Assay dependence of long-term kinetics of SARS-CoV-2 antibodies.

Since the worldwide outbreak of the novel coronavirus (SARS-CoV-2), the question raised whether infected patients would elicit long-lasting protective immunity. Several companies developed serological assays for the detection of SARS-CoV-2 antibodies. In this study, we compared 4 different serology assays in convalescents up to 7 months post-infection. Both Abbott assays showed a significative decrease of IgG antibodies over time. Whereas the Elecsys Anti­SARS­CoV­2 N assay (Roche) initially showed a significant increase, antibody titers significantly decreased at the latest timepoint. Although not significant, the Elecsys Anti­SARS­CoV­2 S assay (Roche) showed tendency towards increasing titers overtime. Our data showed that results of SARS-CoV-2 serology should be interpreted with caution.

Multi-step optimization of the filtration method for the isolation of Campylobacter species from stool samples.

The filtration method (FM) is the most effective isolation technique for Epsilobacteriaceae from stool samples. FM's different adaptations make it difficult to compare data between studies. This study was performed in three phases to optimize FM from a routine laboratory perspective. In July-September 2014 (part I), FM was performed on Mueller-Hinton agar containing 5% sheep blood and Columbia agar containing 5% sheep blood. In July 2016 (part II), FM was performed using 0.60-µm pore size polycarbonate filters (0.6-PC filter) and 0.45-µm pore size cellulose acetate filters (0.45-AC filter); in January 2018 (part III), the addition of hydrogen to incubators was studied. On 1146 stools analyzed in part I, the positive samples that showed no growth on the Butzler medium (n = 22/72, 30.6%) had improved growth of Epsilobacteriaceae when using the Columbia instead of the Mueller-Hinton medium (21/22 strains vs. 11/22, p < 0.05). In part II, on 718 stools, 91 strains grew with FM (12.7%), more with 0.6-PC filter (90/91) than with 0.45-AC filter (44/91) (p < 0.05). In part III, 578 stools were cultured, 98 Epsilobacteriaceae strains grew with FM, and 7% hydrogen finding significantly more Epsilobacteriaceae than without hydrogen (90/98, 91.8%, vs. 72/98, 73.5%; p < 0.05). The use of a Columbia medium containing 5% sheep blood with 0.6-PC filters incubated at 37 °C in a 7% hydrogen-enriched atmosphere led to an almost fourfold increase in the isolation rate of Epsilobacteriaceae among the studied combinations. Reference centers for Campylobacter should use standardized protocols to enable the comparison of prevalence in space and time.

Heterozygous FGA p.Asp473Ter (fibrinogen Nieuwegein) presenting as antepartum cerebral thrombosis.

INTRODUCTION: The propositus - a two-week-old boy - was transferred to our university hospital for investigation of increased head circumference and full fontanel. On ultrasound, thrombosis of the right internal cerebral vein and intraventricular haemorrhage was diagnosed, confirmed by MRI. Family history revealed a bleeding history in the mother. A haemostatic work-up in both mother and child was performed in order to rule out congenital coagulopathy. AIM: We document a clinical case of congenital dysfibrinogenemia, caused by heterozygosity for the mutation FGA p.Asp473Ter, previously reported as fibrinogen Nieuwegein in homozygosity in an asymptomatic patient. METHODS: Fibrinogen activity in plasma was determined by functional Clauss assay, and immunological fibrinogen concentration by nephelometry. In vitro fibrin clot investigations and genetic analysis of the fibrinogen gene were performed. Complete haemostatic work-up was done by conventional methods. RESULTS AND DISCUSSION: After full laboratory work-up, dysfibrinogenemia was diagnosed, based on fibrinogen activity:antigen ratio, thrombin time, and reptilase time. Molecular analysis showed a frameshift mutation in exon 5 of FGA: c.1415_1416 insC, leading to a termination codon immediately after the insertion (CCT GAT>CCC TGA) and resulting in a truncated αC-domain. This mutation has been reported earlier as fibrinogen Nieuwegein. Further in vitro investigations revealed an abnormally tight clot structure, prolonged clot lysis time and affected polymerization, suggesting a thrombotic phenotype. Cerebral imaging revealed thrombosis, most likely developed in the antenatal period, leading to extensive intraventricular haemorrhage and posthaemorrhagic ventricular dilatation. CONCLUSION: We highlight the combined thrombotic and haemorrhagic phenotype linked to heterozygous fibrinogen Nieuwegein, in contrast to the previously reported asymptomatic homozygous case.

Evaluation of the Sebia Capillarys 3 Tera and the Bio-Rad D-100 Systems for the Measurement of Hemoglobin A1c.

OBJECTIVES: We evaluated the Bio-Rad (Irvine, CA) D-100 and the Sebia (Lisses, France) Capillarys 3 Tera for the measurement of hemoglobin A1c (HbA1c) in venous blood samples. METHODS: Whole-blood samples and control material were analyzed with the D-100 and Capillarys 3 Tera and compared with our routine method, HLC-723G7 (Tosoh, Tokyo, Japan). An evaluation protocol to test precision, trueness, linearity, carryover, and selectivity was set up according to Clinical and Laboratory Standards Institute guidelines. The results were presented in National Glycohemoglobin Standardization Program and International Federation of Clinical Chemistry (IFCC) units. RESULTS: Both systems showed excellent precision (total coefficients of variation <2%, IFCC) and bias (<0.3% or 3 mmol/mol). Linearity was demonstrated for HbA1c values from 3.8% (18 mmol/mol) to 18.5% (179 mmol/mol). Results were correlated with the routine method using Bland-Altman analysis, showing a mean difference of 0.33% or 3.6 mmol/mol for the D-100 and of 0.25% or 2.6 mmol/mol for the Capillarys 3 Tera vs HLC-723G7. None of the automated instruments were prone to interferences by labile HbA1c (≤10 g/L glucose), carbamylated hemoglobin (≤0.5 mmol/L potassium cyanate), hemoglobin variants, bilirubin (≤15 mg/dL), and triglycerides (≤3,360 mg/dL). CONCLUSIONS: The Bio-Rad D-100 and the Sebia Capillarys 3 Tera instruments performed well for the determination of HbA1c in terms of quality criteria as well as for sample throughput.