreement (kappa = 0.799). This suggested that the method is rapid and sensitive, making it a promising option for point-of-care testing in the future.

Evaluation of Three Cytomegalovirus IgG Lateral Flow Assays for Rapid Determination of CMV Serostatus.

Cytomegalovirus (CMV) serostatus is a major determinant of CMV infection, disease risk, and transplant outcomes. Current clinical serology assays are limited by relatively slow turnaround time, design for batched testing, need for trained personnel, and/or specialized equipment. Rapid diagnostic assays in development have a role in emerging settings, such as critically ill patients, but have not been systematically evaluated. We assessed the performance of 3 rapid lateral flow assays (LFAs) for the detection of CMV immunoglobulin (Ig)G antibodies compared with a reference commercially available CMV IgG enzyme-linked immunosorbent assay in residual serum samples from 200 consecutive adults who underwent clinical CMV serology testing. Samples with discrepant results between the LFA and reference assay were tested by a second reference assay. A subset of serum samples was assessed for interoperator variability. Operating characteristics of the QooLabs LFA were separately assessed in plasma samples. The sensitivity and specificity of the individual LFA assays using serum varied significantly: 86%/83%, 99/93%, and 57/97%, for Healgen, QNow automated reader, and nanoComposix, respectively, compared with the reference assay. Results for the QNow assay were comparable between automated and manual reads. Among a subset of 10 serum samples assessed by 5 individual operators, 44 of 50 (88%) results were concordant. Among 50 plasma samples assessed by the QooLabs LFA, the sensitivity and specificity were 72% and 96%. The ease of performance, rapid turnaround time, and good operating characteristics provide the rationale for further evaluation of the Qoolabs QNow LFA in specialized settings where rapid assessment of CMV serostatus would be advantageous.

Falsification of home rapid antigen lateral flow tests during the COVID-19 pandemic

During the COVID-19 pandemic, lateral flow tests (LFTs) were used to regulate access to work, education, social activities, and travel. However, falsification of home LFT results was a concern. Falsification of test results during an ongoing pandemic is a sensitive issue. Consequently, respondents may not answer truthfully to questions about LFT falsification behaviours (FBs) when asked directly. Indirect questioning techniques such as the Extended Crosswise model (ECWM) can provide more reliable prevalence estimates of sensitive behaviors than direct questioning. Here we report the prevalence of LFT FBs in a representative sample in England (n = 1577) using direct questioning (DQ) and the ECWM. We examine the role of demographic and psychological variables as predictors of LFT FBs. We show that the prevalence estimates of the FBs in the DQ condition were significantly lower than the ECWM estimates, e.g., reporting a negative result without conducting a test: 5.7% DQ vs 18.4% ECWM. Moral norms, subjective norms, anticipated regret, perception of risk to self, and trust in government predicted some of the FBs. Indirect questioning techniques can help provide more realistic and higher quality data about compliance with behavioural regulations to government and public health agencies.

Development and validation of a rapid lateral flow test for the detection of fluoroquinolones in meat and blood

Development and validation of a rapid lateral flow test for the detection of fluoroquinolones in meat and blood

P583 Infliximab Monitoring in Crohn's Disease and Development of Neural Networks Using Clinical Variables to Predict Disease Activity and Immunogenicity

Abstract Background Infliximab (IFX) is a biological drug that inhibits the action of tumor necrosis factor-alpha (TNFα), a pro-inflammatory cytokine enrolled in the pathogenesis of Crohn's disease (CD). Trough-level drug monitoring (TDM) has been increasingly used in clinical practice to optimize biological therapy and improve precision medicine. Therefore, this study aimed to analyze the serum level of IFX and antidrug antibodies (ADA) in active and in remission CD patients and develop prediction models via neural networks using a combination of clinical variables. Methods Seventy-five CD patients who underwent IFX therapy in the maintenance phase were included. Disease activity was defined by endoscopic and/or radiological criteria, comprising remission (CDR) and active (CDA) groups. Serum IFX levels were measured by ELISA (Promonitor ®) and rapid lateral flow test (Quantum-Blue®). ADA was measured using ELISA (Promonitor ®). For statistical analysis, a non-parametric test was used, with adopted p≤0.05. To create a prediction model, four sets of neural networks were constructed for the following output variables: remission/activity, presence or not of ADA, therapeutic level according to ELISA, and therapeutic level according to the lateral flow test. The neural networks and ROC curves were designed using the Keras package in Python software. The study was approved by the Research Ethics Committee. Results No differences were observed in the IFX level when comparing the CDA and CDR groups in both tests (p&amp;gt; 0.05). There was no statistical difference in IFX levels according to the use of immunosuppressants (IMS) (p&amp;gt;0.05). ADA levels &amp;gt; 5AU/mL were detected in only 11 (14.6%) patients. All patients with positive ADA had infratherapeutic IFX levels in both tests, and 72.7% were on combination therapy with IMS. Of the 4 neural networks developed, two, whose output variables were “remission/activity” and “presence or not of ADA,” showed excellent performance, with AUC ranging from 82% to 92% and 100%, respectively. Conclusion The introduction of IFX monitoring may allow more individualized and precise therapeutic management. Regarding the performance characteristics of the neural networks, an AUC &amp;gt;80% was evident in two of them. Through clinical and non-invasive laboratory variables, disease activity was determined. Furthermore, the finding of combinations of variables that determine the ADA level, and at the same time not having demonstrated good models for IFX serum level measurement, means that the latter continues to be necessary for clinical practice. Otherwise, ADA levels, which indicate immunogenicity, can be predicted by non-invasive clinical variables.

P473 Comparison of clinical performance of fecal calprotectin of laboratory methods with lateral flow based POC and home tests

Abstract Background To confirm an IBD diagnosis and manage IBD patients, endoscopy is the gold standard to assess mucosal inflammation. Fecal calprotectin (fCAL) is a reliable biomarker of intestinal inflammation that highly correlates with endoscopic and histological findings. Fecal calprotectin testing is recommended in most IBD guidelines for diagnosis and disease course evaluation. Different assay technologies exist that need to measure fecal calprotectin comparably. These range from classic enzyme linked immunosorbent assays (ELISA), particle enhance turbidimetric immuno assays (PETIA), and rapid lateral flow assays (LFIA). LFIA[AL1] [RC2] s can be read by conventional tabletop readers or by everyday smartphone applications using the phone’s camera to acquire an image, detect the test cassette and calculate a quantitative result. As there is no international standard to date, fecal calprotectin assay manufacturers rely on their own internal calprotectin standardization. This study compared four different assays measuring the same clinical samples. Methods The 128 raw stool samples that were analyzed in this study were obtained from patients that presented with signs and symptoms suggesting intestinal inflammation and underwent endoscopic evaluation to establish or exclude an IBD diagnosis. Samples were extracted with the BÜHLMANN CALEX® Cap stool extraction device. Each extract was then measured on the BÜHLMANN fCAL® ELISA, fCAL® turbo (PETIA), Quantum Blue® fCAL extended lateral flow assay and smartphone based IBDoc® fCAL home test. For the home test, two phones, iPhone 11 and Samsung Galaxy S7, were used to measure the lateral flow test cassettes. Each sample was measured one time on each assay and Receiver Operating Characteristic (ROC) curve analysis was performed and total agreement between each method was calculated. Results ROC curves were generated to assess the ability of each assay to differentiate between IBS and IBD with area under the curve (AUC) values ranging from 0.827 (Samsung Galaxy S7 to 0.835 (fCAL turbo). There was no significant difference between the methods. Commonly used cut-offs in the assessment of IBD patients are 100 and 250 µg/g, respectively. Positive and negative percent agreement (PPA/NPA) between the smartphone-based home test and the laboratory assays was calculated. The PPA was above 90% for all methods while the NPA was above 88% for all methods. Conclusion The results presented here show that the four BÜHLMANN assays measure fecal calprotectin extremely comparably and show an excellent clinical performance. This allows for the use of the methods interchangeably, depending on the needs of the patients and their care team.