[Evaluation of an algorithm based on quantitative assays of glomerular parameters (albuminuria and urinary IgG) for proteinuria typing]. / Évaluation d'un algorithme basé sur des dosages quantitatifs de paramètres glomérulaires (albuminurie et IgG urinaires) afin de typer une protéinurie.

The first orientation test for proteinuria typing is electrophoresis. However, this technique has several drawbacks, such as delayed turnaround time and subjective readings. Some laboratories therefore use quantitative assays of glomerular markers combined with tubular markers. However, the cost of reagents and the instability of certain markers are significant drawbacks for some peripheral laboratories. The aim of this study is to evaluate the implementation of an algorithm based on parameters that can be used by all laboratories for proteinuria typing within a timeframe compatible with the urgency of the situation. Albuminuria and urinary IgG were determined on 161 urines. ROC curves were produced, using urine electrophoresis read by an expert center as the reference method. The decision thresholds used are: glomerular proteinuria is defined by a Albumin+IgGproteinsratio greater than 75.4% (100% specificity), and tubular or overload proteinuria is defined by by a Albuminproteinsratio less than 37.3% (100% sensitivity). Agreement between the results of the algorithm selected and the reference method used in our study was 88 %, with a kappa value of 0.807 (95% CI [0.729 to 0.885]). The algorithm's performance suggests that it can find its place in the diagnostic strategy for clinically significant proteinuria, despite its limited indications. It is up to each biologist to assess the value of this algorithm in relation to the recruitment, habits and needs of clinicians.

[Evaluation of the performance of Cepheid® GeneXpert MRSA/SA Blood Culture assay and results' extrapolation to coagulase-negative staphylococci]. / Évaluation des performances du test GeneXpert MRSA/SA Blood Culture de Cepheid® et extrapolation des résultats aux staphylocoques à coagulase négative.

In hospitalized patients, staphylococcal blood infection is common and mortality is high. Rapid diagnosis using molecular assay aims to identify the presence of Staphylococcus aureus and its resistance to methicillin as soon as the blood culture is positive. We evaluate performance of GeneXpert MRSA/SA Blood Culture assay (Cepheid®) before and after interpretation of the positivity levels of the various probes estimated by the Cycle threshold (Ct), as well as its contribution to the characterization of coagulase-negative staphylococci blood cultures not offered by the supplier. The study involved 145 samples with gram-positive cocci bacteremias. Ct analysis of the different probes revealed a few positive results with very high Ct values distants from the mean. The reclassification of these results as negative improves the specificity of the probes (spa: 100% vs. 96,8% and mec 100% vs. 91,9%) without degrading the sensitivity (spa: 98,1% vs. 100% and mec 98,6% vs. 98,6%). Then, based on an algorithm integrating the amplification results of each target, we extrapolated the results to the coagulase-negative staphylococci. In the end, reclassifying probes with extreme Ct values as negative and using the algorithm for coagulase-negative staphylococci resulted in a 97,9% (142/145) agreement between the molecular assay conclusion and conventional culture.

A rapid and inexpensive protocol to screen for third generation cephalosporin-resistant and non-fermenting Gram-negative rods directly in positive blood cultures.

Third generation cephalosporins are frequently used in the first-line treatment of Gram-negative rod (GNR) bacteremia but are unsuitable in the case of extended-spectrum-beta-lactamase-producing Enterobacterales (ESBL-E) or non-fermenting GNR infections. The aim of this study was to develop and evaluate a simple and rapid two-test protocol involving oxidase and ß-Lacta tests performed directly on positive blood culture broth as a preliminary screen for non-fermenting or third generation cephalosporins-resistant GNR. The diagnostic performance of this approach was evaluated on 294 bottles for the oxidase test and 267 bottles for the ß-Lacta Test. The sensitivity and specificity of the oxidase test were respectively 93.1% and 100%, and the sensitivity of the ß-Lacta Test for ESBL-E was 100% and the specificity 99.5%. This simple protocol, which can be implemented in all laboratories and performed in only 20 min, may be a valuable tool to optimize first-line antibiotic therapy for bacteremia.

Specific exposure of ICU staff to SARS-CoV-2 seropositivity: a wide seroprevalence study in a French city-center hospital.

BACKGROUND: Most hospital organizations have had to face the burden of managing the ongoing COVID-19 outbreak. One of the challenges in overcoming the influx of COVID-19 patients is controlling patient-to-staff transmission. Measuring the specific extent of ICU caregiver exposure to the virus and identifying the associated risk factors are, therefore, critical issues. We prospectively studied SARS-CoV-2 seroprevalence in the staff of a hospital in Lyon, France, several weeks after a first epidemic wave. Risk factors for the presence of SARS-CoV-2 antibodies were identified using a questionnaire survey. RESULTS: The overall seroprevalence was 9% (87/971 subjects). Greater exposure was associated with higher seroprevalence, with a rate of 3.2% [95% CI 1.1-5.2%] among non-healthcare staff, 11.3% [8.9-13.7%] among all healthcare staff, and 16.3% [12.3-20.2%] among healthcare staff in COVID-19 units. The seroprevalence was dramatically lower (3.7% [1.0-6.7%]) in the COVID-19 ICU. Risk factors for seropositivity were contact with a COVID-19-confirmed household (odds ratio (OR), 3.7 [1.8-7.4]), working in a COVID-19 unit (OR, 3.5 [2.2-5.7], and contact with a confirmed COVID-19 coworker (OR, 1.9 [1.2-3.1]). Conversely, working in the COVID-19-ICU was negatively associated with seropositivity (OR, 0.33 [0.15-0.73]). CONCLUSIONS: In this hospital, SARS-CoV-2 seroprevalence was higher among staff than in the general population. Seropositivity rates were particularly high for staff in contact with COVID-19 patients, especially those in the emergency department and in the COVID-19 unit, but were much lower in ICU staff. Clinical trial registration NCT04422977.

Performance Characteristics of the Vidas SARS-CoV-2 IgM and IgG Serological Assays.

The COVID-19 pandemic, caused by the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), continues to spread worldwide. Serological testing for SARS-CoV-2-specific antibodies plays an important role in understanding and controlling the pandemic, notably through epidemiological surveillance. Well-validated and highly specific SARS-CoV-2 serological assays are urgently needed. We describe here the analytical and clinical performance of Vidas SARS-CoV-2 IgM and Vidas SARS-CoV-2 IgG, two CE-marked, emergency use authorization (EUA)-authorized, automated, qualitative assays for the detection of SARS-CoV-2-specific IgM and IgG, respectively. Both assays showed high within-run and within-laboratory precision (coefficients of variation < 11.0%) and very low cross-reactivity toward sera of patients with a past common coronavirus or respiratory virus infection. Clinical specificity determined on up to 989 prepandemic healthy donors was ≥99% with a narrow 95% confidence interval for both IgM and IgG assays. Clinical sensitivity was determined on up to 232 samples from 130 reverse transcriptase PCR (RT-PCR)-confirmed SARS-CoV-2 patients. The positive percent agreement (PPA) with SARS-CoV-2 PCR reached 100% at ≥16 days (Vidas SARS-CoV-2 IgM) and ≥32 days (Vidas SARS-CoV-2 IgG) of symptom onset. Combined IgM/IgG test results improved the PPA compared to each test alone. SARS-CoV-2 IgG seroconversion followed closely that of SARS-CoV-2 IgM and remained stable over time, while SARS-CoV-2 IgM levels rapidly declined. Interestingly, SARS-CoV-2-specific IgM and IgG responses were significantly higher in COVID-19 hospitalized versus nonhospitalized patients. Altogether, the Vidas SARS-CoV-2 IgM and IgG assays are highly specific and sensitive serological tests suitable for the reliable detection of past acute SARS-CoV-2 infections.

Impact of age and renal function on usefulness of NT-proBNP to diagnose heart failure
.

AIMS: NT-proBNP is a useful biomarker for heart failure (HF) diagnosis. We aimed to determine NT-proBNP's ability to diagnose HF by age and renal function. MATERIALS AND METHODS: We analyzed 3,699 consecutive and unique adults admitted for dyspnea at the Emergency Unit of St. Joseph St. Luc Hospital, Lyon, France, from December 1, 2012 to June 30, 2016, who had concomitant measurement of NT-proBNP and serum creatinine. We excluded patients with acute coronary syndrome and dialysis patients. Receiving operating characteristic (ROC) analysis assessed ability and cut-off points of NT-proBNP to diagnose HF. RESULTS: Mean age was 79.1 ± 13.0 years. Mean estimated glomerular filtration rate (eGFR, CKD EPI formula) was 64 ± 26 mL/min/1.73m2. The ROC area under the curve (AUC) was 0.813 on average, optimal NT-proBNP cut-off point was 1,896 ng/L. AUC decreased (0.882, 0.813, 0.767) by age class (18 - 69, 70 - 84, 85+ years, respectively), and optimal cut-off points increased (1,041, 1,902, 2,321 ng/L). AUC decreased (0.881, 0.830, 0.783, 0.781, 0.705) by eGFR class (≥ 90, 60 - 89, 45 - 59, 30 - 44, < 30 mL/min/1.73m2), and cut-off points increased (757, 1,362, 2,283, 4,108, 7,288 ng/L). The lowest value of cut-off points associated with highest sensitivity and specificity was detected in young patients with eGFR ≥ 90 (597 ng/L) while the worst value was found in age 85+ patients with eGFR < 30 (7,288 ng/L). AUC decreased below 0.8 in age 70+ patients with eGFR < 45 mL/min/1.73m2;. CONCLUSION: The ability of NT-proBNP to diagnose HF decreased strongly with age and renal function. NT-proBNP's usefulness in diagnosing HF in age 70+ patients with eGFR < 45 mL/min/1.73m2 remains uncertain.

Establishment of indicators to improve clinical analysis prescribing patterns.

An appropriate medical analysis prescribing pattern is part of the medical biologists' work as it enhances patient care and reduces costs. In this study, we use four indicators to aim to evaluate the relevance of clinical analysis prescription. We confronted clinical data and medical analysis prescribed in June 2013 in the emergency department (ED) and found that prescriptions were justified in 73% of TnT prescriptions but only in less than 50% of NTproBNP (27%), APTT (37%), PR (33%) or INR (23%) prescriptions. We noted that staff training, an improved communication between biologists and clinical physicians, and better computing devices, have led to better prescribing patterns. From 2013 to 2015, inappropriate associations of PR and APTT have significantly declined in the intensive care unit. At the same period, amounts of medical analysis as well as department spendings decreased in the ED. The use of indicators is essential to evaluate and monitor the relevance of medical analysis patterns. In this work, we propose to combine a global indicator (cost/day of hospitalization or medical analysis amount/month) with a regular follow up on inadequate prescribed analysis associations. These indicators will need to be adjusted to each clinical department.

A major procalcitonin elevation without sepsis in a metastatic small cell lung carcinoma.

We report the case of a 54-year-old man with metastatic pulmonary neuroendocrine tumor associated with major procalcitonin (PCT) elevation without sepsis. Three lines of antibiotic therapies were successively introduced but had no positive effect on PCT kinetic and disease progression. Under palliative care, increasing of PCT level was constant during the hospitalization, along with major asthenia and pain and metastatic progression. PCT is an excellent biological marker of bacterial infection, both sensitive and specific. Nevertheless, we highlight here the existence of a frequent association between neuroendocrine tumors and elevation of PCT in the absence of sepsis.

What is the acceptable hemolysis index for the measurements of plasma potassium, LDH and AST?

Hemolysis is a cause of variability in test results for plasma potassium, LDH and AST and is a non-negligible part of measurement uncertainty. However, allowable levels of hemolysis provided by reagent suppliers take neither analytical variability (trueness and precision) nor the measurand into account. Using a calibration range of hemolysis, we measured the plasma concentrations of potassium, LDH and AST, and hemolysis indices with a Cobas C501 analyzer (Roche Diagnostics(®), Meylan, France). Based on the allowable total error (according to Ricós et al.) and the expanded measurement uncertainty equation we calculated the maximum allowable bias for two concentrations of each measurand. Finally, we determined the allowable hemolysis indices for all three measurands. We observed a linear relationship between the observed increases of concentration and hemolysis indices. The LDH measurement was the most sensitive to hemolysis, followed by AST and potassium measurements. The determination of the allowable hemolysis index depends on the targeted measurand, its concentration and the chosen level of requirement of allowable total error.

Clinical performance of the carbohydrate-deficient transferrin (CDT) assay by the Sebia Capillarys2 system in case of cirrhosis. Interest of the Bio-Rad %CDT by HPLC test and Siemens N-Latex CDT kit as putative confirmatory methods.

BACKGROUND: The CDT assay used to detect chronic alcohol abuse is difficult with cirrhotic patients. This article describes the performances of several CDT assays in case of cirrhosis. The CDT-Capillarys assay by capillary zone electrophoresis was used for initial testing. Two additional methods were tested as putative confirmatory methods. METHODS: 110 patients with known hepatic status had their CDT measured by the Capillarys2 or alternative methods. Self-reported alcohol intake was used to assess the performances of CDT assays. RESULTS: Capillarys2 performance was lower in case of cirrhosis, many electropherograms displaying various abnormalities. We used the proper separation of the di- and tri-sialotransferrin peaks to select reliable profiles. This selection led to the classification of cirrhotic and non-cirrhotic patients in abusers and abstainers with similar performances. However, no interpretation was available for 54% of the cirrhotic patients and neither the BioRad %CDT by HPLC test, nor the Siemens N-Latex CDT kit was suitable as confirmatory methods for these samples. CONCLUSIONS: An attentive profile examination is required for the validation of Capillarys CDT results of cirrhotic patients. Reliability is significantly improved when samples with an improper separation are excluded. To date, no commercial test can confirm the excluded samples.