Bacterial ligands as flexible and sensitive detectors in rapid tests for antibodies to SARS-CoV-2.

Lateral flow immunoassay (LFIA) is widely employed as point-of-care tests (POCT) for the diagnosis of infectious diseases. The accuracy of LFIA largely depends on the quality of the immunoreagents used. Typical LFIAs to reveal the immune response to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) employ anti-human immunoglobulin (hIG) antibodies and recombinant viral antigens, which usually are unstable and poorly soluble. Broad selective bacterial proteins, such as Staphylococcal protein A (SpA) and Streptococcal protein G (SpG) can be considered alternatives to anti-hIG to increase versatility and sensitivity of serological LFIAs because of their high binding capacity, interspecies reactivity, and robustness. We developed two colorimetric LFA devices including SpA and SpG linked to gold nanoparticles (GNP) as detectors and explored the use of a specific, stable, and soluble immunodominant fraction of the nucleocapsid protein from SARS-CoV-2 as the capturing agent. The optimal amount of SpA-GNP and SpG-GNP conjugates and the protein-to-GNP ratios were defined through a full factorial experimental design to maximize the diagnostic sensitivity of the LFIAs. The new LFA devices were applied to analyze 105 human serum samples (69 positive and 36 negatives according to reference molecular diagnostic methods). The results showed higher sensitivity (89.9%, 95% CI 82.7-97.0) and selectivity (91.7%, 82.6-100) for the SpA-based compared to the SpG-based LFA. In addition, 18 serum samples from cats and dogs living with COVID-19 patients were analyzed and 14 showed detectable levels of anti-SARS-CoV-2 antibodies, thus illustrating the flexibility of the SpA- and SpG-based LFAs.

Risk factors of SARS-CoV-2 seroprevalence among hospital employees in Italy: a single-centre study.

BACKGROUND: The SARS-CoV-2 outbreak early in 2020 overwhelmed the Italian national health system, and hospitals were considered places at high risk of spreading the infection. We explored specific antibody seroprevalence of all employees at a single hospital in the epicentre of the outbreak, to identify areas of risk in nosocomial setting and to evaluate the usefulness of antibody testing. AIMS: Aim of this study was to explore SARS-CoV-2 seroprevalence in a single hospital workers cohort. METHODS: All hospital workers were invited to fill in a questionnaire and undergo a blood test for SARS-CoV-2 IgG, using two commercial tests (DiaSorin and Abbott). Seropositivity was determined overall and according to demographic and occupations characteristics, for both tests singly and combined. RESULTS: The study enrolled 1562 hospital workers (95% of the eligible population). Overall, 153 (9.8%) participants were positive for SARS-CoV-2 IgG on DiaSorin test, and 150 (9.6%) were positive on Abbott test; both tests were positive in 123 (7.9%) cases and at least one was positive in 180 (11.5%) cases. Factors associated with SARS-CoV-2 seropositivity included: being a smoker, working in emergency or medicine departments, being a healthcare practitioner, self-reporting a relative with COVID-19 or symptoms suggestive of COVID-19, and having undergone a nasopharyngeal swab test. The tests were accurate in discriminating infected cases, with an area under the receiver operating characteristic curve of 0.867 using manufacturer-suggested cut-offs and 0.929 using optimised cut-offs. For discriminating symptomatic subjects, this value was 0.915 using optimised cut-offs. CONCLUSIONS: Seroprevalence for SARS-CoV-2 in this population of hospital workers was overall about 10%, with an excess prevalence in roles and departments associated with contacts with COVID-19 patients.

Harmonization protocols for TSH immunoassays: a multicenter study in Italy.

BACKGROUND: Systematic difference between thyroid-stimulating hormone (TSH) immunoassays may produce misleading interpretation when samples of the same patients are measured with different methods. The study aims were to evaluate whether systematic differences are present among TSH immunoassays, and whether it is possible to obtain a better harmonization among TSH methods using results obtained in external quality assessment (EQA) schemes. METHODS: Seven Italian clinical laboratories measured TSH in 745 serum samples of healthy subjects and patients with thyroid disorders. These samples were also re-measured by two reference laboratories of the study with the six TSH immunoassays most popular in Italy after 2 months of storage at -80 °C. Moreover, these data were compared to 53,823 TSH measurements, obtained by laboratories participant to 2012-2015 EQA annual cycles in 72 quality control samples (TSH concentrations from about 0.1 mIU/L to 18.0 mIU/L). TSH concentrations were recalibrated using a mathematical approach based on the principal component analysis (PCA). RESULTS: Systematic differences were found between the most popular commercially available TSH immunoassays. TSH concentrations measured by the clinical laboratories were very closely correlated to those measured with the same method by reference laboratories after 2 months of storage at -80 °C. After recalibration using the PCA approach the variation of TSH values significantly decreased from a median pre-calibration value of 13.53% (10.79%-16.53%) to 9.63% (6.90%-13.21%) after recalibration. CONCLUSIONS: Our data suggest that EQA schemes are useful to improve harmonization among TSH immunoassays and also to produce some mathematical formulas, which can be used by clinicians to better compare TSH values measured with different methods.

A semi-quantitative visual lateral flow immunoassay for SARS-CoV-2 antibody detection for the follow-up of immune response to vaccination or recovery.

The lateral flow immunoassay (LFIA) technique is largely employed for the point-of-care detection of antibodies especially for revealing the immune response in serum. Visual LFIAs usually provide the qualitative yes/no detection of antibodies, while quantification requires some equipment, making the assay more expensive and complicated. To achieve visual semi-quantification, the alignment of several lines (made of the same antigen) along a LFIA strip has been proposed. The numbering of the reacting lines has been used to correlate with the quantity of some biomarkers in serum. Here, we designed the first semiquantitative LFIA for detecting antibodies and applied it to classify the immune response to SARS-CoV-2 raised by vaccination or natural infection. We used a recombinant spike receptor-binding domain (RBD) as the specific capture reagent to draw two test lines. The detection reagent was selected among three possible ligands that are able to bind to anti-spike human antibodies: the same RBD, staphylococcal protein A, and anti-human immunoglobulin G antibodies. The most convenient detector, adsorbed on gold nanoparticles, was chosen based on the highest correlation with an antibody titre of 171 human sera, measured by a reference serological method, and was the RBD (Spearman's rho = 0.84). Incorporated into the semiquantitative LFIA, it confirmed the ability to discriminate high- and low-titre samples and to classify them into two classes (Dunn's test, P < 0.05). The proposed approach enabled the semiquantification of the immune response to SARS-CoV-2 by the unaided eye observation, thus overcoming the requirement of costly and complicated equipment, and represents a general strategy for the development of semiquantitative serological LFIAs.

Gluten-free diet affects fecal small non-coding RNA profiles and microbiome composition in celiac disease supporting a host-gut microbiota crosstalk.

Current treatment for celiac disease (CD) is adhering to a gluten-free diet (GFD), although its long-term molecular effects are still undescribed. New molecular features detectable in stool may improve and facilitate noninvasive clinical management of CD. For this purpose, fecal small non-coding RNAs (sncRNAs) and gut microbiome profiles were concomitantly explored in CD subjects in relation to strict (or not) GFD adherence over time. In this observational study, we performed small RNA and shotgun metagenomic sequencing in stool from 63 treated CD (tCD) and 3 untreated subjects as well as 66 sex- and age-matched healthy controls. tCD included 51 individuals on strict GFD and with negative transglutaminase (TG) serology (tCD-TG-) and 12 symptomatic with not strict/short-time of GFD adherence and positive TG serology (tCD-TG+). Samples from additional 40 healthy adult individuals and a cohort of 19 untreated pediatric CD subjects and 19 sex/age matched controls were analyzed to further test the outcomes. Several miRNA and microbial profiles were altered in tCD subjects (adj. p < .05). Findings were validated in the external group of adult controls. In tCD-TG-, GFD duration correlated with five miRNA levels (p < .05): for miR-4533-3p and miR-2681-3p, the longer the diet adherence, the less the expression differed from controls. tCD-TG+ and untreated pediatric CD patients showed a similar miRNA dysregulation. Immune-response, trans-membrane transport and cell death pathways were enriched in targets of identified miRNAs. Bifidobacterium longum, Ruminococcus bicirculans, and Haemophilus parainfluenzae abundances shifted (adj. p < .05) with a progressive reduction of denitrification pathways with GFD length. Integrative analysis highlighted 121 miRNA-bacterial relationships (adj. p < .05). Specific molecular patterns in stool characterize CD subjects, reflecting either the long-term GFD effects or the gut inflammatory status, in case of a not strict/short-time adherence. Our findings suggest novel host-microbial interplays and could help the discovery of biomarkers for GFD monitoring over time.

A multi-target lateral flow immunoassay enabling the specific and sensitive detection of total antibodies to SARS COV-2.

A rapid test for detecting total immunoglobulins directed towards the nucleocapsid protein (N) of severe acute syndrome coronavirus 2 (SARS CoV-2) was developed, based on a multi-target lateral flow immunoassay comprising two test lines. Both test lines bound to several classes of immunoglobulins (G, M, and A). Specific anti-SARS immunoglobulins were revealed by a colorimetric probe formed by N and gold nanoparticles. Targeting the total antibodies response to infection enabled achieving 100% diagnostic specificity (95.75-100, C.I. 95%, n = 85 healthy and with other infections individuals) and 94.6% sensitivity (84.9-98.9, C.I. 95%, n = 62 SARS CoV-2 infected subjects) as early as 7 days post confirmation of positivity. Agreeing results with a reference serological ELISA were achieved, except for the earlier detection capability of the rapid test. Follow up of the three seroconverting patients endorsed the hypothesis of the random rise of the different immunoglobulins and strengthened the 'total antibodies' approach for the trustworthy detection of serological response to SARS CoV-2 infection.

Predictivity of early and late assessment for post-surgical recurrence of Crohn's disease: Data from a single-center retrospective series.

BACKGROUND AND AIMS: Post-surgical recurrence of Crohn's disease (CD) after ileocolonic resection is common. Early identification of features associated with recurrence is a standard procedure of postoperative management, but the prognostic role of such features when detected at later time points is unclear. We compared the predictivity for Crohn's disease recurrence of common clinical-instrumental variables when assessed early (<12 months) or late (>36 months) after surgery. METHODS: This retrospective study considered CD patients who had ileocolonic resection and were followed for a median of 7.6 years. Clinical characteristics, post-surgical therapy, endoscopy recurrence (Rutgeerts' score ≥i2) and ultrasound features were compared between subgroups who had a early or late post-surgical assessment. Univariate and multivariate analyses were done to identify variables associated with recurrence (clinical and surgical). RESULTS: Of 201 patients, 70 (32%) had a early and 39 (19%) had a late post-surgical assessment. The Early and Late subgroups had similar clinical characteristics. Overall, clinical relapse was observed in 131 patients (66%), surgical relapse in 31 (16%), endoscopic recurrence in 149 (75%) and ultrasonographic recurrence in 132 (66%), without significant differences in frequencies between subgroups. By Cox proportional hazard regression, endoscopic recurrence was a significant predictor of clinical recurrence overall (HR=2.31, P = 0.002) and in the Early (HR=3.85, P = 0.002) but not Late subgroup. DISCUSSION: The most informative postoperative CD assessment is the one done within the first year of surgery. Later endoscopic evaluations have no prognostic value and should be done only for clinical needs or for research purposes.

Influence of hemolysis, icterus and lipemia on coagulation tests as performed on Cobas t511 new analyzer.

: In the coagulation laboratory, spurious hemolysis, icterus and lipemia (HIL) in test samples represent by far the leading diagnostic prenalytical challenges. The aim of this study was to assess the performance of the preanalytical module on the new hemostasis analyser Cobas Roche t511. We assessed the influence of HIL on prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (Fib), antithrombin and D-dimer on plasma pools aliquots with different interference degrees. Moreover, we evaluated spontaneous hemolysis by comparing results on 50 paired samples (hemolysed versus nonhemolysed). Spurious hemolysis interference studies highlight the absence of a clinical significant impact on PT, APTT and antithrombin test results at all hemoglobin concentration investigated. For Fib and D-dimer assays a clinically significant difference was observed in the most hemolysed aliquot for Fib and in the two most hemolysed aliquots for D-dimer. Spontaneous hemolysis interference studies showed no clinical significant differences for PT and antithrombin assays, instead for APTT, Fib and D-dimer we found significant statistical and clinical differences between hemolysed and non hemolysed specimens. Bilirubin interference studies and lipemic samples interference studies enable us to confirm that the differences in the results obtained between the different aliquots and reference pool is not clinically significant for all assays. HIL check preanalytical module of Cobas Roche t511 analyzer displaied excellent performance for routine use in clinical laboratories. Regardless of analytical considerations, the type of interference encountered with spurious HIL is substantially different and requires different approaches.

Switching from infliximab originator to a first biosimilar is safe and effective. Results of a case-control study with drug levels and antibodies evaluation.

BACKGROUND: Inflammatory bowel disease is treated with anti-TNF agents such as infliximab and its biosimilars, but use of biosimilars is limited due to perceived risks of adverse events. AIM: To explore safety and effectiveness of switching from the infliximab originator to a first biosimilar. PATIENTS AND METHODS: Clinical and biological outcomes were compared between 53 patients who switched from the infliximab originator to the biosimilar CT-P13 (Switched group) and 13 patients treated with CT-P13 from the beginning (Naïve group). Infliximab trough levels and antidrug antibodies were measured. RESULTS: At enrolment, patients in the Switched group had a longer median duration of infliximab treatment than Naïve (4.0 vs. 0.6 years, p < 0.0001) but similar proportions of patients were in remission (77% and 62%, respectively). Infliximab discontinuation due to adverse events or loss of efficacy was less common in the Switched (26%) than Naïve group (62%, p = 0.017). Variables independently associated with time to discontinuation were disease activity (p < 0.0001) and immunomodulating treatment (p = 0.019) at enrolment. Trough levels and antidrug antibodies were similar between groups during observation. CONCLUSION: This study confirms that switching from infliximab originator to a first biosimilar is safe and effective. Patients at highest risk of losing treatment efficacy are those with active disease, irrespective of the therapeutic switch.

Evaluation of 99th percentile and reference change values of the hs-cTnI method using ADVIA Centaur XPT platform: A multicenter study.

BACKGROUND: According to quality specifications required by international guidelines, the evaluation of the 99th URL value is a very difficult task that is usually beyond the capacity of a single laboratory. The aims of this article are to report and discuss the results of a multicenter study concerning the evaluation of the 99th percentile URL and reference change (RCV) of the ADVIA Centaur High-Sensitivity Troponin I (TNIH), recently distributed to the Italian clinical laboratories. MATERIALS AND METHODS: The reference population evaluated with ADVIA XPT method for the calculation of cTnI reference distribution parameters consisted of 1325 healthy adults subjects (age range from 18 to 86 years), including 653 women (mean age 50.7 years, SD 14.5 years) and 672 men (mean age 50.9 years, SD 13.8 years), well matched for both age (P = .8112) and sex (F/M = 0.97). RESULTS: cTnI distribution values of reference population was highly skewed, while log-transformed cTnI values roughly approximated a log-normal distribution. Men have higher cTnI values than women throughout all the adult lifespan. Moreover, the subjects with age ≤ 55 years had significantly lower cTnI values than those with age > 55 years (p < .0001). Of note, 62% of women and 77% of men had equal or higher than cTnI values than the LoD value of the method (i.e., 2.2 ng/L). CONCLUSIONS: The results of the present study demonstrate that the ADVIA Centaur High-Sensitivity Troponin I using the XPT automated platform fits both the criteria and quality specifications required by the most recent international guidelines for high-sensitivity methods for cTnI assay.

Evaluation of 99th percentile and reference change values of a high-sensitivity cTnI method: A multicenter study.

BACKGROUND: The Italian Society of Clinical Biochemistry (SIBioC) and the Italian Section of the European Ligand Assay Society (ELAS) have recently promoted a multicenter study (Italian hs-cTnI Study) with the aim to accurately evaluate analytical performances and reference values of the most popular cTnI methods commercially available in Italy. The aim of this article is to report the results of the Italian hs-cTnI Study concerning the evaluation of the 99th percentile URL and reference change (RCV) values around the 99th URL of the Access cTnI method. MATERIALS AND METHODS: Heparinized plasma samples were collected from 1306 healthy adult volunteers by 8 Italian clinical centers. Every center collected from 50 to 150 plasma samples from healthy adult subjects. All volunteers denied the presence of chronic or acute diseases and had normal values of routine laboratory tests (including creatinine, electrolytes, glucose and blood counts). An older cohort of 457 adult subjects (mean age 63.0 years; SD 8.1 years, minimum 47 years, maximum 86 years) underwent also ECG and cardiac imaging analysis in order to exclude the presence of asymptomatic cardiac disease. RESULTS AND CONCLUSIONS: The results of the present study confirm that the Access hsTnI method using the DxI platform satisfies the two criteria required by international guidelines for high-sensitivity methods for cTn assay. Furthermore, the results of this study confirm that the calculation of the 99th percentile URL values are greatly affected not only by age and sex of the reference population, but also by the statistical approach used for calculation of cTnI distribution parameters.

Head-to-head comparison of plasma cTnI concentration values measured with three high-sensitivity methods in a large Italian population of healthy volunteers and patients admitted to emergency department with acute coronary syndrome: A multi-center study.

BACKGROUND: The study aim is to compare cTnI values measured with three high-sensitivity (hs) methods in apparently healthy volunteers and patients admitted to emergency department (ED) with acute coronary syndrome enrolled in a large multicentre study. METHODS: Heparinized plasma samples were collected from 1511 apparently healthy subjects from 8 Italian clinical institutions (mean age: 51.5 years, SD: 14.1 years, range: 18-65 years, F/M ratio:0.95). All volunteers denied chronic or acute diseases and had normal values of routine laboratory tests. Moreover, 1322 heparinized plasma sample were also collected by 9 Italian clinical institutions from patients admitted to ED with clinical symptoms typical of acute coronary syndrome. The reference study laboratory assayed all plasma samples with three hs-methods: Architect hs-cTnI, Access hs-cTnI and ADVIA Centaur XPT methods. Principal Component Analysis (PCA) was also used to analyze the between-method differences among hs-cTnI assays. RESULTS: On average, a between-method difference of 31.2% CV was found among the results of hs-cTnI immunoassays. ADVIA Centaur XPT method measured higher cTnI values than Architect and Access methods. Moreover, 99th percentile URL values depended not only on age and sex of reference population, but also on the statistical approach used for calculation (robust non-parametric vs bootstrap). CONCLUSIONS: Due to differences in concentrations and reference values, clinicians should be advised that plasma samples of the same patient should be measured for cTnI assay in the same laboratory. Specific clinical studies are needed to establish the most appropriate statistical approach to calculate the 99th percentile URL values for hs-cTnI methods.

[Metabolic effects of Cholecalciferol supplementation in kidney stone formers with vitamin D deficiency].

INTRODUCTION: In this paper we investigated whether cholecalciferol supplementation, prescribed to treat vitamin D deficiency in patients with nephrolithiasis, increased the risk of stone recurrence. METHODS: Calcium excretion and urine supersaturation with calcium oxalate (ßCaOx) and brushite (ßbsh) were evaluated in 33 kidney stone formers (aged 56±17; 12 males), both before and after therapy with cholecalciferol, prescribed as oral bolus of 100.000-200.000 UI, followed by maintenance doses, repeated every week (5.000-10.000 UI) or month (25.000-50.000 UI). During the study, patients followed a dietary regimen which included a daily calcium intake of about 800-1000 mg. RESULTS: Urinary nitrogen, sodium and ash-acid excretion did not significantly change during the study. After cholecalciferol supplementation, the main results were as follows: both serum calcium and phosphate did not vary significantly; 25(OH)VitD3 increased from 11,8±5,5 to 40,2±12,2 ng/mL (p<0,01); 1,25(OH) 2 VitD3 increased from 41,6±17,6 to 54,0±16,0 pg/mL (p<0,01); PTH decreased from 75,0±27,2 to 56,7±21,1 pg/mL (p<0,01); daily urinary calcium increased from 2,7±1,5 to 3,6±1,6 mg/Kg b.w. (p<0,01), whereas fasting urinary calcium did not change significantly. After therapy, ßbsh increased from 0,9±0,7 to 1,3±1,3 (p=0,02) and ßCaOx did not vary significantly. Before cholecalciferol supplementation, 6/33 patients (18.2%) were hypercalciuric, whereas 13/33 patients (39,4%) showed hypercalciuria after supplementation (pX²=0,03). CONCLUSIONS: Cholecalciferol supplementation for vitamin D deficiency may increase both urinary calcium and urine supersaturation in stone formers. If vitamin D supplements are needed in these patients, a careful monitoring of urine metabolic profile is warranted, in order to customize the metaphylaxis accordingly (hydration, potassium citrate, thiazides).

Clinical relevance and inter-test reliability of anti-infliximab antibodies and infliximab trough levels in patients with inflammatory bowel disease.

BACKGROUND: Treatment with infliximab is a common option for inflammatory bowel disease (IBD) patients. Therapeutic drug monitoring could improve treatment management. AIMS: To test inter-test reliability of two commercially available diagnostic kits for infliximab trough levels and infliximab antibodies, and their association with treatment outcomes. METHODS: 86 IBD outpatients on infliximab maintenance treatment were enrolled in a prospective cross-sectional study, 115 samples were available for inter-test reliability. RESULTS: Inter-test agreement was good both for trough levels (concordance correlation coefficient 0.78, weighted κ 0.60, Sperman's ρ 0.937) and for infliximab antibodies (weighted κ 0.79) measurement, when comparing Promonitor and ImmunDiagnostik kits. According to manufacturers' cut-off values, trough levels were classified as undetectable (17%), low (21%) or in range (63%). The only significant associations were: mucosal healing (p=0.026; OR 6.50), infliximab antibody status (p=0.0015; OR 0.031) and adverse events (p=0.009; OR 0.115). Higher trough levels were observed among patients on concomitant steroid/immunosuppressive therapy and among patients with dose-intensification. Infliximab antibodies were significantly associated to treatment-related adverse events (p=0.0003, OR 30.42), and to lower trough levels, but not to other clinical variables. CONCLUSION: The two tests performed equally well. Infliximab antibodies were associated to adverse events, while trough levels were not associated to treatment outcomes.